AP bio unit 7

Fitness

A measure of the ability of an individual to survive and reproduce in a particular environment; the extent to which the individual's genotype is represented in the next generation.

Adaptation

The close fit between an organism and its environment.

Biodiversity

The total number of species, or, more broadly, the diversity of genetic sequences, cell types, metabolism, life history, phylogenetic groups, communities, and ecosystems.

Phylogenetic Tree

A tree-like diagram representing a hypothesis about the evolutionary relationships among populations or species.

Node

In phylogenetic trees, the point where a branch splits, representing the common ancestor from which the descendant species diverged.

Root

The base of a phylogenetic tree, representing the common ancestor or group from which all the organisms on the tree evolved.

Selective Pressure

The full set of environmental conditions, both abiotic and biotic, that influence the evolution of a population by natural selection.

Convergent Evolution

The independent evolution of similar traits in different species as a result of similar environments or selective pressures.

Artificial Selection

A form of directional selection similar to natural selection, but with selection done intentionally by humans, usually with a specific goal in mind, such as increased milk yield in cattle.

Sexual Selection

A form of selection that promotes traits that increase an individual's ability to find and attract mates.

Natural Selection

A mechanism of evolution that occurs when there is genetic variation in a population of organisms and the variants best suited for survival and reproduction in a particular environment contribute disproportionately to future generations.

Molecular Clock

The observation that the extent of genetic divergence between two groups is a reflection of the time since the groups shared a common ancestor.

Vestigial Structure

A structure that has lost its original function over time and is now much reduced in size.

Fossil

The remains of a once-living organism.

Carbon-14

A radioactive isotope of carbon frequently used in radiometric dating.

Radiometric Dating

Dating ancient materials using the decay of radioisotopes as a yardstick, including the decay of radioactive Carbon-14 to nitrogen for time intervals up to a few tens of thousands of years, and the decay of radioactive uranium to lead for most of Earth history.

Half-life

The time it takes for an amount of a substance to reach half its original value. Radioactive half-life is the time it takes for half of the atoms in a given sample of a substance to decay.

Invasive Species

Non-native species that become established in new ecosystems.

Homologous Structure

A body part or feature in different organisms that shares a similar underlying structure due to a common evolutionary origin, even if they have different functions.

Analogous Structure

Features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestor but evolved in response to a similar environmental challenge.

Morphology

The branch of biology that deals with the form of living organisms, and with relationships between their structures.

Embryology

The branch of biology that studies the formation, development, and structure of embryos and fetuses from the time of fertilization until birth.

Phylogeny

The history of descent with modification and the accumulation of change over time.

Cladogram

A type of phylogenetic tree that shows clades, or monophyletic groups.

Character

An anatomical, physiological, or molecular feature of an organism that varies among taxa.

Shared (Ancestral) Character

A character or trait that is present in two or more groups of organisms.

Derived Character

A character or trait that is newly evolved; an evolutionary innovation.

Outgroup

A group of organisms that has an older common ancestor than the common ancestor of the group of interest, and therefore serves as a reference for evolutionary relationships within the group of interest.

Directional Selection

A type of natural selection where one extreme phenotype is favored over others, leading to a shift in the population's trait distribution towards that extreme.

Disruptive Selection

A type of natural selection where individuals with extreme traits have a higher fitness than those with intermediate traits, leading to a population with two or more distinct forms.

Stabilizing Selection

A type of natural selection that favors intermediate phenotypes (traits) within a population, reducing variation and maintaining the status quo for a particular trait, leading to populations becoming more adapted to their environment.

Phenotypic Variation

The observable differences in traits, characteristics, and behaviors among individuals within a species, which are influenced by both genetic and environmental factors.