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The geography of demography: long-term demographic studies and species distribution models reveal a species border limited by adaptation.

Publication ,  Journal Article
Eckhart, VM; Geber, MA; Morris, WF; Fabio, ES; Tiffin, P; Moeller, DA
Published in: The American naturalist
October 2011

Potential causes of species' geographic distribution limits fall into two broad classes: (1) limited adaptation across spatially variable environments and (2) limited opportunities to colonize unoccupied areas. Combining demographic studies, analyses of demographic responses to environmental variation, and species distribution models, we investigated the causes of range limits in a model system, the eastern border of the California annual plant Clarkia xantiana ssp. xantiana. Vital rates of 20 populations varied with growing season temperature and precipitation: fruit number and overwinter survival of 1-year-old seeds declined steeply, while current-year seed germination increased modestly along west-to-east gradients in decreasing temperature, decreasing mean precipitation, and increasing variation in precipitation. Long-term stochastic finite rate of increase, λ(s), exhibited a fourfold range and varied among geologic surface materials as well as with temperature and precipitation. Growth rate declined significantly toward the eastern border, falling below 1 in three of the five easternmost populations. Distribution models employing demographically important environmental variables predicted low habitat favorability beyond the eastern border. Models that filtered or weighted population presences by λ(s) predicted steeper eastward declines in favorability and assigned greater roles in setting the distribution to among-year variation in precipitation and to geologic surface material. These analyses reveal a species border likely set by limited adaptation to declining environmental quality.

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Published In

The American naturalist

DOI

EISSN

1537-5323

ISSN

0003-0147

Publication Date

October 2011

Volume

178 Suppl 1

Start / End Page

S26 / S43

Related Subject Headings

  • Temperature
  • Seeds
  • Seasons
  • Rain
  • Population Dynamics
  • Models, Theoretical
  • Geography
  • Evolution, Molecular
  • Environment
  • Ecology
 

Citation

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Eckhart, V. M., Geber, M. A., Morris, W. F., Fabio, E. S., Tiffin, P., & Moeller, D. A. (2011). The geography of demography: long-term demographic studies and species distribution models reveal a species border limited by adaptation. The American Naturalist, 178 Suppl 1, S26–S43. https://doi.org/10.1086/661782
Eckhart, V. M., M. A. Geber, W. F. Morris, E. S. Fabio, P. Tiffin, and D. A. Moeller. “The geography of demography: long-term demographic studies and species distribution models reveal a species border limited by adaptation.The American Naturalist 178 Suppl 1 (October 2011): S26–43. https://doi.org/10.1086/661782.
Eckhart VM, Geber MA, Morris WF, Fabio ES, Tiffin P, Moeller DA. The geography of demography: long-term demographic studies and species distribution models reveal a species border limited by adaptation. The American naturalist. 2011 Oct;178 Suppl 1:S26–43.
Eckhart, V. M., et al. “The geography of demography: long-term demographic studies and species distribution models reveal a species border limited by adaptation.The American Naturalist, vol. 178 Suppl 1, Oct. 2011, pp. S26–43. Epmc, doi:10.1086/661782.
Eckhart VM, Geber MA, Morris WF, Fabio ES, Tiffin P, Moeller DA. The geography of demography: long-term demographic studies and species distribution models reveal a species border limited by adaptation. The American naturalist. 2011 Oct;178 Suppl 1:S26–S43.
Journal cover image

Published In

The American naturalist

DOI

EISSN

1537-5323

ISSN

0003-0147

Publication Date

October 2011

Volume

178 Suppl 1

Start / End Page

S26 / S43

Related Subject Headings

  • Temperature
  • Seeds
  • Seasons
  • Rain
  • Population Dynamics
  • Models, Theoretical
  • Geography
  • Evolution, Molecular
  • Environment
  • Ecology