Developmental Temperature Tolerance of Central Texas Populations of Two Anuran Amphibians Bufo valliceps and Pseudacris streckeri

1963 ◽  
Vol 8 (3) ◽  
pp. 142 ◽  
Author(s):  
Clark Hubbs ◽  
Thomas Wright ◽  
Orlando Cuellar
1966 ◽  
Vol 161 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Royce E. Ballinger ◽  
Charles O. McKinney

2019 ◽  
Author(s):  
Stephen Harding ◽  
David Rodriguez ◽  
Jacob Jackson ◽  
David Huffman

AbstractMelanoides tuberculata (Thiaridae) is an old-world freshwater snail that is and now circumtropical. After being introduced in the 1960s via the aquarium trade, populations of M. tuberculata are thriving in spring systems of Texas (USA). Field surveys and experimental investigations of temperature tolerance suggest M. tuberculata is stenothermal, and thus range expansions outside of aquatic habitats with water temperatures between 18° and 32°C should be unlikely. However, in 2012 snails were detected in natural aquatic habitats with seasonal temperatures below the experimentally determined lethal thermal minimum. To test whether genetic and phenotypic variation might be associated with cold-water tolerance and range expansion, we sequenced the 16S ribosomal rRNA gene and measured qualitative conch morphology of 170 snails collected at 26 sites in three central Texas rivers. We also conducted phylogenetic analyses of M. tuberculata collected globally and in Texas to determine potential source populations and estimate the number of invasion events. Our results show snails detected in variable temperature habitats are genetically divergent and morphologically distinct from snails collected in habitats with stable temperatures. These data are consistent with at least three introduction events into Texas of M. tuberculata sensu lato that are characterized by distinct habitat preferences, physiological tolerances, and/or adaptive behaviors.


Author(s):  
David H. Sturm ◽  
Bob F. Perkins

Each of the seven families of rudists (Mollusca, Bivalvia, Hippuritacea) is characterized by distinctive shell-wall architectures which reflect phylogenetic relationships within the superfamily. Analysis of the complex, calcareous, cellular wall of the attached valve of the radiolite rudist Eoradiolites davidsoni (Hill) from the Comanche Cretaceous of Central Texas indicates that its wall architecture is an elaboration of the simpler monopleurid rudist wall and supports possible radiolite-monopleurid relationships.Several well-preserved specimens of E. davidsoni were sectioned, polished, etched, and carbon and gold coated for SEM examination. Maximum shell microstructure detail was displayed by etching with a 0.7% HC1 solution from 80 to 100 seconds.The shell of E. davidsoni comprises a large, thick-walled, conical, attached valve (AV) and a small, very thin, operculate, free valve (FV) (Fig. 1a). The AV shell is two-layered with a thin inner wall, in which original structures are usually obliterated by recrystallization, and a thick, cellular, outer wall.


Sign in / Sign up

Export Citation Format

Share Document