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AP Bio U7 Natural
Natural Selection Unit 7
| Term | Definition |
|---|---|
| Adaptation | the biological mechanism by which organisms adjust to new environments or to changes in their current environment. |
| Adaptive Radiation | evolution of an animal or plant group into a wide variety of types adapted to specialized modes of life |
| Allopatric | a population or species that is physically isolated from other similar groups by an extrinsic barrier to dispersal |
| Analogous Structure | are features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestral feature |
| Artificial Selection | the identification by humans of desirable traits in plants and animals, and the steps taken to enhance and perpetuate those traits in future generations |
| Background Extinction Rate | the number of species that would be expected to go extinct over a period of time, based on non-anthropogenic (non-human) factors |
| Biogeography | the study of the geographic distribution of plants, animals, and other forms of life |
| Common Ancestor | An ancestor that two or more descendants have in common. |
| Coevolution | two groups of organisms reciprocally influencing the evolution of each other |
| Comparative Anatomy | the comparative study of the body structures of different species of animals in order to understand the adaptive changes they have undergone in the course of evolution from common ancestors. |
| Convergent Evolution | the process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities |
| Darwin | a British naturalist who proposed the theory of biological evolution by natural selection. Darwin defined evolution as "descent with modification," the idea that species change over time, give rise to new species, and share a common ancestor. |
| Differential survival | reproduction of classes of entities that differ in one or more characteristics |
| Directional Selection | when individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other |
| Disruptive Selection | a type of natural selection that selects against the average individual in a population |
| Divergent Evolution | the development of dissimilar traits or features (as of body structure or behavior) in closely related populations, species, or lineages of common ancestry that typically occupy dissimilar environments or ecological niches |
| Endosymbiosis | symbiosis in which one of the symbiotic organisms lives inside the other. |
| Epoch | a division of time characterised by the prevalence of similar conditions of the earth |
| Evolution | the change in the characteristics of a species over several generations and relies on the process of natural selection |
| Evolutionary Fitness | The probability that the line of descent from an individual with a specific trait will not die out. |
| Fixation (of alleles) | the change in a gene pool from a situation where there exists at least two variants of a particular gene (allele) in a given population to a situation where only one of the alleles remains. |
| Cladogram | an evolutionary tree that diagrams the ancestral relationships among organisms |
| Paraphyletic | A group composed of a collection of organisms, including the most recent common ancestor of all those organisms |
| Phylum | a direct line of descent within a group |
| Species | a group of organisms that can reproduce naturally with one another and create fertile offspring |
| Founder Effect | the reduction in genetic variation that results when a small subset of a large population is used to establish a new colony |
| Geologic Time Scale | a system of chronological measurement that related stratigraphy (the study of rock strata, especially the distribution, deposition and age of sedimentary rocks) to time |
| Gene Flow | the successful transfer of alleles from one population to another |
| Gene Pool | the total genetic diversity found within a population or a species |
| Genetic Bottleneck | when a population is greatly reduced in size, limiting the genetic diversity of the species |
| Genetic Drift | a mechanism of evolution characterized by random fluctuations in the frequency of a particular version of a gene (allele) in a population. |
| Genetic Equilibrium | a condition where a gene pool is not changing in frequency across generations |
| Genetic Variation | the presence of differences in sequences of genes between individual organisms of a species |
| Genotype | an individual's collection of genes |
| Natural Selection | the process through which populations of living organisms adapt and change |
| Panspermia | the theory that life exists and is distributed throughout the universe in the form of germs or spores that develop in the right environment. |
| Parallel Evolution | the evolution of geographically separated groups in such a way that they show morphological resemblances |
| Phylogeny | the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms. |
| Polymorphism | one of two or more variants of a particular DNA sequence |
| Polyploidy | the heritable condition of possessing more than two complete sets of chromosomes |
| Population | a group of individuals of the same species living and interbreeding within a given area. |
| Postzygotic Isolation | occurs after members of two different species have mated and produced a zygote |
| Prezygotic Isolation | Anything that prevents mating and fertilization |
| Primordial Environment | Originally or earliest formed in the growth of an individual or organ |
| Gradualism (anagenesis) | a mechanism in which one species evolves into another by evolutionary changes within a lineage |
| Hardy-Weinberg Equilibrium | the amount of genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors. |
| Homologous Structures | similar structures that evolved from a common ancestor |
| Homology | similarity of the structure, physiology, or development of different species of organisms based upon their descent from a common evolutionary ancestor. |
| Hybrid | offspring of parents that differ in genetically determined traits |
| Hybrid Vigor | the increase in stature, biomass, and fertility that characterizes the progeny of crosses between diverse parents such that the F1 is superior to the better of the two parents |
| Last Universal Common Ancestor | the most recent population of organisms from which all organisms now living on Earth have a common descent |
| Mass Extinction | when species vanish much faster than they are replaced |
| Migration | the seasonal movement of animals from one habitat to another in search of food, better conditions, or reproductive needs |
| Miller-Urey Experiments | a simulation of conditions on the early Earth testing the idea that life, or more specifically organic molecules, could have formed by nothing more than simple chemical reactions |
| Vestigial Organ | A rudimentary structure in humans corresponding to a functional structure or organ in ancestral animals. |
| Genus | biological classification ranking between family and species, consisting of structurally or phylogenetically related species or a single isolated species exhibiting unusual differentiation |
| Phylogenetic Tree | a diagram that depicts the lines of evolutionary descent of different species, organisms, or genes from a common ancestor. |
| Polyphyletic | a group composed of a number of organisms which might bear some similarities, but does not include the most recent common ancestor of all the member organisms |
| Taxon | any unit used in the science of biological classification, or taxonomy |
| Random Mating | matings in a population that occur in proportion to their genotypic frequencies |
| Reproductive Isolation | a condition of speciation and the primary criterion of the biological species concept |
| RNA world | a hypothetical stage in the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins |
| Speciation | how a new kind of plant or animal species is created |
| Species | a group of organisms that can reproduce naturally with one another and create fertile offspring |
| Stromatolite | layered deposit, mainly of limestone, formed by the growth of blue-green algae (primitive one-celled organisms) |
| Sympatric | the term used to describe populations, varieties, or species that occur in the same place at the same time |
| Transitional Fossil | any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group |
| Cladistics | a biological classification system that involves the categorization of organisms based on shared traits |
| Monophyletic | a group of organisms that are classified in the same taxon and share a most common recent ancestor |
| Shared Derived Characteristic | shared specifically with a common ancestor to other species that also share that character but not to ancestor of that specific common ancestor |
Created by:
Micah Wixom
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