Females of the marbled salamander, Ambystoma opacum, store sperm in exocrine glands called spermathecae in the roof of the cloaca. Eggs are fertilized by sperm released from the spermathecae during oviposition. Some sperm remain in the spermathecae following oviposition, but these sperm degenerate within a month and none persists more than 6 mo after oviposition. Thus, sperm storage between successive breeding seasons does not occur. Apical secretory vaculoes are abundant during the fall mating season and contain a substance that is alcian blue+ at pH 2.5. Production of secretory vacuoles decreases markedly after oviposition, and the glands are inactive by the summer months. Ambystoma opacum is a terrestrial breeder, and some mating occurs prior to arrival at pond basins where oviposition occurs. Mating prior to arrival at the ovipository site may prolong the breeding season, leading to fitness implications for both males and females. Females have opportunities for more matings, and the possibilities for sperm competition in the spermathecae are enhanced. © 1995 Wiley-Liss, Inc.
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http://dx.doi.org/10.1002/jmor.1052230106 | DOI Listing |
Hatching plasticity allows animals to initiate hatching in response to environmental cues including predation, flooding, and hypoxia. In species with terrestrial eggs but aquatic larvae, hatching plasticity often manifests as extended development of embryos when water is not available. Although these effects are taxonomically widespread, little attention has focused on differences in plasticity across closely related species with terrestrial and aquatic embryos.
View Article and Find Full Text PDFJ Therm Biol
May 2022
Division of Biological Sciences, University of Missouri, Columbia, MO, USA.
Small differences in physiological responses are known to influence demographic rates such as survival. We tested for differences in the physiological acclimation responses of two closely-related salamander species that often co-occur, Ambystoma maculatum and A. opacum.
View Article and Find Full Text PDFOecologia
November 2020
Division of Biological Sciences, Univeristy of Missouri, 612 Hitt Street, 105 Tucker Hall, Columbia, MO, 65211, USA.
Population persistence is informed by the ability of individuals to cope with local abiotic conditions, which is commonly mediated by physiological traits. Among biphasic amphibians, juveniles-which are infrequently studied but play a key role in amphibian population dynamics-are the first life stage to experience terrestrial conditions following the aquatic larval stage. To illuminate phenotypic variation that may allow juveniles to survive the physiological challenges presented by this transition, we examined respiratory surface area water loss (RSAWL) and standard metabolic rates (SMR) among juveniles reared under common larval conditions for five salamander species (Ambystoma annulatum, A.
View Article and Find Full Text PDFEcotoxicology
November 2019
Savannah River Ecology Laboratory, University of Georgia, Aiken, SC, USA.
Copper (Cu) appears to be consistently more toxic to anuran species relative to other vertebrate taxa. There are limited Cu toxicity data for salamanders; of the few studies conducted on salamanders, most examined Cu effects on the embryonic, but not the larval, stage. We performed acute toxicity experiments, to quantify LC50s, on Harrison stage 46 larvae (free swimming hatchlings with egg yolk completely absorbed) of three ambystomatid salamander species.
View Article and Find Full Text PDFMol Ecol Resour
January 2020
Department of Environmental Conservation, University of Massachusetts, Amherst, MA, USA.
The importance of assessing spatial data at multiple scales when modelling species-environment relationships has been highlighted by several empirical studies. However, no landscape genetics studies have optimized landscape resistance surfaces by evaluating relevant spatial predictors at multiple spatial scales. Here, we model multiscale/layer landscape resistance surfaces to estimate resistance to inferred gene flow for two vernal pool breeding salamander species, spotted (Ambystoma maculatum) and marbled (A.
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