Unit 2: evolution

Meiosis

Meiosis

A type of cellular reproduction that creates variation through the combination of gametes.

Variation

The differences in traits among individuals in a population, which can be acted upon by environmental factors.

Extinction

The termination of a species, occurring when all individuals of that species die.

Speciation

The process by which new species arise from existing species.

Cladogram

A diagram that shows the evolutionary relationships among various biological species based on similarities and differences in their physical or genetic characteristics.

Paleontology

The scientific study of the history of life on Earth through the examination of plant and animal fossils.

Catastrophism

The theory that the Earth has been shaped by a series of sudden, short-lived, and violent events.

Uniformitarianism

The principle that the same geological processes that operate today also operated in the past.

Natural Selection

The process by which organisms better adapted to their environment tend to survive and produce more offspring.

Artificial Selection

The intentional breeding of organisms to produce desired traits.

Sexual Selection

A mode of natural selection where individuals with certain inherited characteristics are more likely than others to obtain mates.

Intrasexual Competition

Competition between members of the same sex for mates, often leading to the evolution of traits that enhance competitive ability.

Intersexual Selection

A form of sexual selection where one sex (usually females) chooses mates based on certain traits.

Heterozygote Advantage

A situation in which individuals with two different alleles for a trait have a higher fitness than those with two identical alleles.

Frequency-dependent Selection

A type of selection where the fitness of a phenotype depends on its frequency relative to other phenotypes in a given population.

Directional Selection

A mode of natural selection that favors one extreme phenotype over the mean or other extreme.

Stabilizing Selection

A mode of natural selection that favors intermediate variants and acts against extreme phenotypes.

Disruptive Selection

A mode of natural selection that favors extreme phenotypes at both ends of the spectrum over intermediate phenotypes.

Homology

Similarity in characteristics resulting from a shared ancestry.

Transitional Fossils

Fossils that show the intermediate states between an ancestral form and that of its descendants.

Dobzhansky

A biologist known for his work in evolutionary biology, famously stating that "nothing in biology makes sense except in the light of evolution."

Charles Darwin

A naturalist known for developing the theory of evolution through natural selection.

Alfred Russel Wallace

A naturalist who independently conceived the theory of evolution through natural selection and co-published with Darwin.

Malthusian Catastrophe

A prediction that population growth will outpace agricultural production, leading to famine and societal collapse.