The Origin of Species

Flashcards covering vocabulary terms related to speciation, reproductive isolation, and the processes of evolution.

Biological species concept

Emphasizes reproductive isolation.

Speciation

The process by which one species splits into two species.

Microevolution

Changes over time in allele frequencies in a population.

Macroevolution

The broad pattern of evolution above the species level.

Biological species

A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable, fertile offspring with members of other such groups.

Reproductive Isolation

The existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring.

Prezygotic barriers

Block fertilization from occurring

Postzygotic barriers

May contribute to reproductive isolation after the hybrid zygote is formed

Morphological species concept

Distinguishes a species by body shape and other structural features.

Ecological species concept

Defines a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.

Allopatric Speciation

Gene flow is interrupted when a population is divided into geographically isolated subpopulations.

Sympatric Speciation

Speciation occurs in populations that live in the same geographic area.

Polyploidy

A species may originate from an accident during cell division that results in extra sets of chromosomes.

Autopolyploid

An individual that has more than two chromosome sets that are all derived from a single species.

Allopolyploid

Sterile hybrid into a fertile polyploid, are fertile when mating with each other but cannot interbreed with either parent species; thus, they represent a new biological species.

Hybrid Zone

A region in which members of different species meet and mate, producing at least some offspring of mixed ancestry.

Reinforcement

Natural selection should strengthen prezygotic barriers to reproduction, reducing the formation of unfit hybrids.

Punctuated equilibria

New species change most as they branch from a parent species and then change little for the rest of their existence.