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adaptation
an inherited characteristic that enhances and organisms ability to survive and reproduce in a particular environment
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adaptive radiation
period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill new or vacant ecological roles in their communities.
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algae
a protist that produces its food by photosynthesis
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binomial
a two-part latinized name of a species; for example, homo sapeian
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bottleneck effect
genetic drift resulting from a drastic reduction in population size; typically, the surviving population is no longer genetically representative of the original population
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clade
a group of species that includes and ancestral species and all its descendants
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cladistics
an approach to systematics in which common descent is the primary criterion used to classify organisms by placing them into groups called clades
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endosymbiosis
a process by which the mitochondria and chloroplasts of eukaryotic cells probably evolved from symbiotic associations between small prokaryotic cells living inside larger cells
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evolution
descent with modification; the idea that living species are descendants of ancestral species that were different from present-day ones; also the genetic changes in a population over generations
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evolutionary tree
a branching diagram that reflects a hypothesis about evolutionary relationships among groups of organisms
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extinction
it irrevocable loss of a species
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founder effect
genetic drift that occures when a few individuals become isolated from a larger population, whit the result that the composition of the new population's gene pool in not reflective of that of the original population
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gene flow
the transfer of alleles from one population to another, as a result of the movement of individuals or their gametes
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gene pool
all the alleles for all the genes in a population
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genetic drift
a change in the gene pool of a population due to chance; effects of genetic drift are most pronounced in small populations
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homology
similarity in characteristics resulting from a shared ancestry
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hybrid zones
a geographic region in which members of different species meet and mate, producing at least some hybrid offspring
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macroevolution
evolutionary change on a grand scale, encompassing the origin of new taxonomic groups, evolutionary trends, adaptive radiation, and mass extinction
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microevolution
a change in a populations gene pool over generations
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parsimony
in scientific studies, the search for the least complex explination for an observed phenomenon
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polyploidy
an organism that has more than two complete sets of chromosomes as a result of and accident of cell division
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protists
a member of the Kingdom Protista. most protists are unicellular, though some are colonial or multicellular
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protozoan
a protist that lives primarily by ingesting food;a hererotrophic, "animal-like" protists
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sexual dimorphism
marked differences between the secondary sex characteristice of males and females. pecocks
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symbiosis
a close association between organisms of two or more species
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taxon
a named taxonomic unit at any given level of classification
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taxonomy
the branch of biology that identifies, names, and classifies species
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