Unit Summary

Unit 1: Summary Notes for Ecology, Conservation and Evolution IB Biology – Higher Level Topic 5 and Option G

Campbell Text References: Chapter 50: Introduction to Ecology and Biosphere Chapter 52: Population Ecology Chapter 53: Community Ecology Chapter 54: Ecosystems Chapter 55: Conservation Biology Chapter 1: Taxonomy, Evolution and Natural Selection

Chapter 50 – Introduction to Ecology and Biosphere Vocabulary:

• Habitat: the environment in which a species normally lives or the location of a living

organism. • Ecology: The Scientific Study of the Interactions between organisms and the

environment • Abiotic: Non-living (ex. Temp, light, water, nutrients) • Biotic: Living organisms (called biota) • Population: A group of individuals of the same species living in a particular geographic

area. • Population ecology: Concentrates mainly on factors that affect how many individuals of

a particular species live in an area. • Community: Consists of all the organisms of all the species that inhabit a particular

area; it is an assemblage of populations of many different species. • Community ecology: Deals with the whole array of interacting species in a community.

This area of research focuses on how interactions such as predation, competition, and disease, as well as abiotic factors such as disturbance, affect community structure and organization.

• Ecosystem: Consists of all the abiotic factors in addition to the entire community of species that exist in a certain area. An ecosystem—a lake, for example—may contain many different communities.

• Ecosystem ecology: The emphasis is on energy flow and chemical cycling among the various biotic and abiotic components.

• Biome: Any of the world’s major ecosystems, classified according to the predominant vegetation and characterized by by adaptations of organisms to that environment

• Biosphere: The global ecosystem—the sum of all the planet′s ecosystems. This broadest area of ecology includes the entire portion of Earth inhabited by life: the atmosphere to an altitude of several kilometers, the land down to and including water–bearing rocks at least 3 kilometers below–ground, lakes and streams, caves, and the oceans to a depth of several kilometers. An example of research at the biosphere level is the analysis of how changes in atmospheric CO2 concentration may affect Earth′s climate and, in turn, all life.

Activity: Science, technology, and society: DDT

DISCUSS how the science of ecology can help in the process of making difficult and complicated decisions such as whether or not to use DDT.

Relationship between Ecology and Evolutionary Biology Ecology and evolutionary biology are closely related sciences. Darwin′s extensive observations of the distribution of organisms and their adaptation to specific environments led him to propose that environmental factors interacting with variation within populations could cause evolutionary change. Today, we have ample evidence that events that occur in the framework of ecological time (minutes, months, and years) translate into effects over the longer scale of evolutionary time (decades, centuries, millennia, and longer). For instance, hawks feeding on field mice have an immediate impact on the prey population by killing certain individuals, thereby reducing population size (an ecological effect) and altering the gene pool (an evolutionary effect). One long–term evolutionary effect of this predator–prey interaction may be selection for mice with fur coloration that camouflages the animal The Figure Below is a good summary of the different factors that can limit the geographic distribution of a particular species

Concept Check 50.1: How can an event that occurs on the ecological time scale affect events that occur on an evolutionary time scale?

Precautionary Principle Although our ecological information is always incomplete, we cannot abstain from making decisions about environmental issues until all the answers are known. But given what we do know about the interconnectedness of the biosphere, it is probably wise to follow the precautionary principle, which can be expressed simply as “An ounce of prevention is worth a pound of cure.” Aldo Leopold, the famous wildlife conservationist, expressed the precautionary principle well when he wrote, “To keep every cog and wheel is the first precaution to intelligent t **An example of the Precautionary Principle is Global Warming. (ie. Even though we don’t know all the mechanisms by which humans increase the rate of global warming, the negative consequences of it should lead us to take action to reduce our production of greenhouse gases. Flowchart of factors limiting geographic distribution of a species.

CD Activity 50.2: Adaptations to Biotic and Abiotic factors CD Investigation 50.2: How do abiotic factors affect distribution of organisms

Describe which plant species’ at Wissahickon Creek Park were restricted to the floodplane and which were restricted to the hilltop and which seemed to range between both extremes. Outline some of the abiotic factors that produce these differences in distribution.

Explain why stiltgrass is a potentially damaging plant in the Wissahickon Creek Ecossystem. Include an assessment of its potential impact on animal populations.

Explain how abiotic factors such as fertilizer chemical pollutants (nitrogen, phosphorus, potassium) can affect the distribution of benthic macroinvertebrate communities in Wissahickon Creek. (Hint: Eutrophicaton)

Review Sheet for Chapter 50

Summary of the World’s Biomes

Outline the consequences of releasing excess fertilizer or raw sewage into a river or stream.

(Total 6 marks)

• Causes eutrophication of water;

• excess nutrients increase algal/plant growth

• death of excess algae/plants;

• decomposition of algae/plants / sewage;

• This causes an increase in decomposer bacteria;

• These bacteria use up all the oxygen and deoxygenate the water;

• This results in a decrease in population of oxygen sensitive species / lowering of diversity

Biome Moisture Temperature Vegetation

Tropical Rainforest ample rainfall very humid very hot jungle, trees

and vines

Tropical Savanna wet season dry season very hot tall grasses

Deciduous Forest evenly divided throughout the

year

warm season cold season

deciduous trees, oak,

maple

Desert inadequate great daily range

sage brush, cactus

Subarctic Taiga adequate cold winter

cool summer evergreen

trees, spruce

Polar Tundra adequate perpetual cold lichens, mosses

In communities, groups of populations live together and interact with each other. Outline the importance of plants to populations of other organisms in a community.

(Total 6 marks)

• light is the initial source of energy for almost all communities;

• plants absorb light and use it in photosynthesis;

• plants produce food / organic matter for consumers;

• plants produce oxygen which is needed for cell respiration by many organisms

• plants are the main producers in most communities;

• energy flows along food chains / webs from plants;

• first order consumers eat plants / producers;

• second order consumers eat first consumers that have eaten plants / producers;

(a) Temperature is an abiotic factor affecting distribution of plant species in some areas. State three other abiotic factor that affects the distribution of plant species.

• water/moisture

• light

• mineral nutrients in soil

• soil pH

Explain the factors that affect the distribution of terrestrial (land) animal species.

(Total 5 marks) Do not award a mark if a factor is mentioned but not explained.

• breeding sites – animals must breed and may need a special site;

• food supply – may feed on specific foods / abundance;

• territory – need to establish / defend for food/mates;

• predation – can reduce the range of another species / be reduced by predation;

• temperature/climate – need the proper range for survival;

• water – need water to live in (aquatic) / proper amount for bodily functions;

• free of pollution/toxic substances - could cause death; [5]

Precautionary Principle (Concept 50.1 – page 1083) A guiding principle which holds that, if the effects of a human-induced change would be very large, perhaps catastrophic, those responsible for the change must prove that it will not do harm before proceeding.

