Ch37

Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings

PowerPoint Lectures forBiology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon

Lectures by Chris Romero

Chapter 37:Communities & EcosystemsChapter 37:Communities & Ecosystems

Communities and Ecosystems


Ecology…..

•Ecosystem STRUCTURE and FUNCTION depend on the interactions of the community with its abiotic environment

•Community STRUCTURE and FUNCTION depend on the interactions among organisms…(biotic)

Biotic Interactions…parasitic fungi

A dead carpenter ant attached to leaf in the understory of a Thai forest. Before killing the ant, the fungus growing from ant's head changed the ant's behavior, causing it to bite into the leaf vein. (Credit: David Hughes)

Attack of the zombie ant! Though it may seem like the perfect title for a cheesy horror movie, scientists have discovered more about a parasitic fungus that essentially takes over the brain and body of tropical carpenter ants -- ultimately causing its host to die at a spot where the fungus has the best chance of reproducing.


INVASION!!

• Does this “invader” disrupt community structure?


STRUCTURAL FEATURES OF COMMUNITIES

What is a community?

What are some of the key characteristics of a community?

– Species diversity

– Species richness

– Relative abundance

– Dominant species

– Response to disturbances

– Trophic structure: feeding relationships among species


Figure 1.1. Species richness and abundance of termites collected from transects in seven land-use types in Jambi Province, Central Sumatra

http://www.asb.cgiar.org/data/dataset/8.htm

Link to data:

Species richness is the number of different species in a given areaS = species richnessn = total number of species present in sample populationk = number of "unique" species (of which only one organism was found in sample population

:Species abundance is the study of how common a particular species is in a given community.

Temperate Biome, Wetland Ecosystem


Competition: Why does it happen?

Interspecific competition??? …examples…

Intraspecific competition??? …examples…


Competitive exclusion principle

Niche

Results of Interspecific Competition?

Or….maybe…

Resource partitioning may evolve

• What is happening here? ….why?

LE 37-2a

LE 37-2b


Predation leads to diverse adaptations in both predator and prey

• Predation

• Adaptations….how do these evolve?

• Examples???

– Camouflage

– Chemical defense



Biston betularia


Metalmark Moths…Watch Out!

– Batesian mimicry• Palatable species mimics an unpalatable model

http://images.google.com/imgres?imgurl=http://neurophilosophy.files.wordpress.com/2006/12/31.JPG&imgrefurl=http://neurophilosophy.wordpress.com/2006/12/22/the-moth-in-spiders-clothing/&usg=__KTsi4Eu0ERzQHpVhuHSLUm7Ozh0=&h=242&w=646&sz=29&hl=en&start=6&tbnid=fSCkjMPr45n43M:&tbnh=51&tbnw=137&prev=/images%3Fq%3Dmoth%2Bmimicry%2Bspider%26gbv%3D2%26hl%3Den

http://www.youtube.com/watch?v=Y3RdwvEToJw




– Mullerian mimicry• Two unpalatable species mimic each other


Predation….diversity….community?

• Keystone species

– Exerts strong control on community structure because of its ecological niche

• Keystone predator

– May maintain community diversity by reducing numbers of the strongest competitors

– Removal can cause major changes in community dynamics


Vores…..

Herbivores and the plants they eat have various adaptations

• Herbivores are animals that eat plants or algae

• Plants have evolved defenses against herbivores

• Some herbivore-plant interactions illustrate coevolution

– Reciprocal evolutionary adaptations

– Change in one species acts as a new selective force on another species



Coevolution…


Symbiotic relationships

Parasitism


• Commensalism


Mutualism

The obligate pollinating seed-consuming mutualism between senita cacti and senita moths is a mutualism that entails both benefits and costs to both the plant and pollinator. Senita cacti benefit from pollination, but incur costs due to larval fruit consumption. Senita moths benefit from fruit food resources, but incur costs to larval survival from fruit abortions.


Hawaian Bobtail Squid

• Euprymna scolopes, Vibrio fischeri & Counterillumination

FIG. 1. Path of V. fischeri to the entrance of the host light organ. (A) Under conditions of anesthesia, the light organ can be seen as a dark mass (black arrow) through the ventral surface of the body wall. During each ventilatory cycle, the body cavity is expanded, water is drawn into the cavity (lateral green arrows) and then the body wall contracts, expelling water out (central green arrow) through the funnel (yellow). Because the light organ is circumscribed by the funnel, the water that is exiting passes over the light organ surface. Bar, 200 µm. (B) A scanning electron micrograph of one half of the ventral surface of a hatching light organ reveals the transparent, complex ciliated fields (cf) on the lateral surfaces of the organ. Water flows across these surfaces as shown by the broken green line and arrow. Bar, 50 µm. (C) A confocal micrograph of the ciliated surface of a living animal demonstrates that the appendages of the field are dynamic, most often forming a ring-like structure lateral to the main body of the light organ. Staining of the light organ with a fluorochrome that delineates the cells reveals the three pores at the base of the appendage, which are labeled 1, 2, and 3 to the left of each pore, designating the locations of the pore leading to the largest, mid-sized, and smallest crypts, respectively. Bar,

50 µm.


