Co-Evolution Flashcards
What is the purpose of sexual selection theory?
To explain traits that do not seem to ai an organisms in its survival, since natural selection proposes that traits either aid survival or die out
What is sexual selection
The idea that there is mate choice based on one sex (female usually) holding preferences for specific traits in mates
these traits are costly to bear, so they are honest signals of mate quality (expected fitness)
the traits will become exaggerated until balances by natural selection
(sexual selection pushes towards bright colours, but natural selection pushes against because of predators, therefore they will reach equilibrium)
What are intrasexual selection?
male-male competition (or female-female)
includes physical combat, displays of strnegth, territorial battles
selects for the evolution of exaggerated armaments (weapon traits) that can be utilised
contests are often ritualised, starting with displays to avoid costly fights, and may escalate when opponents are evenly matched
males can adapt to remove other males sperm from a female
what is intersexual selection?
male-female conflicts
females can exert mate choice after mating by whether or not they use the sperm after receiving it
chickens can eject sperm they dont want
What are ornaments and armaments
ornaments include peacock feathers
armaments include tusks
they are used to differentiate between who would be the better mate
What is sexual dimorphism?
phenotypic differences between males and females due to sexual selection. For example, size, colouring or even voice
What is cryptic female choice?
process where females bias the paternity of their offspring by favouring the sperm of one male over another after mating
this can occur when females mate with multiple males in succession
a form of post-mating female choice
Male adaptations to sperm competition
can make their ejaculations more efficient or can get rid of another males sperm from the female and replace it with their own
Sexual conflicts
males may want to mate, but females may not, or vice versa
therefore they will develop traits to stop one another, causing an arms race where the other will also develep traits to stop the other
it can occur due to conflicts over whether or not mating occurs, female mating frequency (re-mating) or sperm used for fertilisation
for example, female moths have vaginal teeth to stop male moths mating
Co evolution definition
the process by which two or more species reciprocally influence each others evolution through close ecological interactions
The difference between sexual selection and co-evolution
sexual selection occurs between sexes of the same species, whereas, co-evolution occurs between multiple species or between sexes of the same species
Co-evolution also occurs due to survival, and doesn’t account for maladaptive traits (like flashy feathers etc), like sexual selection does
How does coevolution work?
as one species evolved new traits or adaptations, it exerts selective pressure on the other species to adapt in response and evolve counter-adaptations, leading to an evolutionary arms race, or mutualistic enhancements
can drive significant evolutionary changes in both species involved, including progressive exaggeration of traits
must continually develop new defences, strategies etc. otherwise it would result in a progressive loss of fitness
Therefore it is ultimately a process of natural selection, because each group poses as a selective pressure for the other
Red queen hypothesis
species must keep adapting and evolving in order to survive, whilst pitted against ever-evolving opposing species, such as predators, parasites, and competitiors in their environments
Types of coevolution
antagonistic ways:
predator-prey
plant-herbivore
host-parasite
competition
mutualistic ways:
plant-pollinator
plant-disperser
cleaning relationships
mutual defensive relationships
what is predation
an interaction in which one organism, the predator, gains energy by consuming another organism, the prey
