Co-evolution, Convergent evolution and Adaptive radiation Flashcards
what is co-evolution?
evolution of reciprocal adaptations of two or more species that have prolonged close interactions
what is an arms-race?
where innovation of one species leads to a counter innovation in the other
co-evolution in host pathogen interactions
R1 at low frequencies
selection for R1 allele
R1 at high frequencies
selection against E1 allele
Mutated E1, ineffective R1
selection against R1 allele
R1 at low frequency
selection for E1 allele
co-evolution in mimicry
more abundant species usually the model of the two species as ut is what the selective agent is cueing on
what is Bayesian mimicry?
may not involve co-evolutionary phenomenal evolution of warning colouration is asymmetric
shows warning colourations without being a dangerous species
can mimic to survive
what is adaptive radiation?
spread of new species of common ancestry into different niches
all major groups have undergone it
easily noticed in geographically isolated environments
what in convergent evolution?
organisms not closely related independently evolve similar traits as a result of having to adapt similar environments or ecological niches
what are the factors that promote adaptive radiations?
intrinsic factors
- metabolic and physiological opportunities
- developmental opportunities
efficient dispersal facilities adaptive radiation
- some species disperse well
- others cannot dispers
- changes in environement provide opportunity
extrinsic factors
- empty habitats
- intensity of selection
ecological release
- species expands its niche within own habitat where little competition for resources
Lake Malawi Cichild radiation
three major stages of vertebrate evolution
1. divergence of lineages into different habitats
2. morphological specialisation leading to trophic differentiation within habitats
3. sensory commounication diversification
what is the three stage radiation?
model emphasises importance of intrinsic factors
occur because of some form of selection, natural and or sexual
extrinsic factors only shape the radiation
what are examples of convergent evolution?
marsupials and placental mammals
African euphorbias and north American cacti
stem succulent cacti and stem succulent euphorbs
what is molecular convergent evolution?
example:
antarctic fish vs artic fish
both produce antifreeze
antarctic produce glycoproteins
artic produce unrelated antifreeze proteins
independent episodes of molecular evolution, same functional results
what is a homologous structure?
evidence of radiation
what are analogous structures?
evidence of convergent evolution
what are limitations of convergent evolution?
- contingency- evolution based on chance
- functional/physical constraints limit options
- developmental constraints
- genetic constraints
