Sexual selection: An evolutionary process whereby individual organisms select mates
from the opposite sex by perceiving signals of robustness or other signs of potential
Sexual selection might result in some individuals having
characteristics that are individually costly to maintain or that even reduce the prospects of
The classic example is the big tail feathers of male peacocks, which
render the animal more vulnerable to predation.
But because females pick males with the
biggest, most impressive tail feathers, these males leave behind more offspring than those
less well endowed.
Their reproductive fitness is superior even though they lead shorter
lives, and they pass on the genetic propensity for big tail feathers to their offspring.
The genetic blueprint of an organism, largely inherited from its parents in
complex, sexually-reproducing organisms.
Inherited parental genotypes constitute the
genotype of offspring.
The physical manifestation of the organism (bones, tissues, organs, etc.).
Phenotype is largely inherited through the genes contributed by parents.
sexual selection, etc. work at the level of the phenotypes of individuals, because these are
the interfaces with the larger world.
The Red Queen Principle:
This evolutionary principle states that in many cases
evolutionary changes do not confer an absolute advantage, but simply allow organisms to
metaphorically “stay in the same place by running faster”.
As an example, a population of
predators might evolve better senses of smell, the capacity to run faster, etc.
put new selective pressures on the prey species, which might in response themselves adapt
with greater speed, better camouflage, etc.
Even though both predators and prey species
adapt, their relative fitness does not change (as it would, say, if only the predators
An example of this principle is the arms race of the late 20
century, in which
two sets of political competitors evolved new technological and organizational features in
response to one another, but neither gained a decisive advantage.