Examples of where the precautionary principle might come into play would be: • New drugs/products: If some studies showed that there might be a potential health

problem in using the drug or product , the Precautionary principle would say – Do more tests to make sure its safe because the potential human health risks are too great!

• Global Warming - The exact nature of the link between industrial pollution and global warming is not fully understood. The Precautionary principle would recommend – reduce pollution anyway because the risks of global warming are too great

Definitions: Species: a group of organisms that can interbreed and produce fertile offspring.

Habitat: the environment in which a species normally lives or the location of a living organism.

Population: a group of organisms of the same species who live in the same area at the same time.

Community: a group of populations living and interacting with each other in an area.

Ecosystem: a community and its abiotic environment.

Ecology: the study of relationships between living organisms and between organisms and their environment. Autotroph: an organism that synthesizes its organic molecules from simple inorganic substances.

Heterotroph: an organism that obtains organic molecules from other organisms.

Consumer: an organism that ingests other organic matter that is living or recently killed.

Detritivore: an organism that ingests non-living organic matter.

Saprotroph: an organism that lives on or in non-living organic matter, secreting digestive enzymes into it and absorbing the products of digestion.

Chapter 52- Population Ecology Vocabulary

• Species: a group of organisms that can interbreed and produce fertile offspring. • Density: Number of individuals per unit area or volume. Ex. White Oak trees per

square kilometer in Potter County Pennsylvania or E.coli bacteria per milliliter in a testtube

• Demography: The study of the rise and fall of population sizes over time • Natality: Rate of Birth (# of individuals in a given period of time –usually a year) • Mortality Rate of Death (# of individuals in a given period of time –usually a year) • Immigration: The movement of individuals into a population • Emmigration: The movement of individuals out of a population • Carrying Capacity: The maximum population size that can be supported by the available

resources, symbolized by K. • Exponential Growth: The geometric (larger the quantity gets, the faster it grows)

increase of a population as it grows in an ideal, unlimited environment • Sigmoid (Logistic Growth): A model describing population growth that levels off as

population size approaches carrying capacity • Life History: The series of events from birth through reproduction and death • r-Strategy Growth: The concept that in certain (r-selected) populations, a high

reproductive rate is the chief determinant of life history and survival • K-Strategy Growth: The concept that in certain (K-selected) populations, life history is

centered around producing relatively few offspring that have a good chance of surviva Methods for Estimating Populations Sizes 1) For Animals (mostly)-------Mark-Recapture Method (Lincoln Index) Population size = n1 x n2 n3 n1 = number of individuals initially caught, marked and released n2 = total number of individuals caught in the second sample n3 = number of marked individuals in the second sample 2) For Plants (mostly) -----Quadrat Transect method

Key Aspects of Quadrat Method

• Transects are distributed evenly across the site (for full coverage so you don’t miss any “pockets” of a plant species.

• Each Quadrat is spaced evenly along the transects (for same reason as above) • The percent area of each plant species is estimated within each quadrat which is 1 meter 2 in size. • All the quadrat percentages are added up for each plant species • Each of these total species percentages is divided by the total quadrat percentages to get

the relative percentage of each plant species. As shown below

Survivorship Curves:

Type I: Low death rates during early and middle life, then high death rates in later life Type II Constant death rate over life of the organism Type III: High death rates during early life, then declining death rates in later years

Life history traits are products of natural selection

Natural selection favors traits that improve an organism′s chances of survival and reproductive success. In every species, there are trade–offs between survival and traits such as frequency of reproduction, the number of offspring produced (the number of seeds

produced by plants and litter or clutch size for animals), and investment in parental care. The traits that affect an organism′s schedule of reproduction and survival (from birth through reproduction to death) make up its life history. Life histories entail three basic variables: when reproduction begins (the age at first reproduction or age at maturity), how often the organism reproduces, and how many offspring are produced during each reproductive episode. Keep in mind that, with the important exception of humans, organisms do not choose consciously when to reproduce or how many offspring to have. Life history traits are the products of evolution through natural selection. Population Dynamics To understand why populations increase and decrease, we must understand the definition of some terms like mortality, natality, immigration and emigration. We must also understand that these terms are usually expressed as a rate over a specified time interval – usually one year. Mortality rate = number deaths per year in a species in a specified area Natality rate = number of births per year in a species in a specified area *Immigration rate = number of individual of the species entering a specified area *Emmigration rate = number of individuals of a species leaving a specified area * unlike mortality and natality which are cumulative, these factors are measure at the end of the year or some other specific time.

To Calculate the Yearly Change in Population

Change in population size = births/yr – deaths/yr + immigration - emmigration Now: Imagine that on January 1, 2005 we had a population of 1000 monitor lizards on the Yucatan Peninsula in Mexico. During the course of the year, the following data is confirm: • 103 births • 85 deaths • 15 immigrants (as of Dec 31, 2005) • 8 emmigrants (as of Dec 31, 2005)

Using the equation above and the original population size, calculate the population size on January 1, 2006 (one year later) Show your work Often however, due to the difficulty in measuring immigration and emigration, we assume them to offset one another and deal only with mortality and natality. When we do this, these rates are expresses as Per Capita Rates of Increase. For Example:

If there are 34 births per year in a population of 1000 individuals, the annual per capita natality rate is 34/1000 or 0.034 If there are 16 deaths per year in the same population of 1000, the annual per capita mortality rate is 16/1000 or 0.016 Now for a specific example using different numbers

• Annual Per Capita Natality Rate = 0.18 • Annual Per Capita Mortality Rate = 0.10 • Population Size = 450

What is the population at the end of the year? (Show your Work)

Sigmoid and Exponential Population growth

Populations cannot grow forever because limiting factors slow and eventually stop population growth. Populations typically follow a growth curve with three phases: exponential phase, transitional phase and plateau phase.

Population growth is the result of the interaction of four factors: natality, mortality, immigration and emigration

Carrying capacity

"K" is the carrying capacity, or the maximum stable population any environment can support. This is determined by the available resources.

Two different “Life History Stategies”

K-species and r-species

K-species are characterised by a low reproductive rate, large investment in offspring, long lives and large size.

r-species are characterised by a high reproductive rate, little or no investment in offspring, short lives and small size.

The growth curve for K-species flattens out as the carrying capacity ("K") of the environment is reached. This is because population growth is density-dependent.

The growth curve for r-species shoots through the carrying capacity ('boom') and then falls below it ('bust') once there are more organisms than the environment can support. This is because population growth is determined more by the reproductive rate ("r") than population density.

What are the environmental conditons that favor either r-stategists or K-strategists?

