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85 Cards in this Set
- Front
- Back
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natural selection
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Differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. Evolution occurs when natural selection causes changes in relative frequencies of alleles in the gene pool
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evolutionary adaptation
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An accumulation of inherited characteristics that enhance organisms’ ability to survive and reproduce in specific environments.
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evolution
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All the changes that have transformed life on Earth from its earliest beginnings to the diversity that characterizes it today.
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fossils
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A preserved remnant or impression of an organism that lived in the past
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sedimentary rocks
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Rock formed from sand and mud that once settled in layers on the bottom of seas, lakes, and marshes. Sedimentary rocks are often rich in fossils
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taxonomy
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A set of characteristics used to assess the similarities and differences between various species, leading to a classification scheme; the branch of biology concerned with naming and classifying the diverse forms of life
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paleontology
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The scientific study of fossils.
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catastrophism
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the hypothesis by Georges Cuvier that each boundary between strata corresponded in time to a catastrophe, such as a flood or drought, that had destroyed many of the species living there at that time.
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gradualism
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A view of Earth’s history that attributes profound change to the cumulative product of slow but continuous processes; Hutton
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uniformitarianism
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Charles Lyell’s idea that geologic processes have not changed throughout Earth’s history
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descent with modification
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Darwin’s initial phrase for the general process of evolution.
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artificial selection
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The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits
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inference #1
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Production of more individuals than the environment can support leads to a struggle for existence among individuals of a population, with only a fraction of their offspring surviving each generation
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inference #2
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Survival depends in part on inherited traits. Individuals whose inherited traits give them a high probability of surviving and reproducing in a given environment have higher fitness and are likely to leave more offspring than less fit individuals
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inference #3
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This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations
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vestigial organs
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A structure of marginal, if any, importance to an organism. Vestigial organs are historical remnants of structures that had important functions in ancestors.
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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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Structures in different species that are similar because of common ancestry
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analogous structures
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similar functions; different structures
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biogeography
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The study of the past and present distribution of species
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microevolution
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Evolutionary change below the species level; change in the genetic makeup of a population from generation to generation
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population genetics
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The study of how populations change genetically over time
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modern synthesis
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A comprehensive theory of evolution emphasizing populations as units of evolution and integrating ideas from many fields, including genetics, statistics, paleontology, taxonomy, and biogeography
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population
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A localized group of individuals that belong to the same biological species (that are capable of interbreeding and producing fertile offspring)
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gene pool
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The total aggregate of genes in a population at any one time
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hardy-wineberg theorem
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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; criteria (1) large population (2) no mutations (3) no gene flow (4) random mating (5) no natural selection
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mutations
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A rare change in the DNA of a gene, ultimately creating genetic diversity
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duplication
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An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated
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genetic drift
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Unpredictable fluctuations in allele frequencies from one generation to the next because of a population’s finite size
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bottle neck effect
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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.
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founder effect
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Genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the new population’s gene pool is not reflective of the original population
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gene flow
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Genetic additions to or substractions from a population resulting from the movement of fertile individuals or gametes
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phenotypic polymorphism
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The existence of two or more distinct morphs (discrete forms), each represented in a population in high enough frequencies to be readily noticeable
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genetic polymorphism
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The existence of two or more distinct alleles at a given locus in a population’s gene pool.
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morph
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distinct forms of a allele or phenotype in a population
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average heterozygosity
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The percent, on average, of a population’s loci that are heterozygous in members of the population
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geographic variation
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Differences between the gene pools of separate populations or population subgroups
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cline
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A graded variation in a trait that parallels a gradient in the environment
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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 one genotype to the next generation compared to that of alternative genotypes for the same locus
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directional selection
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selection that shifts the frequency curve for some phenotypic character in one direction or the other by favoring individuals that deviate from the average
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disruptive selection
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Natural selection that favors individuals on both extremes of a phenotypic range over intermediate phenotypes
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stabilizing selection
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Natural selection that favors intermediate variants by acting against extreme phenotypes
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balancing selection
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Natural selection that maintains stable frequencies of two or more phenotypic forms in a population (balanced polymorphism)
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sexual selection
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Natural selection for mating success
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sexual dimorphism
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A special case of polymorphism based on the distinction between the secondary sex characteristics of males and females
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intrasexual selection
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A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex
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intersexual selection
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Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice
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speciation
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The origin of new species in evolution
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microevolution
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Evolutionary change below the species level; change in the genetic makeup of a population from generation to generation
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macroevolution
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Evolutionary change above the species level, including the appearance of major evolutionary developments, such as flight, that we use to define higher taxa
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species
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A group whose members possess similar anatomical characteristics and have the ability to interbreed.
