Halloran Honors Bio - 15 Ch11+12 Natural Selection & Evolution

evolution

change in the allele frequencies (gene pool) of a population over time

microevolution

relatively short-term changes in allele frequencies within a population or species

macroevolution

evolution on a large scale extending over geologic time and resulting in the formation of new species and taxonomic groups

natural selection

process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits

four tenets of natural selection

genetic variation, overproduction of offspring, struggle for existence, differential survival and reproduction

natural selection results in ...

evolution

differential reproduction

occurs when individuals with genetic traits best suited for survival in their environment produce more living offspring than other individuals without those traits

selective pressure

an environmental condition that influences the survival and reproductive success of an organism; can be an abiotic or biotic factor

fitness

the contribution an individual makes to the gene pool of the next generation compared to the contributions of other individuals; reproductive success

antibiotic resistance

condition in which bacteria no longer are affected or killed by an antibiotic; genes for this trait often carried and transferred on plasmids

horizontal gene transfer

process in which an organism incorporates genetic material from another without being the offspring of that organism; transfer between existing individuals of the same generation; ex. bacterial conjugation

vertical gene transfer

passing of genetic material from one generation to another (from parent to child)

coevolution

evolution of two or more interacting species in which a change in one species' population results in a change in the other species' population

sexual selection

mode of natural selection in which some individuals out reproduce others because they are better at securing or being chosen by mates

5 evidences of evolution

fossil record, biogeography, morphological similarities, embryonic development, biomolecular similarities

homologous structures

features with similar structure but different functions; result from divergent evolution (adaptive radiation) from a recent shared common ancestor

analogous structures

features that serve similar function, but are structurally and/or developmentally different; result from convergent evolution

vestigial structures

remnant of a structure that may have had an important function in a species' ancestors but currently has limited/no function in the modern species; may be homologous to a functional organ in a related species; ex. leg bones in a whale

biogeography

study of the geographic distribution of species both in current living species and in the fossil record; organisms that are found closer together geographically are more alike than those that are separated by greater distance

transitional fossils

fossils that show some traits common to both the ancestor and the new species; ex. Archaeopteryx (reptile/bird)

species

a population of morphologically similar organisms that breed and produce fertile offspring in the natural environment

speciation

formation of new species

divergent evolution results in ...

speciation

reproductive isolation

condition in which a reproductive barrier keeps two populations from interbreeding

reproductive isolation may result in ...

speciation

hybrid

an organism produced from the cross of two related species

convergent evolution

process by which species evolve in different places or different times yet develop similar external forms and structures as a result of adaptation to similar environments

divergent evolution

form of evolution in which populations of the same organism are placed into different environments with different selection pressures; causes the populations to evolve differently, over time become increasingly different from their common ancestral form; creates different species that share homologous structures

adaptive radiation

an evolutionary pattern in which many species evolve from a single ancestral species

acquired trait

a physical characteristic that is not genetically inherited, but gained over the period of the organism's life; ex. tattoo, loss of a limb