Novel microsatellite loci identified from the Australian eastern small‐eyed snake (Elapidae: Rhinocephalus nigrescens) and cross species amplification in the related genus Suta

A total of 15 microsatellite primers pairs were developed for the Australian small‐eyed snake Rhinoplocephalus nigrescens. Five primers were used to screen 93 individuals of R. nigrescens and were also tested against eight species of the closely related genus Suta. Allelic diversity in R. nigrescens was high in three loci (12–27) and there was high heterozygosity (0.58–0.82). Observed heterozygosity did not deviate from Hardy–Weinberg expectations for the five loci tested. These primers will be useful in studies of population genetics and mating systems of small‐eyed snakes and related species.     

Isolation and characterization of microsatellite loci from mother‐of‐millions,Bryophyllum delagoense (Crassulaceae), and its hybrid with Bryophyllum daigremontianum, ‘Houghton's hybrid’

Nine microsatellite loci were developed, and are transferable, across the Madagascan succulents Bryophyllum daigremontianum, Bryophyllum delagoense (mother‐of‐millions) and their horticultural hybrid (Houghton's), from enriched libraries of the later two species. For B. delagoense, a tetraploid, three to 13 alleles per locus were found for native Madagascan (H_O = 0.4–1.0), and one to nine in invasive Australian (H_O = 0.0–1.0) samples. In addition for 91 Australian samples, only five multilocus genotypes were found (95% of individuals were of two genotypes), suggesting extensive clonality in its introduced range. These loci will be used to examine genetic diversity, hybrid origin and mating system in natural and introduced populations.     

Do cyclones and forest fragmentation have synergistic effects? A before–after study of rainforest vegetation structure at multiple sites

Abstract Ecological degradation within areas of remnant forest may be amplified if the effects of fragmentation interact with the effects of other environmental disturbances such as wind storms. We used before–after comparisons to assess the effects of Tropical Cyclone Larry on remnant and continuous rainforest in the Wet Tropics uplands of north‐eastern Australia. Vegetation structure was measured 3 years before the cyclone and 6 months afterwards, at eight continuous forest sites and eight remnants (6–37 ha), within 20 km of the cyclone's track. The cyclone caused extensive defoliation, felling and breakage of stems and branches (greatest among the trees >100 cm diameter which had around 50% stem loss), and increased litter and woody debris. Cyclone effects were strongly influenced by a site's spatial position (P = 0.005, 0.001 in multivariate analyses of overall damage). Maximum damage occurred 10–15 km south of the cyclone track, perhaps because of the additive effects of the west‐moving air at the southern eyewall combined with the cyclone's own rapid westward movement. Most fragments were south of the cyclone track, as a consequence of spatially selective deforestation practices, and therefore, showed greatest damage. However, once the effects of spatial position were considered, the independent differences in cyclone effects between fragments and continuous forest were lost (P = 0.23, 0.41 when north‐south distance was included as a covariate in analyses). The expected protection afforded by a continuous forest canopy seems to have disappeared in the face of extremely strong cyclonic winds and down‐draughts. Nevertheless, an interaction between fragmentation and disturbance may yet occur, during the period of post‐cyclone recovery, owing to the effects of landscape context on plant recruitment. For example, there was a higher diversity of exotic seedling germination in fragments, independent of the extent of cyclone damage.     

Seasonal Abundances of Naked Amoebae in Biofilms on Shells of Zebra Mussels (Dreissena polymorpha) with Comparative Data from Rock Scrapings

ABSTRACT. In North America, zebra mussels ( Dreissena polymorpha ) are notoriously known as invasive species. The abundance of naked amoebae sampled from the shells of zebra mussels was compared with abundances from rock scrapings at approximately monthly intervals for 1 year. The sites were 2 km apart along the same shoreline. No significant difference in abundance of naked amoebae ( F =1.44; P ≤0.270) was detected for the two sampling sites. The combined data showed a minimum density of naked amoebae in winter, followed by peaks in early spring. The percent encysted increased from a low of 1% in the summer to 80% in early winter.     

Systematic assessment of terrestrial biogeochemistry in coupled climate–carbon models

With representation of the global carbon cycle becoming increasingly complex in climate models, it is important to develop ways to quantitatively evaluate model performance against in situ and remote sensing observations. Here we present a systematic framework, the Carbon‐LAnd Model Intercomparison Project (C‐LAMP), for assessing terrestrial biogeochemistry models coupled to climate models using observations that span a wide range of temporal and spatial scales. As an example of the value of such comparisons, we used this framework to evaluate two biogeochemistry models that are integrated within the Community Climate System Model (CCSM) – Carnegie‐Ames‐Stanford Approach′ (CASA′) and carbon–nitrogen (CN). Both models underestimated the magnitude of net carbon uptake during the growing season in temperate and boreal forest ecosystems, based on comparison with atmospheric CO₂ measurements and eddy covariance measurements of net ecosystem exchange. Comparison with MODerate Resolution Imaging Spectroradiometer (MODIS) measurements show that this low bias in model fluxes was caused, at least in part, by 1–3 month delays in the timing of maximum leaf area. In the tropics, the models overestimated carbon storage in woody biomass based on comparison with datasets from the Amazon. Reducing this model bias will probably weaken the sensitivity of terrestrial carbon fluxes to both atmospheric CO₂ and climate. Global carbon sinks during the 1990s differed by a factor of two (2.4 Pg C yr^?1 for CASA′ vs. 1.2 Pg C yr^?1 for CN), with fluxes from both models compatible with the atmospheric budget given uncertainties in other terms. The models captured some of the timing of interannual global terrestrial carbon exchange during 1988–2004 based on comparison with atmospheric inversion results from TRANSCOM (r=0.66 for CASA′ and r=0.73 for CN). Adding (CASA′) or improving (CN) the representation of deforestation fires may further increase agreement with the atmospheric record. Information from C‐LAMP has enhanced model performance within CCSM and serves as a benchmark for future development. We propose that an open source, community‐wide platform for model‐data intercomparison is needed to speed model development and to strengthen ties between modeling and measurement communities. Important next steps include the design and analysis of land use change simulations (in both uncoupled and coupled modes), and the entrainment of additional ecological and earth system observations. Model results from C‐LAMP are publicly available on the Earth System Grid.     

