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Larval Anurans (larval + anuran)
Selected AbstractsChondrocranial development in larval Rana sylvatica (Anura: Ranidae): Morphometric analysis of cranial allometry and ontogenetic shape changeJOURNAL OF MORPHOLOGY, Issue 2 2002Peter M. Larson Abstract This study provides baseline quantitative data on the morphological development of the chondrocranium in a larval anuran. Both linear and geometric morphometric methods are used to quantitatively analyze size-related shape change in a complete developmental series of larvae of the wood frog, Rana sylvatica. The null hypothesis of isometry was rejected in all geometric morphometric and most linear morphometric analyses. Reduced major axis regressions of 11 linear chondrocranial measurements on size indicate a mixture of allometric and isometric scaling. Measurements in the otic and oral regions tend to scale with negative allometry and those associated with the palatoquadrate and muscular process scale with isometry or positive allometry. Geometric morphometric analyses, based on a set of 11 chondrocranial landmarks, include linear regression of relative warp scores and multivariate regression of partial warp scores and uniform components on log centroid size. Body size explains about one-quarter to one-third of the total shape variation found in the sample. Areas of regional shape transformation (e.g., palatoquadrate, otic region, trabecular horns) are identified by thin-plate spline deformation grids and are concordant with linear morphometric results. Thus, the anuran chondrocranium is not a static structure during premetamorphic stages and allometric patterns generally follow scaling predictions for tetrapod cranial development. Potential implications regarding larval functional morphology, cranial development, and chondrocranial evolution in anurans are discussed. J. Morphol. 252:131,144, 2002. © 2002 Wiley-Liss, Inc. [source] Fatty acid analyses reveal high degrees of omnivory and dietary plasticity in pond-dwelling tadpolesFRESHWATER BIOLOGY, Issue 7 2010MATT R. WHILES Summary 1.,Understanding the trophic relationships of consumers is central to ecology, but constructing meaningful food webs is often difficult because of a lack of detailed information on consumption versus assimilation and high degrees of omnivory. 2.,We used fatty acid analyses to examine the trophic relationships of three common larval anurans (Pseudacris crucifer, Lithobates catesbeianus and Lithobates clamitans) that are often classified as grazers or detritivores. Tadpoles and potential food sources were sampled in four ponds in southern Illinois and analysed for fatty acid composition. Single linkage cluster analysis was then used to compare fatty acid profiles among tadpole gut contents, tadpole muscle tissues and available food resources. 3.,Diets varied among species and within species among ponds, but organic sediments consistently contributed most to the fatty acid composition of the gut contents of all species. Fatty acid profiles also indicated that larval insects and phytoplankton were consumed by both L. catesbeianus and L. clamitans in one pond, while L. clamitans and P. crucifer consumed mainly periphyton along with sediments in another pond, and these diet differences appeared linked to physical differences among ponds, with periphyton and/or phytoplankton contributing more to tadpole diets in less shaded ponds. 4.,The fatty acid composition of muscle tissues of L. clamitans, the dominant tadpole in these systems, indicated that plant detritus and bacteria, which were the dominant components of organic sediments in the ponds, were common components of the assimilatory diet. 5.,Results demonstrate the utility of fatty acid analyses for assessing both consumption and assimilation. The tadpole assemblages we examined derive much of their energy from heterotrophic and allochthonous sources and exhibit high dietary plasticity. This information will allow for more accurate and comprehensive assessments of trophic interactions in freshwater habitats, as well as aid in amphibian conservation, management and captive propagation efforts. [source] Pond canopy cover: a resource gradient for anuran larvaeFRESHWATER BIOLOGY, Issue 3 2006LUIS SCHIESARI Summary 1.,The gradient in pond canopy cover strongly influences freshwater species distributions. This study tested the effects of canopy cover on the performance of two species of larval anurans, a canopy cover generalist (Rana sylvatica, the wood frog) and an open-canopy specialist (R. pipiens, the leopard frog), and tested which factors co-varying with canopy cover mediate these effects. 2.,A field transplant experiment demonstrated that canopy cover had negative performance effects on both species. However, leopard frogs, which grow faster than wood frogs in open-canopy ponds, were more strongly affected by closed-canopy pond conditions. 3.,Closed-canopy ponds had lower temperature, dissolved oxygen (DO), and food nutritional quality as indicated by carbon-to-nitrogen ratio (C : N) analysis of field-sampled food types, and of gut contents of transplanted larvae. 4.,Laboratory experiments demonstrated that higher temperature and food quality but not DO substantially increased larval growth. However, only food quality increased growth rates of leopard frogs more than wood frogs. 5.,The strong correlation of growth rates to gut content C : N in the field, and the similarity of growth curves as a function of resource quality in the field and laboratory, strongly suggest that resources are of primary importance in mediating intraspecific, and especially interspecific differences in performance across the canopy cover gradient. [source] Effects of Temperature Regime Through Premetamorphic Ontogeny on Shape of the Chondrocranium in the American Toad, Anaxyrus americanusTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 7 2008Michael E. Jorgensen Abstract If one considers the substantial amount of information that exists about phenotypic plasticity in amphibians, it is surprising that few studies have examined abiotic factors that influence phenotype through ontogeny. Phenotypic change and stability of morphology are artifacts of organisms that bear significant relevance to evolution within and among taxonomic groups. Here, we examine development as a phenotypically plastic aspect of larval anurans. Fertilized eggs of the American Toad, Anaxyrus (= Bufo) americanus (Holbrook, 1836), were obtained from two pairs of adults, and larvae were reared in four temperature treatments (constant Mean, constant High, constant Low, and Fluctuating regime [Low night,High day]); developmental series were collected from each treatment, representing larvae of this species from Gosner Stages 28,40. Cleared and stained larvae were analyzed with landmark-based geometric morphometric methods to facilitate examination of differences in overall shape change of the larval chondrocranium through ontogeny, as a result of developmental temperature or temperature regime. Changes in shape of the chondrocranium and in amount and direction of phenotypic change through ontogeny were found in response to temperature treatment and temperature regime. Mean chondrocranial shape of the Fluctuating regime was more similar to the consensus shape of the overall data set than were those of all other treatments. Given that differences in amount and direction of shape change were observed among these treatments and throughout ontogeny, one should consider the affects of abiotic factors (such as temperature) when rearing larval anurans for studies of developmental morphology. Anat Rec, 291:818-826, 2008. © 2008 Wiley-Liss, Inc. [source] | ||||||||||