macroevolution

macroevolution

evolution above the species level

microevolution

refers to processes that occur within species

George Gaylord Simpson
Bernhard Rensch

argued that macroevolution is based on microevolutionary processes, and differs only in scale

facilitated variation

core processes of protein activity and cell and organ devt have properties of robustness and adaptability that cause some variation to arise in ways that facilitate evolution

irreducible complexity

the proposition that a complex organismal feature cant function effectively except by the coordinated action of all its components so that the feature must have required all of its components from the beginning

novel characteristics

include both new modifications of ancestral structures and truly new structures

biological homology

wagner referrd to the similarity based on a common genetic developmental program as ____, characters are defined as homologous if and only if they have been inherited from common ancestors

deep homology

genetic regulatory pathways that may be widely inherited and independently expressed in diff evolving lineages (Neil Shubin and colleagues)

phylogenetic niche conservatism

long continued dependence of related species on much the same resources and environmental conditions

habitat tracking

shift in geographic distribution of species along with changes in the geographic distribution of habitat to which the species are adapted

Eldredge and Gould

proposed punctuated equilibria in 1971

stasis

punctuated by rapid change

phyletic gradualism

traditional notion of slow, incremental change

trend

persistent, directional change in the average value of a feature or perhaps its maximal value in clade over the course of time

passive trend

lineages in the clade evolve in both directions w equal probability but if theres a strong constraint in one direction, the variation among lineages can expand only in the other direction

driven or active trend

changes in one direction are more likely changes in the other so both maximal and minimal character values change along with the mean

genome size

amount of dna in the nucleus

punctuated equilibria

the idea that evolution occurs in spurts instead of following the slow, but steady path

divergent evolution

when two or more biological characs have a common evolutionary origin but have diverged over evolutionary time

adaptive evolution

divergent evolution is aka

convergent evolution

organisms not closely related that independently evolve similar traits as a result of having to adapt to similar environments or ecological niches

analogous structures

convergent evolution is exemplified by

parallel evolution

independent evolution of similar traits, starting from a similar ancestral condition; occurs when related species evolve similar features while being separated from each other

homologous structures

structures involved in divergent evolution

coevolution

two or more species reciprocally affect each other’s evolution

adaptive radiation

organisms diversify rapidly from an ancestral species into a multitude of new forms, micro

gradualist model

popns evolve differences gradually as they become adapted to their local environments

gradualist model

slow and steady, transition forms in the fossil record

gradualism

selection and variation that happens more gradually over a short period of time that is hard to notice

exaptation

may be exhibited by lineages undergoing the gradualist model; shift in the function of a trait during evolution

exaptation

a trait can evolve because it served one particular function but subsequently it may come to serve another

punctuated equilibrium model

popns undergo long periods of equilibrium where little changes take place, punctuated by short periods of rapid change which may account for the lack of transitional stages in fossil records

cambrian explosion

appearance and rapid diversification of most major living animal phyla in the fossil record within an interval of 20m years or less, 544-505mya

hard structures

during cambrian explosion, animals developed ___ which greatly enhanced the chance of an organism becoming a fossil

mass extinction events

widespread or rapid decrease in the amount of life on earth where rate of extinction is greater than rate of speciation

flood basalt events
rapidly falling sea levels
bolide impact

possible explanations for mass extinction events

flood basalt events

result of giant volcanic eruption or series of eruptions that coats large stretcher of land or the ocean floor with basalt lava caused by combi of continental drifting and its associated decompression melting

rapidly falling sea levels

receding of continental shelved could lead to mass extinctions of marine flora and fauna; caused by global cooling

bollide impact

cause by large asteroid hitting the earth; caused acid rains, forest fires tsunamis; disrupt food chain

ordovician-silurian extinction

440-450 mya, 60-70% of all species

late devonian extinction

360-375 mya, 70% of all species

permian triassic extinction

251 mya, 90-96%, provided the niche for archosaurs to predominate

the great dying

permian triassic extinction is also known as

triassic jurassic extinction

200 mya, 70-75%, extinction of most non-dinosaur archosaurs, large amphibians and therapsids

cretaceous-paleogene extinction

66mya, 75%, mammals and birds predominated after the event, likely caused by bollide impact or by colossal volvanic eruptions

Gerta keller et al. Brian gertsch et al

volcanic eruptions proposed by

holocene extinction

ongoing extinction caused by human activities; extinction of megafauna

hunting and foraging

first wave of extinction is attributed to

Raphus cucullatus (dodo)

flightless bird, extinct 1600s

agricultural revolution

second wave of extinction is attributed to

industrial revolution up to the present

third wave of extinction is attributed to