Lecture 13: Species Interactions

coevolution

reciprocal genetic change in interacting species, such that evolution in one species causes adaptive change in another species and vice versa

coevolution can occur in _______

any intimate species interaction

symbioses

initimate species interactions

resources

species that are eaten or used for habitat

competitors

competing for food, space, or habitat

enemies

predators, parasites, etc

mutualists

species that provide fitness benfits

amensalism

one species is hurt while the other species gains nothing

vertically transmitted

mother aphids pass on their Buchnera symbionts to their offspring

interactions between enemies and victims include:

predators and prey, parasites and hosts, and herbivores and host plants

interactions between enemies and victims are unstable because?

enemies can cause extinction of each other’s populations

interactions between enemies and victims can lead to ____?

arms races, where each species adapts in response to the other and leads to extreme traits

counteradaptations

evolutionary changes in one species that develop in response to adaptations in another species, usually as part of an ongoing biological arms race

mimicry

close resemblance of an organism to some different organism such that the mimic benefits from the mistaken identity

batesian mimcry

an unprotected species (mimc) evolves to look like a protected species (model)

müllerian mimicry

a chemically protected species (mimetic #1) evolves to look like another protected species (mimetic #2)

red queen hypothesis

predicts that species are constantly being reshaped by interactions with other species

trait matching

when the traits of two interacting species correspond or align in a way that affects their interaction, often through coevolution

brooke and davis experiments (1988)

• traced the fate of artificial cuckoo eggs placed in the nests of different bird species

• host species that are never parasitized do not reject experimentally placed eggs

• host populations with a history of parasitism have evolved different mechanisms to reject experimentally placed eggs; pushing them out of the nest, abandoning the next, or building over them

virulence

defined as reduction in the survival and reproduction of hosts by a pathogen

mutualisms are what?

interactions between species that benefit individuals of both species

mutualisms do not exemplify altruism, but ___________, in which species obtains something from the other

reciprocal exploitation

mututalisms are not always stable over evolutionary time: many species ___

cheat

cheating leads to ___

coevolution

competition among species may lead to ____ in resource use

divergence

competition for resources occurs … ___

within species (intraspecific competition) and between species (interspecific competition)

interspecific competition has 2 major outcomes

• one species is driven to extinction

• competition imposes selection on one or both species leading to divergence in resource use

divergence in response to competiton between species is called what?

ecological character displacement