What is a Community

What is a Community A Community is any assemblage of populations in

an area or habitat.

Communities: Populations interacting; Population interactions shape communities.

Communities are characterized by the interactions among their component populations.

In this scene, vultures wait for whatever will remain of a lion’s zebra kill.

Yucca community : A web of Interdependence. The mule deer and sap beetle eat yucca flowers, while the ash-throated flycatcher picks off yucca moths. Below-ground, the yucca roots release a soaplike substance that makes scarce water more available for itself and its nitrogen-fixing neighbors.

Coevolution between the yucca moth and the yucca plant. (A) A female yucca moth (Tegeticula yuccasella) pushing pollen into the stigma tube of the yucca flower while visiting the flower to deposit her eggs. (B) Yucca moth larvae feeding on seeds in the yucca fruit.

http://www.britannica.com/ebc/art/print?id=20&articleTypeId=0

A B

Strange Community of Aquatic Organisms Discovered in the Deep-Ocean Abyss. In 1977, scientists discovered an entirely new ecosystem based on the heat energy from hydrothermal vents. The living community in this physical setting included yellow vent mussels, crabs (here, looking like ghostly white spiders), large vent clams, and tube worms with red plumes. These plumes take in oxygen, and the worm’s body contains chemoautotrophic bacteria, which produce fixed carbon compounds in this ecosystem.

Characteristics of a Community• Diversity

– species richness (total number of different species)

– Relative Abundance of different species.

• Prevalent form of vegetation.

• Stability – communities ability to resist change and recover from disturbance.

• Trophic structure

Biodiversity

• Species Richness vs. Relative abundance

A population is a group of organisms of the same species, which live in the same place at the same time, and can interbreed with each other. --- Interacting individuals of the same species

A community is the organisms of two or more populations of different species occupying the same geographical area, and the interaction between those species. Interacting populations of different species

An ecosystem is the interrelationship between organisms and the environment in which they live. A community of species interacting with their physical environment

A habitat is a place where an organisms lives. Home or address

The niche is a role, function, or position of an organism in a biological community. Job – how it gets its supply of energy and materials

Fundamental niche is the potential range of all environmental conditions under which an organism can thrive.

Realized niche is the part of the fundamental niche that a species actually occupies in nature.

Ecological Niches• The total of a species’ use of biotic

and abiotic resources is called the species’ ecological niche

• Ecologically similar species can coexist in a community if there are one or more significant differences in their niches

• As a result of competition, a species’ fundamental niche may differ from its realized niche

• An organism’s niche is its role in the environment

• 2 species cannot coexist if their niches are identical

• Resource partitioning – differentiation of niches that enable two similar species to coexist in a community

The Ecological Niche The sum total of a species use of the biotic

and abiotic resources in its environment

Fundamental Niche

– The theoretical maximum resources that could be used by a population.

Realized Niche

– The actual resources that are used by a population.

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Niche :

An Organism’s Role in the Community.

(a) The fundamental niche is the full range of conditions under which a given organism can operate. As depicted here, a forest warbler can catch insects in a tree at any height and on branches any distance from the trunk, and it can nest any time between early June and late July. (b) The realized niche is the part of the fundamental niche that the organism actually occupies. The Cape May warbler catches insects only in the outer branches toward the top of the tree, and it nests only in June. The bay-breasted and myrtle warbles feed in different places and nest at different times, and thus occupy separate realized niches within the boundaries of the fundamental niche.

Interspecific Interactions

Interspecific Interactions

• Competition

• Predation

• Symbiosis

– Parasitism

– Mutualism

– Commensalism

Competition between species for limited resources:

Interspecific competition – the use of the same resources by 2 different species, --- one or both competitors have a negative effect on the other’s survival or reproduction

Competitive exclusion – a situation where one species eliminates another through competition

--Two species cannot indefinitely occupy the same ecological niche. The one that is more efficient in taking advantage of available resources will exclude the other.

--Two species cannot coexist when they have identical needs of a limited resource.