Postlogging Succession and Habitat Usage of Shrubland Birds

ABSTRACT In the first decades after logging, the vegetation structure of harvested areas changes rapidly due to succession. For shrubland birds, many of which specialize on regeneration of specific ages, the changing vegetation structure makes determining how much habitat is available for individual species difficult. We conducted a meta-analysis to determine how populations of shrubland birds in the eastern United States and Canada respond to succession in the first 20 years after timber harvest. Based on those results, we used the area under the abundance-time regression curves to estimate the proportion of regenerating forest actually used by each bird species. Of the 28 species for which we had sufficient data, 14 showed significant changes in abundance over time. For 6 species, abundance was highest immediately after logging and decreased thereafter. Abundances of 7 other species were initially low, peaked roughly 10 years after harvest, and declined thereafter. Based on these results, shrubland birds would be expected to occupy a mean of just 53% (SD = 17%) of regenerating forests up to 20 years old. Thus, current estimates of habitat availability for shrubland birds may be too high by a factor of 2. Our findings also suggest that managed openings should be maintained on longer rotations than are currently used, providing habitat for birds that prefer older regeneration.     

White-Tailed Deer Foraging Habitat in Intensively Established Loblolly Pine Plantations

ABSTRACT Stand establishment techniques involving multiple herbicide applications are commonly used on industrial pine (Pinus spp.) plantations, raising concern over potential effects on white-tailed deer (Odocoileus virginianus) forage production. We tested effects of stand establishment intensity on deer forage in 1–5-year-old loblolly pine (Pinus taeda) plantations (n = 4) in the East Gulf Coastal Plain of Mississippi using forage biomass and 4 measures of nutritional carrying capacity that reflected crude protein or digestible energy requirements for body maintenance and lactation. We also assessed whether forage biomass combined with a deer use rating effectively indexed nutritional carrying capacity. Treatments were combinations of mechanical site preparation, chemical site preparation (CSP), and herbaceous weed control (HWC). Total forage biomass and forage biomass of grasses and forbs were reduced by broadcast HWC. Forage biomass of vines was reduced both by CSP and by multiple broadcast HWC applications. Maintenance-level carrying capacity estimates were reduced by broadcast HWC; lactation-level estimates were higher in moderate-intensity treatments. We believe the inherently low fertility of this region makes high-quality forage production a more important management priority than increasing forage quantity. Chemical or chemical and mechanical site preparation combined with banded HWC provided the best option for providing both forage quality and quantity in open-canopied, intensively managed pine plantations. Biomass-based indices may be suitable for indexing protein-based maintenance-level carrying capacity in this region, but our results indicated they were not useful for indexing other carrying capacity estimates.     

Estimating Duration of Short-Term Acute Effects of Capture Handling and Radiomarking

ABSTRACT Radiotelemetry is used extensively in zoographic studies of wildlife species, including northern bobwhite (Colinus virginianus). These studies assume that radiomarking does not affect survival of marked individuals. However, most researchers implicitly acknowledge that capture, handling, and radiomarking may have short-term deleterious effects on individuals and, therefore, include in analyses only animals that survive an adjustment period of arbitrary length (often 7 days) following capture and marking. Length of adjustment period is rarely empirically based and may potentially bias survival estimates. We outline an analytical approach to determine an appropriate adjustment period and illustrate this approach by examining effects of time-since-marking on survival of 410 northern bobwhite captured during winter from 1997 to 2001, in Mississippi, USA. We modeled daily survival rates using time-since-marking as a covariate in the nest-survival model of Program MARK. Although survival varied among and within years, we found no evidence to suggest that standard adjustment periods of 7–14 days were appropriate for our sample. If adjustment periods are used in radiotelemetry studies, those that are empirically based may be more appropriate than arbitrarily set periods.     

Phylogeographic analyses reveal distinct lineages of the liverworts Metzgeria furcata (L.) Dumort. and Metzgeria conjugata Lindb. (Metzgeriaceae) in Europe and North America

Seed plant genera often exhibit intercontinental disjunctions where different species are found on different continents. Many morphologically circumscribed bryophyte species exhibit similar disjunctions. We used nucleotide sequences from the plastid and nuclear genomes to test hypotheses of phylogeography within representatives of the genus Metzgeria: Metzgeria furcata, Metzgeria conjugata, and Metzgeria myriopoda. The first two species have sexual and asexual populations, exhibit disjunctions between North America and Europe, and have been split into separate species, numerous subspecies or varieties. The third species occurs in eastern North America but is not reported from Europe. Phylogenetic analyses resolved three distinct lineages within the morphologically defined species, M. furcata: one in North America, and two in Europe. Similarly, three morphologically cryptic clades of M. conjugata were resolved by the molecular data: northern North America, Europe, and south‐eastern North America. For both species, molecular divergence among taxa occurred in the absence of morphological change. In the case of M. myriopoda, all plants from eastern North America were both morphologically uniform and genetically homogeneous (although not identical). The present study provides significant insight into a plant group with complex taxonomy, and indicates that these liverwort taxa with wide distributions, extreme sex ratios, and continental disjunctions harbor cryptic lineages. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 98 , 745–756.