Differences in the Developmental Temperature Tolerance of Central Texas and More Northern Stocks of Percina Caprodes (Percidae: Osteichthyes)

1963 ◽  
Vol 8 (1) ◽  
pp. 43 ◽  
Author(s):  
Clark Hubbs ◽  
Kirk Strawn
Keyword(s):  
Temperature Tolerance ◽  
Developmental Temperature ◽  
Central Texas

Developmental temperature tolerance of certain anuran species

1966 ◽  
Vol 161 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Royce E. Ballinger ◽  
Charles O. McKinney
Keyword(s):  
Temperature Tolerance ◽  
Developmental Temperature ◽  
Anuran Species

scholarly journals Genetic and morphological variation is associated with differences in cold-water tolerance and geographic expansion among invasive snails (Melanoides tuberculata) in central Texas

2019 ◽  
Author(s):  
Stephen Harding ◽  
David Rodriguez ◽  
Jacob Jackson ◽  
David Huffman
Keyword(s):  
Cold Water ◽  
Variable Temperature ◽  
Phylogenetic Analyses ◽  
Temperature Tolerance ◽  
Experimental Investigations ◽  
Rrna Gene ◽  
Aquatic Habitats ◽  
Melanoides Tuberculata ◽  
Water Tolerance ◽  
Central Texas

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.

Architecture of Radiolitid Rudist (Mollusca) Shell-Wall Structures and its Phylogenetic Implications

1975 ◽  
Vol 33 ◽  
pp. 686-687
Author(s):  
David H. Sturm ◽  
Bob F. Perkins
Keyword(s):  
Phylogenetic Relationships ◽  
Outer Wall ◽  
Shell Microstructure ◽  
Shell Wall ◽  
Wall Structures ◽  
Phylogenetic Implications ◽  
Cellular Wall ◽  
Superfamily Analysis ◽  
Central Texas

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.

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