Variations of a given gene.
The frequency with which a particular allele appears among the possible
alleles in a population.
The creation of a new species due to the geographic isolation of a population.
Compare with sympatric speciation.
The creation of a new species from a single lineage. Compare with
The splitting of a single lineage into two new species.
When separated, two populations may have contained different allelic
frequencies than the original population. Selection and genetic drift
will act differently on these two different genetic backgrounds, creating
genetic differences between the two new species.
Genes are the hereditary factors that produce traits.
The movement of genes through a population or between two populations through
Random changes in allelic frequencies due to chance rather than selection.
The theory holding that competition exists within species, determining which
species live to have offspring, and pass their traits on to those offspring.
The principle that two closely related species cannot fill the same role in the
An extremely rare type of speciation that occurs when populations are separated
not by a geographical barrier, such as a body of water, but by an extreme change
Having more than two copies of each chromosome.
The inability of the individuals of a species to create offspring with
members of any other species. Read the SparkNote on Reproductive
The most specific categorization for organisms. The term "species" refers to a
group of organisms that shares the same gene pool and can successfully mate. A
bulldog and a greyhound are of the same species because they can produce young.
A cat and a bulldog, which experience reproductive isolation from each other
and therefore cannot produce young, are separate species.
The creation of a new species from populations that are not geographically
isolated. Compare with allopatric speciation.
A particular expressed characteristic of an individual plant or animal;
natural selection selects for or against some traits.