Page 713 - 714

Interactions between Organisms

Competition results when organisms require the same limited resource.

Competitive exclusion The theory that populations of two species competing for a limited resource can not coexist indefinitely in the same habitat. Example: Lemna polyrhiza grew individually faster than L. gibba. When the two were grown together L. polyrhiza was always replaced by L. gibba. L. gibba – airsacs to float over L polyrhiza, cutting off the light.

Competition between species for limited resources:

Competitive exclusionG. F. Gause, Russian biologist, 1934 –

designed a laboratory experiment,Competition between Paramecium

species for the same resources (bacterial cells) in the same culture.

-- grew them in the same container – interspecific competition occurred and the smaller celled sp drove the larger celled sp to extinction

Reasons: scs 1 was more resistant to bacterial waste products than lcs

2 reproduced more rapidly than lcs

Competition between species for limited resources:Competitive exclusion

P. caudatum – large celled sp (lcs) and P. aurelia – small celled sp (scs) -- grew each sp in its own container – population growth reflected the standard S-shaped curve

Natural causes of Competitive Exclusion1. Resource (Exploitation) competition =

Occurs when use of a resource by one individual/population/species reduces the availability of that resource to other individuals/populations. (Two sp. exploit and have equal access to identical resources)

2. Interference competition = Competition between two individuals/populations/species in which one physically or chemically excludes the other from a portion of habitat and hence from the resources that could be exploited there. (The use of aggressive behavior to keep competitors from a resources)

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How have some species reduced or avoided competition

• Resource partitioning - dividing up the scarce resources so that species with similar requirements use them at different times, in different ways, or in different places.

• Ex. If lions and leopard live in the same area the lions take the bigger prey while the leopards take the smaller

Page 715, and Fig. 35.6

A. insolitususually percheson shady branches.

A. ricordii

A. insolitus

A. christophei

A. cybotes

A. etheridgei

A. alinigerA. distichus

A. distichusperches onfence postsand othersunnysurfaces.

Seven species of Anolis lizards live in close proximity at La Palma in the Dominican Republic.

Character DisplacementCharacter displacement is a tendency for characteristics to

be more divergent in sympatric populations of two species than in allopatric populations of the same two species

Ex. Anolis lizards split up the territory and occupy a different niche as their hereditary changes in physical and behavior characteristic. Such change is called character displacement.

Character displacement is an example of coevolution, heredity changes in two or more species as a consequence of their interactions within a community.

Character displacement brings about a partitioning of resources by competing species.

Resource Partitioning

Interspecific Interactions

• Competition • Predation - page 716

• Symbiosis

– Parasitism

– Mutualism

– Commensalism

Predation

• Animals eating animals

• Animals eating Plants - herbivory

• Parasitism - parasite feeding on body fluids of host.

Predation and parasitism directly benefit one species (the predator or parasite) and directly harm the other (the prey or host).

Interactions between Organisms

Predation refers to interaction where one species, the predator, kills and eats the other, the prey.

Some feeding adaptations of predators are claws, teeth, fangs, stingers, and poison

Predators that pursue their prey are selected for speed and intelligence.Carnivores store information about the prey’s escape strategies and must make quick choice while in pursuit

Predator Adaptations • Acute Senses - Smell, Eyesight, Hearing.

Interactions between organisms

Predation: Predator and Prey

Genetic changes in response to natural selection resulting in a grand co-evolution race, with predators evolving more efficient ways to catch prey and prey evolving ways to escape.

Predator needs a way to catch its food – pursuit and ambush

Predator-Prey and Parasite-Host Coevolution:

The relationships between predator and prey, and parasites and hosts, have coevolved over long periods of time.

Predation- when an organism captures and feeds on another organism.

Predators tend to be larger than their prey, and consume many prey during their lifetimes.

