Evolution: Mechanisms, Evidence, and Implications Flashcards

This set of flashcards covers vocabulary and key concepts related to the mechanisms, evidence, and history of evolution as detailed in the lecture notes.

Evolution

The change in the genetic composition of a population over successive generations, potentially resulting in new species.

Population

A group of a particular species living and interbreeding in the same geographical area.

Genetic Variation

The differences in DNA sequences between individuals within a population; it is the foundation of evolution.

Divergent Evolution

Occurs when related species evolve different traits to adapt to distinct environments, stemming from a common ancestor.

Convergent Evolution

Happens when unrelated species independently develop similar physical traits or behaviours as they adapt to similar ecological niches or environmental pressures.

Mutation

A spontaneous or induced change in DNA sequence that serves as the ultimate source of all new genetic variation; must occur in gametes to be heritable.

Gene Flow

The movement of alleles between populations via migration, which introduces existing alleles into a new population.

Genetic Drift

Random changes in allele frequency that are not driven by selection and have a greater effect in smaller populations.

Founder Effect

A type of genetic drift occurring when a small group splits from a larger population, leading to reduced genetic diversity and unique traits.

Bottleneck Effect

A type of genetic drift where a population is drastically reduced by a disaster or human activity, carrying forward only a limited set of alleles.

Natural Selection

The process by which individuals with beneficial traits survive and reproduce more, causing favourable alleles to become more frequent over generations.

Selection Pressure

Environmental factors, such as predation, competition, or climate, that determine which traits are favoured in a population.

Selective Advantage

Traits that increase an organism's chances of survival and reproduction in a specific environment.

Speciation

The process by which populations evolve to become distinct species, requiring geographic or reproductive isolation and genetic divergence.

Artificial Selection

The intentional breeding of organisms by humans for desirable traits, driven by human preference rather than environmental pressure.

Species Diversity

The number and abundance of different species in a given area.

Genetic Diversity

The number of different alleles of genes within a population.

Ecosystem Diversity

The variation in ecosystems across a given region.

Endemism

The state of a species being unique to a defined geographical location, such as species unique to Australia due to isolation.

Megafauna

Animals with a body mass greater than $45\,kg$, such as the extinct Australian marsupial Diprotodon optatum.

Fossilisation

The process of preserving remains, which ideally requires rapid burial in oxygen-poor sediment and the presence of hard parts like bones or shells.

Index Fossils

Organisms of known age, wide distribution, and distinctive appearance used in biostratigraphy to date the rock layers they are found in.

Relative Dating

A method that determines the order of fossils based on stratigraphy, identifying them as older or younger than others without providing an actual numerical age.

Absolute Dating

A method that gives an actual numerical age for a fossil using the known decay rate of radioactive isotopes.

Half-life

The time it takes for $50\%$ of a parent radioisotope to decay into its daughter form.

Homologous Structures

Body structures inherited from a common ancestor that have similar underlying anatomy but may have evolved different functions, such as the pentadactyl limb.

Analogous Structures

Body structures with similar functions that evolved independently from different ancestors due to similar environmental pressures, such as the wings of birds and fins of sharks.

Pentadactyl Limb

The $5$-digit limb found in all tetrapod vertebrates, serving as evidence of a shared common ancestor.

Comparative Embryology

The study of vertebrate embryos which look nearly identical in early development stages, suggesting shared developmental genes from a common ancestor.

Biogeography

The study of the geographic distribution of species, which explains similarities between organisms on once-connected continents like Gondwana.

DNA Hybridisation

A molecular biology technique where DNA from two species is heated and mixed to measure relatedness based on the degree of base-pair bonding.

Molecular Clock

A technique that estimates when two species last shared a common ancestor by counting DNA mutations that accumulate at a roughly constant rate.

Cytochrome c

An essential mitochondrial protein whose amino acid sequence is compared across species to trace evolutionary ancestry.

Gene Bank

A facility that stores genetic material, such as seeds or DNA, to preserve biodiversity for the future.

Insurance Population

A living population maintained outside its natural habitat, such as in a zoo, to safeguard a species against extinction.

Hominidae

The biological family that includes modern humans, archaic humans, and great apes.

Bipedal

A term describing an organism that walks on two legs, a key characteristic of the genus Australopithecus and Genus Homo.