Browsing by Subject "habitat"
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Item Analysis of Instream Flows for the Lower Brazos River - Hydrology, Hydraulics, and Fish Habitat Utilization(Surface Water Resources Division, Texas Water Development Board, 2004-06) Osting, Tim; Mathews, Ray; Austin, BarneyItem Analysis of Instream Flows for the Sulphur River: Hydrology, Hydraulics and Fish Habitat Utilization(Surface Water Resources Division, Texas Water Development Board, 2004-07) Osting, Tim; Mathews, Ray; Austin, BarneyItem The Anatomy and Some Biological Aspects of the "Ball Moss," Tillandsia recurvata L.(University of Texas at Austin, 1911-08-08) University of Texas at AustinItem Charlie's Pasture Nature Preserve - by The Reserve(2016-06-13) Mission-Aransas National Estuarine Research ReserveItem Contrasting Patterns Of Phenotype-Dependent Parasitism Within And Among Populations Of Threespine Stickleback(2014-06) Stutz, William E.; Lau, On L.; Bolnick, Daniel I.; Stutz, William E.Variation in infection rate arises from variation in host exposure and resistance to parasites both within and among populations. All things being equal, phenotypes that increase exposure risk should covary positively with infection among individuals. It might therefore be expected that populations with mean phenotypes that increase exposure might also have higher rates of infection. However, such positive covariance between exposure and infection at the population level might be undermined by other factors such as geographic variation in parasite abundance or host resistance, negating or reversing in between-population comparisons. We studied rates of infection of two parasites among 18 populations of threespine stickleback (Gasterosteus aculeatus). As predicted, within populations, trophic morphology covaries with infection of two trophically transmitted parasites: individuals with benthic (or limnetic) phenotypes were more likely to be infected with a benthic (or limnetic) parasite. However, across populations, the relationship between morphology and infection rate was absent (limnetic parasite) or reversed (benthic parasite). Our results confirm the importance of phenotype-dependent exposure, but stress different factors or processes, such as the evolution of reduced susceptibility, might shape variation in infection at larger spatial scales.Item Distributional Survey and Habitat Utilization of Freshwater Mussels(Texas Water Development Board, 2008-01) Karatayev, Alexander; Burlakova, LyubovItem Letter to John Q. Burch from H.B. Stenzel on 1960-05-09(1960-05-09) Stenzel, Henryk B.Item Reserve Size And Fragmentation Alter Community Assembly, Diversity, And Dynamics(2013-11) Lasky, Jesse R.; Keitt, Timothy H.; Lasky, Jesse R.; Keitt, Timothy H.Researchers have disputed whether a single large habitat reserve will support more species than many small reserves. However, relatively little is known from a theoretical perspective about how reserve size affects competitive communities structured by spatial abiotic gradients. We investigate how reserve size affects theoretical communities whose assembly is governed by dispersal limitation, abiotic niche differentiation, and source-sink dynamics. Simulations were conducted with varying scales of dispersal across landscapes with variable environmental spatial autocorrelation. Landscapes were inhabited by simulated trees with seedling and adult stages. For a fixed total area in reserves, we found that small reserve systems increased the distance between environments dominated by different species, diminishing the effects of source-sink dynamics. As reserve size decreased, environmental limitations to community assembly became stronger, species richness decreased, and richness increased. When dispersal occurred across short distances, a large reserve strategy caused greater stochastic community variation, greater richness, and lower richness than in small reserve systems. We found that reserve size variation trades off between preserving different aspects of natural communities, including diversity versus diversity. Optimal reserve size will depend on the importance of source-sink dynamics and the value placed on different characteristics of natural communities. Anthropogenic changes to the size and separation of remnant habitats can have far-reaching effects on community structure and assembly.Item Status of Biotic Integrity, Water Quality, and Physical Habitat in Wadeable East Texas Streams(Resources Protection Division, Texas Parks and Wildlife Department, 2004-02) Kleinsasser, Leroy; Jurgensen, Tim; Bowles, David; Boles, Steve; Aziz, Karim; Saunders, Kenneth; Linam, Gordon; Trungale, Joseph; Mayes, Kevin; Rector, Jason; Fields, Jacqueline Renee; Portis, Kip; Steinmetz, Gary; Moss, RandallItem Waller Creek: A very urban stream(City of Austin Watershed Protection Department, 2015) Scoggins, MateoItem Water Quality in the Trinity River Basin, Texas, 1992-95 (USGS Circular 1171)(U.S. Department of the Interior, 1998) Ulery, Randy L.; Shipp, Allison A.; Mahler, Barbara J.; Reutter, David C.; Van Metre, Peter C.; Moring, J. Bruce; Land, Larry F.