Predator- hunter; Prey- hunted

Predation

Prey and Defense (page 719)

Prey species have various forms of protection. They can run, jump, swim or fly. Some have developed keen eyesight or sense of smell that alerts them to the presence of predators

Prey display various defensive adaptationsBehavioral defenses include hiding, fleeing, self-defense, and alarm callsAnimals also have morphological and physiological defense adaptations

Plant Defenses Against Herbivores • Chemicals, Crystals, Thorns.

Animal Adaptations against Predators • Passive defenses - hiding

• Active defenses - running away

Insect Camouflage and Mimicry are adaptations Self - Protection: Camouflage and MimicryAvoiding Predation -- minimize the risk of being preyed upon

Camouflage comes from the French word camouflager which means to "blind or veil".

Camouflage, called cryptic coloration – an outcome of an organism’s form, patterning, color or behavior that helps it blend with its surroundings and escape detection. An animal that uses camouflage looks like things in its environment. It might look like a leaf, a twig, or a rock.

Mimicry – the evolution of similar appearance in two or more species, which often gives one or all protection.Animals that use mimicry use colors and markings to look like another animal.

WARNING AND MIMICRY• Predator deterrent evolves• Warning

– color of bees & wasps– coral snakes– monarch butterflies

• Convergence in warning – Mullerian Mimicry• Copy the warning without the deterrent Batesian

Mimicry– moths & flies– king snakes– viceroy butterfly

Defensive Mechanisms• Batesian Mimicry - Harmless species

evolve characteristics that mimic unpalatable, dangerous or poisonous species– Viceroy and Monarch butterfly

• Mullerian Mimicry - Two unpalatable species evolve to look alike– Bees and Wasps

• Camouflage• Advertising and warning (coral snake)• Attracting prey, pollinators, mates, etc.

Cryptic Coloration (camouflage)

Occurrence of shapes, colors, patterns or even behaviors that enable organisms to blend in with their background.

One defense strategy avoids confrontation through camouflage.

Cryptic Katydids: Katydids camouflage to a wide variety of environments. Can you find the katydid in each picture?

http://www.thewildones.org/Animals/camo.html

Cryptic Coloration, making a potential prey difficult to spot against its background.

The motionless twig caterpillar complete with "buds" and "lenticels" escapes detection by birds (but pays for its cleverness by occasionally having some other insect lay eggs on it by mistake).

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mimicry.html

Walking sticks have adapted to resemble their surroundings. Most of the time, their predators pass them by as they would a real twig.

Aretaon asperrimus.  This appears to be a moss and lichen mimic, and blends in well, if you don't already know something is there

http://www.bugsincyberspace.com/mimicry_and_camouflage.html

Phyllium bioculatum

http://www.bugsincyberspace.com/mimicry_and_camouflage.html

Eyespots: Io Moth (Automeris io)

Eyespots: Common BuckeyeJunonia coenia

http://www.fieldmuseum.org/butterfly/thumb10.htm

Large eye spots that make them look like scary animals and frighten predators away.

Deceptive colorationAnother form of adaptive coloration, large fake eye or false head can apparently deceive predators momentarily, allowing the prey to escape.

Hickory horned devil, large caterpillar scares away its enemies by its appearance

Sometimes harmless insects look ferocious, frightening their enemies.

Aposematic Coloration, Warning colors

Animals with effective physical or chemical defense often exhibit bright warning coloration, called aposematic coloration.

Poisonous prey species usually evolve brightly colored patterns, enabling the experienced predator to recognize and avoid them.

Mimicry is a different type of camouflage. Animals do not try to blend in with their surroundings, but instead mimic a different type of animal.

Many nonpoisonous prey species masquerade as poisonous species. Ex. A number of harmless snakes have evolved very similar coloration to highly poisonous snakes. Many types of harmless, stingless flies have evolved a very similar appearance to bees and wasps.

Bright warning coloration and mimicry occur in many groups of butterflies. The monarch caterpillar feeds on milkweed, which makes the adult butterfly bitter and poisonous to birds. Birds learn quickly to avoid its bright orange and black pattern.

Aposematic colorationMonarch butterfly Danaus plexippus

• Monarch Butterfly – Toxic model

•

•

•

•

•

• • Viceroy Butterfly –

Harmless mimic.

