Speciation and Extinction

Flashcards covering key vocabulary terms related to Speciation and Extinction, including definitions of species concepts, reproductive barriers, types of speciation, and models of evolutionary pace.

Speciation

The process by which new species form.

Extinction

The disappearance of a species from Earth.

Evidence of Evolution

Includes the fossil record, biogeography, vestigial structures, convergent evolution, and homologies (anatomical, developmental, molecular).

Homologies

Similarities in structures, development patterns, or molecular sequences due to common ancestry.

Developmental Homology

Similarities in embryonic development patterns among different species, indicating shared evolutionary relationships.

Molecular Homology

Similarities in DNA and protein sequences between species, revealing detailed evolutionary relationships.

Cytochrome c

A mitochondrial protein expressed in all eukaryotes, used to determine evolutionary relationships; more amino acid differences indicate more distant common ancestors.

Microevolution

Small evolutionary changes that accumulate in a population over a relatively short period, often a few generations.

Macroevolution

Large-scale evolutionary changes that occur more slowly, resulting from major events like speciation.

Species

Distinct groups of organisms, defined differently over time but fundamentally representing populations that can share genetic material.

Biological Species Concept

Defines species based on their potential to interbreed and produce fertile offspring.

Phylogenetic Species Concept

Defines species as groups of organisms that share a pattern of ancestry and descent, forming a single branch on the tree of life.

Cryptic Species

Lineages that have historically been treated as a single species but are later revealed to be genetically distinct.

Reproductive Isolation

The inability of individuals from two populations to interbreed and produce fertile offspring, leading to the formation of new species.

Prezygotic Barriers

Reproductive isolating barriers that impede gene flow before a zygote can form (e.g., preventing mating or fertilization).

Postzygotic Barriers

Reproductive isolating barriers that act after a zygote has formed, resulting in reduced fitness or infertility of hybrid offspring.

Allopatric Speciation

A type of speciation where a physical barrier separates a population into two groups that cannot interbreed, leading to independent evolutionary paths.

Parapatric Speciation

A type of speciation where part of a population enters a new habitat bordering the range of the parent species; mating can occur between populations, but most individuals mate within their own group.

Disruptive Selection

A mode of natural selection that favors individuals at both extremes of the phenotypic range over intermediate phenotypes.

Sympatric Speciation

A type of speciation where populations diverge genetically while living together in the same shared habitat, often due to adaptation to different microenvironments.

Gradualism

A model of speciation suggesting that evolution proceeds in small, incremental changes over long periods.

Punctuated Equilibrium

A model of speciation suggesting that the pace of evolution varies, characterized by short bursts of rapid change interspersed with long periods of little change.

Adaptive Radiation

A process in which a population inhabiting a patchy or heterogeneous environment gives rise to multiple specialized forms in a relatively short time.