Predictable Envionment- K-strategies favored

Unstable Environment - r-strategis favored

Why are K strategies favored in a predicable env. And r strategies favored in an unpredictable environment??

Are humans a K-species or an r-species?

In traditional societies, high birth rates have always been balanced by high infant mortality. Now that modern medicine has sharply reduced mortality, the high natality has created a 'boom' in the world human population. The question is: will the human population exceed the carrying capacity of the planet, with a subsequent 'bust' phase?

http://www.unfpa.org/index.htm

Website for Populus Population Computer Model

www.cbs.umn.edu/populus/ Commercial Fishing and Fish Populations Some methods used to estimate the size of commercial fish stocks

• Catch-Mark-Release (Lincoln Index) clip a fin to mark • Sonar methods (possibly the ships would run transects across the ocean-then they would

multiply this number by the area they didn’t cover) • Gill nets (nets are set in areas known to be inhabited by certain species. The net has a

certain cross-sectional area and is laid out for a certain time period. The number of fish caught should be proportional to the total population.

Maximum Sustainable Yield: The maximum number of fish that can be caught by commercial fishing fleets per year and still sustain a relatively large population. In other words, if you exceed the maximum sustainable yield of a certain species, the population would “crash” and become locally rare or possibly even extinct. (ex. Chilean Sea Bass became very rare after they became popular in restaurants-this led to increased fishing pressure (because they became more valuable) and their maximum sustainable yield was exceeded. Another example is the fate of the North Atlantic bluefin tuna . Until the past few decades, this big tuna was considered a sport fish of little commercial value—just a few cents per pound for cat food. Then, in the 1980s, wholesalers began airfreighting fresh, iced bluefin to Japan for sushi and sashimi. In that market, the fish now brings up to $100 per pound . With that kind of demand, it took just ten years to reduce the North American bluefin population to less than 20% of its 1980 size. The collapse of the northern cod fishery off Newfoundland in the 1990s is a more recent example of how it is possible to overharvest what was formerly a very common species.

International Measures that would promote the conservation of fish

• International agreements on quotas (maximum # caught) for specific species • Increased scientific research on the life histories of fish species • Increased efforts to monitor the populations of specific fish species

Study Review Sheet for Chapter 52

Define the term random sample (1 mark)

A sample where every member of a population has an equal chance of being selected / sample selected without bias.

Outline the quadrat method of random sampling and how it could be used to determine and compare the population size of two plant species.

(Total 8 marks)

• a shape (rectangular or circular frame) of known area, often one square meter but sometimes larger

• several transects are evenly randomly through each area and quadrats placed evenly along transect to avoid bias.

• transects placed on mapping prior to site visit to avoid human bias;

• number of individuals or percent aerial coverage of the species estimated in each quadrat;

• small quadrats placed many times / large quadrats fewer times along transect;

• enough quadrats must be taken to make the sample representative of the area;

• size of quadrats determined by size or distribution of species (trees require larger quadrats than herbaceous species)

• population density is number of plants or relative percent divided by total area;

• Population density of different species can then be compared

Outline the use of a transect to correlate the distribution of plant or animal species with an abiotic variable

• To correlate plant species with soil type

• several transects are evenly randomly through study area with more than one soil type and quadrats are placed evenly along transect to avoid bias

• Approximately the same number of quadrats are placed in each soil type

• number of individuals or percent aerial coverage of the species estimated in each quadrat;

• enough quadrats must be taken to make the sample representative of the area;

• population density of each species is determine

• The population densities for each species are added up according to soil type

• Species which have a higher than expected density according to probability laws in a particular soil type may be correlated with that soil type;

Describe the use of one technique that ecologists use to estimate accurately the size of a population of animals, including details of any calculations that need to be done.

(Total 6 marks) • capture-mark-release-recapture method; • capture a sample of the population; • example of method of capture; • mark each captured individual and release; • allow to settle back into the environment /

wait for at least 24 hours / until randomly dispersed; • recapture as many individuals as possible; • count the marked and unmarked individuals; • number marked originally x recaptured

Lincoln Indexrecapturedandmarkednumber

recapturedoriginallymarkednumbercalculate ×=

Be able to demonstrate the use of the Lincoln Index with real data (from lab exerecise)

Describe with the aid of a diagram the phases and their underlying reasons on a sigmoid population growth curve.

(Total 8 marks)

• must have a correct s-shaped curve.

• Must have 3 phases correctly labelled on diagram (3 points)

• (exponential) – rapid increase in population; due to unlimited resources and larger population

sizes Natality much higher than mortality

• (transitional) – slowing of growth; resources beginning to become limited. Natality still higher than mortality but not as big of a difference as in exponential phase

• (plateau) – levelling off, birth rate = death rate; Population has reached its carrying capacity which is the maximum population for that species in that particular environment

• carrying capacity K must be labelled;

Explain the reasons for the sizes of animal populations within communities changing and the reasons for them remaining constant.

(Total 8 marks

• natality / births / reproduction increases populations;

• as long as natality is higher than mortality;

• abundant food allows increase / food shortage causes decrease;

• low level of predation allows increase / high level causes decrease;

• low level of disease allows increase / high level causes decrease;

• immigration increases populations;

• as long as immigration is greater than emigration;

• population rise until a plateau is reached

• this is the carrying capacity of the environment when the resources of the environment cannot support any more individuals;

Distinguish between r-strategies and K-strategies

• Review table comparing these two strategies from notes • Know that most organisms have reproductive strategies that are intermediate on the

continuum between these two. Some organisms like Drosophila switch strategies depending on environmental conditions

Discuss the environmental conditions that favor either r-strategies or K-strategies

• In a predictable environment, it pays to invest resources in long-term development and long life (K strategy).

• In an unstable environment, it is better to produce as many offspring as possible and reproduce only one time (r-strategy).

• This r-strategy is timed to coincide with favorable environmental conditions

Know what annual per capita birth and death rates mean and how to estimate population change if you know these two figures. Also know that effect of immigration and emigration on population size (see notes)

Know what the intrinsic rate of increase in a species is and why – even though this rate stays the same, populations can grow exponentially Hint: more individuals added per unit time as population size increases

Know what density dependent factors are that regulate populations Multiple Choice Questions

1. A population of ground squirrels has an annual per capita birth rate of 0.06 and an annual per capita death rate of 0.02. Estimate the number of individuals added to (or lost from) a population of 1,000 individuals in one year. a. 120 individuals added b. 40 individuals added c. 20 individuals added d. 400 individuals added e. 20 individuals lost

2. A small population of white-footed mice has the same intrinsic rate of increase (r) as a large population. If everything else is equal, a. the large population will add more individuals per unit time. b. the small population will add more individuals per unit time. c. the two populations will add equal numbers of individuals per unit time. d. the J-shaped growth curves will look identical. e. the growth trajectories of the two populations will proceed in opposite directions.

