Successful captive breeding of Mitchell's water monitor,Varanus mitchelli (Mertens 1958), at Perth Zoo

Mitchell's water monitors (Varanus mitchelli) have been maintained on display at Perth Zoo since 1997. They are generally a timid species but have been maintained and bred in a mixed species water feature exhibit. In this article we describe their captive management and behavior with an insight into their reproductive biology. Between 2002 and 2005, 11 clutches were laid ranging from 13 to 27 (X? = 20) eggs from one female. Egg size ranged between 3.00 and 6.08 g (X? = 4.77 g) in weight, 22.8 and 31.9 mm (X? = 28.3 mm) in length, and 11.1 and 19.3 mm (X? = 17.1 mm) in width. Oviposition included double and triple clutches ranging between 41 and 60 days apart (X? = 48 days), events n = 6. Four clutches were incubated at three different temperatures and hatchlings emerged after 157–289 days. The weight of the hatchlings ranged between 2.60 and 4.52 g (X? = 4.34 g). Total length ranged between 140.1 and 178.0 mm (X? = 165.9 mm) and snout–vent length ranged from 53.8 to 70.0 (X? = 64.4 mm). Juvenile growth and development information is presented from hatching through to approximately 3 years of age. Zoo Biol 29:615–625, 2010. © 2009 Wiley‐Liss, Inc.     

Range edges in heterogeneous landscapes: Integrating geographic scale and climate complexity into range dynamics

The impacts of climate change have re‐energized interest in understanding the role of climate in setting species geographic range edges. Despite the strong focus on species' distributions in ecology and evolution, defining a species range edge is theoretically and empirically difficult. The challenge of determining a range edge and its relationship to climate is in part driven by the nested nature of geography and the multidimensionality of climate, which together generate complex patterns of both climate and biotic distributions across landscapes. Because range‐limiting processes occur in both geographic and climate space, the relationship between these two spaces plays a critical role in setting range limits. With both conceptual and empirical support, we argue that three factors—climate heterogeneity, collinearity among climate variables, and spatial scale—interact to shape the spatial structure of range edges along climate gradients, and we discuss several ways that these factors influence the stability of species range edges with a changing climate. We demonstrate that geographic and climate edges are often not concordant across species ranges. Furthermore, high climate heterogeneity and low climate collinearity across landscapes increase the spectrum of possible relationships between geographic and climatic space, suggesting that geographic range edges and climatic niche limits correspond less frequently than we may expect. More empirical explorations of how the complexity of real landscapes shapes the ecological and evolutionary processes that determine species range edges will advance the development of range limit theory and its applications to biodiversity conservation in the context of changing climate.     

The C. elegans Male Exercises Directional Control during Mating through Cholinergic Regulation of Sex-Shared Command Interneurons

Background

Mating behaviors in simple invertebrate model organisms represent tractable paradigms for understanding the neural bases of sex-specific behaviors, decision-making and sensorimotor integration. However, there are few examples where such neural circuits have been defined at high resolution or interrogated.

Methodology/Principal Findings

Here we exploit the simplicity of the nematode Caenorhabditis elegans to define the neural circuits underlying the male’s decision to initiate mating in response to contact with a mate. Mate contact is sensed by male-specific sensilla of the tail, the rays, which subsequently induce and guide a contact-based search of the hermaphrodite’s surface for the vulva (the vulva search). Atypically, search locomotion has a backward directional bias so its implementation requires overcoming an intrinsic bias for forward movement, set by activity of the sex-shared locomotory system. Using optogenetics, cell-specific ablation- and mutant behavioral analyses, we show that the male makes this shift by manipulating the activity of command cells within this sex-shared locomotory system. The rays control the command interneurons through the male-specific, decision-making interneuron PVY and its auxiliary cell PVX. Unlike many sex-shared pathways, PVY/PVX regulate the command cells via cholinergic, rather than glutamatergic transmission, a feature that likely contributes to response specificity and coordinates directional movement with other cholinergic-dependent motor behaviors of the mating sequence. PVY/PVX preferentially activate the backward, and not forward, command cells because of a bias in synaptic inputs and the distribution of key cholinergic receptors (encoded by the genes acr-18, acr-16 and unc-29) in favor of the backward command cells.

Conclusion/Significance

Our interrogation of male neural circuits reveals that a sex-specific response to the opposite sex is conferred by a male-specific pathway that renders subordinate, sex-shared motor programs responsive to mate cues. Circuit modifications of these types may make prominent contributions to natural variations in behavior that ultimately bring about speciation.     

IRTKS (BAIAP2L1) Elongates Epithelial Microvilli Using EPS8-Dependent and Independent Mechanisms

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An NDVI analysis of vegetation trends in an Andean watershed

We performed a Landsat 5-TM derived normalized difference vegetation index (NDVI) analysis in a semi-arid watershed (2700 km²) in the Andes of southern Peru from 1985 to 2010. There, pastoralists rely on wetlands (bofedales) particularly during dry season months and in drought. We calculated annual dry season NDVI for 20 of the 26 years from 1985 to 2010 and used the mean to delineate wetlands in the watershed. To investigate the trends in NDVI, a multiple regression model with the covariates precipitation, temperature, Julian day, and year of image acquisition was performed on each cell (three million individual regressions). Results indicate there is a modest increase in NDVI for the majority of cells (81 %) in the watershed. Approximately 30 % of wetland areas display a decrease in NDVI. Dry season NDVI is moderately correlated with wet season precipitation (R ² = 0.56, p < 0.05) but absent a trend in precipitation, NDVI trends are not explained by this variable. Changes in land management may result in more intensive use of wetlands, causing the decreasing vegetation trends in some locations.     

The molecular weight of NADPH-cytochrome C reductase isolated by immunoprecipitation from detergent-solubilized rat liver microsomes

The molecular weight of detergent-solubilized NADPH-cytochrome c reductase from rat liver microsomes has been estimated to be 79,000. The method used for this determination involves immunoprecipitation of deoxycholate-solubilized enzyme from ¹²⁵I-labeled microsomal proteins. The antibody was prepared against a purified preparation of Bromelain-solubilized enzyme (molecular weight 71,000). The immunoprecipitate was then subjected to SDS-polyacrylamide gel electrophoresis and the enzyme located by ¹²⁵I-gamma counting.