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Terms in this set (47)
The scientific study of distribution, abundance and relations of organisms and their interaction with the environment.
What two time scales is Evolutionary ecology thought to act on?
Ecology takes places over ?
Evolution takes places over?
(the change in inherited traits of a population of an organism through successive generations)
What did he say?
The preservation of favourable variations, and the rejection of unfavourable variations, I call natural selection.
What is the primary unit of selection expressed in?
What is the change in selection recorded in?
What levels can selection (thought to) act on? X4
It is most often accepted that selection operates on?
particular trait level
the expressed phenotype
What two conditions are required for selection to operate?
1. Must be variation among individuals in lifetime reproductive success
2. Traits must be heritable (the state of the trait, better or worse than average is inherited by the offspring)
If a trait is not under selection what is is subject to?
The neutral, random, process where mutations proliferate in a population, or become extinct through chance alone.
Why is natural selection not technically survival of the fittest?
what example could you use for this?
fitness is not typically measured by survival but by reproductive output
Lonesome George, the last Pinta Island Tortoise (dead now), didn't successfully father offspring, but was the survived the longest.
what is fitness typically measured as?
what is intrinsically correlated with reproductive success?
selections against extremes, lowers the frequency of deleterious alleles
selected against intermediates, lowers frequency of alleles causing an intermediate phenotype
favours the extremes, increases the frequency of favoured alleles
Evolution drives the _______ strategy
What kind of selection could be said to be acting on 'living fossils'
What can be a mediator of natural selection?
Mate choice can directly ________ or not ____________ ecological traits and natural selection
favour or not favour
give an example of mate choose favouring ecological traits and natural selection
females preferring individuals with less disease, or better diet so favouring this with better ecological traits
give an example of mate choice not favouring ecological traits and natural selection
female peacocks choosing males with the most flamboyant tail feathers
Natural selection is either_______ or _________ by sexual selection
constrained or promoted
Where can you see conflict between natural and sexual selection?
Why must you be careful when describing functional variation as adaptive?
a fully functional treat may not have evolved through natural selection and so its current utility may differ form its reasons of origins
e.g. human vision and skin colour
Who gave the spandrels of San Marco argument?
What was the main point of this?
So what should you do?
Gould and Lewontin 1979
that current function does not always relate to reasons for origin
should not construct arguments for adaptive function without good evidence
Why might phenotypic differences be observed between samples other than genetic differences?
What is an example of phenotypic plasticity?
Daphnia and predator-induced phenotypes
Other than predators, what could phenotypic plasticity be invoked by?
give an example of this
Melanoides tuberculata in Lake Malawi:
- infected with treated that causes gigantism by enlarged digestive gland and gonads (to provide good conditions for itself and protect the host form predation)
How could you show natural selection is in operation?
measure it with a selection gradient
what steps are involved in measuring selection gradient?
measuring the trait
seeing how they are associated
regression of trait value vs survivorship (or reproductive success)
trait values standardised across population, so mean = 0, SD = 1
slope of relationship indicates association with fitness
How can you calculate the selection differential?
What does this give you?
Taking the average of all 'surviving individuals'
A difference of the selected traits in those that reproduce compared to total average of the population
What did Hoekstra et al., 2001 find?
That most selection gradients are relatively weak.
That selection on viability (measured by survival) was weaker than sexual selection.
therefore both natural and sexual selection are commonplace
Parallel adaptation/ evolution
what is the effect of this?
what timescales does this take place over?
the idea that organisms with the same phenotype undergoing the same pattern of selection in multiple habitats.
a shift in phenotype in the same direction
relatively quick timescales
What did Boughman et al., 2005 demonstrate with sticklebacks in lakes in British Columbia?
what had occurred in these lakes?
on what forms?
demonstrated parallel evolution
same phenotypes had evolved independently multiple times
Species pairs had evolved had evolved with large benthic forms and smaller limnetic forms
Define parallel adaptation/evolution
the idea that organisms begging with the same phenotype undergo the same pattern of selection in multiple habitats
SO the shift in phenotype is in the same direction
can lead to the independent evolution of similar phenotypes
e..g species pairs of sticklebacks in BC
- Boughman et al., 2005
What is the genomic footprint of selection?
the rate of non-synonymous to synonymous substitutions
as expected by disruptive (divergent) selection what is higher in sexually dichromatic birds
the ratio of dN/dS is higher in sexually dichromatic birds (Mc1R)
Adaptive Radiation describes?
the evolution of ecological diversity within a rapidly multiplying lineage
what for criteria are there for Adaptive Radiation?
Phenotype- environment correlation (any trait needs to be useful within the environment)
Trail utility (directly related to phenotype-environment correlation)
Rapid speciation (generally < million years though at least rapid in a phylogenetic sense of evolution
Adaptive radiations tend to be found where?
What factors are present in these kinds of environments?
At the edge of species ranges.
predators are absent and are aided by 'key innovation' so able to occupy a completely new niche
What bird species could you demonstrate have undergone adaptive radiations?
- phylogeny shows common ancestry and rapid speciation
- phenotype-environment correlations and treat utility is how by a diversity in range of ecological and signalling traits
What fish species could you show have undergone adaptive radiation?
African cichlid fishes
- each lake has a different evolutionary history, producing diverse adaptive forms, appearing to be the same age as the lake they live in
- lakes have monophyletic radiations = common ancestry
what is trait utility?
the performance or fitness advantage of trait values in their corresponding environments
what is a phenotype-environment correlation?
a significant association between environments and the morphological and physiological traits used to exploit those environments
What plant could you use as an example of adaptive radiation?
Lupins of the Andes
- range form shrubs to tree forms
- diversity peaks at higher elevations, potentially of key innovations e.g. thermal tolerance at high altitude
- timescales corresponds with formation of the Andes
Recommended textbook explanations
Miller and Levine Biology
Joseph S. Levine, Kenneth R. Miller
Modern Biology: Student Edition
Janet L. Hopson, Postlethwait
Biology The Dynamics of Life
Biology Study Guide
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