An Examination of Scale-Dependent Resource Use by Eastern Hognose Snakes in Southcentral New Hampshire

ABSTRACT The decline of many snake populations is attributable to habitat loss, and knowledge of habitat use is critical to their conservation. Resource characteristics (e.g., relative availability of different habitat types, soils, and slopes) within a landscape are scale-dependent and may not be equal across multiple spatial scales. Thus, it is important to identify the relevant spatial scales at which resource selection occurs. We conducted a radiotelemetry study of eastern hognose snake (Heterodon platirhinos) home range size and resource use at different hierarchical spatial scales. We present the results for 8 snakes radiotracked during a 2-year study at New Boston Air Force Station (NBAFS) in southern New Hampshire, USA, where the species is listed by the state as endangered. Mean home range size (minimum convex polygon) at NBAFS (51.7 ± 14.7 ha) was similar to that reported in other parts of the species’ range. Radiotracked snakes exhibited different patterns of resource use at different spatial scales. At the landscape scale (selection of locations within the landscape), snakes overutilized old-field and forest edge habitats and underutilized forested habitats and wetlands relative to availability. At this scale, snakes also overutilized areas containing sandy loam soils and areas with lower slope (mean slope = 5.2% at snake locations vs. 6.7% at random locations). We failed to detect some of these patterns of resource use at the home range scale (i.e., within the home range). Our ability to detect resource selection by the snakes only at the landscape scale is likely the result of greater heterogeneity in macrohabitat features at the broader landscape scale. From a management perspective, future studies of habitat selection for rare species should include measurement of available habitat at spatial scales larger than the home range. We suggest that the maintenance of open early successional habitats as a component of forested landscapes will be critical for the persistence of eastern hognose snake populations in the northeastern United States.     

Barcoding,molecular taxonomy,and exploration of the diversity of shrews (Soricomorpha: Soricidae) on Mount Nimba (Guinea)

We tested the efficiency of cytochrome oxidase I (COI)‐barcoding as a taxonomic tool to discriminate and identify sympatric shrew species on Mount Nimba (Guinea). We identified 148 specimens at the species level using morphological characters and comparison with type specimens, including several taxa from Mount Nimba. We identified ten morphospecies and tested aspects of genetic diversity and monophyly using genetic data from three mitochondrial (16S, cytochrome b, and COI) and one nuclear marker (the breast cancer gene, BRCA). Nine morphospecies were validated under the phylogenetic and genetic species concepts, including the recently diverged species Crocidura buettikoferi, Crocidura theresae, and Crocidura grandiceps. Under the same concepts, our analyses revealed the presence of two cryptic species amongst animals identified as Crocidura muricauda. We then tested the efficiency of barcoding thanks to commonly used phenetic methods, with the 148 specimens representing 11 potentially valid species based on morphological and molecular data. We show that COI‐barcoding is a powerful tool for shrew identification and can be used for taxonomic surveys. The comparison of genetic divergence values shows the presence of a barcoding gap (i.e. difference between the highest intraspecific and the lowest interspecific genetic divergence values). Given that only a few COI sequences are available for Afrotropical shrews, our work is an important step forward toward their enrichment. We also tested the efficiency of the three other sequenced markers and found that cytochrome b is as efficient as COI for barcoding shrews. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 672–687.     

Sexual and Asexual Development of Cryptosporidium parvum in Five Oocyst– or Sporozoite-Infected Human Enterocytic Cell Lines

ABSTRACT. The human enterocytic cell lines Caco-2, HT29, HCT8 and the Caco-2 clones TC7 and PF11 were studied for their ability to support Cryptosporidium parvum development. Following the addition in cultures of either oocysts or excysted sporozoites, immunofluorescent and transmission electron microscopy revealed the presence of all stages of the parasite life cycle by both procedures, and no difference in the ration of infected cells was found among cell lines. More oocysts were seen in cell monolayers infected with oocysts than with sporozoites (p < 0.0001). The number of meronts observed was the same after either oocysts or sporozoites inoculation. Data suggest that the two methods yield a same cell infection rate.     

The role of the kinase OXI1 in cadmium‐ and copper‐induced molecular responses in Arabidopsis thaliana

The hypothesis that mitogen‐activated protein kinase (MAPK) signalling is important in plant defences against metal stress has become accepted in recent years. To test the role of oxidative signal‐inducible kinase (OXI1) in metal‐induced oxidative signalling, the responses of oxi1 knockout lines to environmentally realistic cadmium (Cd) and copper (Cu) concentrations were compared with those of wild‐type plants. A relationship between OXI1 and the activation of lipoxygenases and other initiators of oxylipin production was observed under these stress conditions, suggesting that lipoxygenase‐1 may be a downstream component of OXI1 signalling. Metal‐specific differences in OXI1 action were observed. For example, OXI1 was required for the up‐regulation of antioxidative defences such as catalase in leaves and Fe‐superoxide dismutase in roots, following exposure to Cu, processes that may involve the MEKK1‐MKK2‐WRKY25 cascade. Moreover, the induction of Cu/Zn superoxide dismutases in Cu‐exposed leaves was regulated by OXI1 in a manner that involves fluctuations in the expression of miRNA398. These observations contrast markedly with the responses to Cd exposure, which also involves OXI1‐independent pathways but rather involves changes in components mediating intracellular communication.     