3. As N approaches K for a certain population, which of the following is predicted by the logistic equation? a. The growth rate will not change. b. The growth rate will approach zero.

c. The population will show an Allee effect. d. The population will increase exponentially. e. The carrying capacity of the environment will increase.

4. All of the following characteristics are typical of an r-selected population except a. occurrence in variable environments. b. high intrinsic rate of growth. c. onset of reproduction at an early age. d. extensive parental care of offspring. e. occurrence in open habitats.

5. Which of the following can contribute to density-dependent regulation of populations? a. the accumulation of toxic waste b. intraspecific competition for nutrients c. predation d. all of the above e. none of the above

6. In a mature forest of oak, maple, and hickory trees, a disease causes a reduction in the number of acorns produced by oak trees. Which of the following would least likely be a direct result of this? a. There might be fewer squirrels because they feed on acorns. b. There might be fewer mice and seed-eating birds because squirrels would eat more seeds and compete with the mice and birds. c. There might be an increase in the number of hickory trees because the competition between hickory nuts and acorns for germination sites would be reduced or eliminated. d. There might be fewer owls because they feed on baby squirrels, mice, and young seed-eating birds, whose populations would be reduced. e. There might be a decrease in the number of maple seeds as the disease spreads to other trees in the forest. Answer key for multiple choice: 1. b 2. a 3. b 4. d 5.d 6.e

Chapter 53 – Community Ecology Vocabulary

• Habitat : A particular environment, the typical location of a particular species. Habitat is a place = an organism's 'address'

• Ecological niche: The totality of an organism's relationships with all the biotic and abiotic factors which make up the organism's habitat.

• Interspecific Competition: When two species compete for a resource, the result is detrimental to both species (−/−) such as when two different species compete for a particular resource that is in short supply ex1 When bison and grasshoppers compete for grass on the Great Plains ex2: When a red oak seedling and a white ash seedling compete for sunlight

• Competitive exclusion: . Strong competition can lead to the local elimination of one of the two competing species, a process called competitive exclusion

• Symbiosis: is a special type of interaction, where one organism lives on or in another • Biomass: The total mass of all individuals in a population • Biodiversity: The number of different species in a given geographical area

Concept 53.1 Interspecific Interactions

Ecological niche is an idea = an organism's 'profession'

Actual descriptions of ecological niches are always approximations, since the list of abiotic and biotic factors is necessarily incomplete.

An ecological niche can be thought of as existing in a multi-dimensional ecological conceptual 'space', in which all possible 'professions' can be located.

For example, to see how the ecological niche of a squirrel fits into this ecological conceptual 'space', we could reduce ecological space to just three dimensions: temperature, food size and branch density. The niche occupied by a squirrel is then defined by the upper and lower limits on each of these three axes.

The result is a cube, the volume of ecological space which corresponds to the 'profession' of the squirrel.

The volume of ecological space occupied by any species may overlap with that occupied by some other species (niche overlap).

Fundamental niche: The niche potentially occupied by that species

Realized niche: The niche it actually occupies in a particular environment.

• Competition, co-existence and niche specialization

Different species in the same habitat are in competition for at least some of the resources of that habitat.

Two species in different habitats=no competition

co-existence

co-existence

co-existence

Not Possible*

* 'No two species can occupy the same niche'

Where only some of the resources are competed for, species can co-exist in the same habitat. Increasing specialization limits niche overlap by exploiting different food supplies, and by separation in time (night-hunters or day-hunters) or space (ground-living or tree-iving).

Interspecific Interactions

Species 1 Species 2 Example

Competition - - Red Squirrels and Gray Squirrels for

acorns

Herbivory - + Clover/Rabbits

Predation - + White tailed deer/Mt. Lion

Symbiosis Host Symbiont

Commensalism 0 +

Cattle egrets (birds) feeding on insects flushed by

moving cattle

Mutualism + +

Lichen (green algae and fungi) Fungi provide

algae with environment for growth and algae provide carbon

compounds through photosyn.

Parasitism + Tapeworm/human

0 No Affect, either negative or positive

+ Positive Affec

- Negative affect

Coevolution

Reciprocal evolutionary adaptations of two interacting species. A change in one species acts as a selective force on another species, whose adaptation in turn acts as a selective force on the first species. This linkage of adaptations requires that genetic change in one of the interacting populations of the two species be tied to genetic change in the other population. An example of this might be how specific butterflies have evolved alongside the specific flowers that they help to pollinate

Concept Check 53.1: According to the competitive exclusion principle, what outcome is expected when two species compete for a resource? Why?

• Predator-prey relationships

The interaction between primary and secondary consumers, and between secondary and tertiary consumers, comes under the special category of predator-prey relationships.

The inter-relationship between two animals where one animal, the prey, is food for the other, the predator. The size of the first population depends upon the number of predators; the size of the second population depends on the availability of the prey. Both populations are locked into a cycle of mutually dependent population fluctuations.

• Food Chain

A food chain is the simplest way of conceptualising the movement of matter and energy from organism to organism.

diatoms > copepods > 'krill' > whales

Diatoms are phytoplankton. Copepods and 'krill' are zooplankton. Plankton are small creatures in the sea which swim without direction (kinesis).

Diatoms are microscopic one-celled algae. They are the producers in the food chain. Sometimes called 'the grass of the sea'.

Copepods are small crustaceans which feed on the phytoplankton (i.e. they are herbivores).

'Krill' are a mix of larger crustaceans which feed on the copepods. Plankton-feeding whales feed on 'krill' by straining the water with special modified mouthparts.

• Food Web

A food web is a more realistic conceptualisation, as it recognises that a predator may have more than one prey, and prey may have more than one predator.

Biodiversity

Biodiversity: Generally speaking, higher biodiversity in a given ecosystem is a good thing because it leads to more stable food webs.

Why?

Biodiversity in an ecosystem can be estimated using the Simpson’s Diversity Index

Simpson’s Diversity Index = 1-D

where

D = Sum of n(n-1) (the greater the #, the N(N-1) greater the sample diversity) Where n = Total # of organisms of a particular species N = Total # of organisms of all species

Concept 53.2: Food Web Activity

Disturbance Influences Species Diversity and Composition

A disturbance is an event, such as a storm, fire, flood, drought, overgrazing, or human activity, that changes a community, removes organisms from it, and alters resource availability.

