large scale patterns of biological diversity

chapter 26

what is biological diversity

the number of living organisms inhabiting the earth

what is the most diverse group of organisms

insects

how many insects have been described

over 1 million

what is the result of speciation and extinction

long-term evolutionary changes in global diversity

is the number of species increasing or decreasing

increasing

have dominate groups changed or stayed the same through geologic time

changed

the trend of biodiversity increasing over time has changed due to 

several mass extinctions

when was the end of the permian

225 mya

what happened at the end of the permian (225 mya)

90% of marine invertebrates lost most likely due to volcanic activity

when was the end of the cretaceous

65 mya

what happened at the end of the cretaceous

dinosaurs and many other species went extinct likely due to asteroid

when was the pleistocene

10,000 years ago

what happened at the end of the pleistocene

ice-age mammals went extinct caused by movement of ice sheets and/or hunting by humans

what percent of extinctions have resulted from human activity

75%

what are the ecological and evolutionary drivers or global and regional patterns of species richness

energy availability, climate, habitat heterogeneity, evolutionary history, area, and isolation

what is the latitudinal diversity gradient

biodiversity increases from the poles towards the tropics

which has more species: high/low latitudes

low latitudes

which has less species: high/low latitudes

high latitudes

the (tundra or rainforest) has fewer species than the (tundra or rainforest)

the tundra has fewer species than the rainforest

vascular plants tend to show peak diversity in the region

around the equator

looking at tree movement during the ice ages helps see the effects of

climate stability

species richness is related to

available environmental energy

climate controls

how much heat and energy ecosystems recieve

what is PET

potential evapotranspiration

high PET means

lots of energy

more energy supports more life:

higher biomass, bigger populations, more species

more environmental energy usually means

more productivity

more productivity means

more plant growth and resources for animals

studies show that areas with higher primary productivity also tend to have

more plant species, both regionally and globally

more productive plant communities support

more animal species

structural diversity and species diversity of the plant community is

positively correlated with animal species diversity

plants provide both ___ and ___ for heterotrophs

food and habitat for heterotrophs

ocean NPP actually increases

from the equator twoard the poles

ocean NPP increases from the equator toward the poles because

seasonality strongly shapes marine biodiversity

changes in thermoclines and vertical nutrient mixing affect

how much NPP occurs through the year

in higher latitudes, surface waters are highly productive in

spring

in higher latitudes, surface waters are lowly productive in

winter

permanent thermocline in tropical oceans gives a consistent

low pattern of primary productivity

vertebrate species richness relates more strongly to

temperature and thermal energy than to plant productivity

temperature affects animals differently

ectotherms and endotherms

ectotherms rely on

external heat to regulate body temperature

endotherms spend less energy on

heating their bodies when the environment is warmer

as elevation increases,

temperature and productivity decreases

besides energy and climate, what other factors shape biodiversity patterns

size of habitat and its isolation

what is the island biogeography theory

species richness on an island reflects a balance between immigration and extinction

lower populations mean

lower risk of stochastic extinction

smaller populations mean

higher vulnerability to stochastic events

near islands have higher

immigrations rates

far island have

lower immigration

what is alpha diversity

the local species diversity of individual communities

what is beta diversity

variation in species composition among sites (communities) in a geographic area

what is gamma diversity

total species diversity across all communities within a geographic area (region)

one site, habitat, or community

alpha diversity

species found across a variety (two or more) of habitats

beta diversity

all species across a large region that contains many habitats

gamma diversity

what does endemic mean

species have small, restricted geographic range

endemic species are not evenly

distributed globally or regionally

what are hotspots

regions of unusually high diversity

hotspots are high in both

species richness and endemism

how many endemic plant species

150,000 (50% of world total)

how many endemic terrestrial vertebrate species

22,000 (77% of world total)