Chapter 24: The Mystery of Mysteries — Speciation and Evolution (Vocabulary Flashcards)

Vocabulary flashcards covering key terms related to evolution, speciation, and reproductive barriers as presented in the notes.

Mutations

Changes in DNA that lead to genetic diversity within a population.

Genetic drift

Random changes in allele frequencies in a population over time.

Gene flow

Exchange of alleles between populations through interbreeding or migration.

Natural selection

Process by which heritable traits that improve survival and reproduction become more common.

Sexual selection

Form of natural selection favoring traits that increase mating success.

Biological species concept

A group of populations that interbreed in nature and produce viable, fertile offspring, and are reproductively isolated from other groups.

Hybrid

Offspring produced from the mating of two different species or distinct populations.

Hybridization

Interbreeding between individuals from different species or populations.

Asexual reproduction

Reproduction without fertilization; a factor complicating the biological species concept.

Fossils

Preserved remains or traces of organisms used as evidence for evolutionary history; limitations in completeness.

Speciation

Formation of new species; requires reproductive isolation between populations.

Allopatric speciation

Speciation that results from geographic isolation separating populations.

Sympatric speciation

Speciation occurring in the same geographic area, often via ecological or temporal isolation, polyploidy, or hybridization.

Polyploidy

Condition of having extra sets of chromosomes, often leading to instant speciation (e.g., 4n vs 2n) due to meiotic errors.

Prezygotic barriers

Reproductive barriers that prevent fertilization from occurring.

Temporal isolation

Differences in timing of reproduction that prevent mating between populations.

Habitat isolation

Different preferred habitats reduce contact and mating between populations.

Behavioral isolation

Differences in courtship or mating behavior that prevent interbreeding.

Mechanical isolation

Incompatible reproductive structures prevent successful mating.

Gametic isolation

Gametes from different species are incompatible and cannot fertilize.

Postzygotic barriers

Barriers that occur after fertilization, reducing hybrid success.

Reduced hybrid viability

Hybrids have lower survival rates or die before reaching reproductive age.

Reduced hybrid fertility

Hybrids are sterile or have reduced fertility (e.g., mules).

Hybrid breakdown

First-generation hybrids may be viable/fertile, but their offspring are weak or sterile.

Hybrid zones

Regions where interbreeding occurs between distinct populations or species.

Ring species

A connected series of populations that can interbreed with neighboring populations but ends cannot mate.

Subspecies

Populations within a species with distinct traits; can interbreed but may be genetically or morphologically unique.

Phylogenetic species concept

Species defined by evolutionary history and diagnostic traits, often using DNA data.

Morphological (phenetic) species concept

Species defined by observable physical traits, such as bone shapes.

Tempo of evolution

The speed at which evolutionary changes occur in lineages.

Punctuated equilibrium

Evolution with periods of rapid change interspersed with long periods of little or no change.

Gradualism

Evolution through slow, constant, incremental changes over time.