Eric Pianka --Abstract: A Desert Lizard Data Book for the 21st Century
A Desert Lizard Data Book for the 21st Century

© Eric R. Pianka

This proposal has two goals. One is to organize a large and invaluable data set and preserve it for future generations. Another is to exploit these data in a variety of innovative new syntheses. I have spent 45 years collecting extensive data on ecological relationships of lizard faunas at some 32 desert study sites at similar latitudes on three continents: western North America, the Kalahari desert of southern Africa, and Australia's Great Victoria Desert.

Intensive studies of vertebrates such as these are unfortunately no longer possible due to habitat loss and fragmentation, which now requires that species be protected. While I have made extensive use of my data, a great deal more information can and should be extracted. Data like these simply cannot be collected anymore.

Lizards are ideal subjects for ecological studies: work on them has revealed many basic ecological principles. They respond rapidly to climatic change and can be used to monitor global weather changes. My data can be used to study long-term changes (Pianka 1996) such as those that occur in response to fires and shrub encroachment due to increased precipitation caused by climate change.

Lizards have evolved in response to desert conditions independently within each of these 3 continental desert systems. Intercontinental comparisons reflect the extent to which interactions between the lizard body plan and desert environments are determinate and predictable. Convergences observed between such independently evolved ecological systems provide important insights into the operation of natural selection and underscore general principles of community organization.

A major virtue of these data is that identical methods and resource categories were used by the same investigator for each of three continental desert-lizard systems, enabling meaningful intercontinental comparisons. This unique body of data has thus allowed detailed analyses of resource utilization patterns and community structure in these historically independent lizard faunas.

I summarized the first half of my life's work in a book "Ecology and Natural History of Desert Lizards" in 1986. Since then, from 1989-2008, I have collected 12,634 new Australian desert lizards in an extensive pit-trapping program (over 62,000 trap days) at 3 sites in the Great Victoria Desert. These new specimens provide adequate sample sizes for many uncommon species, which will greatly facilitate under- standing rarity (a major challenge for ecologists).

If funded, I will undertake a detailed GIS analysis of point diversity and habitat requirements using precisely located positions of traps on high-resolution aerial photos. Correlations between trapping records and landscape features will reveal habitat and microhabitat requirements for various lizard species. Whether species are positively or negatively correlated with each other over space and time will also be assessed.

A census was taken in 1992 on a long unburned site to obtain pre-burn data, which was burned in 1995, with subsequent post-burn censuses in 1995, 1998, 2003 and 2008. Lizard faunas and foods eaten on this area will be examined at different time intervals in the fire succession cycle from original long unburned to 13 years post-burn to better understand the dynamics of this ecosystem. Stomach contents of these lizards reflect how arthropod prey resources change during the fire succession cycle. Changes in relative abundances of species from site to site and through time at two long-term study sites will be compared and related to fires and global weather change.

Phylogenies are available for many lizard clades, which allows application of modern comparative methodology to elucidate the probable actual course of evolution. Evolution of morphology, reproductive tactics, thermal biology, microhabitat utilization, and diet among clades of closely-related species (Ctenotus skinks, Diplodactylus geckos, and Pygopodids) will be examined from an explicit phylogenetic perspective. A phylogenetic analysis of evolution of body size and shape will be undertaken to identify anatomical ecological equivalents. Convergent pairs will be compared ecologically using data on microhabitats and diets.

If this project is funded, I will be able to make major advances in understanding the ecology and diversity of Australian desert lizards. I plan to undertake a series of important phylogenetic analyses elucidating probable evolutionary pathways for a wide variety of important traits including functional anatomy, activity times and temperatures, foraging tactics and diets, reproductive tactics, habitat and microhabitat utilization, and relative abundances. I will make progress towards understanding the ecology of rare and uncommon species as well as why they are uncommon. I will be able to document long-term ecosystem changes due to global climate change as well as those occurring during the fire succession cycle. Also, I will undertake pioneering studies on point diversity and habitat requirements, and map the ever-changing multidimensional spatial-temporal waves of relative abundances. Finally, funding this proposal will help in organizing invaluable old 'fossil' data as well as a large amount of new data so that they can be safely preserved for future generations.

Almost 28,000 specimens representing more than 100 different species in 17 of the 37 currently recognized lizard families have been deposited in major museums (DNA samples of Australian species were also deposited). Each specimen has its own unique number with accompanying information on locality, date, habitat and microhabitat, time, air and body temperature, fresh body weight, snout-vent length, and tail length and condition. Lizard specimens were dissected and their sex and reproductive condition assessed. Stomach contents were analyzed and summarized. Ten body measurements were made on preserved specimens.

The culmination of my life's work will preserve for posterity as much information as possible for each individual lizard. These data will be organized in a mySQL relational database format and published on a DVD describing different types of data with queries to extract particular subsets. These data will constitute an invaluable resource for a wide variety of future studies, including long-term changes, ontogenetic changes, variation and sexual dimorphisms in morphology and ecology, habitat requirements, thermal biology, reproductive biology, and dietary and microhabitat niche breadth and overlap.

Link to an expanded version of this proposal

Budget for A Desert Lizard Data Book for the 21st Century

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