After Disturbance, plant and animal communities gradually re-colonize the disturbed area

When this process begins in a virtually lifeless area where soil has not yet formed, such as on a new volcanic island or on the rubble (moraine) left behind by a retreating glacier, it is called primary succession. Often the only life–forms initially present are autotrophic prokaryotes. Lichens and mosses, which grow from windblown spores, are commonly the first macroscopic photosynthesizers to colonize such areas. Soil develops gradually, as rocks weather and organic matter accumulates from the decomposed remains of the early colonizers. Once soil is present, the lichens and mosses are usually overgrown by grasses, shrubs, and trees that sprout from seeds blown in from nearby areas or carried in by animals. Eventually, an area is colonized by plants that become the community′s prevalent form of vegetation. Producing such a community through primary succession may take hundreds or thousands of years.

Concept 53.3 Succession

Secondary succession occurs when an existing community has been cleared by some disturbance that leaves the soil intact, as in Yellowstone following the 1988 fires (see Figure 53.22). Often the area begins to return to something like its original state. For instance, in a forested area that has been cleared for farming and later abandoned, the earliest plants to recolonize are often herbaceous species that grow from windblown or animal–borne seeds. If the area has not been burned or heavily grazed, woody shrubs may in time replace most of the herbaceous species, and forest trees may eventually replace most of the shrubs.

Concept Check 53.3

How do primary and secondary succession differ?

Chaper 53 Review

Vocabulary:

Autotroph: An organism that synthesizes its organic molecules from simple inorganic molecules (for example, in photosynthesis, glucose is made from inorganic CO2)

Heterotroph: An organism that obtains organic molecules from other organisms.

Define the term niche.

• Within a specific habitat of an organism it is the species role/profession

• For example, its nutrition/what it eats

• It’s feeding habits (like the Nuthatch “hammering” the seeds)

• Its interactions with other species (aggression/competition)

• The time of day or night that it feeds

Explain the niche concept using a named organism. (5 marks)

• Within a specific habitat it is the species’ role/profession

• It allows different species to co-exist with each other by reducing competition

• For example, The white-breasted nuthatch shares temperate forest habitat with many species

• Nuthatches go down a tree in search of insects hiding under bark unlike most species which go up the tree looking for insects. In this way, it is able to get insects that others miss.

• Another aspect of it’s unique niche is that takes seeds, wedges them into a crevice of tree bark and then “hammers’ the bark – this opens the seeds for eating.

• Yet another aspect of this birds niche is that it flocks together with black-capped chickadees and titmice. In this way, it is protected from predators by being able to hear the warning calls of these species when predators approach

Explain the significance of the principle of competitive exclusion. (3 Marks)

• no two species can coexist in same niche;

• one is out-competed and displaced/eliminated through strong competition

• Give a brief example of this concept using two species of barnacles (Balanus and Chthamalus) from Figure 53.2 in book.

Interspecific Interactions

Species 1 Species 2 Example

Competition - - Red Squirrels and Gray Squirrels for

acorns

Herbivory - + Clover/Rabbits

Predation - + White tailed deer/Mt. Lion

Symbiosis Host Symbiont

Commensalism 0 +

Cattle egrets (birds) feeding on insects flushed by

moving cattle

Mutualism + +

Lichen (green algae and fungi) Fungi provide

algae with environment for growth and algae provide carbon

compounds through photosyn.

Parasitism + Tapeworm/human

0 No Affect, either negative or positive + Positive Affect - Negative affect

For each of these, be able to Explain how they differ with reference to the organisms

For example: Compare and Contrast how parasitism differs from mutualism with reference to named organisms

• Parasitism is a type of interspecific interaction where one organism benefits and one suffers;

• whereas mutualism is when both benefit (neither suffer);

• An example of parasitism is a tapeworm and it’s human host

• The parasite gains food and energy whereas the human host loses food.

• Because of this, the host suffers weight loss and impaired nutrition

• In a mutualistic interaction such as green algae and fungi in Lichens

• The algae gains protection

• Whereas the fungi gains carbon compounds through the algae’s photosynthesis

Define Trophic Structure: The feeding relationships between species of a community. Trophic levels would include Producers, 1st order Consumers, 2nd order Consumers etc

Food Webs

Be able to construct/draw an Antarctic Marine food web with the following species or groups (see Figure 53.13 for example)

Fishes, Copepods, phytoplankton, leopard seals, elephant seals, baleen whales, sperm whales, birds, krill, carnivorous plankton, crab-eater seals, smaller toothed whales, humans squids

• Make sure arrows are going in the right direction

• Be able to identify one or more food chains within this food web of at least 4 species long

Explain why there are limits on food chain length by describing how energy enters, moves through, and exits a food chain in an ecosystem.

(Total 8 marks)

• energy enters from (sun)light;

• autotrophs capture (sun)light;

• energy flows through the trophic levels / stages in food chain; (eg. Producer>>Primary Consumer>>Secondary consumer>> Tertiary Concemer>>Quarternary Consumer

• energy transfer efficiency between each trophic levels is (approximately) 10 % from one level to the next; (in other words, 90% is lost at each level)

• Energy is lost through Cell respiration

• Energy is lost through heat

• Energy is lost because not all material is consumed

• Energy is lost because food that is comsumed is not all assimilated and is lost as waster

• Include a labeled energy pyramid (using kJ per square meter per year as x axis)

• \ • • • • • •

Know how to calculate Simpson’s Diversity Index and what it can suggest about an ecosystem

( )( )∑ −−

=1

1nn

NND

1-D = the Simpson’s diversity index, N = the total number of all species found and n = the number of individuals of a particular species.

(3)

What does a high value of 1-D suggests about an ecosystem.?

• High biodiversity of the community. This-in turn- suggests: • stable ecosystem / absence of changes; • ecosystem not under stress; • well established ecosystem;

Distinquish between Primary and Secondary Ecological Succession using an example of each

• When this process begins in a virtually lifeless area where soil has not yet formed, such as on a new volcanic island or on the rubble (moraine) left behind by a retreating glacier, it is called primary succession

• Secondary succession occurs when an existing community has been cleared by some disturbance that leaves the soil intact, as in Yellowstone following the 1988 fires

Outline the changes in species diversity and production during primary succession and role of the abiotic environment (5 marks)

• Often the only life–forms initially present are autotrophic prokaryotes existing in shallow puddles.

• Lichens and mosses come next, which grow from windblown spores • Soil develops gradually, as rocks weather and organic matter accumulates. Lichens

secrete acidic products that help to break down the rock. • From the decomposed remains of these early colonizers soil is formed. • Once soil is present, the lichens and mosses are usually overgrown by grasses, shrubs,

and trees that sprout from seeds blown in from nearby areas or carried in by animals.

