miller & levine biology chapter 19.2 & 19.3

macroevolutionary patterns

grand transformations in anatomy, phylogeny, ecology and behavior which usually take place in glades larger than a single species

what processes influence whether species and clades survive or become extinct?

if the rate of speciation in a clade is equal to or greater than the rate of extinction, the clade will continue to exist. it the rate of extinction in a clade is greater than the rate of speciation, the clade will eventually become extinct

background extinction

extinction of species at a slow and steady process of natural selection

mass extinction

an event during which many species become extinct over a relatively short period of time

how fast does evolution take place?

evidence shows that evolution has often proceeded at different rates for different organisms at different times over the long history of life on earth

gradualism

evolution that is slow and steady

punctuated equilibrium

periods of equilibrium (little to no change) interrupted by brief periods of more rapid change

reasons rapid evolution occurs

after a small population becomes isolated from the main population because genetic changes spread more quickly among fewer individuals and after mass extinctions because they open more ecological niches and create more opportunities for organisms that survive

coevolution

the process by which two species evolve in response to changes in each other over time

what evolutionary characteristics are typical of coevolving species?

the relationship between two coevolving organisms often becomes so specific that nether organism can survive without the other. thus, an evolutionary change in one organism is usually followed by a change in the other organism

what do scientists hypothesize about early earth and the origin of life?

earth's early atmosphere contained little or no oxygen

composition of earth's early atmosphere

carbon dioxide, water vapor, and nitrogen, lesser amounts of carbon monoxide, hydrogen sulfide and hydrogen cyanide

miller and urey's experiment

had similar conditions of earth's atmosphere bombarded with electricity; formed amino acids and other organic compounds

what did miller and urey's experiment suggest

suggested how mixtures of the organic compounds necessary for life could have arisen from simpler compounds on a primitive earth

endosymbiosis theory

proposes that a symbiotic relationship developed over time, between primitive eukaryotic cells and the prokaryotic cells within them: cells living together, where one organism lives inside another organism

how endosymbiosis happens

cell engulfs another cell through its membrane, blob cell absorbs more/different cells making it more complex and become better adapted

evidence of endosymbiosis

mitochondria and chloroplasts have similar DNA to ancient bacteria, have ribosomes with similar size and structure as ancient DNA, reproduce by binary fission like ancient bacteria

what's the evolutionary significance of sexual reproduction?

the development of sexual reproduction sped up evolutionary change because sexual reproduction increased genetic variation