Chapter 13: How Populations Evolve

These vocabulary flashcards cover the key concepts of evolution, historical theories, evidence of evolutionary change, and mechanisms of microevolution as detailed in the lesson.

Evolution (biological)

The processes that have transformed life on Earth from its earliest forms to the vast diversity observed today; heritable changes.

Microevolution

Generation-to-generation changes in a population’s allelic or genotypic frequencies.

Macroevolution

Large-scale evolution occurring over very long periods of time at or above the species level, involving the formation or extinction of taxonomic groups.

Aristotle

Ancient Greek philosopher who believed species are fixed and do not evolve, arranging life on a scale of increasing complexity (Natural Scale of Life).

The Voyage of the Beagle

A 1831-1836 expedition to South America where Charles Darwin observed and collected exotic faunas, floras, and fossils.

Fossils

Preserved remains of organisms that lived in the past, documenting differences between past and present organisms and species extinctions.

Casts or mold fossils

Fossils created when an organism is buried and decays, leaving an empty hole that is filled in with sediments or minerals.

Trace Fossils

Fossils recording an organism's activity, such as footprints, burrows, and tracks.

Homology

Anatomical similarities between species that reflect common descent, also known as morphological divergence.

Homologous structures

Variations on an anatomical structure of an ancestral organism that may have different uses but similar internal structure due to descent with modification.

Analogous Structures

Structures that have similar functions but different internal structures and evolved independently; they do not infer evolution from a common ancestor.

Morphological Convergence

The process by which independent evolution produces analogous structures that perform similar functions.

Vestigial structures

Body parts that have no apparent function, such as tail bones in humans, suggesting they are remnants of ancestral traits.

Comparative Embryology

The study of organisms within a group that show similar developmental patterns directed by the same master genes.

Molecular Biology

The study of similarities in DNA and protein sequences that reflect evolutionary relationships.

Charles Lyell

Author of "The Principles of Geology" who proposed Uniformity Theory and Gradualism, suggesting Earth changed slowly over millions of years.

Thomas Malthus

A thinker who correlated human population decreases with disease, famine, and war, proposing that population reproduction can exceed the environment's sustaining capacity.

Alfred Russel Wallace

A scientist who independently developed the theory of evolution by natural selection in 1858 based on his work in Indonesia.

Descent with modification

Darwin’s main idea that living species have descended from earlier life-forms and that species change over time.

Natural selection

The mechanism of evolution defined as differential success in survival and reproduction within a population.

Fitness

The degree of adaptation to an environment, measured by an individual's genetic contribution to future generations.

Adaptive trait

A heritable trait that enhances an individual’s fitness in a specific environment.

Population

A localized group of individuals belonging to the same species with the potential to interbreed.

Gene pool

All alleles at all gene loci in all individuals of a population.

Allele frequency

The abundance of a particular allele among members of a population.

Hardy-Weinberg genetic equilibrium

A theoretical state where allele and genotype frequencies in a population remain constant over generations under specific conditions.

$p$ and $q$

In the Hardy-Weinberg equation, $p$ represents the frequency of the dominant allele and $q$ represents the frequency of the recessive allele.

Hardy-Weinberg Equation

The mathematical formula to determine genotype frequencies: $p^2 + 2pq + q^2 = 1$, where $p^2$ is homozygous dominant, $2pq$ is heterozygote, and $q^2$ is homozygous recessive.

Directional selection

Selection that shifts the range of variation in traits in one direction, favoring variants at one extreme.

Stabilizing selection

Selection that removes extreme variants from the population and favors intermediate phenotypes.

Disruptive selection

Selection that favors variants at opposite extremes of a phenotypic range over intermediate individuals.

Sexual selection

A form of natural selection where individuals with certain traits have an advantage in securing mates.

Sexual dimorphism

Distinct physical differences between males and females of the same species beyond reproductive organs.

Genetic Drift

A change in the gene pool due to chance that reduces genetic variation, especially pronounced in small populations.

Bottleneck event

A drastic reduction in population size due to events like earthquakes or fires, resulting in a small surviving population with reduced genetic variation.

Founder effect

Genetic drift occurring when a small group of organisms colonizes a new habitat, leading to less genetic variation and potentially higher frequencies of inherited disorders.

Gene Flow

The genetic exchange between populations, which can drive microevolution.