Chapter 54 – Ecosystems Vocabulary • Ecosystem: All organisms (species) living in a community as well as the abiotic factors

they interact with. (As you might imagine, this can get complicated!!!!) • Autotrophs. Most autotrophs make food by photosynthesis, a few by chemosynthesis. • Heterotrophs.: Heterotrophs cannot make their own food, so they have to feed on other

organisms, either autotrophs or each other. • Trophic Level: Producers, consumers, and decomposers • Herbivores: primary consumers, feed directly on producers • Carnivores: secondary, tertiary consumers which feed on herbivores or each other • Top Carnivores: animals that eat other animals, but no other animals eat them (top of the

food chain • Omnivores: animals which eat both plants and other animals, e.g. humans • Detritivores: animals which feed on the dead remains of other organisms

There are Two major concepts involved with Ecosystems

1. Energy Flow (Continual Supply to Earth’s Ecosystems from Sun) 2. Chemical Cycling (Finite Supply – What we have is What we Have!!!)

• Trophic Levels (Producers, consumers & decomposers)

Producers Consumers DecomposersHerbivores Carnivores Top

Carnivores Detritivores e.g. green plants,

phytoplankton e.g. sheep, zooplankton

e.g. wolves

e.g. tigers, sharks

e.g. dung beetles

e.g. bacteria & fungi

An ecosystem must always include producers and decomposers in order to be self-sustaining. Most ecosystems have consumers, but an ecosystem can be self-sustaining without them.

• Energy flow

The ultimate source of energy for almost all organisms is the sun. As organisms eat each other the energy passes up the food chain.

Each population of organisms corresponds to a certain amount of energy. Energy is recorded as

kJ m¯2 yr ¯1

The transfer of energy between trophic levels can be represented as a pyramid of energy, in which the width of each block represents the energy.

The transfer of energy from one organism to another in a food chain is only 10% - 20% efficient. This explains why the blocks in a pyramid of energy get smaller as they go up.

*Net Primary Production = Gross Primary Production – Respiration (of Producers) Where: Gross Primary Production (KiloJoules/m2/yr) is all the solar energy plants convert to chemical energy through photosynthesis and Respiration is the energy used by the plants to carry on their life process (that is unavailable to 1st order consumers) Therefore, the Net Primary Production is the bottom of the energy pyr

Pyramids of Production Concept 54.3

Note: A Biomass Pyramid would be very similar in shape the Energy Pyramid because the Energy represented in the Energy Pyramid is really locked up in the bodies of all the animals represented at each trophic level. Therefore, these two pyramids are, in a sense, reflections of each other. Biological Magnification. One tangible consequence of the biomass pyramid is called biological magnification and occurs because the biomass at any given trophic level is produced from a much larger biomass ingested from the level below. In addition to ingesting the larger biomass, these animals are also ingesting any contaminants that are contained in that food. This leads to toxins becoming more concentrated in successively higher trophic levels of a food web. Thus, top–level carnivores tend to be the organisms most severely affected by toxic compounds in the environment.

This occurs because many toxins cannot be degraded (broken down) by microorganisms and consequently persist in the environment for years or even decades.. For example, mercury, a by–product of plastic production and coal–fired power generation, has been routinely expelled into rivers and the sea.. Bacteria in the bottom mud convert the waste to methyl mercury, an extremely toxic soluble compound that accumulates in the tissues of organisms as you move up the food chain/biomass pyramid, including humans who consume fish from the contaminated waters.

Activity: Science, technology, and society: DDT

Why are there limits to Food chain Length based on the Concept of Energy Flow through the Ecosystem described above?

How does this explain why there are relatively few top-level carnivores in any given ecosystem”

• Recycling of inorganic elements

An ecosytem must have decomposers, because otherwise the inorganic materials (carbon, nitrogen, phosphorus etc.) would be trapped inside the bodies of dead organisms for ever. Eventually there would be no inorganic materials available for the producers to use and the ecosystem would fail.

The result of the activity of decomposers is that inorganic materials get recycled. e.g. the carbon cycle

Website about Carbon Cycle http://mvhs.shodor.org/coresims/carboncycle/index.php

Carbon Cycle Concept 54.4

2 Problems: The Human Population is disrupting chemical processes throughout the Biosphere. Examples of this are increased combustion of

greenhouse gases and depletion of the earth’s ozone layer/ 1) Increased Global Warming Gases from Human Combustion (coal, oil, gas) First, you need to understand that the Greenhouse Effect is a Good Thing!!! Without it, our world would be a frozen wasteland!!!

However, since the Industrial Revolution, the concentration of CO2,, Methane, and Nitrogen Oxide in the atmosphere has been increasing as a result of the combustion of fossil fuels and the burning of enormous quantities of wood removed by deforestation. This has increased the natural Greenhouse Effect to Produce a rapid and dangerous rise in global temperature In 1958, a monitoring station began taking very accurate measurements on Hawaii′s Mauna Loa peak, where the air is free from the variable short–term effects that occur near large urban areas. The result are shown below and indicate a steadily increasing concentration of carbon dioxide in the world’s atmosphere.

375

370

365

360

355

350

345

335

330

325

320

1970

1975

1980

1985

1990

1995

2000

COconcentration

/ ppm

2

Negative Outcomes of Rapid Global Warming • Negative impact on plant and animal populations such as the Polar Bear and

Caribou • Increased range of human diseases caused by pathogens which formerly restricted

to tropical climates establishing in cooler temperate climates • Increased ocean levels, causing inundation of coastal communities

Question to Answer: Based on the Carbon Cycle Diagram, what effect will the following activities have on atmospheric Carbon Dioxide levels

• Combustion of Fossil Fuels • Deforestation • Increased rates of decomposition • Planting more trees

2) Depletion of Atmospheric Ozone: Read pages 1205-1206 The basic deals is this: Ozone (O3) is formed when one atom of oxygen is added to atmospheric oxygen (O2) The role of Ozone is to filter Ultraviolet (UV) Radiation from sunlight. Without this filtering, living things would be exposed to lethal doses of radiation and life would not be possible. Chloroflourocarbons (CFC’s) from aerosol cans, refrigeration chemicals etc. released in the atmosphere can destroy the Ozone layer and reduce the filtering

capacity of the atmosphere. Since world governments have decreased or eliminated production of CFC’s, there are signes that the ozone layer is replenishing itself. Yeah!!!

Chapter 54 Review Sheet

Outline ways in which leaves take part in the carbon cycle in ecosystems, apart from photosynthesis.

