Using California Gnatcatcher to Test Underlying Models in Habitat Conservation Plans

Abstract: Habitat Conservation Plans are a widely used strategy to balance development and preservation of species of concern and have been used in southern California, USA, to protect the coastal California gnatcatcher (Polioptila californica). Few data exist on gnatcatcher abundance and distribution, and existing data have problems with issues of closure (i.e., sampling occurs in a short enough time period such that abundance or distribution are not changing), detectability, and proper attention to probability-based sampling schemes. Thus, a habitat model has been relied upon in reserve design. California gnatcatchers are the flagship and umbrella species of many plans and we provide the first estimates that incorporate probabilistic sampling and test predictions from the habitat model. Probability of occurrence was 26% (SĚ = 0.06); however, occupancy varied by modeled habitat quality with slopes <40%, warm, and wet sagebrush habitat having higher occupancy probabilities. Interpreting abundance and occupancy probabilities by vegetation type was complicated by error detected in Geographic Information System vegetation metadata files. The slope (1.08, SĚ = 0.66), temperature (0.79, SĚ = 0.70), and precipitation (—2.62, SĚ = 1.21) variables associated with habitat models were stronger influences on occupancy than was patch size (0.48, SĚ = 0.66). Previous models weight patch size equal to slope and climate. Our work demonstrates that probabilistic sampling can be carried out on a large scale and the results provide better information for managers to make decisions about their reserves.     

Anti-Rous sarcoma response of major histocompatibility (B) complex haplotypes B23, B24 and B30

Responses to Rous sarcoma virus (RSV) induced tumours were studied in UNH 105, a non-inbred line of New Hampshire chickens. Six single male matings encompassing a total of 50 dams produced 345 progeny which segregated for B complex genotypes B23/B23, B23/B24, B23/B30, B24/B24, B24/B30 and B30/B30. Six-week-old chicks were wingweb inoculated with a pseudotype of Bryan high titre Rous sarcoma virus, BH RSV (RAV-1). Tumours were scored for size six times over a 10-week period post-inoculation. Each chick was assigned a tumour profile index (TPI) as an indicator of immunological response. The number of days to death (DTD) was recorded for 148 chicks with terminal tumours. Genotypes B23/B23, B23/B24 and B23/B30, with TPIs of 1.8, 1.7 and 2.0 respectively, did not differ significantly from each other, suggesting dominance of response of B23 over B24 and B30 haplotypes. B24/B30 chicks with the highest TPI (3.4) and shortest DTD (34.6) were significantly different from B30/B30 (2.8; 41.6) but not from B24/B24 (3.1; 34.9) suggesting dominance of response of the B24 haplotype over B30 in the absence of B23.     

Mosquito female response to the presence of larvivorous fish does not match threat to larvae

1. Several species with complex life‐history traits such as amphibians and insects with aquatic immature stages and terrestrial adults avoid ovipositing in pools containing larvivorous fish. This avoidance response was assumed to be a general one for most fish species. 2. The generality of ovipositing Culex to the presence of three, widespread larvivorous fish species was tested in a set of field experiments with artificial oviposition pools using caged fish. 3. Larval performance was further examined under actual predation by these three fish species. 4. Results show that ovipositing females responded strongly to the presence of caged mosquitofish, Gambusia affinis, while showing no significant response to the presence of caged green sunfish, Lepomis cyanellus, or the pirate perch, Aphredoderus sayanus. All three fish species consumed similar amounts of larvae. 5. This is the first example of species‐specific response differences to predators during mosquito oviposition habitat selection. These results point to the existence of predator‐released kairomones affecting mosquito behaviour. These kairomones may either be species‐specific or vary in concentration among fish, and probably have an important role in the understanding of mosquito spatial distribution.     

