The process by which one species splits into two of more species

speciation

Changes over time in allege frequencies in a population

Micro-evolution

The broad pattern of evolution above the species level

Macroevolution

According to this concept a species, is a group of population whose members have the potential to interbreed in nature and produce viable, fertile offspring- but do not produce viable, fertile offspring with other such groups

Biological species concept

The existence of biological factors that impede members of two spices from interbreeding and producing viable, fertile offspring

Reproductive isolation

Offspring that result from an interspecific mating

Hybrids

Block fertilization from occurring

prezygotic barriers

Contribute to reproductive isolation after the hybrid zone is formed

Post zygotic barriers

Two species occupy different habitats within the same area may encounter each other rarely, if ever, even though they are not isolated by obvious physical barriers

Habitat isolation

Species that breed during different times of the day, or different seasons, cannot mix their gazettes

Temporal isolation

Courtship rituals that attract mates and other behaviors unique to a species

Behavioral isolation

Mating is attempted, but morphological differences prevent its successful completion

Mechanical isolation

Sperm of one species Amy not be able to fertilize the eggs of another species

gametic isolation

The genes of different parent species may interact in ways that impair the hybrids development or survival in its environment

Reduced hybrid viability

Hybrids may be sterile. If the chromosomes of the two species differ in number or structure, meiosis in the hydride may fail to produce normal gazettes.

Reduced hydride fertility

Some first generation hybrids are viable and fertile but when they mate wit one another or with either parent species offspring of the next generation are feeble or sterile.

hybrid breakdown

Characterizes a species by body shape and other structural features

Morphological species concept

Views 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

Ecological species concept

Defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life. Biologist trace the phylogenetic history of a speed by comparing its characteristics such as morphology or molecular sequences, with those of other organisms.

Phylogenetic species concept

gene flow is interrupted when a population is divided into geographically isolated subpopulations

Allopathic speciation

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

Sympatric speciation

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

Polyploidy

An individual that has more than two sets of chromosomes that are all derived from a single species

Autopolyploid

When an infertile hybrid may be able to propagate itself asexually. In sesubsequent generations various mechanisms can change a sterile hybrid into a fertile Polyploid

Allopolyploid

Sympatric speciation can occur if gene flow is reduced by what such factors?

Polyploidy, habitat differentiation, sexual selection

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

Hybrid zone

Reinforcing reproductive barriers

Reinforcement

What are 3 possible ways that hybrid zones can change over time?

Reinforcement, fusion, stability

Describe these periods of apparent stasis punctuated by sudden change

Punctuated equilibria