Biology: Speciation and Evolution Concepts

Flashcards covering essential vocabulary and concepts related to speciation, evolution, and the various species concepts.

Morphological Species Concept

Defines a species by body shape and other structural features; the oldest method used to distinguish most species.

Ecological Species Concept

Defines a species in terms of its ecological niche, emphasizing the role of disruptive natural selection.

Phylogenetic Species Concept

Defines a species as the smallest group of individuals that share a common ancestor and form one branch on the tree of life.

Biological Species Concept

Defined as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

Prezygotic Barriers

Impediments to mating or fertilization that occur before zygote formation.

Habitat Isolation

Individuals from different areas cannot mate as they do not meet.

Temporal Isolation

Different periods of sexual activity or breeding seasons prevent mating.

Behavioral Isolation

Individuals from different species may not recognize each other as potential mates due to differing mating rituals.

Mechanical Isolation

Different species may have incompatible reproductive organs that prevent mating.

Gametic Isolation

Gametes from different species do not recognize each other, preventing fertilization.

Postzygotic Barriers

Prevent hybrid zygotes from developing into viable, fertile adults.

Allopatric Speciation

Geographic separation of populations restricts gene flow, leading to speciation.

Sympatric Speciation

Speciation occurs in populations that live in the same geographic area, often through mechanisms like polyploidy.

Heterozygote Advantage

A heterozygous genotype has a higher relative fitness than either homozygous genotype.

Genetic Drift

Chance events cause allele frequencies to fluctuate unpredictably from one generation to the next.

Founder Effect

A new colony is started by a few members of the original population, leading to a loss of genetic diversity.

Population Bottleneck

A significant reduction in population size that decreases genetic diversity.

Natural Selection

Process where individuals with favorable traits survive and reproduce more than others.

Adaptation

An inherited characteristic of an organism that enhances its survival and reproduction in a given environment.

Molecular Clock

The average rate at which a species' genome accumulates mutations, used for measuring evolutionary divergence.

Clade

A group of species that includes an ancestral species and all its descendants.

Monophyletic Group

A valid clade consisting of an ancestor and all its descendants.

Paraphyletic Group

A grouping consisting of an ancestor and some, but not all, of its descendants.

Polyphyletic Group

A grouping consisting of various species with different ancestors.