Macroevolution Flashcards
What is macroevolution?
Evolution on a scale at or above the level of species.
What is microevolution?
Refers to smaller evolutionary changes of allele frequencies within a species or population.
What was the Neo-Darwinism evolutionary theory from 1895?
Combination and integration of natural selection and genetics, Darwin’s theory and Mendel’s theory, refers to modern synthesis, unified theory.
Patterns of biodiversity?
Processes generating biodiversity, biodiversity pump, processes reducing biodiversity, cull biodiversity.
Characteristics of speciation?
Geological and environmental changes, natural selection favour particular aleles, separation due to mountains lakes etc, populations different, no interbreeding, different species.
Characteristics of extinction?
Species completely dies out, new competition predators disease, changes in environment, lack of adaptation, volcanoes earthquakes, cyclical nature of speciation, taxonomic change.
Sympatric evolution?
Evolution of a new species from surviving ancestral species, both same geographic region.
Parapatric evolution?
New species evolve in contiguous spatially segregated habitats.
Peripatric speciation?
Speciation in which new species formed from isolated peripheral population.
Allopatric speciation?
Geographic of vicariant speciation, biological populations become geographically isolated.
Cladogenesis?
Evolutionary splitting of a parent species into two distinct species, forming a clade.
Anagenesis?
Evolution within a lineage.
Genetic drift?
Change in composition of a gene pool as a result of a random or change event.
Selection?
Change in gene pool as a result of differentially selective environmental pressues.
What is adaptive radiation?
Event in which lineage rapidly diversifies with newly formed lineages evolving different adaptations, different factors may trigger adaptive radiations but each is a response to an opportunity.
Pros of island systems?
No competition, reduced predation, less food increase inbreeding, founder effect, selective pressures.
Characteristics of Hyracotherium?
Earliest horse like form, more dog like, pads for feet, 3 hind toes, 4 front toes, small brain case, herbivory teeth, browser not grazer (tooth crown), common in Miocene.
Why did Hyracotherium have separate evolutionary paths?
Consequence of the isolation of continents resulting from continental drift - speciation.
Characteristics of Miohippus?
Evolution of Hyracatherium, not quite horse, larger, big brain case, different forefeet, loss of little digit, lateral digits reduced, several lineages existed, one branch gave rise to true horse.
Characteristics of Merychippus?
True horse line, larger bodied, premolars and molars like modern horse, long high crowned teeth, lengthened enamel ridges, ridges filled with cement, major change in teeth.
Reasons why grass shaped horse evolution?
Tough, high silica, apical meristem close to ground, adaptations against herbivory.
Reasons why teeth shaped horse evolution?
High crowned, adaptation against wear from silica, merychippus grazer and deeper skull, accommodate lengthened teeth.
Characteristics of spring foot?
Hoofed feet, elastic ligaments, more efficient, better mechanism, foot bent upon impact, suspensorio ligament provides lift, adaptation to running.
What is convergent evolution?
Organisms that are not closely related evolve similar features or behaviours.
Characteristics of convergent evolution?
Same traits evolved independently, solutions to same problems, lead to adaptive radiations, similar habitat selection pressures.
Total number of described species?
2 million.
Total number predicted species?
15 million.
Characteristics of Coelacanth (living fossil)?
Example of species persistence, carnivorous fish, live up to 60 years, up to 2 meters length, lobed fins, extinct.
Examples of extinct animals due to human infleunce?
Pleistocene megafauna - sabre toothed cat, giant ground sloth, woolly mammoth.
Example of a type of species badly affected?
Island species.
How old is the Earth?
4.55 billion years old.
How long has life been on Earth?
3.8 billion years.
How long did bacteria dominate Earth for first?
3.1 billion years.
Composition of primitive atmosphere?
Nitrogen, CO2, hydrogen, water vapour.
Why did the primitive atmosphere favour prokaryotes?
Environment creates a primordial soup where prokaryotes developed a range of metabolic adaptations.
Bacteria vs Cyanobacteria?
Cells small vs large, flagella vs none, autotrophic and heterotrophic vs only autotrophic, anoxygenic vs oxygenic, aerobic and anaerobic vs aerobic, reserve food glycogen vs cyanophycean starch.
Characteristics of atmospheric revolution?
Arrival of Cyanobacteria, oxygen released, initially soaked up by iron dissolved in oceans, starts building up in atmosphere, arrival of atmospheric oxygen and mass extinction.
When did mitochondria evolve?
After great oxygenation event (GOE).
What happened during Cambrian?
Diversity gradually increased and exploded.
What is the rate of accumulation of diversity like?
Not constant, periods of diversification followed by stable periods and mass extinction.
What was the K-T event?
End of Cretaceous, excitation of dinosaurs etc, due to meteorites near Mexico and Ukraine, also mantle plume eruption on Indian subcontinent, volcanic eruption.
What did K-T mass extinctions result from?
Short term acid rain, long term atmospheric barrier to solar radiation.
Why would early mammals likely survive K-T adverse conditions?
Burrowing habits.
Rate of current extinction?
Sixth mass extinction, increasing global temps.
When did large animal extinctions coincide with?
Arrival of modern humans.
The Holocene extinctions?
Describes ongoing extinction events of species during present Holocene epoch due to human activity.
Consequences of climate change resulting in species extinctions?
Decline of amphibians, rising temps and acidification, coral reef communities predicted extinct.
What do alien species do?
Become pests and arrive to colonise area they’re not supposed to be.
What has spread of chytridiomycosis been attributed to?
Trade in amphibians.
Characteristics of Alfred Wefener’s hypothesis?
Inspired by unexpected distributions of plants and animals, due to continental drift.
Wallace’s line?
Imaginary line used to delineate faunas among islands, similar lines applied to mammals.
Why do we get distinctive distributions?
Continental drift and lower sea levels (due to ice age).
Genetic consequences of Pleistocene ice age?
5 ice ages have occurred, currently warm interglacial, glaciation, 18,000-20,000 years, altered landscape.
Effects of ice age?
Extinction of species, formation of barriers, splitting of populations, speciation.
Genetic consequences of ice age?
Recolonisation, subpopulations bottlenecked, less genetic diversity.