Disturbia….

Disturbance is a prominent feature of most communities

– Events such as fire, storms, floods

– Damage communities

– Remove organisms from communities

– Alter the availability of resources

– Can have positive effects


Ecological Sucession

– Primary succession: gradual colonization of barren rocks


Trophic Structure

• Trophic structure: a pattern of feeding relationships consisting of several different levels

• Food chain: sequence of food transfer up the trophic levels

– Moves chemical nutrients and energy


…more trophic structure terms…

• Producers

– Autotrophs that support all other trophic levels

– Plants on land

– In water, mainly photosynthetic protists and cyanobacteria

• Primary consumers

– Herbivores that eat plants, algae, or phytoplankton


• Secondary, tertiary, and quaternary consumers

– Eat consumers from the level below them

• Detritivores (decomposers)

– Animal scavengers, fungi, and prokaryotes

– Derive energy from detritus produced at all trophic levels

– Decomposition is essential for recycling nutrients in ecosystems

The fiddler crab, an important detritovore in the salt marsh community.



The cyclic flow of nutrients within an ecosystem. The arrows show the paths of nutrient flow between the living and nonliving players.


The sun's energy is converted by green plants to food energy.

Red arrows: Light energy absorbed and utilized byplants. This includes blue and small amounts of green (1), red and small quantities of near infrared (2), and some far red (3) wavelengths.

Green outline and arrow: net potential food energy produced through photosynthesis.

Blue arrows: Energy reflected as light or heat into space.


The path of energy flow through a prairie ecosystem.

Red arrow : sunlight energy coming in; Green arrows: food energy being passed from plants to animalsBlue arrows: heat energy being dispersed to space.

LE 37-9Trophic level

Quaternaryconsumers

Tertiaryconsumers

Hawk

Snake

Mouse

Grasshopper

Plant

A terrestrial food chain An aquatic food chain

Producers

Primaryconsumers

Secondaryconsumers

Phytoplankton

Zooplankton

Herring

Tuna

Killer whale


Food Webs

• A food web is a more realistic view of trophic structure

– Consumers usually eat more than one type of food

– Each food type is consumed by more than one type of consumer

LE 37-10Quaternary,

tertiary,

and secondaryconsumers

Tertiaryand

secondaryconsumers

Secondaryand

primaryconsumers

Primaryconsumers

Producers(plants)


ECOSYSTEM STRUCTURE AND DYNAMICS

Ecosystem ecology emphasizes energy flow and chemical cycling

• An ecosystem consists of all the organisms in a community and the abiotic factors with which they interact

• Ecosystem dynamics involve two processes

– Energy flow through the components of the ecosystem

– Chemical cycling within the ecosystem

LE 37-11

Energyflow

Lightenergy

Chemicalcycling

Chemicalenergy

Chemical elements

Heatenergy


Primary production sets the energy budget for ecosystems

• Primary production: amount of solar energy converted by producers to chemical energy in biomass

– Biomass: amount of organic material in an ecosystem

– Net primary production: amount of biomass produced minus amount used by producers in cellular respiration

– Varies greatly among ecosystems

– http://www.youtube.com/watch?v=Y3RdwvEToJw

http://ngm.nationalgeographic.com/2008/07/kingman-reef/warne-text

LE 37-12

Open ocean

Estuary

Algal beds and coral reefs

Desert and semidesert scrub

Tundra

Temperate grassland

Cultivated land

Boreal forest (taiga)

Savanna

Temperate deciduous forest

Tropical rain forest

0 500 1,000 1,500 2,000 2,500

Average net primary productivity (g/m2/yr)

LE 37-13

Tertiaryconsumers

Secondaryconsumers

Primaryconsumers

Producers

10 kcal

100 kcal

1,000 kcal

10,000 kcal

1,000,000 kcal of sunlight


10% Rule… Laws of T-Dynamics

Energy supply limits the length of food chains

• Only about 10% of the energy stored at each trophic level is available to the next level

– Pyramid of production, (Energy), shows loss of energy from producers to higher trophic levels

– Amount of energy available to top-level consumers is relatively small

• Most food chains have only three to five levels


CONNECTION

A production pyramid, (AKA Pyramid of Energy), explains why meat is a luxury for humans

• Human meat or fish eaters are tertiary or quaternary consumers

• Humans eating grain have ten times more energy available than when they process the same amount of grain through meat

• Using land to raise animals consumes more resources than using the land to cultivate crops

LE 37-14

Trophic level

Secondaryconsumers

Primaryconsumers

Humanvegetarians

Producers

Corn Corn

Cattle

Humanmeat-eaters


Ecological Pyramids

• http://ngm.nationalgeographic.com/2008/07/kingman-reef/warne-text

• http://en.wikipedia.org/wiki/Kingman_Reef

http://en.wikipedia.org/wiki/Kingman_Reef


BGC’s

Chemicals are recycled between organic matter and abiotic reservoirs

• Biogeochemical cycles

– Cycle nutrients through both biotic and abiotic components

– Can be local or global

Consumers

Producers

Nutrientsavailable

to producers

Detritivores

Abioticreservoir

General BGC….