Batesian mimicry

Monarch Danaus plexippusViceroy Limenitis archippus

http://www.fieldmuseum.org/butterfly/thumb5.htm

The viceroy butterfly, on the other hand, is better tasting, but still unpleasant. Because its orange color and black stripes are like the colors of the monarch, birds learn to avoid both at once -- butterflies of both species and the birds benefit!

Batesian mimicry, a palatable species mimics an unpalatable model.

Many animals that eat spiders find ants distasteful. The ant-mimic spider is more likely to survive because it resembles its two less-edible ant companions.

Batesian mimicry

Batesian Mimicry A palatable or harmless species mimics an unpalatable or

harmful model.

The back of the hawk moth caterpillar actually looks like a snake head, a frightening visage for most predators the moth would come across.

Hawk Moth Mimicry: This moth caterpillar defends itself by mimicing a snake.

Mullerian Mimicry • Two or more unpalatable species resemble

each other

Aggressive Mimicry Some carnivores have evolved devices with which they mimic the prey (or potential mate) of other (usually smaller) predators. They use these devices as lures.

The angler fish (Antennarius) displays a lure resembling a small fish. The lure is a development of the spine of the first dorsal fin. This species of anglerfish, which was found in the Philippines, is 9.5 cm long. Note its use of camouflage: its texture (and color) closely resemble the sponge- and algae-encrusted rocks found in its habitat.

http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/M/Mimicry.html

The beetle emits an evil-smelling fluid from its abdomen, as a defence mechanism. This fluid rapidly evaporates into a gas, which appears like a minute jet of smoke when in contact with air, and blinds the predator about to attack. ClassificationBombardier beetles in genus Brachinus, family Carabidae, order Coleoptera, class Insecta, phylum Arthropoda.

http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0063590.html

http://www.talkorigins.org/faqs/bombardier.html

Bombardier beetle

Chemical warfare

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Jakobs and Renner (1988), Biologie und Okologie der insecten: Ein Taschelexikon

Eisner and Aneshansley (1999), Spray aiming in the bombardier beetle: Photographic evidence, Proc. Natl. Acad. Sci. (96).

http://www.math.canterbury.ac.nz/~afj15/BEETLES/beetles.html

the African Stenaptinus insignis

Interspecific Interactions

• Competition

• Predation • Symbiosis – (page 721), any relationship where two

species live closely together. (3 types)

– Parasitism

– Mutualism

– Commensalism

Interactions between organisms

ParasitismParasites: the intimate predatorsEctoparasites and Endoparasites

Sometimes, parasites -- less harmful to the host Ex. Native antelope in Africa -- tolerance to trypanosomeswhich cause lethal cases of sleeping sickness in domestic cattle.

Parasitism

• In parasitism, one organism, the parasite, derives nourishment from another organism, its host, which is harmed in the process

• Parasitism exerts substantial influence on populations and the structure of communities

Parasites and Pathogens as Predators • Parasitism is a symbiotic interaction in with

one organism, the parasite, derives nourishment from the other organism, the host.

Interactions between organisms

Parasites: the intimate predators

Cuckoos – social parasitism– one sp exploits the social behavior of another sp during a critical phase of its life cycle.

Lay an egg in the nest of other bird sp and leave the foster parents hatch the egg and nurture the young cuckoo baby

Cowbirds – lay their eggs in the nest of oropendolas or large black birds. Oropendola already accepted the cowbird eggs. The young cowbirds snapped at adult botflies and picked maggots from the skin of oropendola nestling. This explain how they would evolve alleles that favor the acceptance of cowbird egg despite the added cost of an extra mouth to feed

Parasitic plants.

Tapping phloem sap with an aphid. Aphids feeding on rosebuds. HERBIVORE

Parasitoids hunt their prey like predators, but lay their eggs within the body of a host, where they develop like parasites.

