Ecology

• Global climate and productivity

• Species diversity

• Island biogeography

• Niche partitioning

Discussion readings• Stevens RD, Cox SB, Strauss RE, Willig MR 2003 Patterns of

functional diversity across an extensive environmental gradient: vertebrate consumers, hidden treatments and latitudinal trends. ECOLOGY LETTERS 6: 1099-1108

• Aguirre LF, Herrel A, van Damme R, et al. 2002 Ecomorphological analysis of trophic niche partitioning in a tropical savannah bat community. P ROY SOC LOND B BIO 269: 1271-1278.

• Giannini NP, Kalko EKV 2004 Trophic structure in a large assemblage of phyllostomid bats in Panama. OIKOS 105: 209-220.

• Bernard E, Fenton MB 2002 Species diversity of bats (Mammalia : Chiroptera) in forest fragments, primary forests, and savannas in central Amazonia, Brazil. CANADIAN JOURNAL OF ZOOLOGY 80: 1124-1140.

• Freeman PW 2000 Macroevolution in Microchiroptera: Recoupling morphology and ecology with phylogeny. EVOLUTIONARY ECOLOGY RESEARCH 2: 317-335.

Source of the seasons

Earth’s axis tilts 23.5o

Orbital cycles influence temperature

100,000 y period

41,000 y period

22,000 y period

Ice ages can be predicted from orbital cycles

Ice sheets influence species ranges

Greenhouse emissions may lead to accelerated warming

Global atmospheric patterns

Ocean currents

Surface ocean temperaturesPacific coast Atlantic coast

Rain shadows

Temperature and precipation create biomes

Biome distribution

Global primary productivity

Annual productivity increases with mean temperature and rainfall

Energy flow

• Only 1% of energy from sun is trapped by plants during photosynthesis

• Approximately 10% of energy is passed to next trophic level

Food chain length depends on primary productivity and ecological efficiency of each trophic level

Energy pyramid

Bat species diversity

Bat species diversity by

latitude

Reasons for tropical diversity

• Energy stability: more solar energy allows for more diversity

• Greater specialization: individual abundance decreases as diversity increases

• Habitat diversity is greater so there are more niches to fill

Species range patterns

• Tropical species have smaller ranges than expected

• Temperate species have larger ranges than expected

Restricted vs widespread species

Gleaners haverestricted ranges

Body size and species abundance

• Bergman’s rule: species become larger away from the equator - bats do not show this

• Body mass does not correlate with abundance in bats. Other mammals show negative correlation between body mass and abundance.

Per

cent

spe

cies

Log body mass

Island biogeography

How many species do we expect on the island?

Island biogeography

• S = equilibrium number of species

• I = immigration rate

• E = extinction rate

Island biogeography predictionsArea effect

Island biogeography predictionsDistance effect

Species-area relationships

Bat species-area patterns

Tropical forests

Habitats

Larger areas sustain more species

Area and distance effect for Polynesian

megachiroptera

Bat wing shape has been used to define feeding guilds

• Wing loading = mass/wing area

• Aspect ratio = wingspan2/wing area– Low AR =

short, broad wings– High AR =

long, narrow wings

Niche partitioning

Niche space

expansion

Temperate

Tropical