Thursday, October 6, 2011

3.29 Species Variation

Understand that variation within a species can be genetic, environmental or a combination of both.

1. variation = difference we can see in the phenotype (how things appear)
it is possible to count and measure these differences in graphic form.

An individual has a phenotype --> genotype --> which is modified by the environment.

variation pop = variation genotype = variation environment

Differences in the appearance of individuals in a species population  is because those individual have different genotypes and are living+surviving in different environments.

Graph "1" - suggests variation in the pop (species) is due to the variation in genotypes. (environment is normal here)
Discontinuous variation --->

Graph "2" suggests variation in the pop and variation in species.
The variation here is caused by genetic variation in the genotype

eg: Height in humans (affected by your diet)
Combo of genes + the environment.

these groups are modified by the environment which results in a smooth curve.

3rd case: Variation in a population (phenotypic variation) is due to environmental variation. The genes have no role to play in differences in pop.

eg: the home language you speak.

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