• leaves release carbon dioxide when they respire;

• leaves release carbon dioxide when they are burned/combustion;

• C passed to decomposers when they die;

• C passed to detritus feeders from leaf litter;

• C passed to consumers/herbivores in the food chain;

• carbon removed from the carbon cycle when leaves are fossilized / turn to peat/coal;

BE ABLE TO DO THIS WITH ANY LIVING MEMBER OF THE CARBON CYCLE ( Ie, Animals, Detritivores, Decomposers

Know that in the Cycle Shown Above, Decomposers (Fungi and Bacteria) are the primary recycler’s of Nutrients

Gross Primary Production – Respiration = Net Primary Production

Define the term Gross Primary Production. • total amount of light energy converted to chemical energy by plants per unit time

Define Net Primary Production • Gross primary production minus the energy used by the primary producers for

respiration

Define Biomass: The dry weight of organic matter comprising a group of organisms in a particular habitat

***Explain to students that it is usually biomass that we can more easily “measure” and that it is sometimes used as a surrogate (replacement) for Energy since energy is harder to measure. Hence, the similarity between the Energy Pyramid and the Biomass Pyramids Figure 54.11 and 54.12

Biomagnification and Ozone Depletion Note: Concentration of toxins is often measure in parts per million (ppm) This is the number of toxin molecules per million molecules of the substance it is contained in.

Explain the concept of Biomagnification: (5 marks)

• Biomagnification is a process in which toxic chemical substances become more concentrated (accumulate) at each higher trophic level

• toxins that most easily accumulate are ones that are not broken down by normal metabolic processes in living organisms (ex. Heavy metals like Lead, mercury, insecticides like DDT, industrial chemicals like PCB’s

• these toxins tend to accumulate in fatty tissue and - at high concentrations – disrupt the normal metabolism of a species, especially those high on the food chain. Ex. DDT disrupted the deposition of calcium in eagle eggs causing the eggs to break prematurely – thereby increasing mortality of young eagles.

Outline the effects of UV radiation on living tissues and biological productivity (2)

• UV radiation can penetrate living cells and damage DNA, thereby disrupting cell function and sometimes causing cancer

• UV radiation can be harmful to phytoplankton and other producers, thereby reducing the productivity of ecosystems

Explain the effects of Depletion of Atmospheric Ozone: (4 marks) The basic deals is this:

• Ozone (O3) is formed when one atom of oxygen is added to atmospheric oxygen (O2) • The role of Ozone is to filter Ultraviolet (UV) Radiation from sunlight. • Without this filtering, living things would be exposed to lethal doses of radiation. • Chloroflourocarbons (CFC’s) from aerosol cans, refrigeration chemicals etc. released

in the atmosphere can destroy the Ozone layer and reduce the filtering capacity of the atmosphere.

• Since world governments have decreased or eliminated production of CFC’s, there are signs that the ozone layer is replenishing itself. Yeah!!!

Chapter 55- Conservation Biology Vocabulary

• Restoration Ecology: a branch of biology that applies ecological principles in an effort to return degraded (damaged) ecosystems to conditions as similar as possible to their natural, predegraded state

• Introduced/Invasive Species: Species that humans move, either intentionally or accidentally, from the species’ native locations to new geographic locations.

Introduced/Invasive Species Invasive species outcompete “native” species because their populations are not limited as much (think carrying capacity and sigmoid population growth) by predation or the impacts of disease. They left their natural predators or diseases back in their old ecosystem!! This could explain the high biomass that invasive species can attain in environments lacking their natural predators and pathogens. Three examples of Invasive species and their impact on local ecosystems

• Stiltgrass: outcompetes native plants upon which native animals depend.\ • Ducth Elm disease Fungus: Has killed almost all American Elm trees • Gypsy Moth: Has killed many forest trees throughout the eastern U.S.

Biological Control of Invasive species: One example of this is the use of a small insect called the purple loostrife weevil that has been used to some success in contolling the spread of the purple loostrife plant in the eastern U.S. Active Role of Management Techniques in Conservation:

1) Installing fence at Wissahickon Creek to keep out the deer and allow native species to grow

2) Pulling out stiltgrass or other invasive plant to allow native species to grow Indicator Species: Some species in an ecosystem are more sensitive to environmental changes and are therefore used to “indicate” changes. An example of this is the caddis fly from our Wissahickon Creek Benthic Macroinvertebrate sampling. These aquatic insects are “Very Sensitive” to pollution. Species Extinction About 20% of the known freshwater fishes in the world have either become extinct during historical times or are seriously threatened. One of the largest rapid extinction events yet recorded is the ongoing loss of freshwater fishes in East Africa′s Lake Victoria. About 200 of the more than 500 species of cichlids in the lake have been lost, mainly as a result of the introduction of a nonnative predator species, the Nile perch, in the 1960s. Anothr example is the hunting of the Passenger pidgeon to extinction in the 19th century. Endangered species can be protected in two ways 1) In-situ Conservation of Endangered Species- Preserving large terrestrial (land) or aquatic reserves (tracts of land) from being developed or otherwise damaged. This basically protects the organisms habitat for future generations. This is the most effective way of protecting endangered species Large Nature Reserves Better: Generally, large nature reserves are better than small ones and promost biodiversity better than small reserves because they contain “interior” habitat as well as “edge” habitat. Different animals are adapted to edge vs. interior habitat, so having both available will mean that the habitat will be acceptable to a larger range of species. Habitat “Corridors” are good These are strips of habitat that connect tracts of land that are separated from each other. Many times, they are riparian (river) corridors which allow the passage of animals from one large tract of habitat to another and thereby increase the amount of habitat available to them. 2) Ex.-situ Conservation on Endangered Species: Captive breeding of animals in zoos, keeping rare plants in botanical gardens. This method is not as effective but still can play a role in being a source of animals and plants to reintroduce to the nature preserves described above

Chapter 55 Review Sheet Conservation of Biodiversity

Distinguish between in situ and ex situ conservation.

• in situ is conservation of species in their habitats and ex situ is conservation of species removed from their habitat;

(1)

List three examples of ex situ measures that could be used to conserve endangered species.

• (captive) breeding programs (in zoos);

• cultivation of plants (in botanic gardens);

• storage of seeds (in seed banks);

• storage of sperm /ova / micro-organisms; (3)

List three advantages of in situ conservation of endangered species.

• cheaper than ex situ conservation;

• species continues to evolve in the natural environment;

• larger populations can be maintained bigger breeding pool / more genetic variation;

• less stress / injury to animals during capture / transport; (3)

• species can have large territories/space;

Explain the use of indicator species in monitoring environmental change.

• indicator species can be used to assess environmental conditions, particularly as an indication of pollution or degradation of habitat

• these indicator species need a particular environment to survive

• for example, some species of aquatic macroinvertebrates (caddis flies or mayflies or stoneflies) require high oxygen content

• if these species are not present, or become less common over time, it indicates pollution through eutrophication

• these changes can be monitored over a long period and can lead to adequate measures to protect the environment;

(4)

Outline the factors that contributed to the extinction of one named animal species

Use your own example .............

