Introduction to Evolution & Population Genetics

Flashcards covering key vocabulary, historical figures, mechanisms of evolution, evidence of evolutionary change, and population genetics from the lecture.

Binomial Nomenclature

A system of classifying organisms using a two-part scientific name consisting of Genus and species, developed by Carolus Linnaeus.

Buffon's Law

The observation made by Georges-Louis Leclerc, Comte de Buffon, that environmentally similar but geographically distant lands possess distinct species of mammals and birds.

Inheritance of Acquired Characteristics

The hypothesis proposed by Jean-Baptiste Lamarck stating that physical modifications acquired during an organism's lifetime (such as a giraffe stretching its neck) can be passed on to its offspring.

Charles Lyell

Prominent geologist known as the Father of Geology who established that geological features were formed over long periods through gradual processes like uplift and erosion.

Artificial Selection

Programs and procedures designed to modify traits in domesticated species by having breeders choose parents that exhibit desirable phenotypes; also called selective breeding.

Vicariance Biogeography

A concept championed by Joseph Hooker proposing that species distribution patterns occur because fauna are separated by land shifts rather than long-distance dispersal.

Natural Selection

The evolutionary process in which heritable traits that increase survival and reproductive success become more common in a population over successive generations.

Microevolution

Changes in a single gene or changes in allele frequencies within a population over time from one generation to the next.

Macroevolution

Evolutionary changes on a large scale over long periods that lead to the formation of new species or higher taxonomic groups.

Species

A group of related organisms sharing a distinctive form that, among sexually reproducing organisms, are capable of interbreeding to produce viable and fertile offspring.

Population

A group of individuals of the same species occupying the same area at the same time, having the opportunity to encounter one another and interbreed.

Evolutionary Species Concept

A species concept defined by Peter Grant as an entity that maintains its identity separate from other entities through time and space and possesses its own independent evolutionary fate.

Morphological Species Concept

A species concept based on observable physical differences or similarities that have an underlying genetic basis, though it fails to distinguish cryptic-sibling species.

Biological Species Concept

A species concept defining a species as a group of interbreeding natural populations that are reproductively isolated from other such groups.

Endemic

Describing a species that is naturally found only in one specific geographical location, such as the Island fox on the Channel Islands.

Convergent Evolution

The independent evolution of similar structural or functional adaptations in two or more distantly related species occupying similar environments.

Analogous Structures

Structures in different species that perform a similar function but evolved independently from different evolutionary origins, such as the snouts of giant anteaters and echidnas.

Homologous Structures

Structures in different species that are anatomically similar because they were inherited and modified from a common ancestor.

Vestigial Structures

Anatomical features that have lost their original function over the course of evolution, such as the tailbone in humans or pelvis remnants in whales.

Developmental Homology

Similarities observed during embryonic development across different species that point to shared ancestry, such as the temporary presence of gill ridges and bony tails in human embryos.

Molecular Homology

Similarities at the cellular and molecular level, such as identical basic genetic codes and shared biochemical pathways across diverse species, indicating common descent.

Population Genetics

The study of genes and genotypes in a population, focusing on the extent, cause, maintenance, and temporal change of genetic variation.

Gene Pool

All of the alleles for every gene present within a given species population.

Polymorphic Gene

A gene that exists as two or more alleles within a population, giving rise to phenotypic variation.

Single Nucleotide Polymorphism (SNP)

The smallest and most common type of genetic variation in a gene sequence, involving a single nucleotide base substitution, insertion, or deletion, accounting for $90\%$ of human genetic variation.

Directional Selection

A pattern of natural selection that favors individuals at one extreme of a phenotypic distribution, shifting the population mean toward that phenotype over time.

Stabilizing Selection

A pattern of natural selection that favors intermediate phenotypes and selects against extreme phenotypes, reducing overall genetic diversity for that trait.

Diversifying Selection

A pattern of natural selection that favors two or more different genotypes producing distinct phenotypes in heterogeneous environments; also known as disruptive selection.

Balancing Selection

A pattern of natural selection that maintains two or more alleles in a population across generations, such as through heterozygote advantage in sickle cell anemia.

Intrasexual Selection

A form of sexual selection involving direct competition among members of the same sex (usually males) for access to mates or territories.

Intersexual Selection

A form of sexual selection between members of opposite sexes, where individuals of one sex (usually females) actively select mates based on desirable traits.

Cryptic Female Choice

A mechanism of sexual selection where a female's genital tract or egg selects against sperm from genetically related males to prevent inbreeding.

Genetic Drift

A change in allele frequencies from generation to generation caused by random chance events, exerting a significantly stronger impact on small populations.

Bottleneck Effect

A form of genetic drift occurring when a population's size is drastically reduced by an environmental event, randomly eliminating individuals and reducing genetic variation in the surviving population.

Founder Effect

A form of genetic drift occurring when a small group of individuals separates from a main population to colonize a new area, resulting in lower genetic variation and distinct allele frequencies.

Neutral Theory of Evolution

The proposal that much of the genetic variation observed in natural populations is non-Darwinian and driven by genetic drift acting on neutral mutations that do not affect phenotype or fitness.

Gene Flow

The movement of alleles into or out of a population due to the migration of breeding individuals, which homogenizes allele frequencies between populations and increases local genetic diversity.

Tiktaalik roseae

A fossil transitional form (often called a 'fishapod') connecting fish and early amphibian tetrapods, possessing a flat skull with top eyes, a flexible neck, primitive wrists, and five digits.

Hardy-Weinberg Equation

The mathematical formula $p^2 + 2pq + q^2 = 1$ used to calculate genotype frequencies in a population at genetic equilibrium, where $p$ and $q$ represent allele frequencies.