Lecture notes
Types of Adaptation
- Institution
- University Of Exeter (UoEX)
A summary of the lecture on adaptation and the various forms of adaptation that organisms can undergo.
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Co-evolutionThe evolution of reciprocal
Mimicry
Mullerian mimics – both species are Adaptation
adaptations of two or more species unpalatable and can affect the
For something to be classed as an
that have prolonged close evolution of each other as they
example of adaptive radiation, it
interaction. exhibit similar characteristics –
needed to meet the following
Expected it to occur in situations reciprocal evolutionary patterns
criteria:
where there is a cost or benefit to depending on frequency
- A recent shared origin of
both species: Batesian mimicry – one unpalatable
members of the radiation
- Mutualism (++) and one palatable – palatable one
(common ancestry)
- Parasitism, predation (-+) tries to mimic the unpalatable one
- An accordance between
- Competition (--) but without actually having a
diverse genetically based
It is unlikely to occur in situations defence mechanism.
phenotypic traits and their
where one of the species doesn’t
divergent environment
have a cost or a benefit (is neutral): Adaptive radiation describes the spread
(phenotype – environment
- Commensalism (o+) – one of new species of common ancestry into
different niches, involving an excess of correlation)
benefits, the other is
cladogenesis over extinction. (i.e. - A benefit of the specific
unaffected e.g. sea
diversification of a group of organisms phenotypic trait in the
anemones growing on crabs
into many forms filling different ecological correlated environment (trait
to catch more food (crabs
niches) utility)
unaffected)
Factors that promote adaptive radiation: - A relative high rate of lineage
- Amensalism (-o) – one Key evolutionary innovations e.g. intrinsic splitting (rapid speciation)
organism is factors like metabolic and physiological - A link between key
harmed/inhibited and the opportunities and developmental
evolutionary innovation and
other is unaffected e.g. opportunities
rapid diversification
cattle trampling on grass Efficient dispersal
Co-evolution and arms race: an Extrinsic factors
innovation in one species leads to a Provide opportunities for diversification. Adaptationist programme – seeks
counter innovation in the other E.g. empty habitats, novel environments, to find adaptive explanations for
intensity of selection and founder effects all trait – but no explanation
In pathogens this can lead to a cycle
Ecological release – a species expands it should be accepted simply for
of virulence and resistance. niche within its own habitat or into a new
being plausible.
one where there is little competition. E.g.
Human-induced evolution. Humans Cichlids in Lake Malawi
Adaptations are defined in terms
are helping to select for animals e.g. Convergent evolution is the process of their ability to promote fitness
fisheries selecting for large fish has whereby organisms not closely related, – it comes down to trade-offs
decrease fish sizes, and urban independently evolve similar traits as a (costs/benefits)
environments are changing species result of having to adapt to similar We can test to see if something is
like mosquitos. environments or ecological niches. adaptive (multiple tests) via:
Climate change is also causing Diversification into different ecological Manipulating the species by
organisms to respond in migration roles, or niches, permits the coexistence varying pop. Size, variation
of multiple species (in/outbreeding), attributes and
and in situ (plastic change or
e.g. marsupials and placental animals
evolutionary change). modifying the species. Or alter the
come from different lineages but are very
Note that for human-induced similar. Can also be on a molecular level environment by modifying
evolution, a quick generation time i.e. produce similar substances e.g competition and predators/hosts
helps species to adapt. Antarctic and arctic fish. or altering abiotic factors.
Plus see experiment on microbes: Limits: Contingency, function/physical You can also modify/inactivate the
restraints, developmental and genetic adaptive trait and see the effect.
constraints. SO, before we can say it’s
adaptive it must show:
- Variation in trait
- Heritability of trait
- Trait utility (function)
- Fitness consequences of
altering trait
- Correspondence between trait
and specific niche
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