A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism which it ultimately kills (and often consumes) in the process. Thus

Interactions between organisms

Some organisms produce chemicals that inhibit the growth of the others – Allelopathy

Example: effect of black walnuts (Juglans nigra) on other plants – tomato (Solanum lycopersicum) and alfafa (Medicago sativa) wilt when grown near the black walnuts and the seedlings die if their roots contact walnut roots.

Interactions between organisms

Plants produce toxic chemicals in response to herbivores – “chemical warfare”. They are chemical metabolites.

Helanin by Helenium sp. – a powerful repellentPyrethrum by Chrysanthemum – a natural insecticide

Phytoalexins– stimulated by carbohydrate molecule elicitors from fungi and bacteriaTannins – gypsy moths and oak treesResins – snowshoe hares and paper birch

Interactions between Organisms

Mutualism is an interaction in which both species benefit.

Mycorrhizae are associations between roots and fungi.Fungi – Zygomycetes, endomycorrhizae Basdiomycetes, ectomycorrhizaePlants – vascular plantsRole of fungi – absorption of phosphorus and other nutrients required by plants

EctomycorrhizaeEndomycorrhizae

Arbuscular mycorrhizal (AM) colonization in Crassocephalum crepidioides (Benth.) S. Moore (Asteraceae) from Kra chai dam field: vesicle and

arbuscules

Facultative vs. Obligate Mutualisms

• Facultative Mutualisms are not essential for the survival of either species. Individuals of each species engage in mutualism when the other species is present.

• Obligate mutualisms are essential for the survival of one or both species.

CASE STUDY CORALS/ZOOXANTHELLAE

• Corals & anemones (Cnidarians) have obligate relationship with dinoflagellates

• If dinoflagellates leave, Cnidarian dies

• Dinoflagellates get byproducts from metabolism of cnidarians

• Cnidarians get food from metabolism of dinoflagellaltes

Mutualism• Giant Clam

Tridacna squamosa

• The mantle (soft tissue) within the shell is brightly coloured brown, blue and/or green. This is due to the microscopic algae known as zooxanthellae living inside the tissues which photosynthesise (manufacture food) from sunlight and the waste metabolic products of the clam. They are then "harvested" by the clam as supplementary food.

• Despite being "farmed" this way, the algae are assured of a safe "residence" and a continued supply of nutrients.

Interactions between Organisms

Mutualism is an interaction in which both species benefit.

Acacia trees and ants interact in a mutually beneficial way:Bull’s acacias, Acacia cornigera Ants, Pseudomyrmex ferruginea

Ants and acacias: Pseudomyrmex ferruginea and Acacia cornigera, Beltian bodies at the tips of acacia leaflets are rich in protein and oils which are food source for adult and larval ants.

Ant protects the acacia from other insects

Mutualistic relationship

Mutualism • An interspecific

interaction that benefits both species

Yucca whipplei, also called Our Lord’s Candle, grows in the Mojave Desert and has an intimate relationship with the yucca moth (inset). The moth lays its eggs in the ovary at the base of a yucca flower and then pollinates the same flower. Moths depend on the plant for food and reproduction; the plant depends on the moth for pollination. This mutually beneficial relationship is called mutualism.

Coevolutionary Partners : The Yucca Moth and Yucca Flowers.

Root nodules on a legume. The nodules of this pea root contain symbiotic bacteria that fix nitrogen and obtain photosynthetic products supplied from the plant.

To fix nitrogen:Nitrogenase catalyses the conversion of nitrogen gas to ammonium ion, to do this, it needs a supply of hydrogen, ATP and anaerobic condition. -Hydrogen from reduced NADP-ATP from sucrose by photosynthesis-protein by plant called leghaemoglobin which has high affinity for oxygen – mops up oxygen

Lichens

http://www.nhm.ac.uk/botany/lichen/air/poster.html

Association of fungi and algae in which both the organisms interwine to form a single thallus

Figs have a symbiotic relationship with particular species of wasps. These wasps lay their eggs in the flowers of the fruit and in the process pollinate the flower for the fig. The ripening fig then provides a food source for the larva of the wasp. Neither can exist without the other.

