the development of many different forms from an originally homogeneous group of organisms as they fill different ecological niches
Severe reduction in the size of a population, brought about by intense selection pressure or a natural calamity, and reduces the genetic diversity of the population
A chromosomal alteration in which the organism possesses more than two complete chromosome sets.
movement of alleles into or out of a population due to the migration of individuals to or from the population
change in a DNA sequence that affects genetic information
the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations
within a population, individuals have slightly different characteristics that may or may not help them survive in an environment
the proportion of variation among individuals that we can attribute to genes
inherited characteristic that increases an organism's chance of survival
form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve
form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end
form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle
theory of a stable, nonevolving population in which frequency of alleles do not change; only occurs in large, isolated populations with random mating, and no natural selection or mutations
Conditions of Hardy-Weinberg
learning that certain events occur together. The events may be two stimuli (as in classical conditioning) or a response and its consequences (as in operant conditioning).
Fixed action pattern
A sequence of behavioral acts that is essentially unchangeable and usually carried to completion once initiated.
decreasing responsiveness with repeated stimulation
the process by which certain animals form attachments during a critical period very early in life
also called reasoning; learning process in which an animal applies something it has already learned to a new situation without a period of trial and error
A type of learning that occurs when an organism's responding is influenced by the observation of others, who are called models.
a movement that is a response to a stimulus but is not oriented with respect to the source of stimulation
the periodic passage of groups of animals (especially birds or fishes) from one region to another for feeding or breeding
a locomotor response toward or away from an external stimulus by a motile (and usually simple) organism
A type of behavior involving a contest of some kind that determines which competitor gains access to some resource, such as food or mates.
self-sacrificing behavior that benefits another individual
coefficient of relatedness
The probability that a particular gene present in one individual will also be inherited from a common parent or ancestor in a second individual.
a form of social ranking within a group in which some individuals are more subordinate than others
the act of searching for food and provisions
The total effect an individual has on proliferating its genes by producing its own offspring and by providing aid that enables other close relatives to increase the production of their offspring.