Meeting Abstract
7.2 Jan. 4 Quantifying the resource dynamics of a lizard community: Coupling abiotic drivers and ecosystem productivity to reproduction in lizards WARNE, R.W.*; PERSHALL, A.D.; WOLF, B.O.; University of New Mexico rwarne@unm.edu
Desert animals must integrate unpredictable and often ephemeral pulses of resources, yet how these animals allocate limited resources to survival and reproduction in the face of climate extremes has not been directly quantified. During 2005 and 2006 precipitation in New Mexico alternated between one of the wettest recorded winters to the driest; while summer monsoons in 2006 produced the most summer rain in recorded history. In this study we examine how these extreme climate patterns drive the seasonal and inter-annual resource dynamics within a lizard community in the Chihuahuan Desert of New Mexico. Through the use of naturally occurring carbon and nitrogen stable isotopes we quantify the relative importance of C3 and C4 plant productivity to the nutritional and reproductive ecology of lizard consumers at the Sevilleta LTER in New Mexico. The summer monsoonal rains characteristic to our site support the abundant growth of C4 plants, a functional plant group with a unique form of photosynthesis that produces carbon isotope values (-14� VPDB) distinct from spring dominant C3 plants (-26� VPDB). Because the carbon isotope values of animal consumers reflect those of their diet we show that with an increased summer abundance of C4 plants, the resources used by insectivorous lizard consumer�s shift from 21% C4 derived plant sources in June 2005 to 38% by August 2005. In comparison resource patterns for 2006 reflect the importance of rain as an abiotic driver of this arid ecosystem. Further isotope analysis of these lizard�s fat stores, eggs and muscle provides insight into the allocation strategies these lizards use to meet the demands of survival and reproduction in the face of extreme climate patterns.
