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Evolution 1&2
AdaptationsAdaptations
Adaptations: biological traits that help an individual to
survive and reproduce in its habitat.Adaptations perform a specific
function that make an organism better suited to its
environment.
o For example,your eyes enable you to recognize and respond
effectively to thingsaround you by detecting and analyzing the
reflected light.
Adaptationists
Biological traits arent simply morphological; perceptual
processes and behaviours are alsobiological adaptations.
Scientists categorized as Adaptationistsuse this label to
describe how hypotheses aboutadaptive function guide their
investigations.
Is the Job any differentfor higher mental processes?
Cognitive psychologists study things like selective attention,
and memory encoding andretrieval.
o Attention, retrieval, and so on- refer to tasks that the mind
needs to accomplishto doits job. In other words, they refer to the
adaptive functions of mental activity.
oHigher Mental processes
Selective attention Memory encoding Memory retrieval Word
recognition
Evolution by Natural Selection
How Do Adaptations Arise
Adaptations emerge in development as a result of the activation
of relevant aspects of theenvironment.
Three Essential Components to their Insight
Natural Selection: differential survival and reproduction of
organisms as a result of the heritabledifferences between them.
o Individual Differences: within any population, there is
variation among individuals forany given characteristic.
o Differential Reproduction: These differences affect
individuals chances of surviving andreproducing. Some individuals
will have more offspring than others.
o Heritable: the offspring of successful reproducers will
resemble their parents withrespect to these variable
characteristics.
Selective Transmission
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Evolution 1&2
Over successive generations, there will be selective
transmission of heritable parental traits andthe population will be
mostly blue. This is because the specific characteristics that are
best
adaptedfor survival and reproduction are going to be reproduced
at higher rates.
Natural Selection in the Wild
Beak size and ability to crack seeds
1977, a severe drought hit the island and decimated the
vegetation. Food was scarce and all ofthe small seeds were quickly
eaten up, leaving only the large, tough seeds that the finches
usually didnt bother with.
The birds that had unusually big, heavy beaks were able to eat
the hard seeds that remainedand so survived the drought whereas the
birds with small beaks died from starvation.
Between 19776 and 1978, the average beak depth increased from
9.4 mm to 10.2 mm. Thelarge-beaked survivors went on to reproduce
when the conditions were again favourable forbreeding, and because
beak size is heritable, their offspring inherited large beaks as
well.
Reproductive Success = Fitness
Natural Selection favours
What natural selection favours are not simplythose individuals
who are best at surviving.Itsthose who are best at reproducing.
Reproductive Success
Darwinian Fitness: average reproductive success of genotype
relative to alternative genotypes. Fitness: biologists use the term
to describe how good a particular genotype is at leaving copies
of its genes in the next generation relative to other genotypes.
Therefore, the fittest individual
is not always the smartest, bigger or fastest.
DNA, Alleles & Evolutionary Biology Because fitness is
ultimately about the competition between genotypes to leave copies
of
themselves in the next generation, some evolutionary biologists
like to defineevolution as a
change in gene frequencies over generations.
Sexual Selection
Evolution by Natural Selection in Nature
Sexual selection: in sexually reproducing organisms there is
often competition for mates, andnatural selection acts on mate
finding and reproductive behaviours.
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Darwinian fitness isntjust a matter of survival, its a matter
ofreproduction, and this crazy tailcontributes to a males fitness
by increasing his chances ofmating.
Two Subtypes of Sexual Selection
Sexually Selected Traits:o Both traits have negative effect on
survivalo For the elk: antlers are used in combato For the peacock:
the tail-feathers are used in courtship
The two subtypes of sexual selection is being chosen by the
opposite sex and defeating same-sex rivals in mating
competition.
Species-Typical Behaviour & The Comparative Approach
Adaptations
Behaviours are evolved, species specific adaptations.
Species-Typical Behaviour
o Physical form (typography)o Habitat preferenceo Group sizeo
Social system
