Bio Chapter 17.doc

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22 Apr 2012
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Chapter 17 – Evolution of Species Interaction
(346-458, C; 359-362, A; 363-366, C)
Crypsis: the blending of an organism with its background by matching colour and pattern of bark, twigs or leaves;
employed by palatable organisms (e.g. stick insect).
Warning colouration/aposematism: the advertisement of unpalatability with bright, recognizable colours or patterns
(e.g. Monarch butterfly).
Batesian mimicry: a palatable organism will mimic the colouration of an unpalatable one to confuse predators.
Mullerian mimicry: several unpalatable organisms will resemble each other’s colouration to more efficiently teach
predators to avoid them.
With sufficient variety in resource, specialization can decrease competition and promote coexistence between two species.
Although related species that live together differ in their utilization of resources, one cannot assume this is because of a
prior history of interaction.
Sympatric: the geographic ranges of two species overlap. Allopatric: the geographic ranges of two species do not
overlap.
Assume species 1 lives in A and B and species 2 lives in B and C. Species in B are sympatric, species in A and C are
allopatric. One would then assume that species 1 and 2 would differ more in B than 1 and 2 in their A and C, respectively.
This is called character displacement. While some ecologists contest its prevalence, one observable example is Darwin’s
finches on the Galapagos Islands which diversified very rapidly into many different species which have distinct food
sources (adaptive radiation).
Genotype-genotype interaction: the expression of genotype in one population depends on that of another population,
this results in coevolution or joint (either complementary or antagonistic) evolutionary responses.
In some cases, coevolution may result in mutualism, such as between pollinating insects and flowers.
In other cases, it may be more comparable to an arms race, particularly between herbivores and plants. A plant will adapt
some trait to prevent herbivores from consuming it (perhaps a secondary component or structural deterrent), an herbivore
will then mount some counterattack (e.g. many herbivores are capable of bypassing plant toxins).
Whether long associations between species or fleeting circumstance are cause coevolution depends on the specific
instance.
Preadaptation: a trait which becomes useful for something other than what it was initially evolved for.