A New Locality Record for Branchinecta Coloradensis, with Habitat Notes on Two Species of Fairy Shrimp in Central Texas

Ecology ◽  
1950 ◽  
Vol 31 (4) ◽  
pp. 655-657 ◽  
Author(s):  
Walter G. Moore
Keyword(s):  
Fairy Shrimp ◽  
Locality Record ◽  
Central Texas ◽  
Branchinecta Coloradensis

Genetic population structure of the fairy shrimp Branchinecta coloradensis (Anostraca) in the Rocky Mountains of Colorado

1998 ◽  
Vol 76 (11) ◽  
pp. 2049-2057 ◽  
Author(s):  
Andrew J Bohonak
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Rocky Mountains ◽  
Regional Scale ◽  
Local Scale ◽  
Genetic Population Structure ◽  
Fairy Shrimp ◽  
Genetic Population ◽  
Contemporary Gene Flow ◽  
Branchinecta Coloradensis

Dispersal rates for freshwater invertebrates are often inferred from population genetic data. Although genetic approaches can indicate the amount of isolation in natural populations, departures from an equilibrium between drift and gene flow often lead to biased gene flow estimates. I investigated the genetic population structure of the pond-dwelling fairy shrimp Branchinecta coloradensis in the Rocky Mountains of Colorado, U.S.A., using allozymes. Glaciation in this area and the availability of direct dispersal estimates from previous work permit inferences regarding the relative impacts of history and contemporary gene flow on population structure. Hierarchical F statistics were used to quantify differentiation within and between valleys (thetaSV and thetaVT, respectively). Between valleys separated by 5-10 km, a high degree of differentiation (thetaVT = 0.77) corresponds to biologically reasonable gene flow estimates of 0.07 individuals per generation, although it is possible that this value represents founder effects and nonequilibrium conditions. On a local scale (<=110 m), populations are genetically similar (thetaSV = 0.13) and gene flow is estimated to be 1.7 individuals exchanged between ponds each generation. This is very close to an ecological estimate of dispersal for B. coloradensis via salamanders. Gene flow estimates from previous studies on other Anostraca are also similar on comparable geographic scales. Thus, population structure in B. coloradensis appears to be at or near equilibrium on a local scale, and possibly on a regional scale as well.

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.

Water quality in south-central Texas, 1996-98

Circular ◽  
2000 ◽  
Author(s):  
Peter W. Bush ◽  
Ann F. Ardis ◽  
Lynne Fahlquist ◽  
Patricia B. Ging ◽  
C. Evan Hornig ◽  
...  
Keyword(s):  
Water Quality ◽  
South Central ◽  
Central Texas

An early Eocene florule from central Texas

1925 ◽  
pp. 87-92
Author(s):  
Edward Wilber Berry
Keyword(s):  
Early Eocene ◽  
Central Texas
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