Evolution Latest Version with Complete Solutions

Evolution Latest Version with Complete Solutions Natural Selection A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits. Evolution Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms. Speciation A process typically caused by the genetic isolation from a main population resulting in a new genetically distinct species. Charles Darwin English natural scientist who formulated a theory of evolution by natural selection () Sexual Selection An evolutionary mechanism by which traits that increase the ability of individuals to attract or acquire mates appear with increasing frequency in a population; selection in which a mate is chosen on the basis of a particular trait or traits Artificial Selection Selection by humans for breeding of useful traits from the natural variation among different organisms Mutation A change in the nucleotide-base sequence of a gene or DNA molecule Beneficial Mutation any change to the genetic code that results in noticeable physiological changes that are of benefit to the organism Harmful Mutation is a mutation that decreases the fitness of the organism. Heredity The biological process whereby genetic factors are transmitted from one generation to the next Lamarckism An evolutionary theory (proved false by Darwin) stating that species change over time by the use and disuse of structures and the inheritance of acquired traits. Fossils Preserved remains of once-living organisms Biogeography Geographic distribution of species Homologous Structures Structures that have different mature forms in different organisms but develop from the same embryonic tissues Analagous Structures Similar function but different structure - does not show common ancestry - Ex: butterfly wing and bat wing) Vestigial Structures A structure that is present in an organism but no longer serves its original purpose Survival of the Fittest Process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection Adaptation A characteristic that improves an individual's ability to survive and reproduce in a particular environment. Directional Selection Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve Stabilizing Selection Form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end Disruptive Selection Form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle Bottleneck Effect Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population. Founder Effect 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. Genetic Drift A change in the allele frequency of a population as a result of chance events rather than natural selection. Hardy-Weinberg Principle The principle that frequencies of alleles and genotypes in a population remain constant from generation to generation, provided that only Mendelian segregation and recombination of alleles are at work. Allopatric Speciation The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier. Sympatric Speciation The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population. No geographic barrier is present. Reproductive Isolating Mechanism Any barrier that prevents genetic exchange between species Prezygotic Mechanism Mechanisms which reduce the likelihood of mating. Postzygotic Mechanism Mechanisms that allow fertilization but prevent hybrid offspring from surviving or reproducing. Adaptive Radiation An evolutionary pattern in which many species evolve from a single ancestral species Divergent Evolution A form of evolution in which the same organism is placed into different environments with different selection pressures. This causes organisms to evolve differently, to diverge from their common ancestor. The resulting (new) species may share structural (but not necessarily functional) similarity; divergent evolution produces homologous structures. Convergent Evolution Process by which unrelated organisms independently evolve similarities when adapting to similar environments Coevolution Evolutionary change in which adaptations in one species act as a selective force on a second species, inducing adaptations that in turn act as a selective force on the first species; mutual influence on the evolution of two different interacting species. Extinction A procedure in which the reinforcement of a previously reinforced behavior is discontinued. Also may be used to describe the "process" by which a previously learned behavior disappears as a result of non-reinforcement. Cambrian Explosion A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 545 to 525 million years ago. Gradualism A proposed explanation in evolutionary biology stating that new species arise from the result of slight modifications (mutations and resulting phenotypic changes) over many generations. Punctuated Equilibrium A proposed explanation in evolutionary biology stating that species are generally stable over long periods of time. Occasionally there are rapid changes that affect some species which can quickly result in a new species.