In the lowland species complex, there is striking uniformity of PGI polymorph frequencies at a number of sites across the American West; this fits with earlier findings of strong, similar differences in fitness components over this range.
These differences in fitness response might also imply that selection acts on different regions in the genome.
Therefore, differences in fitness and survival are expected among populations initiated with different genetic effective sizes, unless the fertility of diploid males offsets the genetic load of their production.
There were, remarkably, almost no differences in fitness gains among the groups.
Objective: We aimed to examine the differences in fitness components between rural and urban Spanish children and adolescents.
Differences (in fitness and anthropometry) by place of residence were examined by one-way analysis of covariance.
Drift samples without concern for adaptation; selection samples discriminately on the basis of differences in fitness.
Conversely, differences in fecundity alone can create differences in fitness, even if survival rates are identical among individuals.
Darwin (1872) argued that interspecific competition drives extinctions, with differences in fitness between species being responsible for one species completely replacing another (competitive displacement).
In addition, some evolutionary biologists were suspicious of the magnitude of the differences in fitness of the two forms suggested by Kettlewell's results (Kettlewell 1973).
This is not incorrect per se (Avidians are indeed "color-coded," based on their metabolic rate or generation time), but their color is essentially a proxy for representing differences in fitness among individuals, which result from being able to perform complex functions and use resources.
