Mechanisms Of Evolution Ap Biology Exam

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natural selection

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states that a population can change over the course of time if individuals with certain heritable traits produce more viable offspring thatn the other individuals

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evolutionary adaptation

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tendency of the characteristics of a spiecies to change over generations to enable that species to better fit the environment, because of natural selection

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taxonomy

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sector of biology dedicated to the naming and classification of all forms of life (binomial nomenclature)

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fossils

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found in sedimentary rock, impressions of organisms that are no longer living. proof of evolution

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paleontology

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study of fossils

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gradualism

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geologic theory that states that profound changes in earth's features over the course of geologic time is the result of slow, continuous processes.

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uniformitarianism

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the idea that the geologic processes that have shaped the planet have not changed over the course of the earth's history

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Jean Baptiste Lamarck

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published an early theory of evolution, which stated that characteristics acquired during an organism's lifetime could be passed on to the next generation.

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Charles Darwin

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voyage on the Beagle in 1831 was the impetus for the development of his theory of evolution

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descent with modification

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refers to Darwins idea that all living organisms are related by descent from an unknown common ancestor n the past

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Darwin's 3 theories

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1. Natural selection is the result of differing reproductive success that is due to the unequal ability of individuals to survive to reproduce.
2. The process of natural selection occurs through interactions between the environment and organisms that vary in their genotype in a population
3. The result of natural selection is the adaptation of a population to its environment.

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artificial selection

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the process by which species are modified by humans. Plants and animals are specifically chosen to breed with the desired goal of producing offspring with specific characteristics

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population

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defined as a group of interbreeding individuals that live in a certain geographic area- it is the smallest unit that can evolve

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heritable traits

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natural selection only works on this

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homology

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since organisms are related evolutionarily, species that share common ancestry should have similarities. A phenomenon, in which related species share characteristics

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vestigial organs

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historical remnants of structures that were functional in ancestors

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embryological homologies

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most prominent during development

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molecular homologies

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occur when organisms share characteristics on the molecular level, such as using the same method for reproducing DNA

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Biogeography

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refers to the geographic distribution of species. species that live closer to one another tend to be more closely related than those who do not.

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endemic

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species in a certain geographic location that are found nowhere else

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natural selection acts on blank but evolution acts on blank

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natural selection, evolution

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population genetics

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study of the genetic variation that exists within populations and of how it changes

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species

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is a group of populations of individuals that can interbredd successfully and produce a viable offspring. Populations of the same species may be geographically isolated and only exchange genetic material rarely.

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gene pool

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total aggregate of genes in a population at any one time.

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fixed

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all members of a population are homozygous for the same copy of an allele

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Hardy-Weinberg theory

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used to describe a population that is not evolving. States that the frequencies of alleles and genes in a population's gene pool will remain constant over the course of generations unless they are acted upon by forces other than mendelian segregation and the recomination of alleles

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hardy-weinberg equilibrium

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situation in which the allele frequencies within a population are not changing

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Hardy-weinberg equation

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p squared + 2pq + q squared

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5 criteria in order for a population to be in Hardy-Weinberg equilibrium

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1. large population
2. no migration in a population, gene flow - transfer of alleles between populations
3. no mutations
4. mating must occur randomly
5. natural selection may not be taking place

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evolving

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organisms that deviate from the hardy-weinberg equilibrium

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microevolution

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defined as a generation to generation change in allelic frequency in a population. Main causes are genetic drift, natural selection, gene flow, and mutation.

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genetic drift

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refers to a change in a population's allele frequencies due to chance

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the bottleneck effect

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occurs when natural disaster or some other event causes a drastic reduction in the size of a population, which in turn causes genetic drift. Reduces genetic variability in a population, since some alleles are lost form the gene pool.

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the founder effect

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occurs when a few members of a population colonize an isolated location-the smaller number of founders the more limited the variability of the gens in the population

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genetic variation

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exists naturally in populations. Quantitative characters, such as height, vary in a continuum in a population.

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polymorphic

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a character in a population in two or more discrete forms, such as a plant bearing two different kinds of flowers in a population.

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geographic variation

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differences in gene pools between population or parts of populations

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cline

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graded change in a trait along a geographic axis.

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two processes leading to variation in a gene pool

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1. mutation (only on gametes)
2. sexual recombination (most genetic differences)

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diploidy (factor contributing to preservation of genetic variation)

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fact that most eukaryotes are diploid means that they are capable of hiding genetic variation (recessive alleles) from selection

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balanced polymorphism (other factor contributing to preservation of genetic variation)

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the ability of natural selection to keep stable the frequencies of two or more phenotypes in a population

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heterozygote advantage

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individuals with heterozygous at a certain locus that confers to them an advantage (cycle cell ammenia)

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macroevolution

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origin of new taxonomic groups

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speciation

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process by which a new species arise.

