AP Bio Vocab Unit 7

Flashcards for key vocabulary and concepts.

Abiotic factors

Non-living chemical and physical factors in the environment.

Adaptation

An inherited characteristic that enhances an organism's survival and reproduction in a specific environment.

Adaptive radiation

The diversification of a group of organisms into forms filling different ecological niches.

Allele frequency

The relative frequency of an allele at a particular locus in a population.

Allopatric speciation

Speciation that occurs when biological populations of the same species become isolated due to geographical changes.

Analogous structures/traits

Structures in different species that have the same function but have evolved separately.

Artificial selection

The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits.

Atmospheric oxygen

The amount of oxygen present in the atmosphere.

Background extinction rate

The normal rate of extinction of species before any major extinction event.

Balancing selection

Natural selection that maintains two or more phenotypic forms in a population.

Binomial nomenclature (genus, species)

The formal system of naming species of living things by giving each a genus and species name.

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem.

Biogeography

The study of the geographic distribution of species and ecosystems.

Biological species

A group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

Biotic factors

Living components of an ecosystem.

Bottleneck effect (genetic drift)

A sudden reduction in population size due to a change in the environment causing a loss of genetic variation.

Carbon-14

A radioactive isotope of carbon used in dating organic material younger than 50,000 years.

Clade

A group of species that includes an ancestral species and all its descendants.

Cladistics

An approach to systematics in which organisms are placed into groups called clades based primarily on common descent.

Cladogram

A branching diagram representing the evolutionary history of a group of organisms.

Coevolution

The joint evolution of two interacting species, each in response to selection imposed by the other.

Common ancestor

An ancestor that two or more lineages share.

Comparative anatomy

The comparison of body structures in different species.

Conserved processes

Fundamental molecular and cellular processes that are conserved across different taxa due to their early origin.

Convergent evolution

The evolution of similar features in independent evolutionary lineages.

Darwin

The scientist who formulated the theory of evolution by natural selection.

Derived characteristics

An evolutionary trait that is unique to a particular clade.

Descent with modification

The concept that living species are descendants of ancestral species that were different from present-day ones.

Directional selection

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals.

Disruptive selection

Natural selection in which individuals on both extremes of a phenotypic range are favored over intermediate phenotypes.

Divergent evolution

The process by which an interbreeding population or species diverges into two or more descendant species, resulting in once smiliar species becoming increasingly different.

Embryology

The study of the early developmental stages of animals and plants.

Emigration (gene flow)

The movement of individuals out of a population, resulting in the removal of alleles from the gene pool.

Endemic

A species that is confined to a specific geographic area.

Endosymbiosis

A process in which certain unicellular organisms engulf other cells, which become endosymbionts and organelles in the host cell.

Environmental pressures

Factors in the environment that affect an organism's survival and reproduction.

Evolution

The change in the heritable characteristics of biological populations over successive generations.

Evolutionary fitness

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

Extant

A species that is still living.

Extinction

The state or process of a species, family, or other group of organisms becoming extinct.

Fertile

Able to reproduce.

Fossil

The remains or impression of a prehistoric organism preserved in petrified form or as a mold or cast in rock.

Fossil record

The ordered array of fossils, found in layers of sedimentary rock, that documents the pattern of evolution over time.

Founder effect (genetic drift)

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.

Gene flow

The transfer of alleles from one population to another.

Gene pool

The aggregate of all copies of every type of allele at all loci in every individual in a population.

Genetic drift

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

Genetic variation

Differences among individuals in the composition of their genes or other DNA segments.

Genotype frequency

The relative frequency of a particular genotype in a population.

Gradualism

A model of evolution where species descend from a common ancestor and gradually diverge more and more in morphology as they acquire unique adaptations.

Hardy-Weinberg equilibrium

The principle that the shuffling of alleles that accompanies sexual reproduction does not alter the genetic makeup of the population.

Heritable trait

A trait that is passed from parent to offspring.

Heterozygote advantage

Greater relative fitness of heterozygous individuals

Hierarchical classification (DKPCOFGS)

A system for organizing species into a series of increasingly inclusive groups from domain to species.

Homology

Similarity in characteristics resulting from a shared ancestry.

Homologous structures

Structures in different species that are similar because of common ancestry.

Hybrid

Offspring that results from the mating of individuals from two different species or from two true- breeding varieties of the same species.

Immigration (gene flow)

The influx of new individuals into a population, resulting in an increase of alleles in the population's gene pool.

Lamarck

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

Lineage

A series of ancestral and descendant populations, each of which is derived from its predecessor over time.

Mass extinction

The extinction of a large number of species within a relatively short period of geological time.

Migration

The movement of organisms from one place to another.

Molecular clock

An approach used to date evolutionary events based on the observation that at least some regions of genomes evolve at constant rates.

Morphology

The form and structure of an organism or any of its parts.

Niche

The sum of a species' use of the biotic and abiotic resources in its environment.

Node

The point on a cladogram where two lineages diverge.

Organic molecules

Carbon-based compounds.

Origin of life

The process by which life arose from non-living matter.

Out-group

A species or group of species from an evolutionary lineage that is known to have diverged before the lineage containing the group of species being studied.

Paleontology

The scientific study of fossils.

Pangea

A supercontinent that existed about 250 million years ago.

Phylogenetic tree

The evolutionary history of a species or group of related species.

Phylogeny

The evolutionary history of a species or group of related species.

Plate tectonics

A theory stating that the earth's crust is divided into irregularly shaped plates that float on a plastic-like layer of the mantle.

Population dynamics

The study of factors that affect population size, density, and distribution.

Population

A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.

Postzygotic barriers

Barriers that prevent the formation of a zygote after fertilization.

Prezygotic barriers

Barriers that impede mating or hinder fertilization if interspecific mating is attempted.

Primitive Earth Protocells

Early, membrane-bound precursors to cells that contained RNA and other organic molecules.

Punctuated equilibrium

A model of evolution where species experience long periods of little or no evolutionary change, punctuated by relatively short periods of rapid evolution.

Radiometric dating

A method for determining the age of a rock or fossil by measuring the decay of radioactive isotopes.

Relative dating

A method of determining the age of rocks and fossils based on their position in rock strata.

Relative fitness

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

Reproductive isolation

A condition in which genes of different populations do not intermingle, leading to reproductive isolation.

RNA World Hypothesis

A hypothesis that the first genetic material was RNA and that early life existed in an RNA world.

Rock strata

Layers of sedimentary rock.

Selective pressures

Any factor that affects the survival or reproduction of individuals in a population.

Sexual dimorphism

The existence of two distinct forms based on sex.

Sexual selection

A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.

Shared characteristics

Traits that two or more species have in common.

Speciation

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

Species

A population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

Species diversity

The number and relative abundance of species in a biological community.

Stabilizing selection

Natural selection in which intermediate variants are favored over extreme variants.

Stromatolite

Fossilized microbial mats consisting of layers of sediment.

Sympatric speciation

Speciation occurs in populations that live in the same geographic area.

Systematics

A scientific discipline focused on classifying organisms and determining their evolutionary relationships.

Taxonomy

The branch of biology concerned with classifying organisms.

Theory of evolution by natural selection

The concept that Earth's many species are descendants of ancestral species that were different from the present-day species.

Vestigial structures

A structure that has no apparent function and is thought to be a remnant of a structure that functioned in an ancestor.