Ch 11. Species and Races Flashcards Preview

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Flashcards in Ch 11. Species and Races Deck (50)
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1

species

group whose members have the greatest resemblance. each has 2 part name

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2 part name of species

1st: indicates genus, a broader group
2nd: specific to species within genus

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biological species

consistent definition to determine differences between species

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reproductively isolated

can interbreed and produce fertile offspring, but cant reproduce with other species

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gene pool

sum total of all alleles within a species. makes an impermeable container for gene pool. change in frequency can only happen within a species

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prefertilization barriers

failure to mate/produce an embryo

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spatial isolation

prefert. different species dont come in contact

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behavioral isolation

prefert. ritual mating behaviors differ

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mechanical isolation

prefert. incompatible sex organs

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temporal isolation

prefert. timing of readiness to reproduce is diferent

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gamete incompatibility

prefert. proteins on egg that allow sperm to bind dont work for another species

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postfertilization barriers

fertilization occurs, but hybrid cant reproduce

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hybrid inviability

postfert. zygote cant complete development because genetic instructions incomplete

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hybrid sterility

postfert. hybrid cant produce offspring because chromosome number is odd. (mule)

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speciation

evolution of species from an ancestral form. isolated population diverge in traits. divergance can lead to reproductive isolationa nd formation of a new species. 3 steps necessary

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3 necessary steps for speciation

1.isolation of gene polls of subgroups/populations of the species
2.evolutionary changes in gene pools of 1 or both of isolated population
3. evolution of reproductive isolation between population, preventing future gene flow

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founder hypothesis

diversity of unique species on oceanic islands and isolated bogs, caves, and lakes resulted from colonization by 1 species that rapidly speciated, taking advantage of many different resources. allopatric or sympatric.

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allopatric

isolation due to geographic barrier

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sympatric

separation of gene pool even when near each other

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polyploidy

process of chromosome duplication. if occurs in hybrid, fertility may be possible again. mostly in plant and some insects and frogs.

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instantaneous speciation

hybrids from polyploidy may produce offspring and are immediately creating a new species (can't reproduce with parental species) due to genetic incompatability (polyploidy creates double the genes as the parents)

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gradualism

speciation occurring over millions of years with tiny changes accumulating

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punctuated equilibrium

dramatic changes in few thousand years, followed by many thousands or millions of years of little changes

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biological race

populations of a single species that have diverged. little gene flow between them, evolutionary changes differ between populations

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geneological species concept

species is smallest group of reproductively compatible organisms containing all known descendants of a common ancestor. emphasizes unique evolutionary lineages, increasing number of identifiable species

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human races

white, black, pacific islander, asian, australian, aborigine, and native american. physical differences used to define are skin color, hair texture, eye, skull, and nose shape

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morphological species concept

individuals of same species look alike (similar morphology). correlated with isolation of gene pools. mostly used by paleontologists

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out-of-africa concept

homio sapiens evolved once in africa from homo erectus. most supportive data

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multiregional hypothesis

homo sapiens evolved throughout range of homo erectus

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hybridization-and-assimilation hypothesis

homo sapiens evolved out of africa and migrated and hybridized with homo erectus in different areas of globe