Population dynamics of the Concho Water Snake in rivers and reservoirs

The Concho Water Snake (Nerodia harteri paucimaculata) is confined to the Concho-Colorado River valley of central Texas, thereby occupying one of the smallest geographic ranges of any North American snake. In 1986, N. h. paucimaculata was designated as a federally threatened species, in large part because of reservoir projects that were perceived to adversely affect the amount of habitat available to the snake. During a ten-year period (1987-1996), we conducted capture-recapture field studies to assess dynamics of five subpopulations of snakes in both natural (river) and man-made (reservoir) habitats. Because of differential sampling of subpopulations, we present separate results for all five subpopulations combined (including large reservoirs) and three of the five subpopulations (excluding large reservoirs). We used multistate capture-recapture models to deal with stochastic transitions between pre-reproductive and reproductive size classes an d to allow for the possibility of different survival and capture probabilities for the two classes. We also estimated both the finite rate of increase (λ) for a deterministic, stage-based, female-only matrix model using the average litter size, and the average rate of adult population change, λ, which describes changes in numbers of adult snakes, using a direct capture-recapture approach to estimation. Average annual adult survival was about 0.23 and similar for males and females. Average annual survival for subadults was about 0.14. The parameter estimates from the stage-based projection matrix analysis all yielded asymptotic values of λ < 1, suggesting populations that are not viable. However, the direct estimates of average adult λ for the three subpopulations excluding major reservoirs were λ = 1.26, SÊ(λ) = 0.18 and λ = 0.99, SÊ(λ) = 0.79, based on two different models. Thus, the direct estimation approach did not provide strong evidence of population declines of the riverine subpopulations, but the estimates are characterized by substantial uncertainty.8 page(s

Comparative transcriptome analysis reveals potentially novel roles of Homeobox genes in adipose deposition in fat-tailed sheep

Abstract Adipose tissues are phenotypically, metabolically and functionally heterogeneous based on the sites of their deposition. Undesirable fat deposits in the body are often detrimental to animal and human health. To unravel the potential underlying mechanisms governing accumulation of adipose tissues in various regions of the body, i.e., subcutaneous (SAT), visceral (VAT) and tail (TAT), we profiled transcriptomes from Tan sheep, a Chinese indigenous breed with notable fat tail using RNA-seq. Upon comparison, we identified a total of 1,058 differentially expressed genes (DEGs) between the three adipose types (218, 324, and 795 in SAT/VAT, SAT/TAT, and VAT/TAT, respectively), from which several known key players were identified that are involved in lipid metabolic process, Wnt signals, Vitamin A metabolism, and transcriptional regulation of adipocyte differentiation. We also found that many elevated genes in VAT were notably enriched for key biological processes such as cytokine secretion, signaling molecule interaction and immune systems. Several developmental genes including HOXC11, HOXC12 and HOXC13, and adipose-expressed genes in the tail region, such as HOTAIR_2, HOTAIR_3 and SP9 were specially highlighted, indicating their strong associations with tail fat development in fat-tailed sheep. Our results provide new insight into exploring the specific fat deposition in tail, also contribute to the understanding of differences between adipose depots