Stream characteristics and their implications for the protection of riparian fens and meadows

1. Running waters, including associated riparian areas, are embraced by international legal frameworks outlining targets for the preservation, protection and improvement of the quality of the environment. Interactions between stream and river processes and riparian habitats have not received much attention in the management of stream ecosystems, and integrated measures that consider both the ecological status of streams and rivers (sensu EU Water Framework Directive, WFD) and the conservation status of riparian habitats and species (sensu EU Habitats Directive, HD) are rare. 2. Here, we analysed the influence of stream size, morphology and chemical water characteristics for the distribution of water‐dependent terrestrial habitat types, i.e. alkaline fens, periodically inundated meadows and meadows in riparian areas in Denmark using an extensive data set covering a total of 254 stream reaches. A species‐based classification model was used to translate species lists into a standardised interpretation of habitat types protected by the HD in Denmark. 3. No size dependency was found regarding the distribution of fen and meadow vegetation. Instead, the distribution of fen and meadow vegetation was strongly affected by the morphology of the streams. Alkaline fens, periodically inundated meadows and meadows occurred six, five and four times, respectively, less frequently along channelised compared with natural stream reaches. Our results indicate that stream channelisation strongly interfered with the natural hydrology of riparian areas, affecting conditions needed to sustain protected fen and meadow communities. 4. We also found that water chemistry strongly influenced the occurrence of fen and meadow vegetation in riparian areas. The probability of finding fen and meadow vegetation was reduced when total phosphorus (TP) concentration exceeded 40–50 μg P L^?1, whereas meadow vegetation responded less strongly to TP. 5. Our findings highlight the importance of restoring hydrology of riparian areas to improve conditions for fen and meadow vegetation, but also that the water chemistry should be considered when measures that increase hydrological connectivity result in an increase in the probability of flooding.     

Gut length plasticity in perch: into the bowels of resource polymorphisms

Resource polymorphisms, intraspecific variation in morphology due to differential resource use, are common across a wide range of animal taxa. The focus in studies of such polymorphisms has been on external morphology, but the differential use of food resources could also influence other phenotypic traits such as the digestive performance. In the present study, we experimentally demonstrate that Eurasian perch ( Perca fluviatilis L.) display adaptive plasticity in gut length when exposed to different food types. Perch fed a less digestible food type developed relatively longer guts compared to fish fed a more easily digested food type. This divergence in gut length was also apparent under natural conditions because perch inhabiting the littoral and pelagic habitats of a lake differed in resource use and relative gut length. Despite that the digestive system in perch is plastic, we found that individuals switching to a novel food type might experience an initial fitness cost of the diet switch in the form of a temporary reduction in body condition. These results show the importance of gut length plasticity for an ontogenetic omnivore but also a cost that might prevent diet switching in polymorphic populations.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 517–523.     

Effects of stream flooding on the distribution and diversity of groundwater‐dependent vegetation in riparian areas

1. Effects of the frequency and duration of flooding on the structural and functional characteristics of riparian vegetation were studied at four sites (n = 80, 50 × 50 cm, plots) along medium‐sized naturally meandering lowland streams. Special focus was on rich fens, which – due to their high species richness – are of high priority in nature conservation. 2. Reed beds, rich fens and meadows were all regularly flooded during the 20‐year study period, with a higher frequency in reed bed areas than in rich fen and meadow areas. In rich fens, species richness was higher in low frequency flooded areas (≤3 year^?1) than in areas with a high frequency of flooding (>3 year^?1) or no flooding, whereas species richness in reed beds and meadows was unaffected by flood frequency. 3. The percentage of stress‐tolerant species was higher in low intensity flooded rich fen areas than in high intensity and non‐flooded areas, indicating that the higher species richness in low frequency flooded rich fens was caused by competitive release. We found no indication that increased productivity was associated with high flooding frequencies. 4. We conclude that the restoration of morphological features in stream channels to increase the flooding regime can be beneficial for protected vegetation within riparian areas, but also that groundwater discharge thresholds and critical levels for protected vegetation should be identified and considered when introducing stream ecosystem restoration plans.     

SENSORY AND INSTRUMENTAL FLAVOR ANALYSES OF CHEESE CURD COCULTURED WITH SELECTED YEAST AND BACTERIA

Relationships between odor properties and volatile chemical composition were explored on 39 cocultures of three different yeasts, three Geotrichum candidum and five bacteria, commonly used in bacteria and mold surface ripened cheese. Sensory profiling was performed by ten trained judges by scoring the intensity of 14 odor attributes. At the same time, the volatile compounds of the cocultures were extracted and analyzed by dynamic headspace gas chromatography and mass spectrometry. Sensory and instrumental data were compared and correlated using correlation analysis and partial least squares regression analysis. The sample plot including the whole set of samples evidenced a clustering of the associations containing the yeast strain Kluyveromyces lactis and any bacteria. They developed strong fruity olfactory notes related to their high content of ethyl esters and various alcohols. The sample plot on a restricted set of samples evidenced the fruity characteristics of Debaryomyces hansenii and bacteria associations and the cheesy odors of Yarrowia lipolytica and Geotrichum candidum cocultures that produced sulfur compounds.