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79 Cards in this Set
- Front
- Back
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Natural Selection
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survival of the fittest
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Evolutionary Adaptation
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an accumulation of inherited characteristics that enhance an organisms ability to survive and reproduce in specific environments
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Evolution
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Change over time in genetic composition of a population
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Taxonomy
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branch of biology for naming/classifying organisms
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Sedimentary Rocks
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formed from sand and mud that settle to bottom of seas, lakes and marshes
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Paleontology
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study of fossils
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Catastrophism
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each boundary between strata represents a catastrophe
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gradualism
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idea that change can take place through slow but continuous processes
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uniformitarianism
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same geologic processes from the past are still operating today, at the same rate
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descent with modification
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all organisms are related through descent from an ancestor that lived in the past
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artificial selection
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human modification of breeding species with desired traits
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homologous structures
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same structure, different function
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vestigial organs
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structures that have no importance to the organism/ remnants of important functions of ancestors
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biogeography
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geographic distribution of species
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endemic
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found nowhere else in the world
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microevolution
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evolutionary change on the smallest scale
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population genetics
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study of how populations change genetically over time
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modern synthesis
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theory of evolution that integrated ideas from other fields
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gene pool
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aggregate of genes in a population at any one time
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Hardy-Weinberg Theorem
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frequencies of alleles and genotypes in a populations gene pool remain constant from generation to generation
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Hardy Weinberg Equlibrium
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genotype frequencies can be predicted from allele frequencies
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duplication
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important source of variation
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genetic drift
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allele frequiencies can fluctuate unpredictably in one generation to the next
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bottleneck effect
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A Genetic drift resulting from the reduction of a population, from 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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when a few individuals become isolated from a larger population this smaller group may establish a new population whose gene pool is not reflective of the source population
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gene flow
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genetic additions to or subtractions from a population resulting from the movement of fertile individuals or gametes
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Geographic variation
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differences between gene pools of separate populations or population subgroups
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fitness
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the contribution an individual makes to the gene pool of the next generation, relative to contributions of other individuals
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Directional selection
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most common when a populations environment changes or when members of a population migrate to a new habitat with different environmental conditions than their former one
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Stabilizing selection
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acts against extreme phenotypes and favors intermediate variants
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Balancing Selection
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occurs when natural selection maintains 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 gene locus have greater fitness than the homozygotes, natural selection will tend to maintain two or more alleles at that locus
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frequency- dependent selection
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fitness of any one morph declines if it becomes too common in the population
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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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differences between the sexes in secondary sexual characteristics, which are not directly associated with reproduction
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intersexual selection
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called mate choice, indviduals of one sex(females usually) are choosy in selecting mates from other sex
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intrasexual selection
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means "selection with same sex" direct competition among indviduals of one sex for mates of opposite sex ( most obvious in males). rawr.
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speciation
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origin of new species
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macroevolution
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evolutionary change above the species level
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reproductive isolation
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existence of biological barriers that impede members of two species from producing viable, fertile hybrids.
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prezygotic barriers
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(before the zygote) impede mating between species or hinder the fertilization of ova if members of different species attempt to mate
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morphological species concept
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characterizes a species by its body, shape, size, and other structural features
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paleontological species concept
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focuses on morphologically descrete species known only from the fossil record.
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sympatric speciation
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speciation that takes place in geographically overlapping populations
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polyploidy
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extra set of chromosomes resulting from mutational change
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allopolyploid
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various mechanisms that can change a sterile hybrid into a fertile polyploid
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adaptive radiation
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the evolution of many diversely adapted species from a common ancestor upon introduction to various new environmental opportunities and challenges
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punctuated equilibrium
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periods of apparent stasis punctuated by sudden change
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allometric growth
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proportioning that gives a body its specific form
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paedomorphosis
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the sexually mature stage of a sepcies may retain body features that were juvenile structures in an ancestral species
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homeotic genes
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determines basic features-
such as a pair of wings and legs will develop on a bird of how a plants flower parts are arranged |
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phylogeny
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evolutionary history of a species or group of species
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systematics
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an analytical approach to understanding diveristy and relationships of organisms both present day and extinct
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molecular systematics
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uses comparisons of DNA, RNA, and other molecules to infer evolutionary relationships between indivudla genes and even between entire genomes
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fossil record
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based on sequence in which fossils have accumlated in strata
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homoplasies
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analogous structures that have evolved independently
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binomial
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two part format of scientific name
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genus
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first part of name to which a species belongs
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domains
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divisions of kingdoms
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taxon
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taxonomic unit at any level
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cladogram
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patterns of shared characteristics that can be depicted in a diagram
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cladistics
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analysis of how species may be grouped into clades
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outgroup
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species or group of species that is closely related to the ingroup* - (the various species we are studying)
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phylogram
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the length of a branch reflects the number of changes that have taken place in a particular DNA sequence in Lineage (figure 25.12) Pg 499
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orthologous genes
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homologoues genes that are passed in a straight line from one generation to the next but have ended up in different gene pools because of speciation
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paralogous genes
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result from gene duplication so they are found in more than one copy in the same genome
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molecular clock
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a yardstick for measuring abosolute time of evolutionary change based on the observation that some genes and other regions of genomes appear to evolve at constant rates
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horizontal gene transfer
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genes are transferred from one genome to another through mechanisms such as transposable elements, and perhaps through fusions of different organisms
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protobionts
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aggregates of abiotically produced molecules surrounded by a membrane or membrane like structure
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ribozymes
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RNA that carrys out a number of enzyme like catalytic functions
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radiometric dating
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based on the decay or radioactive isotopes
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half life
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number of years it takes for 50$ of the original sample to decay UNAFFECTED by temperature, pressure, and other variables
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magnetic reversals
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produced by earths north and south magnetic poles reversing in the past
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geologic record
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earths history divided into 3 eons
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serial endosymbiosis
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a sequence of endosymbiotic events - supports that mitochondria evolved before palstids
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genetic annealing
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horizontal gene transfers occured between many different bacterial and archean lineages
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snowball earth hypothesis
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life confined to areas near deep sea vents/ hot springs or those sparse regions of the ocean where enough ice has melted to penetrate surface waters for sunlight
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Pangea
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"means all land" supercontinent
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3 domain system
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Bacteria, Archaea, and Eukarya
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