Habitat Use by Female Mallards in the Lower Mississippi Alluvial Valley

ABSTRACT Mallard (Anas platyrhynchos) populations in the lower Mississippi Alluvial Valley (LMAV), USA, historically averaged 1.6 million and represented the largest concentrations of wintering mallards in North America. Effective management of this wintering population requires current information on use of habitats. Accordingly, we employed radiotelemetry techniques to assess proportional use of habitats by female mallards during winters 2004–2005 and 2005–2006. We divided winters into 4 time periods defined by hunting seasons (FIRST, SPLIT, SECOND, and POST) and recorded diurnal and nocturnal locations. We examined variations in proportional use of habitats and use of areas closed to hunting due to effects of age (immature or ad), winter (2004–2005 or 2005–2006), time period (SECOND or POST), individual female, and all potential interactions of these effects, using locations recorded during the latter 2 time periods. We found that diurnal and nocturnal proportional use of habitats varied inconsistently among time periods and winters. Mean proportional use of forested wetlands ranged from 0.475 to 0.816 and from 0.428 to 0.764 during diurnal and nocturnal sampling periods, respectively. Diurnal proportional use of areas closed to hunting varied inconsistently among time periods and winters. Mean proportional use of areas closed to hunting ranged from 0.183 to 0.423 during diurnal sampling periods. Nocturnal use of areas closed to hunting varied inconsistently among female ages and time periods and among female ages and winters. Mean proportional use of areas closed to hunting ranged from 0.211 to 0.445 during nocturnal sampling periods. Our research suggests that forested wetlands in the LMAV provide important wintering habitats for female mallards; continued restoration and establishment of these habitats should benefit female mallards.     

Emergence of Zoonotic Canine Leishmaniasis in the United States: Isolation and Immunohistochemical Detection of Leishmania infantum from Foxhounds from Virginia.

ABSTRACT. Previously considered an exotic disease, canine leishmaniasis caused by Leishmania infantum has recently been detected within the foxhound population in the United States and parts of Canada. Leishmania infantum is the etiologic agent of visceral leishmaniasis in many areas of the world and dogs are considered a major reservoir host for human Leishmania infections. Human visceral leishmaniasis has recently emerged as an opportunistic infection among individuals co-infected with HIV/AIDS and in persons taking immunosuppressive drugs. We report the isolation of L. infantum from 3 naturally infected foxhounds from Virginia by culture of popliteal lymph node and bone marrow, and the development of an immunohistochemical test to detect the parasite in tissues.     

Structure, expression, and developmental function of early divergent forms of metalloproteinases in Hydra

Metalloproteinases have a critical role in a broad spectrum of cellular processes ranging from the break-down of extracellulax matrix to the processing of signal transduction-related proteins. These hydrolyticfunctions underlie a variety of mechanisms related to developmental processes as well as disease states.Structural analysis of metalloproteinases from both invertebrate and vertebrate species indicates that theseenzymes are highly conserved and arose early during metazoan evolution. In this regard, studies from vari-ous laboratories have reported that a number of classes of metalloproteinases are found in hydra, a memberof Cnidaria, the second oldest of existing animal phyla. These studies demonstrate that the hydra genomecontains at least three classes of metalloproteinases to include members of the 1) astacin class, 2) matrix met-alloproteinase class, and 3) neprilysin class. Functional studies indicate that these metalloproteinases playdiverse and important roles in hydra morphogenesis and cell differentiation as well as specialized functionsin adult polyps. This article will review the structure, expression, and function of these metalloproteinasesin hydra.     

What do human economies,large islands and forest fragments reveal about the factors limiting ecosystem evolution?

What factors limit ecosystem evolution? Like human economies, ecosystems are arenas where agents compete for locally limiting resources. Like economies, but unlike genes, ecosystems are not units of selection. In both economies and ecosystems, productivity, diversity of occupations or species and intensity of competition presuppose interdependence among many different agents. In both, competitive dominants need abundant, varied resources, and many agents’ products or services, to support the activity and responsiveness needed to maintain dominance. Comparing different‐sized land masses suggests that productivity is lower on islands whose area is too small to maintain some of the interdependences that maintain diversity, productivity and competitiveness in mainland ecosystems. Islands lacking the rare, metabolically active dominants that make competition so intense in mainland ecosystems are more easily invaded by introduced exotics. Studies of islets in reservoirs identify mechanisms generating these phenomena. These phenomena suggest how continued fragmentation will affect future ‘natural’ ecosystems.