http://hdl.handle.net/1957/12558 2013-05-16T10:29:39Z 2013-05-16T10:29:39Z Gardner, Andy Allsop, David J. Charnov, Eric L. West, Stuart A. http://hdl.handle.net/1957/38594 2013-05-16T00:49:22Z 2005-05-01T00:00:00Z

A Dimensionless Invariant for Relative Size at Sex Change in Animals: Explanation and Implications Gardner, Andy; Allsop, David J.; Charnov, Eric L.; West, Stuart A. Recent comparative studies across sex-changing animals have found that the relative size and age at sex change are strikingly invariant. In particular, 91%–97% of the variation in size at sex change across species can be explained by the simple rule that individuals change sex when they reach 72% of their maximum body size. However, this degree of invariance is surprising and has proved controversial. In particular, it is not clear why this result should hold, given that there is considerable biological variation across species in factors that can influence the evolutionarily stable timing of sex change. Our overall aim here is to explain this result and determine the implications for other life-history variables. Specifically, we use a combination of approaches to formalize and make explicit previous analytical theory in this area, examine the robustness of the empirical invariance result, and carry out sensitivity analyses to determine what the empirical data imply about the mean value and variation in several key life-history variables. This is the publisher’s final pdf. The published article is copyrighted by University of Chicago Press and can be found at: http://www.press.uchicago.edu/ucp/journals/journal/an.html.

2005-05-01T00:00:00Z Charnov, Eric L. Warne, Robin Moses, Melanie http://hdl.handle.net/1957/38593 2013-05-15T23:15:01Z 2007-12-01T00:00:00Z

Lifetime Reproductive Effort Charnov, Eric L.; Warne, Robin; Moses, Melanie In a 1966 American Naturalist article, G. C. Williams initiated the study of reproductive effort (RE) with the prediction that longer-lived organisms ought to expend less in reproduction per unit of time. We can multiply RE, often measured in fractions of adult body mass committed to reproduction per unit time, by the average adult life span to get lifetime reproductive effort (LRE). Williams’s hypothesis (across species, RE decreases as life span increases) can then be refined to read “LRE will be approximately constant for similar organisms.” Here we show that LRE is a key component of fitness in nongrowing populations, and thus its value is central to understanding life-history evolution. We then develop metabolic life-history theory to predict that LRE ought to be approximately 1.4 across organisms despite extreme differences in production and growth rates. We estimate LRE for mammals and lizards that differ in growth and production by five- to tenfold. The distributions are approximately normal with means of 1.43 and 1.41 for lizards and mammals, respectively (95% confidence intervals: 1.3– 1.5 and 1.2–1.6). Ultimately, therefore, a female can only produce a mass of offspring approximately equal to 1.4 times her own body mass during the course of her life. This is the publisher’s final pdf. The published article is copyrighted by University of Chicago Press and can be found at: http://www.press.uchicago.edu/ucp/journals/journal/an.html.

2007-12-01T00:00:00Z Briggs, John C. http://hdl.handle.net/1957/38583 2013-05-14T22:20:06Z 2010-03-01T00:00:00Z

Charles Darwin’s Notebooks from the Voyage of the `Beagle` Briggs, John C. This is an author's manuscript version. The published book review is copyrighted by John Wiley & Sons, Inc. and can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1520-6300.

2010-03-01T00:00:00Z Thomton, Jamie D. Mellish, Jo-Ann E. Hennen, Daniel R. Horning, Markus http://hdl.handle.net/1957/38582 2013-05-14T21:51:29Z 2008-01-01T00:00:00Z

Juvenile Steller sea lion dive behavior following temporary captivity Thomton, Jamie D.; Mellish, Jo-Ann E.; Hennen, Daniel R.; Horning, Markus Wild-caught juvenile Steller sea lions Eumetopias jubatus (n = 21) were maintained in temporary captivity for up to 12 wk to investigate health, disease, nutrition and behavior. We assessed the effects of captivity on post-release dive behavior and movement of each animal using externally mounted satellite data recorders. Based on a 74.1 ± 9.6 (SE) d tag transmission period, the mean dive depth (26.2 ± 4.0 [SE] m), dive duration (1.4 ± 0.1 [SE] min), dive rate (10.1 ± 0.5 [SE] dives h¹), trip duration (10.8 ± 0.7 [SE] h), haul-out duration (11.3 ± 0.9 [SE] h) and time wet (46.9 ± 2.6 [SE]%) were within the range of previously published values. Movement (190.0 ± 31.9 [SE] km) between haul-outs and rookeries during the tracking period was also typical of juvenile Steller sea lions in Alaska. This study indicates that temporary captivity has little or no detrimental effect on dive performance or movement in the tracking period following release. J. E. M. and M. H. were supported in part by NOAA #NA17FX1429 and the ASLC.

2008-01-01T00:00:00Z