AP Biology Chapters 22, 23, 24, 25, 26 – Flashcards
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natural selection
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the mechanism for evolution -Variation -Overproduction -Competition -Differential Success -Reproduction -Repetition
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evolutionary adaptation
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individuals with beneficial heritable traits leave more offspring, and the frequency of such traits in a population increases over generations
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taxonomy
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the branch of biology that names and classifies organisms; originated in the work of Linnaeus
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fossils
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remnants or impressions of past organisms
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paleontology
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the study of fossils
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catastrophism
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Cuvier maintained that the differences he observed in the fossils found in different strata were the result of locat catastrophic events such as floods or drought and were not indicative of evolution
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gradualism
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the idea that immense change is the cumulative result of slow but continuous processes; proposed by Hutton and Lyell
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artificial selection
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humans have modified other species over many generations by selecting and breeding individuals that posses desired trait
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homology
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similarity in characteristics resulting from a shared ancestry
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homologous structures
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represent variations on a structural theme that was present in their common ancestry
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vestigial organs
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structures of marginal importance to the organism
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biogeography
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the study of the past and present distribution of species
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endemic
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plants and animals found nowhere else in the world
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sedimentary rocks
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how most fossils are formed; sand and mud that settles to the bottom of seas, lakes, and marshes.
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uniformitarianism
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Lyell's idea that geologic processes have not changed throughout Earth's history
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descent with modification
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a phrase that condenses Darwin's view of life
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population genetics
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emphasizes the extensive genetic variation within populations and recognizes the importance of quantitative characters
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modern synthesis
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a comprehensive theory of evolution that integrates discoveries and ideas from many different fields, including paleontology, taxonomy, biogeography, and, of course, population genetics
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population
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a localized group of individuals belonging to the same species
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species
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group of populations whose individuals have the potential to interbreed and produce fertile offspring in nature
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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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Hardy-Weinberg theorem
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the frequencies of alleles and genotypes in a population's gene pool remain constant over the generations unless acted upon by agents other than Mendalian segregation and recombination of alleles
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Hardy-Weinberg equilibrium
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A population that matches the following five main conditions: very large population size, no migration, no net mutations, random mating, and no natural selection
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p2
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homozygous dominant individuals in a population
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2pq
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heterozygous individuals in a population
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q2
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homozygous recessive individuals in a population
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bottleneck effect
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a drastic reduction in population size
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founder effect
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genetic drift in a new colony
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gene flow
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genetic exchange due to the migration of fertile individuals or gametes between populations
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mutation
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change in an organism's DNA
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polymorphic
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two or more distinct morphs are each represented in high enough frequencies to be readily noticeable
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gene diversity
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measures the average percentage of gene loci that are heterozygous
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nucleotide diversity
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comparing the nucleotide sequences of DNA samples from two individuals then pooling the data from many such comparisons of two individuals
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geographic variation
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differences in gene pools between populations or subgroups of populations
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cline
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a graded change in some trait along a geographic axis
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balanced polymorphism
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the ability of natural selection to maintain stable frequencies of two or more phenotypic forms in a population
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heterozygote advantage
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Individuals who are heterozygous at a particular locus have greater survivorship and reproductive success than any type of homozygote
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frequency-dependent selection
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the survivial and reproduction of any one morph declines if that phenotypic form becomes too common in the population
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neutral variation
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confer no selective advantage for some individuals over others
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Darvinian fitness
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the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals
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relative fitness
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the contribution of a genotype to the next generation compared to the contributions of alternative genotypes for the same locus
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directional selection
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when members of a population migrate to some new habitat with different environmental conditions
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diversifying selection
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environmental conditions are varied in a way that favors individuals on both extremes of a phenotypic range over intermediate phenotypes
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stabilizing selection
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acts against extreme phenotypes and favors the more common intermediate variants
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sexual dimorphism
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marked differences that are not directly associated with reproduction
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intrasexual selection
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direct competition among individuals of one sex for mates of the opposite sex
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Phylogeny
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The evolutionary history of a species or group of related species.
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How are fossils significant to our study of biology?
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Fossil records are a substantial, but incomplete, chronicle of evolutionary history
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Fossil key Points
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-Sedimentary rocks are the richest source of fossils. -Paleontologists use a variety of methods to date fossils. -The fossil record is a substantial, but incomplete, chronicle of evolutionary history. -Phylogeny has a biogeographic basis in continental drift. -The history of life is punctuated by mass extinctions.
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Examples of fossils
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Insects preserved in amber and mammals frozen in ice.
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What techniques does relative dating use to place fossils in their place in geologic time?
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Radiometric dating, which is based on the decay of radioactive isotopes, the rate of decay is experienced by the half-life. Method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock.
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What marks the separation between the major eras in the geologic time scale?
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Mass extinctions
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Absolute dating
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give rocks an actual date, or date range, in number of years.
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Relative dating
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Only puts geological events in time order, meaning it does not indicate the rocks age.
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Describe the two main characteristics of the Linnaean system of classification.
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-The genus: The first part of the latin name which describes where the species belonged. -The specific epithet: The second part of the latin name which described what was unique to the species within the genus Family---->Orders---->Classes----->Phyla----->Kingdoms---> Domains (Archea, Bacteria, Eukarya)
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Phylogenetic Trees
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The evolutionary history of a group of organisms.
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When classifying organisms in a cladistic diagram, identify three pitfalls scientists might encounter classifying creatures.
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-Over the course of evolution, a species has lost a key feature shared by its closest relatives. -Linnaean system may distinguish groups, such as mammals, reptiles, birds, and other classes of vertebrates, it tells us nothing about these group' evolutionary relationship to one another. -Some commonly recognized groups would become part of other groups previously of the same rank. For example, because birds evolved from a group of reptiles, Aves (the Linnaean class to which birds are assigned), would be considered a subgroup of Reptilia (also a class in the Linnaean system).
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What do scientists use when placing an organism on a cladistic diagram?
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Patterns of shared characteristics. Each branch point represents the divergence of two evolutionary lineages from a common ancestor.
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How have molecular clocks influenced our thoughts on evolutionary paths?
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Molecular clocks are a yardstick for measuring the absolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates.
