lecture 23 Flashcards

evolution above species level, origination, diversification, and extinction of species over time

evolution within populations, changes in allele frequencies (both adaptive and neutral changes)

study of distribution of species across space and time

• Greater species diversity in tropical areas (amazon in south america and tropical deciduous in africa and asia), more ocean structures = more diversity

increase from polar to tropics -> latitudinal species richness gradient

organisms unaware of other islands via tree height, do not leave original island

Panama has high diversity due to continent interchange and mountainous landscape (allopatric speciation/speciation)

communities diversify (new species) with time, temperate less rich than tropical due to younger age (only recently recovered from ice age)

large areas have more species than small areas due to being able to support larger pop. (more resistant to extinction) and range of habitats

available energy determines species richness, increased solar + water = more plants, more plant production -> more herbivores -> more predators, parasites, and scavengers

largest land area

originated in south america, ocean creates harder migration/dispersal routes, some did cross over via panama land bridge

more so in pacific than atlantic due to origination and more hurricanes in atlantic

assemblage of different animals species that live together (in ecosystem, region, or whole planet)

assemblage of diff. Plant specie the live together

movement of populations from one region to another with limited or no return exchange

formation of geographic barriers to dispersal that divide a once continuous (living together) population distinct phylogenetic signature.

Example: marsupials (only found in australia and the americas) evolved via dispersal and vicariance

D1 (diversity) + originations – extinctions = D2 (new diversity)

new species originating faster than old species become extinct

fauna change in diversity due to intrinsic properties from large-scale changes in climate or environment

# of species (OTU) present in particular area at given time, origination and extinction rates determine this number

1. Cambrian 2. Paleozoic 3. Modern

high number of beetles due to new species originating faster than old species become extinct

positively correlated with mean temperature

wholesale transformation of lineage from one form to another (alt to splitting lineage or speciation)

periods of stasis punctuated by periods of change (associated with speciation events) (metrarabdotos fit the pattern)

slow, gradual morphological changes over time (can incllude speciation event; traditional view)

1. Old species went through anagenesis (new lineage/morphology formed)
2. New species branched off from old one, rapid evolution -> new stasis (no change)

when α (origination rate) eclipses Ω (extinction rate) [ex. silverswords in the hawaiian archipelago]

enables adaptive radiation, is a novel trait that allows subsequent radiation and success of a clade

Example: evolution of nectar spurs allowed columbine (flowers) clade to diversify rapidly (radiation)

animals began to diversify

animal phyla emerged

cambrian, giving rise to new species

cloudina- predator earliest signs

normal rate of extinction for taxa or biota

statistically significant increase above background extinction rates

Example: asteroid 66 mya -> mass extinction, known via K-T boundary with high levels of rare iridium, impact crater near yucatan, and quartz crystals

imbalance in earth’s energy budget -> global warming, etc.

However, diversity is positively correlated with mean temperature

is the decrease in the pH of the earth's ocean

average fell and primary cause are human carbon dioxide emissions

habitat loss via deforestation (i.e. tigers) is biggest biotic factor, others are invasive species, pollution, and direct exploitation

carbon dioxide emission increase -> warmer temps

Leads to ocean acidification: decrease in ocean pH due to increasing CO2 levels and depletion of oxygen