Hydrologic Cycle…by another name??

Water moves through the biosphere in a global cycle

– Solar energy drives the global water cycle

– Precipitation

– Evaporation

– Transpiration

– Water cycles between the land, oceans, and atmosphere

– Forest destruction and irrigation affect the water cycle

LE 37-16

Solar energy

Net movement ofwater vapor by wind

Evaporationfrom ocean

Precipitationover ocean

Evaporation andtranspiration fromland

Transportover land

Precipitationover land

Percolationthroughsoil

Runoff andgroundwater


Carbon Cycle

The carbon cycle depends on photosynthesis and respiration

• Carbon cycles through the atmosphere, fossil fuels, and dissolved carbon in oceans

– Taken from the atmosphere by photosynthesis

– Used to make organic molecules

– Decomposed by detritivores

– Returned to the atmosphere by cellular respiration

• Burning of wood and fossil fuels is raising the level of CO2 in the atmosphere

LE 37-17

Cellularrespiration

Photosynthesis

CO2 in atmosphere

Burning offossil fuelsand wood

Primaryconsumers

Higher-levelconsumers

DetritusCarbon compoundsin water

Decomposition


Nitrogen Cycle

The nitrogen cycle relies heavily on bacteria

• Atmospheric N2 is not available to plants

– Soil bacteria convert gaseous N2 to usable ammonium (NH4

+) and nitrate (NO3-)

– Some NH4+ and NO3

- are made by chemical reactions in the atmosphere

• Human activity is altering nitrogen cycle balance in many areas

– Sewage treatment and fertilization


The complex nitrogen cycle is a marvelous example of how microbes are important to life itself (parts of cycle illustrated by red or green arrows); this cycle also includes abiotic processes (blue arrows).


Some representatives of the many groups of microorganisms, primarily bacteria, that are involved in the five steps of the nitrogen cycle.

LE 37-18

Nitrogen in atmosphere (N2)

Nitrogenfixation

Nitrogen-fixingbacteria in rootnodules of legumes Detritivores

Decomposition

Assimilationby plants

Denitrifyingbacteria

Nitrifyingbacteria

Nitrates

(NO3–)

Nitrogen-fixingsoil bacteria

Ammonium (NH4)


Phosphorous Cycle

The phosphorus cycle depends on the weathering of rock

• Phosphorus and other soil minerals are recycled locally

• Weathering of rock adds PO43- to soil

– Slow process makes amount of phosphorus available to plants low

• Human activity has created phosphate pollution of water

LE 37-19

Rain

Plant uptake

of PO43–

PlantsWeatheringof rocks

Geologicupliftof rocks

Runoff

Consumption

Sedimentation

SoilLeaching

Decomposition


• Phosphorus moves through ecosystems from rock and guano deposits to the sea and back to land again. Along the way, phosphorus is cycled between the living and nonliving Players.


ECOSYSTEM ALTERATION CONNECTION

Ecosystem alteration can upset chemical cycling

• The Hubbard Brook Experimental Forest is a long-term study of nutrient cycling

– Natural conditions

– Water loss balanced between runoff and transpiration/evaporation

– Flow of nutrients in and out of watersheds nearly balanced


– Logged and sprayed watershed

• Runoff increased 30 -40%

• Net loss of nutrients was huge

• Nitrate concentration in creek was 60 times greater

– Other long-term findings

• Acid precipitation has resulted in calcium loss

• Forest plants are not adding new growth because of calcium deficiency

LE 37-20c

Control

Deforested

Completion oftree cutting

80.0

60.0

40.0

20.0

4.0

3.0

2.0

1.0

Nit

rate

co

nce

ntr

atio

n i

n r

un

off

(m

g/L

)

1965 1966 1967 1968


TALKING ABOUT SCIENCE

David Schindler talks about the effects of nutrients on freshwater ecosystems

• Dr. David Schindler was involved in environmental research that resulted in the banning of phosphates in detergents

• Nutrient runoff from agricultural lands and large livestock operations may cause excessive algal growth

• This cultural eutrophication reduces species diversity and harms water quality


Freshwater Ecosystems Under Siege?

• A combination of factors threaten freshwater ecosystems

– Acid precipitation

– Climate warming

– Changes in land use

– Cultural Eutrophication


Figure 37-21b

Ch37

Education

keystone species

unpalatable species

light organ surface

given community

community diversity

host light organ

community dynamics

species richness n