Ecology and Physiology of Nesting and Early Development of the American Alligator

Joanen, Ted; McNease, Larry

doi:10.1093/icb/29.3.987

Cited by 104 publications

(87 citation statements)

References 6 publications

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“…3), rainfall varied considerably, with 1.4 cm in 2008 vs 32.1 cm in 2009. Joanen & McNease (1989) found increased nest abundance during periods when water levels were above average but reduced nest abundance if water levels increased to the point of extreme flooding. Conversely, they found nest abundance was lowest during periods of drought.…”

Section: Discussionmentioning

confidence: 92%

“…A great deal has been learned about the reproductive biology of the American alligator (Alligator mississippiensis) in recent decades, fueled in part by increased research efforts following precipitous population declines in the 1960s (Groombridge 1987, Joanen & McNease 1989, Guillette et al 1997, Lance et al 2009). While the majority of American alligators reside in freshwater and have been the focus of much of this research, comparatively little data are available detailing the geographical variation that exists in the reproductive endocrinology of adult alligators, especially of alligator populations living in barrier island locales.…”

Section: Introductionmentioning

confidence: 99%

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The reproductive hormone cycle of adult female American alligators from a barrier island population

Hamlin

Lowers²,

Kohno

et al. 2014

Reproduction

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Comparatively, little data are available detailing the geographic variation that exists in the reproductive endocrinology of adult alligators, especially those living in barrier islands. The Merritt Island National Wildlife Refuge (MI) is a unique barrier island environment and home to the Kennedy Space Center (FL, USA). Seasonal patterns of sex steroids were assessed in adult female American alligators from MI monthly from 2008 to 2009, with additional samples collected at more random intervals in 2006, 2007, and 2010. Plasma 17b-estradiol and vitellogenin concentrations peaked in April, coincident with courtship and mating, and showed patterns similar to those observed in adult female alligators in other regions. Plasma concentrations of progesterone, however, showed patterns distinctly different than those reported for alligator populations in other regions and remained relatively constant throughout the year. Plasma DHEA peaked in July around the time of oviposition, decreased in August, and then remained constant for the remaining months, except for a moderate increase in October. Circulating concentrations of DHEA have not been previously assessed in a female crocodilian, and plasma concentrations coincident with reproductive activity suggest a reproductive and/or behavioral role. Interestingly, plasma testosterone concentrations peaked in May of 2008, as has been shown in female alligator populations in other regions, but showed no peak in 2009, demonstrating dramatic variability from year to year. Surveys showed 2009 to be particularly depauperate of alligator nests in MI, and it is possible that testosterone could serve as a strong indicator of breeding success.

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Section: Discussionmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

The reproductive hormone cycle of adult female American alligators from a barrier island population

Hamlin

Lowers²,

Kohno

et al. 2014

Reproduction

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show abstract

“…The reproductive development of alligators from a contaminated and a control Lake in (2)(3)(4)(5). The American alligator (Alligator mississippiensis) was listed as an endangered species in the early 1970s, but populations throughout the southeastern United States grew rapidly after federal protection was instituted (6)(7)(8).…”

mentioning

confidence: 99%

Developmental abnormalities of the gonad and abnormal sex hormone concentrations in juvenile alligators from contaminated and control lakes in Florida.

Guillette

Gross

Masson

et al. 1994

Environ Health Perspect

994

436

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“…Access to O 2 from inside the nest chamber depends on maternal nest-site selection, climate events such as excess rainfall and flooding, and the metabolism of microbes and sibling eggs that may modify the composition of gases within the nest chamber (Seymour et al 1986;Joanen & McNease 1989;Booth 1998;Ackerman & Lott 2004). In addition, external regional hypoxia may occur within an egg when eggs are partially immersed in liquid water (Booth 1998;Corona & Warburton 2000).…”

Section: Introductionmentioning

confidence: 99%

Reduced egg shell permeability affects embryonic development and hatchling traits in Lycodon rufozonatum and Pelodiscus sinensis

Tang

Chen

2018

Integrative Zoology

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The response of embryos to unpredictable hypoxia is critical for successful embryonic development, yet there remain significant gaps in our understanding of such responses in reptiles with different types of egg shell. We experimentally generated external regional hypoxia by sealing either the upper half or bottom half of the surface area of eggs in 2 species of reptiles (snake [Lycodon rufozonatum] with parchment egg shell and Chinese softshelled turtle [Pelodiscus sinensis] with rigid egg shell), then monitored the growth pattern of the opaque white patch in turtle eggs (a membrane that attaches the embryo to the egg shell and plays an important role in gas exchange), the embryonic heart rate, the developmental rate and the hatchling traits in turtle and snake eggs in response to external regional hypoxia. The snake embryos from the hypoxia treatments facultatively increased their heart rate during incubation, and turtle embryos from the upper-half hypoxia treatment enhanced their growth of the opaque white patch. Furthermore, the incubation period and hatching success of embryos were not affected by the hypoxia treatment in these 2 species. External regional hypoxia significantly affected embryonic yolk utilization and offspring size in the snake and turtle. Compared to sham controls, embryos from the upper-half hypoxia treatment used less energy from yolk and, therefore, developed into smaller hatchlings, but embryos from the bottom-half hypoxia treatment did not.

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Ecology and Physiology of Nesting and Early Development of the American Alligator

Cited by 104 publications

References 6 publications

The reproductive hormone cycle of adult female American alligators from a barrier island population

The reproductive hormone cycle of adult female American alligators from a barrier island population

Developmental abnormalities of the gonad and abnormal sex hormone concentrations in juvenile alligators from contaminated and control lakes in Florida.

Reduced egg shell permeability affects embryonic development and hatchling traits in Lycodon rufozonatum and Pelodiscus sinensis

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