LO's: large scale patterns of biological diversity

describe how biodiversity has changed over geologic time through speciation and extinction

long-term evolutionary changes in global diversity have largely been the results of speciation and extinction

the number of species has been increasing for the past 600 million years

• end of the permian (225 mya)

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

• end of the cretaceous (65 mya)

  • dinosaurs and many other species went extinct likely due to asteroid

• during the pleistocene (10,000 years ago)

  • ice age mammals went extinct

  • caused by movement of ice sheets and/or hunting by humans

• modern extinctions (since 1600)

  • 75% of extinctions have been the result of human activity

explain major global patterns of biodiversity, including latitudinal, elevational, and species–area trends

1. latitudinal diversity gradient: biodiversity increases from the poles toward the tropics.

   1. high latitudes have fewer species than low latitudes

   2. arctic tundra has fewer species than tropical rainforests

   3. this pattern is seen in both aquatic and terrestrial environments

2. vascular plants tend to show peak diversity in the region around the equator

identify the main drivers behind biodiversity patterns, such as energy, climate, habitat heterogeneity, and geographic isolation

energy:

• more environmental energy usually means more productivity

  • more plant growth and more resources for animals

climate:

• climate controls how much heat and energy ecosystems receive

• PET (potential evapotranspiration)

• higher PET means logs of energy, and more energy supports more life

  • higher biomass

  • bigger populations

  • more species

habitat heterogeneity:

geographic isolation:

interpret how energy availability and productivity influence species richness on land and in the ocean

• ocean NPP actually increases from the equator toward to poles, especially in the northern hemisphere during summer

• changes in thermoclines and vertical nutrient mixing affect how much NPP occurs through the year

apply island biogeography theory to predict how island size and distance affect species richness

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

island area strongly influences this balance

large island support more species and smaller island support fewer species

differentiate among alpha, beta, and gamma diversity across spatial scales

alpha diversity: the local species diversity of individual communities

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

gamma diversity: total species diversity across all communities within a geographic area