Exam 1 Study Guide Flashcards

Vocabulary flashcards covering Chapters 22, 23, 24, and 25 based on the study guide transcript.

Evolution

Change in heritable traits of populations over time, driven by natural selection which is testable and based on measurable evidence.

Natural Selection

A mechanism of evolution that acts on individuals, while populations evolve; it is testable, based on measurable evidence, and is not goal-directed or progressive.

Pre-Darwinian Evolutionary Ideas

Early ideas about evolution proposed by thinkers such as Plato and Lamarck.

Darwin & Wallace's Contributions

Emphasized variation within populations and descent with modification as key components of evolutionary thought.

Genetic Drift

Random changes in allele frequencies, which are particularly significant in small populations.

Gene Flow

The movement of alleles between populations.

Mutation

The only source of new genetic variation.

Hardy-Weinberg Principle

A principle that describes populations in genetic equilibrium and is used as a null hypothesis to detect evolution.

Hardy-Weinberg Assumptions

The five conditions required for genetic equilibrium: no mutation, no gene flow, no genetic drift, no natural selection, and random mating.

Inbreeding

A violation of Hardy-Weinberg equilibrium that increases homozygosity and exposes recessive deleterious alleles.

Sexual Selection

A evolutionary force leading to traits that enhance reproductive success, such as sexual dimorphism.

Directional Selection

A mode of natural selection that favors one extreme phenotype.

Stabilizing Selection

A mode of natural selection that favors intermediate phenotypes.

Disruptive Selection

A mode of natural selection that favors extreme phenotypes over intermediate phenotypes.

Balancing Selection

A mode of natural selection that maintains genetic diversity.

Founder Effects and Bottlenecks

Examples of genetic drift that both reduce genetic diversity, differing in how the reduction occurs.

Speciation

The evolutionary process through which one species splits into two or more distinct species, occurring when gene flow between populations stops.

Species

An evolutionarily independent population or group of populations.

Biological Species Concept

A criteria for identifying species that focuses on reproductive isolation.

Prezygotic Barriers

Barriers that prevent mating from occurring, such as habitat, temporal, or mechanical isolation.

Postzygotic Barriers

Barriers where hybrid offspring are inviable or sterile.

Morphospecies Concept

A criteria for identifying species based on morphological (physical) differences.

Phylogenetic Species Concept

A criteria for identifying species based on evolutionary history and monophyletic groups.

Binomial Nomenclature

A scientific naming system consisting of Genus (capitalized) + Specific epithet (italicized), such as Canis lupus.

Carl Linnaeus

The scientist who formalized taxonomic classification and introduced binomial nomenclature.

Allopatric Speciation

Speciation caused by geographic isolation leading to divergence through mechanisms such as dispersal or vicariance.

Dispersal

A mechanism of allopatric speciation in which a population colonizes a new habitat.

Vicariance

A mechanism of allopatric speciation in which physical barriers split a population.

Sympatric Speciation

Speciation occurring without geographic isolation, initiated by external events (disruptive selection) or internal events (chromosomal mutations such as polyploidy).

Phylogenetic Trees

Hypotheses showing evolutionary relationships used as tools for studying history.

Fossil Record

A tool that provides direct evidence of past organisms, though it is limited by habitat, tissue type, and abundance biases.

Adaptive Radiation

Rapid diversification due to favorable environmental conditions or the evolution of new traits (e.g., Hox genes).

Mass Extinctions

Catastrophic events contrasted with background extinctions, including the 'Big Five' events.

Cambrian Explosion

A significant adaptive radiation event occurring ~541 mya influenced by oxygen, predation, niches, and genetic innovations.