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
100,000 y period Orbital cycles influence temperature 41,000 y period 22,000 y period
Surface ocean temperatures Pacific coast Atlantic coast
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
Energy pyramid Food chain length depends on primary productivity and ecological efficiency of each trophic level
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 have restricted ranges
Percent species Log body mass 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.
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 predictions Area effect
Island biogeography predictions Distance effect
Habitats Bat species-area patterns Larger areas sustain more species Tropical forests
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 space expansion Temperate Tropical