Fig wasps pollinate flowers of the fig plant and in return the fig provides food and shelter for the larval stage of the wasps

Protozoa live in the gut of termites and wood roaches and obtain food from the foraging activities of the insects. In return, the protozoa use their specialized enzymes to break down cellulose, a polymer of glucose, for the insects.

Pseudomyrmex ants have a mutualistic relationship with certain species of Acacia. The ant protects the plant against herbivory and the plant provides the ants with protein, carbohydrate and a place to live

Coevolution

Flower - pollinator relationships

http://www.evowiki.org/wiki.phtml?title=Orchid_flowers

Insect Mimics

Protocooperation

A hermit crab and the sea anemone

Symbiosis

• Commensalism – One member of a symbiotic relationship benefits and the other is neither helped or harmed

• Ex. Holes used by bluebirds in a tree were chiseled out by woodpeckers after it has been abandoned .

Shark and Remora fish

Caribbean Reef Shark With Remora

Commensalism

Commensalism; One species benefits, the other

doesn't but is not harmed.

Sea anemone and Cartoon Fish

Commensalism: Epiphytes:

Neutralism

Neutralism the most common type of interspecific interaction. Neither population affects the other. Any interactions that do occur are indirect or incidental.

Example: the tarantulas living in a desert and the cacti living in a desert

AmensalismAmensalism is when one member harmed but other unaffected.

Amensalism is a biological interaction between two species in which one impedes or restricts the success of the other without being affected positively or negatively by its presence. It is a type of symbiosis. Usually this occurs when one organism exudes a chemical compound as part of its normal metabolism that is detrimental to another organism.

The bread mold Penicillium is a common example of this; penicillium secrete penicillin, a chemical that kills bacteria.

Antibiosis

Epicoccum nigrum and Sclerotinia sclerotiorum

Antibiosis test of bacteria

Amensalism

Interspecific relations

Relation Species A

Species B

Neutralism 0 0 Neither effects the other

Commensalism

+ 0

Protocooperation

+ + Free relation

Mutualism (symbiosis)

+ + Closed relation

Amensalism 0 – Sp. A produces compounds harmful for Sp. B

Parasitism + –

Predation + –

Competition + –

Keystone Species What Is a Keystone Species?A keystone species is a species that has a major influence on the structure of an ecosystem. Its presence impacts many other members of the ecosystem, and if its population dwindles or disappears, there can be far-reaching consequences for the ecosystem.

Keystone species help to support the ecosystem (entire community of life) of which they are a part.

For instance, removal of a certain species of starfish caused a rapid growth in the numbers and biomass of mussel upon which the starfish fed.

Figs are an important food source for a variety of birds, mammals and insects consequently they are generally classified as being 'key stone' species.

www.anhs.com.au/cluster%20fig.htm

Predation, Parasitism, Herbivory

• Predators, parasites, parasitoids, and herbivores obtain food at the expense of their hosts or prey.

Ecological Succession

• Primary Succession - lifeless area where no soil has formed

What is "ecological succession"?

"Ecological succession" is the observed process of change in the species structure of an ecological community over time.

Why does "ecological succession" occur?

Every species has a set of environmental conditions under which it will grow and reproduce most optimally.

Does ecological succession ever stop?

There is a concept in ecological succession called the "climax" community. The climax community represents a stable end product of the successional sequence.

Disturbance • Stability? Tendency of a community to

reach and maintain an equilibrium. Nonequilibrium Model ? Communities are constantly changing after being disturbed.

Secondary Succession • Occurs where an existing community has been

cleared by some disturbance

Succession of plant species on abandoned fields in North Carolina. Pioneer species consist of a variety of annual plants. This successional stage is then followed by communities of perennials and grasses, shrubs, softwood trees and shrubs, and finally hardwood trees and shrubs. This succession takes about 120 years to go from the pioneer stage to the climax community.

http://www.physicalgeography.net/fundamentals/9i.html