John W. Gibbons

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Some freshwater turtles appear unable to produce eggs large enough to achieve the balance between size and number of eggs predicted by optimal egg size theory. We present evidence that pelvic girdle structure constrains egg size and thus offspring size in females of smaller-bodied species (Chrysemys picta and Deirochelys reticularia). The constraint is(More)
A s a group [reptiles] are nei t h er ‘good ’n or ‘b ad ,’ but ia re intere s ting and unu su a l , a l t h o u gh of m i n or i m port a n ce . If t h ey should all disappe a r, it wo u l d not make mu ch differen ce one way or the other ”( Zim and Smith 1953, p. 9 ) . Fortu n a tely, this op i n i on from the Golden Gu i de Series does not persist tod ay;(More)
Restriction-fragment polymorphisms in mitochondrial DNA (mtDNA) were used to evaluate population-genetic structure in the desert tortoise Xerobates agassizi and to clarify evolutionary affinities among species of the gopher tortoise complex. Fourteen informative endonucleases were employed to assay mtDNAs from 56 X. agassizi representing 22 locations(More)
Reports of declining amphibian populations in many parts of the world are numerous, but supporting long-term census data are generally unavailable. Census data from 1979 to 1990 for three salamander species and one frog species at a breeding pond in South Carolina showed fluctuations of substantial magnitude in both the size of breeding populations and in(More)
Climate change has had a significant impact globally on the timing of ecological events such as reproduction and migration in many species. Here, we examined the phenology of reproductive migrations in 10 amphibian species at a wetland in South Carolina, USA using a 30 year dataset. We show for the first time that two autumn-breeding amphibians are breeding(More)
A wetland ecosystem, no matter how small or isolated, includes biotic and abiotic features that interact to promote biodiversity at larger landscape scales. Isolated wetlands, in particular, harbor a significant portion of regional fauna and are often critical habitats for maintaining herpetofaunal biodiversity in southern wetlands. Long-term research on(More)
Created ponds were built as an experiment in mitigating the loss of a wetland to construction. We monitored amphibian breeding population sizes and juvenile recruitment at these “created ponds” for 8.5 years and compared the populations to those observed at the original wetland, Sun Bay (≤600 m from the created ponds), and at an undisturbed reference(More)
1 Joseph W. Jones Ecological Research Center, Newton, GA, USA 2 Department of Biological Science, Florida State University, Tallahassee, FL, USA 3 The Pacific Northwest Turtle Project, Portland, OR, USA 4 Department of Natural Resources Conservation, Holdsworth Natural Resources Center, University of Massachusetts, Amherst, MA, USA 5 USGS/Florida Integrated(More)
Understanding potential for range expansion is critical when evaluating the risk posed by invasive species. Burmese pythons (Python molurus bivittatus) are established in southern Florida and pose a significant threat to native ecosystems. Recent studies indicate that climate suitable for the species P. molurus exists throughout much of the southern United(More)
Most aquatic habitats are temporally dynamic, and selection has favored diverse strategies to persist in the face of fluctuating environmental conditions. Isolated wetlands in the southeastern United States harbor high diversities of aquatic and semi-aquatic organisms. However, drought may render these wetlands temporarily unsuitable for many species,(More)