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Gonzaga University Biology 101

gene flow

movement of alleles from one population to another


DNA polymerase makes an error, the base sequence changes, the protein coded by the sequence may be different

Biological species concept

the definition of a species as a population or group of populations that are reproductively isolated from other groups

disadvantages of biological species concept

what about species that reproduce asexually? it can only be applied to populations that overlap geographically

prezygotic isolation

individuals of different species are prevented from mating

postzygotic isolation

offsprings of matings between members of different species do not survive or reproduce

mechanical isolation

morphology prevents breeding

behavioral isolation

different mating behaviors

genetic isolation

breeding occurs, but gametes don't match

hybrid inviability and infertility

offspring die or can't reproduce

morphospecies concept

distinguishing features are most likely to arise if populations are independent and isolated from gene flow

phylogenetic species concept

reconstruct the evolutionary history of populations

monophyletic group

an ancestral population plus all of its descendants


trait found in certain groups of organisms that exists in no others, "unique forms"


populations that live in discrete geographic areas and have distinguishing features


population colonizes a new habitat and forms a new population


physical barrier splits a population into subgroups that are physically isolated

allopatric speciation

speciation that begins with physical isolation via dispersal or vicariance

sympatric speciation

speciation of populations that live in the same time and place

ecological isolation

species use different habitats

temporal isolation

species breed at different times

phylogenetic trees

document the evolutionary relationships among organisms and are estimated from data

mass extinction

environmental catastrophes that rapidly eliminate species and have occurred repeatedly throughout the history of time

phylogenetic inference

studies of living specimens, fossils, DNA, RNA, protein, and genetics


calculate a statistic that summaries similarity


identify synapomorphies, shared derived traits...closely related taxa should share the most

ancestral trait

a characteristic that existed in an ancestor

derived trait

a modified form of the ancestral trait, found in a descendant

convergent evolution

similarities evolve independently


similar traits due to shared ancestry


similar traits but independent evolution

background extinction

average rate of extinction caused by gradual change, competition, new diseases

End-Permian extinction hypothesized causes

intense global warming, oceans became anoxic, sea level dropped dramatically, low O2 and high CO2 levels in the atmosphere

ecological opportunity

new or novel resources become available

morphological innovation

evolution of key trait


sticky layer outside of cell wall (polysaccharide or protein)


attachment pili (protein appendages)


motility, high velocity potential

membrane folding

increases surface area for chemical reactions


prokaryotes use them to battle harsh environments


uptake of foreign DNA from surroundings


phage construction error. horizontal gene transfer


combining DNA with other bacteria


bacteria that cause disease


first organisms to perform oxygenic photosynthesis, became chloroplast

unique prokaryotic adaptations

diverse metabolic pathways, cell walls, surface adaptations, membrane folding, reproductive strategies

adaptive radiation

The diversification of a group of organisms into forms filling different ecological niches


spherical, very tiny. endosymbionts--they live as parasites inside animal cells


diverse morphology, some are multicellular, use every metabolic pathway except oxygenic photosynthesis, E. coli is a member, became mitochondria


live in virtually every habitat, including extreme environments. no known parasitic


3.5 bya

prokaryotic photosynthesis

2.7 bya

eukaryotic cells/oxygen increases

2.2-2.1 bya

cambrian explosion, animals appear

550 mya


400 mya


300 mya


200 mya


150 mya

dinosaurs go extinct

65 mya


200,000 ya

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