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biological species concept
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Definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations
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reproductive isolation
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The existence of biological factors (barriers) that impede members of two species from producing viable, fertile hybrids
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prezygotic barriers
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A reproductive barrier that impedes mating between species or hinders fertilization of ova if interspecific mating is attempted (habitat isolation, temporal isolation, behavorial isolation, mechanical isolation, gametic isolation)
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postzygotic barriers
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Any of several species-isolating mechanisms that prevent hybrids produced by two different species from developing into viable, fertile adults (reduced hybrid vaibility, reduced fertility, hybrid breakdown)
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morphological species concept
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Defining species by measurable anatomical criteria; useful b/c can be applied to asexual & sexual organisms, info on gene flow not necessary; bad b/c subjective assessment
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paleontological species concept
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Definition of species based on morphological differences known only from the fossil record
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ecological species concept
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Defining species in terms of ecological roles (niches)
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phylogenetic species concept
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Definition of a species as a set of organisms with a unique genetic history—that is, as one branch on the tree of life.
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allopatric speciation
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A mode of speciation induced when an ancestral population becomes segregated by a geographic barrier or is itself divided into two or more geographically isolated subpopulations
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sympatric speciation
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A mode of speciation occurring as a result of a radical change in the genome of a subpopulation, reproductively isolating the subpopulation from the parent population
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polyploidy
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A chromosomal alteration in which the organism possesses more than two complete chromosome sets.
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autopolyploid
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An individual that has more than two chromosome sets, all derived from a single species
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allopolyploid
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A common type of polyploid species resulting from two different species interbreeding and combining their chromosomes
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adaptive radiation
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The emergence of numerous species from a common ancestor introduced into an environment that presents a diversity of new opportunities and problems.
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punctuated equilibrium
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In evolutionary theory, long periods of apparent stasis (no change) interrupted by relatively brief periods of sudden change
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heterochrony
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Evolutionary change in the timing or rate of an organism’s development.
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allometric grwth
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The variation in the relative rates of growth of various parts of the body, which helps shape the organism
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paedomorphosis
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("paedos"-child; "morphosis"-form) The retention in an adult organism of the juvenile features of its evolutionary ancestors
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homeotic genes
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Any of the genes that control the overall body plan of animals and plants by controlling the developmental fate of groups of cells.
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species selection
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A theory maintaining that species living the longest and generating the greatest number of species determine the direction of major evolutionary trends
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habitat isolation
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different habitats
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temporal isolation
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species breed during different times
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behavioral isolation
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different courtships rituals for different species
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mechanical isolation
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morphological differences prevent successful mating
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gametic isolation
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sperm of one species may not be able to fertilize egg of another species
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reduced hybrid viability
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genes of different parent species may interact and impair the hybrid's development
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hybrid breakdown
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fertile first generation hybrids produce sterile offspring
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reduced hybrid fertility
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sterile hybrid; mule
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anagenesis
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("ana"=different; "genesis"=race) accumulation of changes that gradually transform a given species into a species with different characteristics
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cladogenesis
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("klados"-branch) splitting of gene pool into two or more separate pools; only one that can promote biological diversity by increasing # of species
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frequency dependant selection
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fitness of one morph declines if it becomes too common on the population
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neutral variation
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genetic diversity taht confers no genetic advantage
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pseudogene
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genes taht have become inactive
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