Conservation Biology; Population Ecology; Global Change
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Jessica
J. Hellmann
Assistant
Professor
Ph.D.,
Stanford University
Postdoctoral,
Stanford University & University of British
Columbia
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The
Hellmann lab addresses cutting-edge questions in conservation
biology. These include: How does global change alter the
risk of species and population extinction? How do interactions
among species amplify or buffer the effects of change?
What steps might we take to mitigate negative impacts
of change when they occur? We bring field studies, laboratory
research, and mathematical modeling to bear on such questions,
and we integrate ecology and evolution to predict the
trajectory of populations and communities under change.
Answering such questions is crucial for predicting the
future of biodiversity. To preserve ecosystem services
and other biodiversity values, we need to understand how
the distribution and abundance of species is currently
being altered and shaped.
With
these goals in mind, current research in the lab examines
grassland communities of western North America . We are
comparing two butterfly species with contrasting life
histories to test how their responses might differ under
regional climate warming. Theory predicts that species
will shift their ranges northward under climate change
due to gene flow from the center of a species’ range toward
the periphery. But this theory might not apply to all
taxa . For example, northern populations with restricted
gene flow may contain few southerly genes that prepare
them for a warmer world. Will these species shift, or
will they show widespread declines? Our studies involve
field surveys in British Columbia and the coastal US,
translocation experiments among field populations, genetic
studies of gene flow in the lab, and greenhouse experiments
that manipulate environmental variables.
Figure:
Alternative models of the distribution of fitness (and
population density) across latitudes. In (A), fitness
is highest in the center of a range. In (B), fitness is
equal throughout. If climate shifts from the solid lines
to the dashed lines, population response is quite different
under the two models. In (A), the range shifts; in (B),
extinctions are widespread.
Other
research in the lab includes: 1) the influence of genetic
trade-offs in determining population composition and size
under climate change; 2) the potential for reintroductions
to serve as a management tool for endangered species;
3) the indirect effects of regional warming on populations
through their resource use; 4) the influence of non-native
species on endangered habitats; and 5) the assessment
of species diversity in contrasting ecosystems. A central
aim is to generate principles that can be applied to a
range of natural systems, inform conservation and public
policy, and aid in restoration.
Students
are welcome to pursue research in a wide range of areas
within conservation biology; the use of insects and/or
plants as models is especially encouraged. The lab is
actively recruiting undergraduate, Masters, and Ph.D.-level
researchers.
Erynnis
propertius
is a highly specialized butterfly that feeds only on oak
and lives in western North America . This species is one
of two model species in our current climate change research.
Selected
Publications
Hellmann,
J. J. 2002. The effect of an environmental change on mobile
butterfly larvae and the nutritional quality of their
hosts. Journal of Animal Ecology 70: 925-936.
Hellmann,
J. J., S. B. Weiss, J. F. McLaughlin, C. L. Boggs, P.
R. Ehrlich, A. E. Launer , and D. D. Murphy. 2003. Do
hypotheses from short-term studies hold in the long-term?
An empirical test. Ecological Entomology 28: 74-84.
McLaughlin,
J. F.*, J. J. Hellmann*, C. L. Boggs, and P. R. Ehrlich.
2002. Climate change hastens population extinction. Proceedings
of the National Academy of Sciences 99: 6070-6074. (*=authors
contributed equally)
Hellmann,
J. J. 2002. Butterflies as model systems for understanding
and predicting the biological effects of climatic change.
Pages 93-126 In Wildlife Responses to Climate Change.
Schneider, S. H., and T. L. Root, eds. Island Press, Washington,
D.C.
McLaughlin,
J. F., J. J. Hellmann, P. R. Ehrlich, and C. L. Boggs.
2002. The route to extinction: population dynamics of
a threatened butterfly. Oecologia 132: 538-548.
Smith,
J. N. M., and J. J. Hellmann. 2002. Population persistence
in fragmented landscapes. Trends in Ecology and Evolution
17: 397-399.
Hughes,
J. B., J. J. Hellmann, T. H. Ricketts, and B. J. M. Bohannan
. 2001. Counting the uncountable: statistical approaches
to estimating microbial diversity. Applied and Environmental
Microbiology 67: 4399-4406.
Heal,
G., G. C. Daily, P. R. Ehrlich, J. Salzman , C. L. Boggs,
J. J. Hellmann, J. B. Hughes, C. Kremen , and T. H. Ricketts.
2001. Protecting natural capital: ecosystem service districts.
Stanford Environmental Law Journal 20: 333-364.
Hellmann,
J. J., and G. W. Fowler. 1999. Bias, precision, and accuracy
of four measures of species richness. Ecological Applications
9: 824-834.
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