Outline the biogeographical features of nature reserves that promote the conservation of diversity (edge effects, habitat size, habitat corridors use cowbird as example) (6 marks)

• Generally, large nature reserves are better than small ones and promote biodiversity

better • This is because they contain “interior” habitat as well as “edge” habitat. • Different animals are adapted to edge vs. interior habitat, so having both available will

mean that the habitat will be acceptable to a larger range of species. • Habitat “Corridors” are good for wildlfife • These are strips of habitat connect tracts of land that are separated from each other and

allow animals fop have larger ranges in search of food/mates etc • Many times, these corridors are riparian (river) corridors which allow the passage of

animals from one large tract of habitat to another and thereby increase the amount of habitat available to them.

Discuss the role of active management techniques in conservation

Use Wissahickon Park as example

• Wood duck boxes

• Control of Japanese Knotweed and other invasives

• Planting of native plant species to enhance habitat

• Making sure habitat corridors are intact – planting where necessary to maintain corridor with major rivers like Schuylkill R.

Chapter 1- Classification and Evolution through Natural Selection Vocablulary

• Taxonomy: The branch of biology concerned with the naming and classifying of the diverse forms of life.

• Binomial Nomenclature: The identification of a species using its Genus (capitalized) and species (lower case). Always written in italics. Example: Red Oak is Quercus rubra. And White Oak is Quercus alba

• Dichotomous Key: a method of identifying a species using a series of Yes/no decisions. After successfully answering these, the species is identified.

• Evolution: All the changes that have transformed life on earth from its earliest beginnings to the diversity that characterizes it today

• Natural Selection: The mechanism (method) by which evolution occurs. It involves differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Evolution occurs when natural selection causes changes in the relative frequency of alleles in the gene pool

• Allele: Alternative versions of a gene that produce distinguishable phenotypic traits. New alleles are produce by the genetic mutation of specific nucleotide sequences during DNA copying at cell division.

• Gene Pool: The total aggregate of genes in a population at any given time Classification (Taxonomy) Levels of Biological Organization Biosphere>>Ecosystems>>Communities>>Populations>>Organisms>>Organs>>Organ Systems>>Tissues>>Cells>>Organelles>>Molecules>>Atoms

Do CD Activity: Levels of Life Card Game

Concept Check Question 1. For each biological level in Figure 1.3, write a sentence that includes the next “lower”

level. Example: “A community consists of populations of the various species inhabiting a specific area.”

5 Basic Kingdoms of Living Things Multicellular Unicellular Prokaryote Eukaryote Photosynthesis Plantae Yes No No Yes Yes (573) Animalia Yes No No Yes No (626) Protoctista Some colonial* mostly No Yes some (549) Fungi Most a few No Yes No (608) Prokaryotae No Yes Yes No some (537) *Ex. Volvox page 568

At the kingdom level, these above characteristics are used to separate living groups, but at lower taxonomic levels (phyla, class, order, family, genus) some of the characteristics used to separate groups are:

• Morphology What they look like • Reproduction How they reproduce • Energy/Food How they obtain or process it

****However, the “best” way to separate groups is according to their genetics, because this is the most reliable measure of how closely 2 groups are related

Classifying life. The taxonomic scheme classifies species into groups that are then combined into even broader groups. Species that are very closely related, such as polar bears and brown bears, are placed in the same genus, genera (plural) are grouped into families, and so on. This example classifies the species Ursus americanus, the American black bear.

Cilia structure illustrates the evolutionary relationship among all living Review Page 15 The cilia of paramecium are indistinguishable from human cilia in the human windpipe. Once a structure was “developed” through evolution, it was used in many different ways!!!!

An example from two different kingdoms for each level Use Pneumonic Device for Taxonomic Groups King Phillip Can Operate For Good Spines

Remember, the example from class. You can live in the same Kingdom (country) but not live in the same state (phyla). However, if you live in the same genus (street), you automatically live in the same Neighborhood!!!! Major Plant Phyla: Bryophyta: (moss, liverworts, hornworts) Low to the ground, No Vascular System, No Seeds Filicinophyta: (Ferns, club mosses, Horsetails) Vascular System, No Seeds Coniferophyta (Pines, Spruce, Fir) Evergreen Foliage, Vascular System, “Naked” Seeds Angiospermophyta (Decidious Plants) Deciduous Foliage, Vascular System, Covered Seeds/ Major Animal Phyla Porifera: (Sponges) - Have pores – very simple structure Cnidaria (Jellyfish, Corals). Have Stinging cells called nematocysts Platyhelminthes (Flatworms) – worms that are flat in cross section Annelida (Round Worms) - Worms that are round in cross section Mollusca (Clams, Muscles) Hard Shell Covering and muscular “foot” called pseudopod Arthropoda (Insects, Crustaceans) Segmented Body, Jointed legs, Exoskeleton

Do CD Activity: Classification Schemes

Evolution through Natural Selection

Key Elements of Natural Selection It works at the intraspecies level (within a species). A few key elements are necessary for evolution to occur through natural selection

1. Variation within the species is necessary (caused by genetic mutations and meiosis)

Why this is important: There have to be differences (sometimes undetectable or at the cellular level) which give one member of a species a slight advantage over its fellow species member)

2. There has to be overproduction and a struggle for existence

Why this is important: The variation between individuals would be unimportant and would not lead to individual “advantages” if there were enough “resources” to go around. Ie. There have to be “winners and losers” in evolution.

3. Some members (the “winners” of the species have to survive and reproduce at a higher rate. Over years and years, the phenotypic traits (and their underlying genes) that led to their success will become more common in the “gene pool.

The Effects of Natural Selection on Populations The pressures of natural selection can affect the distribution of phenotypes in a population in several ways.

Stabilizing Selection

Natural selection often works to weed out individuals at both extremes of a range of phenotypes resulting in the reproductive success of those near the mean. In such cases, the result is to maintain the status quo.

It is not always easy to see why both extremes should be handicapped; perhaps sexual selection or liability to predation is at work. In any case, stabilizing selection is common. In humans, for example, the incidence of infant mortality is higher for very heavy as well as for very light babies.

Directional Selection

A population may find itself in circumstances where individuals occupying one extreme in the range of phenotypes are favored over the others.

Since 1973, Peter and Rosemary Grant — aided by a succession of colleagues — have studied Darwin's finches in the Galapagos Islands.

Investigation: Concept 1.4 How do environmental changes affect a population

Website about Evolution http://nsm1.nsm.iup.edu/rgendron/EvolutionOnTheWeb.shtml

Which type of species is most vulnerable to environmental changes in an ecosystem (wheter human-caused or otherwise), species that are highly adapted to a specific niche (called ecological specialists) or species which have a broad range of acceptable ecological conditions (called ecological generalists)??