Descent with Modification: A Darwinian View of Life, and The Evolution of Populations, and The Origin of Species

Flashcards based on lecture notes covering Darwinian evolution, geological influences, microevolution, population genetics, and mechanisms of speciation.

Evolution

Descent with modification, encompassing both pattern and process.

Darwinian Revolution

Challenged traditional views of a young Earth inhabited by unchanging species.

Scala Naturae

Aristotle's concept of species as fixed and arranged on a ladder of increasing complexity.

Carolus Linnaeus

Developed the system of taxonomy and binomial nomenclature.

Taxonomy

The scientific discipline of classifying organisms.

Binomial Nomenclature

A two-part naming system for species (e.g., Homo sapiens).

Fossils

Remains or traces of organisms from the past, usually found in sedimentary rock layers (strata).

Georges Cuvier

Founded paleontology and advocated catastrophism.

Paleontology

The study of fossils.

Catastrophism

The principle that each boundary between strata represents a sudden catastrophe.

Hutton and Lyell

Proposed that changes in Earth's surface result from slow, continuous actions, leading to uniformitarianism.

Uniformitarianism

The principle that mechanisms of change are constant over time.

Lamarck's Hypothesis

Proposed that species evolve through the use and disuse of body parts and the inheritance of acquired characteristics.

Darwin's Theory

Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life.

Natural Selection

A process in which individuals with favorable inherited traits are more likely to survive and reproduce.

Alfred Russell Wallace

Independently developed a theory of natural selection similar to Darwin's.

The Origin of Species

Charles Darwin's book published in 1859, presenting his theory of evolution by natural selection.

Artificial Selection

The human practice of modifying species by selecting and breeding individuals with desired traits.

Malthus's Principle

The potential for human population to increase faster than food supplies and other resources.

MRSA

Methicillin-resistant Staphylococcus aureus, a dangerous pathogen resistant to multiple antibiotics.

Homology

Similarity resulting from common ancestry.

Homologous Structures

Anatomical resemblances that represent variations on a structural theme present in a common ancestor.

Comparative Embryology

Reveals anatomical homologies not visible in adult organisms.

Vestigial Structures

Remnants of features that served important functions in the organism’s ancestors.

Evolutionary Trees

Hypotheses about the relationships among different groups of organisms, often based on homologies.

Convergent Evolution

The independent evolution of similar features in distantly related groups, not due to common ancestry.

Analogous Features

Similar features that evolve independently in different lineages due to similar environmental pressures.

Fossil Record

Provides evidence of the extinction of species, the origin of new groups, and changes within groups over time.

Biogeography

The geographic distribution of species, providing evidence of evolution.

Pangaea

A single large continent that Earth’s continents were formerly united in.

Endemic Species

Species that are not found anywhere else in the world.

Microevolution

A change in allele frequencies in a population over generations.

Adaptive Evolution

Evolution that results in a better match between organisms and their environment, often driven by natural selection.

Genetic Variation

Differences in DNA among individuals, leading to phenotypic variation.

Gene Variability

Genetic variation measured by the average heterozygosity of loci in a population.

Nucleotide Variability

Genetic variation measured by comparing DNA sequences.

Geographic Variation

Differences between the gene pools of separate populations.

Cline

A graded change in a trait along a geographic axis.

Mutation

A random change in the nucleotide sequence of an organism's DNA, a primary source of genetic variation.

Point Mutation

A change in a single nucleotide base pair, often harmless but can be significant.

Chromosomal Mutations

Mutations that delete, disrupt, or rearrange long segments of DNA in chromosomes, typically harmful.

Population

A localized group of individuals capable of interbreeding and producing fertile offspring.

Gene Pool

All the alleles for all loci in a population.

Fixed Locus

A locus where all individuals in a population are homozygous for the same allele.

Allele Frequency

The proportion of a specific allele in a population's gene pool (p and q, where p + q = 1).

Hardy-Weinberg Principle

States that the frequencies of alleles and genotypes in a population remain constant from generation to generation in the absence of evolutionary influences.

Hardy-Weinberg Equilibrium Conditions

No mutations, random mating, no natural selection, extremely large population size, and no gene flow.

