Evolutionary Biology: Mechanisms, Evidence, and History

Evolution

A change in the genetic make-up of a population over time.

Natural Selection

The process where organisms with favorable phenotypes survive and reproduce more than those without.

Variation

Differences in traits exhibited by individuals within a population.

Overproduction

Producing more offspring than the environment can support.

Competition

The struggle among offspring for limited resources necessary for survival.

Differential Reproductive Success

The concept that individuals with favorable traits are more likely to survive and reproduce.

Fitness

The reproductive success of an organism, measured by the number of fertile offspring.

Trade-offs

Balancing pressures where a trait enhances one aspect (like mating success) but may compromise another (like survival).

Artificial Selection

The process by which humans select which individuals reproduce, resulting in changes in population traits.

Hardy-Weinberg Equilibrium

A state where allele frequencies in a population remain constant, indicating no evolution is occurring.

p + q = 1

The formula representing the frequency of alleles in a population.

p^2 + 2pq + q^2 = 1

The formula representing the genotype frequencies in a population.

Allele Frequency

The proportion of a specific allele among all allele copies in a population.

Homozygous Dominant Genotype

The genotype consisting of two dominant alleles (AA).

Heterozygous Genotype

The genotype consisting of one dominant and one recessive allele (Aa).

Homozygous Recessive Genotype

The genotype consisting of two recessive alleles (aa).

No Mutation

One of the conditions for Hardy-Weinberg Equilibrium, indicating no changes in the DNA sequence.

Random Mating

A condition in which all individuals have an equal chance of mating, important for Hardy-Weinberg Equilibrium.

No Natural Selection

A condition where all genotypes have equal survival and reproductive success, part of Hardy-Weinberg Equilibrium.

Genetic Drift

Random fluctuations in allele frequencies, more impactful in small populations.

Bottleneck Effect

A sharp reduction in population size that can lead to a loss of genetic variability.

Founder Effect

When a new population is established by a small number of individuals, leading to reduced genetic diversity.

Gene Flow

The transfer of alleles between populations, usually through migration.

Morphological Homologies

Similar structures in different species due to common ancestry.

Vestigial Structures

Remnants of structures that served a function in ancestral species but have reduced or no function in descendants.

Analogous Structures

Structures that serve similar functions but evolved independently, representing convergent evolution.

Embryology

The study of the early developmental stages of organisms, providing evidence for common ancestry.

Molecular Evidence

The use of DNA and protein similarities to infer evolutionary relationships.

Paleontology

The branch of science concerned with fossils and the history of life on Earth.

Relative Dating

Determining the age of fossils based on their location in layers of rock.

Radiometric Dating

Determining the age of rocks and fossils through the decay of radioactive isotopes.

Phylogenetic Trees

Diagrams that show the evolutionary relationships among various biological species.

Cladograms

A diagram that shows the relationships among organisms based on shared characteristics.

Speciation

The process by which one species splits into two or more distinct species.

Reproductive Barriers

Mechanisms that prevent gene flow between populations.

Pre-zygotic Barriers

Barriers that prevent mating or fertilization between species.

Post-zygotic Barriers

Barriers that prevent hybrid offspring from developing into viable, fertile adults.

Allopatric Speciation

Speciation that occurs when populations are geographically isolated from one another.

Sympatric Speciation

Speciation that occurs in the same geographic area, often due to other factors like behavioral isolation.

Gradualism

The theory that evolution occurs slowly and steadily over long periods.

Punctuated Equilibrium

The theory that species undergo rapid changes during short, significant events of speciation.

Primitive Atmosphere

The early atmosphere of Earth, believed to be rich in gases conducive to the formation of organic molecules.

Miller-Urey Experiment

An experiment that simulated early Earth conditions and demonstrated the abiotic synthesis of organic compounds.

RNA World Hypothesis

The hypothesis that RNA was the first genetic material, capable of both storing information and catalyzing reactions.

Lamarck vs. Darwin

Lamarck believed in the inheritance of acquired traits, while Darwin proposed natural selection.

'Survival of the Fittest'

A phrase often misunderstood as 'survival of the strongest'; it actually refers to reproductive success.