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two barriers to speciation

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1. prezygotic barriers - prevent mating or hinder fertilization
2. postzygotic barriers - those that prevent a fertilized egg from developing into a fertile adult

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5 examples of prezygotic barriers:

Habitat isolation

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two species can live in the same geographic area, but not in the same habitat; this will prevent them from mating.

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behavioral isolation

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some use certain signals or types of behavior to attract mates, the signals are unique to their species, members of other species will not recognize them preventing mating

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temporal isolation

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species may breed at different times of the day, different seasons, or different years, and this can prevent them from mating

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mechanical isolation

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species may be anatomically incompatible

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gametic isolation

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gametes may not be able to form zygote

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postzygotic barriers:

Reduced hybrid vitality

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when a zygote is formed, the fact that the two species are genetically incompatible may cause development to cease.

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reduced hybrid fertility

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even if the two species produce viable offspring, reproductive isolation is still occurring if the offspring are sterile

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hybrid breakdown

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if the two different species produce offspring that are viable and fertile, these hybrids may mate to produce weak or sterile offspring

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allopatric speciation

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a population forms a new species because it is geographically isolated from the parent population, small newly isolated pops are more likely to have their gene pools significantly changed, occurs when it is no longer able to mate with parent population

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sympatric speciation

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a small part of a population becomes a new population without being geographically isolated from parent pop

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geologic events or processes

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can fragment a population, formation of land bridge, evaporation of large lake to smaller lakes

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adaptive radiation

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occurs when many new species arise from a single common ancestor

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autopolyploid

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can be an example of sympatric speciation, species gets 4n chromosomes through nondisjunction and are unable to breed with the parent pop, but can with other tetrads

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polyploid speciation

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occurs in animals, but not common, instead, in animals, sympatric speciation can result from part of the population switching to a new habitat, food source, or other resource.

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punctuated equilibrium model

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species diverge in relatively quick spurts rather than slowly and gradually.

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evo-devo

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the field where evolutionary biology and developmental biology meet

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allometric growth

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different growth rates of various parts of an organism's body during development

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homeotic genes

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determine the location and organization of body parts. Hox genes are one class of homeotic genes

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phylogeny

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evolutionary history of a species or a group of related species

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systematics

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study of biological diversity in an evolutionary context.

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fossil record

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sequence in which fossils appear in the layers of sedimentary rock that constitute the earth's surface.

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paleontologists

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study the fossil record

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sedimentary rock

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formed from layers of minerals settling out of water Dead organisms settle along with the sediments and are compacted and sometimes preserved as fossils.

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relative dating

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can be used to date fossils. The fossils in each layer of sedimentary rock repersent certain time periods;

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index fossils

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found in more than one location that can be used to correlate information about the strata in both locations

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geologic time scale

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shows a consistent sequence of periods and events in the history of earth, divided into four eras, precambian, paleozoic, mesozoic, and cenozoic

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absolute dating

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refers to fossils' age given in years, rather than given in reference to one another.

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radiometric dating

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involves measuring the level of certain radioactive isotopes in fossils or rocks to determine their ages

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half-life

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of an isotope is the length of time it takes for 50% of the original sample of the isotope to decay.

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continents

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are not fixed; rather , they move slowly on tetonic plates of the earth's crust, which in turn float on the liquid mantle of the earth.

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pangaea

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about 250 million years ago, all of the major landmasses were brought together in a supercontinent which shaped much of biological evolution

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geographic isolation

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the brakeup of pangaea caused this

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two major extinctions

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permian extinction and the cretaceous extinction

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systematics

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study of biological diversity in the context of evolution, and it includes taxonomy, which is the naming and classification of species and groups of species.

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binomial

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used to describe species, consists of the genus and the species

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8 taxons

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domain, kingdom, phylem, class, order, family, genus, species

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phylogenic trees

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show the hierarchical classification of taxonomic levels for organisms

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cladograms

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each branch of the diagram is called a clade. the sequence of branches on cladogram is based on shared anscestry

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convergent evolution

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takes place when two organisms become alike because they adapted to similar environmental challenges, likenesses the result from convergent evolution are called analogies instead of homologies

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mollecular systematics

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of different organisms allows us to determine evolutionary relationships on a molecular level, allowing for new breakthroughs

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parsimony

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dictates that theories should be kept as simple as possible while still being consistent with the evidence, this way of thinking is used to create phylogneies

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molecular clocks

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methods used to place the origin of taxonomic groups more precisely in time