Hardy-Weinberg Equation

p^2 + 2pq + q^2 = 1, where p^2 and q^2 represent homozygous genotype frequencies, and 2pq represents heterozygous genotype frequency.

Genetic Drift

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next, especially in small populations.

Founder Effect

Occurs when a few individuals become isolated from a larger population, creating a new population whose gene pool differs from the source population.

Bottleneck Effect

A sudden reduction in population size due to a change in the environment, causing the resulting gene pool to not reflect the original population.

Relative Fitness

The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals.

Sexual Selection

Natural selection for mating success.

Sexual Dimorphism

Marked differences between the sexes in secondary sexual characteristics.

Intrasexual Selection

Competition among individuals of one sex (often males) for mates of the opposite sex.

Intersexual Selection

Individuals of one sex (usually females) are choosy in selecting their mates.

Directional Selection

Favors individuals at one end of the phenotypic range.

Stabilizing Selection

Favors intermediate variants and acts against extreme phenotypes.

Disruptive Selection

Favors individuals at both extremes of the phenotypic range.

Heterozygote Advantage

Occurs when heterozygotes have higher fitness than both homozygotes, leading to the maintenance of multiple alleles at a locus (e.g., sickle-cell allele and malaria resistance).

Speciation

The origin of new species.

Macroevolution

Broad patterns of evolutionary change above the species level.

Species (Biological Concept)

A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but not to produce viable, fertile offspring with members of other such groups.

Hybrids

The offspring of crosses between different species.

Reproductive Isolation

The existence of biological barriers that impede two species from producing viable, fertile offspring.

Prezygotic Barriers

Reproductive barriers that prevent mating or fertilization from taking place.

Habitat Isolation

Two species rarely encounter each other because they occupy different habitats, even if not isolated by physical barriers.

Temporal Isolation

Species that breed during different times of the day, different seasons, or different years.

Behavioral Isolation

Courtship rituals and other behaviors unique to a species prevent successful mating.

Mechanical Isolation

Morphological differences can prevent successful mating (e.g., genitalia incompatibility).

Gametic Isolation

Sperm of one species may not be able to fertilize the eggs of another species.

Postzygotic Barriers

Reproductive barriers that prevent a hybrid zygote from developing into a viable, fertile adult.

Reduced Hybrid Viability

Genes of the different parent species may interact and impair the hybrid's development or survival.

Reduced Hybrid Fertility

Hybrids are sterile and cannot produce offspring (e.g., a mule).

Hybrid Breakdown

First-generation hybrids are fertile, but when they mate, offspring of the next generation are feeble or sterile.

Morphological Species Concept

Defines a species by its distinct structural features.

Ecological Species Concept

Defines a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.

Phylogenetic Species Concept

Defines a species as the smallest group of individuals that share a common ancestor, thus forming one branch on the tree of life.

Allopatric Speciation

Speciation that occurs when gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations.

Sympatric Speciation

Speciation that takes place in geographically overlapping populations.

Polyploidy

A condition in which an organism has more than two complete sets of chromosomes, often due to accidents during cell division, common in plants.

Autopolyploid

An individual that has more than two chromosome sets, all derived from a single species.

Allopolyploid

A fertile individual that has more than two chromosome sets as a result of two different species interbreeding and combining their chromosomes.

Habitat Differentiation

Sympatric speciation can arise when a subpopulation exploits a habitat or resource not used by the parent population.

Hybrid Zone

A geographic region in which members of different species meet and mate, producing offspring of mixed ancestry (hybrids).

Reinforcement

The strengthening of reproductive barriers, causing the rate of hybridization to decrease over time, especially when hybrids are less fit than parent species.

Fusion

The process where reproductive barriers weaken sufficiently for two species to fuse into a single species due to substantial gene flow between them.

Stability (Hybrid Zones)

Continued formation of hybrid individuals within a hybrid zone, which can occur if hybrids are relatively fit or there's extensive gene flow from outside the zone.

Punctuated Equilibria

In the fossil record, describes periods of apparent stasis (no change) punctuated by sudden changes (speciation events).