Ch. 8 Survival of the fittest
process where organisms become better matched to their environment and the specific features that make organism more fit
adaptation
there is not always a single optimum ________ for an environment
adaptation
__________ increase fitness
adaptations
individuals with one extreme of the range of variation in the population have higher fitness
directional selection
individuals with extreme phenotypes are most fit
disruptive selection
an individuals fitness depends on their __________ and ___________ success
environment, reproductive
an environmental factor that prevent populations from progressing inevitably toward perfection
environments change quickly
a measure of the relative amount of reproduction of an individual with a particular phenotype
fitness
an individuals fitness is measured relative to other _________ & _________ in the population
genotypes, phenotypes
"survival of the fittest" refers to
reproductive success
directional selection is also called
selective pressure
when individuals with intermediate phenotypes are most fit
stabilizing selection
factor that prevents populations from progressing inevitably toward perfection: ___________ is needed as the raw material of selection
variation
factor preventing populations from progressing inevitably towards perfection: there may be ________ alleles for a trait, each causing ______ fitness
multiple, equal
_________ __________ can cause the evolution of complex traits and behaviors
natural selection
natural selection does NOT lead to ________ organisms
perfect
