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Organism

Population

Community

EcosystemBiosphere

Scales of Ecological OrganizationCoevolution

A change in one species acts as a newselective force on another species.

Counteradaptation of the secondspecies, in turn, affects selection of

individuals in the first species.

Coevolution

Many species have close, regular relationships with other species.

Parasitism: One species benefits, the other is harmed

Commensalism: One species benefits, the other is unaffected

Mutualism: Both species are benefited

If both interacting species have reciprocal effects on the fitness ofthe other species, the two species may co-evolve.

Examples of parasitism:

Parasitoid wasps are very specific asto the host species they will lay theireggs in. The host is eventually killedby the time the larvae emerge andspin their cocoons. Some parasitoidwasps are used for natural biologicalcontrol of certain crop pests

Natural selection wouldfavor parasite traits thatmore effectively exploitthe host, and host traitsthat more effectivelyresist the parasite.

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Coevolution of doves and bird lice

Coevolution of SFV (simianfoaming virus) and primates

SFV: non-pathogenic RNAretroviruses that infect allprimates

COII from monophyleticlineages within the Hominoidea(Pan/Homo, Gorilla, Pongo andHylobates) and sevenmonophyletic lineages withinthe Cercopithecoidea, infraorderCatarrhini (Colobidae,Trachypithecus/ Pygathrix/Colobus, Cercopithecus/Chlorocebus/ Erythrocebus,Allenopithecus, Macaca,Mandrillus/ Cercocebus andPapio/ Theropithecus/Lophocebus)

Things that make you go hmmmm…….

Pubic lice from humans and gorillas seem to have diverged morerecently from one another, than gorillas and humans did.

Insects and Host Plants: An analogue of parasitism

Insects that eat plants without being effective pollinators areessentially the same thing as parasites. Many insects are veryspecialized on the plant species they eat.

True coevolution -- two species each having reciprocal influence onevolutionary change in the other -- has occurred between insects andtheir host plants via an evolutionary arms race.

• Insects go through adaptive radiation onto host plants• Plants evolve mechanical or chemical defenses against the insects• Plants undergo adaptive radiation once “freed” from the insects• Insects evolve ways to cope with the new plant defenses• Insects go through adaptive radiation onto new host plants

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Evolutionary Toxicology

• Study of the “arms race” between toxins and their biological targets

- insect resistance to pesticides

- toxins involved in predator/prey relationships

- pathogen resistance to drugs

Pyrethroid resistant CEWChloroquine resistant

Plasmodium merozoitesTetrodotoxin resistant garter snakeeating toxic Taricha newt

Pathogen - Plant system

Rust (Pucciniagraminis) infectswheat plants

Resistant wheatstrains are bred bycrop geneticists

New rust strainsmigrate in, ormutations occur

Commensalism

Examples of commensalism

Birds and some epiphytic plants,such as bromeliads, benefit fromliving in tree branches but do notharm the tree.

The clownfish or anemonefish hasevolved the ability to resist thepotentially dangerous stings ofsea anemones. Different speciesof fish associate with differentspecies of anemones. The fishgains a habitat safe from predators.The anemone does not benefit,nor is it harmed.

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Coevolution ofaphids (insects)and their obligatebacterialsymbionts (that donot benefit theaphids)

trophic -- partners that cooperate to obtainenergy and nutrients

defensive -- partners that exchange food fordefense against parasites, competitors, orpredators

Types of Mutualisms

dispersive -- animals that transport pollenbetween flowers, or that eat fruit anddisperse seeds

Examples of mutualism:Lichens consist of a species of fungusand a species of algae. The fungus holdswater and can help attach the lichen to asunny place, while the alga conductsphotosynthesis, providing energy for both.

The caterpillars of Lycaenid butterfliesproduce liquids that are nutritious toants; in return for these liquids, theants “tend to” the caterpillars andprotect them from predators.

Some fishes called gobies live togetherinside a burrow with a shrimp. The gobykeeps a watch out for predators, andprotects the shrimp while the shrimptends the burrow and cleans the goby.

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Co-speciation of psyllidinsects and theirendosymbiotic (gut)bacteria Carsonella thataid in digestion

• Leafcutter ants of the genus Atta live in intimate symbiosis with Basidiomycete fungi that cannot live without the ants.

• Different species of ants tend different species of fungi.

• Termites have a similar fungal symbiosis

Occasional host shifts in fungi associated with fungus-growing ants Coevolution of flowering plants and their pollinators

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plant: Acaciaant: Pseudomyrmex

Ant - Plant Mutualism

The ant is dependent uponthe acacia for food andshelter

The acacia is dependentupon on the ant forprotection from herbivorousinsects and neighboringplants

Enlarged stipularthorns normallytenanted by ants

Ant - Plant Mutualism

Swollen-thorn acacias

Ant - Plant Mutualism

Modified leaflet tips called Beltian Bodies areeaten by ants as a protein source

Ants get sugar from enlarged foliar nectaries Workers attack any other insects on the acacia and drivethem off by biting and stinging

Ants also attack plants which touch the swollenthorn acacia

Ant-Plant Mutualism

Ants receive carbohydrates and protein andhousing from the plant

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Benefits:- Acacias can grow in spacesfree of other plants, furtherprotecting them from fire

- Year round leaf productionand maintenance, even inareas with a strong dry seasonwhen most other trees aredeciduous

Unoccupied swollen-thornacacias show severedefoliation and competitionwith vines that shade it.

Coevolution

A change in one species acts as a newselective force on another species.

Counteradaptation of the secondspecies, in turn, affects selection of

individuals in the first species.

Heliconiusbutterflies

Passifloravines

Coevolution “gone wild”The vines produce toxic chemicals to reduce damage to young shootsand leaves by butterfly larvae.

Butterfly larvae of can tolerate these chemicals due to digestive enzymeswhich break down the toxic chemicals (a counteradaptation).

Females of some butterfly species avoid laying eggs (which are brightyellow) on leaves where other yellow egg clusters have been laid;reduces intraspecific competition on individual leaves, SO…

…some species of passionflowers develop large, yellow nectaries whichresemble eggs; an adaptation that may divert egg-laying butterflies toother plants.

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Coevolution “gone wild”The vines produce toxic chemicals to reduce damage to young shootsand leaves by butterfly larvae.

Butterfly larvae of can tolerate these chemicals due to digestive enzymeswhich break down the toxic chemicals (a counteradaptation).

Females of some butterfly species avoid laying eggs (which are brightyellow) on leaves where other yellow egg clusters have been laid;reduces intraspecific competition on individual leaves, SO…

…some species of passionflowers develop large, yellow nectaries whichresemble eggs; an adaptation that may divert egg-laying butterflies toother plants.

These nectaries, as well as smaller ones, also attract ants and waspswhich prey on butterfly eggs and larvae.