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Ryan Calsbeek
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| Dartmouth College |
| Ryan Calsbeek’s Lab |
Ryan and I are investigating the nature of
intralocus sexual conflict and the mechanisms by which this conflict is
resolved in the brown anole, Anolis sagrei. One intriguing
possibility is that females are able to mitigate sexual conflict by
mating with multiple males and then differentially sorting their sperm to
produce sons and daughters by different sires. These studies are funded by a recent grant from the National Science Foundation, and also include measures of natural and sexual selection in the wild, as well as large-scale experimental manipulations of lizard phenotypes and the selective environment. We also study the effects of sex steroids on behavior, performance, and physiology, the maintenance of polymorphism in wild populations, and the cost of reproduction in female anoles. |
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Henry John-Alder
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| Rutgers, The State University of New Jersey
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| Henry John-Alder’s home page
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Henry was my Ph.D. advisor at Rutgers and we continue to collaborate on
studies of the evolution and development of sexual dimorphism in Sceloporus lizards. One of our most exciting findings is that the sex steroid testosterone has
opposite effects on growth in species with opposite
patterns of sexual size dimorphism. Building on this result, Henry and
his collaborators at Rutgers have
begun to characterize the molecular endocrinology of the somatotrophic axis in Sceloporus. These studies will help us to understand if
the opposite effects of testosterone that we observe at the organismal level
are indicative of a bipotential effect of testosterone on the underlying
endocrine growth axis. |
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Joe Williams |
| The Ohio State University
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| Joe Williams’ Lab
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Joe and I, along with Agustí
Muñoz-Garcia, investigated physiological
plasticity in whole-animal cutaneuous water loss rates of house sparrows, Passer domesticus. We found that the enzyme beta-glucocerebrosidase,
previously studied in the context of human skin disease, may be an
important regulatory mechanism that allows birds to adjust the lipid content
of their skin in response to environmental demands on water homeostasis. Our results suggest that physiological plasticity is an important component of population differences in cutaneous water loss and metablolic rate. This
research is part of a larger project investigating the comparative
physiology and life history of birds adapted to arid versus mesic
environments. Check out Joe’s website for other cool studies on the
physiology and life history of birds and mammals. |
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Emily Taylor |
| California Polytechnic State University—San Luis Obispo
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| Emily Taylor’s Lab |
While I was
studying sexual size dimorphism in Sceloporus lizards, Emily was coincidentally conducting a very similar dissertation project on Crotalus atrox rattlesnakes with Dale DeNardo at Arizona State University. We have since synthesized our results from these two squamate lineages in joint publications and presentations. In collaboration with Henry John-Alder, Emily and her group at Cal Polytech have picked up where my studies left off and are in the process of characterizing the effects of testosterone on growth of Sceloporus uniformis and S. occidentalis, two species in which males are larger than females.
This will help us evaluate the generality of bipotential growth regulation by testosterone in Sceloporus lizards. |
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Marguerite Butler |
| University of Hawaii at Manoa
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| Marguerite Butler’s Homepage
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Marguerite and I recently coauthored a book chapter on the evolution of
sexual size dimorphism in reptiles. Marguerite’s research on Anolis lizards has shown that the repeated evolution of different “ecomorphs” is
associated with characteristic changes in sexual size dimorphism. Moreover,
sexual dimorphism greatly increases morphological diversity among species and
may therefore facilitate “species packing” in Anolis communities. |
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Rocco
Carsia
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University of
Medicine and Dentistry of New Jersey, School of Osteopathic Medicine
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| Rocco Carsia's Homepage
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Rocco uses dispersed
adrenocortical cell preparations to conduct in vitro studies of adrenal steroidogenesis in birds and reptiles. In collaboration with Henry John-Alder, Rocco and I have begun to characterize the regulation of adrenal steroidogenesis in Sceloporus lizards. Our studies add a
comparative, ecological twist to this classic area of endocrine research. Using surgical castrations, ovariectomies, and testosterone replacement, we found that the gonads regulate the sensitivity of adrenal steroid production (cortocosterone, progesterone, aldosterone) in response to
adrenocorticotropin (ACTH). Surprisingly, the effects of testosterone on adrenal steroidogenesis differ among Sceloporus species, reminiscent of species differences in growth regulation by testosterone. We have also found that dietary stress (food restriction) has a strong,
stimulatory effect on adrenal sensitivity to ACTH.
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