R21 Running with the red queen Flashcards
What does natural selection require ?
variation amongst individuals, some of the variation must be heritable, the variation affects survival and reproduction.
What are the two types of selection pressures ?
- Abiotic pressure: temperature and humidity
- Biotic pressure: other organisms, predators, parasites, mutualists, biotic can change rapid and reciprocally
What are the different types of interspecific interactions ?
- Predation: whole or partial consumption of prey
o True predation: consumption of whole organisms, grazing: some of the organism, parasite/ parasitoids: take the resources from another organism.
Species 1 has a positive effect and species 2 has a negative effect - Competition: organisms which both species are harmed
o Negative effect on both species 1 and 2 - Mutualism: mutual benefits shared through an exchange of goods or services like food, defence and transport
o This has a positive effect on both species 1 and 2
Who benefits in predation, mutualism, competition and paratism ?
Predator +, prey -
parasite +, host -
Mutualist 1 +, Mutualist 2+
competitor 1-, competitor 2-
What is coevolution ?
change in the genetic composition of one species in response to a genetic change in another
What is reciprocal selection ?
may act directly on performance, but it is ultimately the evolution of these underlying components that shape the patterns of coevolutionary adaptation in performance
- The idea of reciprocal evolutionary change in interacting species
- Such reciprocal selection should result in reciprocal adaptations if the traits under selection are heritable. However, not all adaptations of one species to other species are necessarily coevolved.
- If a wasp increases fitness, then figs increase in fitness as they adapt together (one adaption causes another to adapt)
When does coevolution occur ?
tight ecological relationship (specificity), reciprocal natural selection, important ecological relationships that may coevolve are predator/prey, parasite/ host, mutualists, competitors
What is the difference between coevolution and parallel evolution
Coevolution occurs between species which influence each other, and parallel evolution occurs between different species which have similar ancestors but maintain similar traits due to similar environments.
- Species A will change species B evolving but not the other way around parallel evolution
What are the two types of co-evolution ?
Mutualistic - adaptation in each species increase the fitness of the other specie
antagonistic - adaptation in each species reduces the fitness of the other species e.g., predation
Other than coevolution and parallel evolution, what is another explanation for coadaptation ?
incidentally having the same outcome for the same selection for other purposes.
What is an ‘arms race’?
Coevolution between species where one suffers can lead to cycles or an arm race:
- Cycles are created when one mutant or adaptation favours another species mutant
- Arms race (red queen coevolution): you may keep evolving but staying in the same place (surviving) because interacting species are also continuing to evolve
o Despite dramatic adaptations both species have stayed in the same place relative to one another – parasites stay infective and hosts stay susceptible even though evolution is active
o Prey get fasters and so do predators
How will the ‘arms race’ end ?
may just stop, may move to a different character, predator might leave and hunt something else, may lead to extinction.
Who will win an ‘arms race’ ?
the life/dinner principle: selection pressures are not symmetrical
What is some evidence for coevolution of mutualistic species ?
- There is a direct exchange of goods or services between the two species (an ecological relationship)
- Both species appear to have a greater survival and reproduction (fitness) from their interaction
- Interdependence between the two species has led to cospeciation
Why isn’t genetic variation in the two populations associated with interaction phenotypes always evidence for co-evolution ?
If coevolution occurred a long time ago, we would not see much genetic variation as the interacting alleles have gone to fixation over time. Drift may have occurred leading to the loss or fixation of alleles.
