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Intra-Guild Compensation Regulates Species Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown Jan 2006

Intra-Guild Compensation Regulates Species Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown

Biology Faculty Publications

Null models have had a long and contentious history in community ecology (Connor and Simberloff 1979, Harvey et al. 1983, Gotelli and Graves 1996, Graves and Rahbek 2005). Much of this debate has arisen because multiple strategies for null models can be used to address a particular question of interest, and the present exchange is no exception. To assess constancy in species richness through time in a desert rodent community, Nichols et al. (2006) have proposed a Markov Chain model as an alternative to the random-walk model we developed (Goheen et al. 2005). While both null models simulate stochastic local …


A Comparison Of The Species-Time Relationship Across Ecosystems And Taxonomic Groups, Ethan P. White, P. B. Adler, W. K. Lauenroth, R. A. Gill, D. Greenberg, D. M. Kaufman, A. Rassweiler, J. A. Rusak, M. D. Smith, J. R. Steinbeck, R. B. Waide, J. Yao Jan 2006

A Comparison Of The Species-Time Relationship Across Ecosystems And Taxonomic Groups, Ethan P. White, P. B. Adler, W. K. Lauenroth, R. A. Gill, D. Greenberg, D. M. Kaufman, A. Rassweiler, J. A. Rusak, M. D. Smith, J. R. Steinbeck, R. B. Waide, J. Yao

Biology Faculty Publications

The species-time relationship (STR) describes how the species richness of a community increases with the time span over which the community is observed. This pattern has numerous implications for both theory and conservation in much the same way as the speciesarea relationship (SAR). However, the STR has received much less attention and to date only a handful of papers have been published on the pattern. Here we gather together 984 community time-series, representing 15 study areas and 9 taxonomic groups, and evaluate their STRs in order to assess the generality of the STR, its consistency across ecosystems and taxonomic groups, …


Intra-Guild Compensation Regulatesspecies Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown Jan 2006

Intra-Guild Compensation Regulatesspecies Richness In Desert Rodents: Reply, J. R. Goheen, Ethan P. White, S.K. Morgan Ernest, J. H. Brown

Biology Faculty Publications

No abstract provided.


The Offspring/Clutch Size Tradeoff In Mammals, E. L. Charnov, S.K. Morgan Ernest Jan 2006

The Offspring/Clutch Size Tradeoff In Mammals, E. L. Charnov, S.K. Morgan Ernest

Biology Faculty Publications

The Smith‐Fretwell model for optimal offspring size assumes the existence of an inverse proportional relationship (i.e., trade‐off) between the number of offspring and the amount of resources invested in an individual offspring; virtually all of the many models derived from theirs make the same trade‐off assumption. Over the last 30 years it has become apparent that the predicted proportionality is often not observed when evaluated across species. We develop a general allometric approach to correct for size‐related differences in the resources available for reproduction. Using data on mammals, we demonstrate that the predicted inverse proportional relationship between number of offspring …


Age And Population Structure Of Joshua Trees (Yucca Brevifolia) In The Northwestern Mojave Desert, K D. Gilliland, Nancy J. Huntly, J E. Anderson Jan 2006

Age And Population Structure Of Joshua Trees (Yucca Brevifolia) In The Northwestern Mojave Desert, K D. Gilliland, Nancy J. Huntly, J E. Anderson

Biology Faculty Publications

Many desert perennials are long-lived, but there are few data on ages or population structures of desert plants. We used 2 methods to estimate ages of a population of Yucca brevifolia (Joshua tree) in southwestern Utah from a 14-year census of plant sizes. Plant height at the 1st census ranged from 0.08 m to 6.0 m, and trees grew in height at a mean rate of 3.75 cm ⋅ yr–1. Plants also increased slowly in basal diameter (0.142 cm ⋅ yr–1) and branch length (0.024 m ⋅ yr–1), but basal diameter varied greatly from year to year, with many plants …