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Liz & Whale

• Behavioral Ecology &
Cultural Evolution

Conservation Biology

Ecosystem & Global Ecology

Evolutionary Biology, Molecular Evolution, & Population Genetics

Physiological & Functional Ecology

Population Biology & Demography

Species Interactions & Community Ecology

Research Opportunities for Undergraduates

Population Biology and Demography

What are the factors that affect population dynamics of small populations?  We are testing several hypotheses to account for the explosion of a small introduced population of butterflies in Colorado, especially the role of climate change.  Additionally, much of our other work described elsewhere is at the population level.
gillettii pupa
Current research in the Ehrlich lab is concentrated on a global evaluation of the population-environment-resource situation, with special focus on conservation biology and cultural evolution.
Demographic studies of son-preference in China.  The demographic and environmental effects of rural-to-urban migration in China.
pop structure
Jasper Ridge
A 25-year study of a population of about 350 harvester ant colonies shows effects of climate and resource availability. We are studying the population genetics of the unusual two-lineage genetic system.

For the past 15 years we have monitored the spread of the invasive Argentine ant in Stanford's Jasper Ridge Biological Reserve. Genetic and behavioral studies show clear colony structure with seasonal patterns of expansion and contraction. We are examing the influence of human disturbance, rainfall. species interactions and the availability of nesting sites on the rate of spread of Argentine ants.

Response of small mammals to late Pleistocene extinction event
center image
Caracol y Pepino
We utilize field comparative studies, field experiments, isotopic and genetic analyses to investigate the population dynamics of marine species, particularly exploited marine invertebrates.
We have projects looking at gene flow and larval movement of a variety of organisms in a number of oceans around the world.  Projects range from a tight focus on Balanus glandula on the west coast of the US, to modeling larval dispersal around the Caribbean (see figure).  We participate in PISCO (the Partnership for Interdisciplinary Study of Coastal Oceans)
larval release
The Petrov group is interested in a wide range of questions in molecular evolution and molecular population genetics.
One key line of research is focused on understanding molecular adaptation. How frequent is adaptation? Does it generally involve mutations of small or large phenotypic effect? Does it tend to involve new mutations or use the standing variation? Are adaptive mutations typically coding or regulatory? How frequent is population-specific versus whole-species adaptations? What effect does recurrent adaptation has on patterns of neutral variation? We carry out whole genome analyses using newly developed methodology to generate putative general answers to these questions and also attempt to verify these putative answers with studies of individual test cases. As part of this research program we are investigating patterns of current adaptation that many organisms are undergoing in response to anthropogenic changes in the environment.
The second major focus is on the evolution of genomes. Why are some genomes small and others large in the sheer amount of DNA? What determined the numbers and kinds of genes found in different genomes? Chromosomal numbers? How do multigene families come to be and maintain their sizes? What role does horizontal gene transfer have on genome evolution? Mutational biases? Natural selection?
We presently study the evolution of social behavior and mutualism, emphasizing the role of cooperation, and using cooperative game theory. We are working on the ``social selection project'' to develop alternatives to sexual selection theory and its corollaries. Previous work in the lab has also investigated the evolutionary community ecology of Caribbean Anolis lizards, the role of coupled oceanic and benthic processes in the population dynamics of intertidal invertebrates, and the theory of ecological economics.
US pop pyramid
Mark-recapture analysis of natural populations. Dynamic and fixed heterogeneity. Stage structure and senescence.
Stanford Seal Stanford Department of Biology