Winter Forage Selection in White-Tailed Deer at High Density: Balsam Fir is the Best of a Bad Choice

Abstract: We assessed winter forage selection by white-tailed deer (Odocoileus virginianus) on Anticosti Island, Quebec, Canada, using cafeteria-feeding trials. Winter habitat on Anticosti is degraded and free-ranging deer at high densities consume 70% balsam fir (Abies balsamea) and 20% white spruce (Picea glauca), even though spruce is much more available than fir. Deer ate 89.9% balsam fir and 10.1% white spruce when the availability of both trees was equal. Deer did not eat shredded twigs more than intact twigs. Fiber content and condensed tannins were greater in white spruce than in balsam fir. Deer preference for fir was not based on texture but, more likely, on plant constituents, so we concluded that deer will nearly eliminate fir before they use any significant amount of white spruce. Management actions, therefore, need to be undertaken to enhance balsam fir regeneration.     

Data-Mining Discovery of Pattern and Process in Ecological Systems

ABSTRACT Most ecologists use statistical methods as their main analytical tools when analyzing data to identify relationships between a response and a set of predictors; thus, they treat all analyses as hypothesis tests or exercises in parameter estimation. However, little or no prior knowledge about a system can lead to creation of a statistical model or models that do not accurately describe major sources of variation in the response variable. We suggest that under such circumstances data mining is more appropriate for analysis. In this paper we 1) present the distinctions between data-mining (usually exploratory) analyses and parametric statistical (confirmatory) analyses, 2) illustrate 3 strengths of data-mining tools for generating hypotheses from data, and 3) suggest useful ways in which data mining and statistical analyses can be integrated into a thorough analysis of data to facilitate rapid creation of accurate models and to guide further research.     

Molecular markers allow sibling species identification in red wood ants (Formica rufa group)

Red wood ants (Formica rufa group) constitute a group of species that are considered to be among the most promising bioindicators in forest ecosystems. However, because of their morphological similarity and intraspecific variability, morphological species identification can be difficult. Considerable expertise is necessary to discriminate between the sibling species F. lugubris and F. paralugubris, two species that often live in sympatry in the same Alpine forests. New taxonomic tools providing rapid and reliable species identification are needed. We present a simple and reliable molecular technique based on mtDNA (COI gene) and a restriction enzyme for discriminating between F. lugubris and F. paralugubris. We confirm the validity of this method with a Bayesian analysis based on microsatellites. This new molecular tool represents a clear breakthrough for discriminating between F. lugubris and F. paralugubris and is likely to be helpful in large‐scale biomonitoring.     

Habitat selection and breeding success in Yellow-legged Gulls Larus cachinnans

The habitat selection and breeding performance of Yellow-legged Gulls Larus cachinnans were studied in the Medes Islands colony, northeastern Spain, during 1995 and 1996. Of the three main habitats on the islands (shrubs, grass and bare areas), gulls first occupied those with the highest percentage of tall vegetation. Gulls tended to select nest sites with 20–75% cover despite great differences in the cover in the habitats and territories, suggesting that the presence of a suitable nest site may play a major role in the choice of breeding habitat. Nest-site tenacity did not influence the preferences of gulls at any level since the same pattern of choice was observed in an area subjected to annual culls (i.e. where most of the breeding pairs were culled annually and replaced by naive birds). In spite of great differences in the physical characteristics of the habitats, little difference was found in breeding performance of the gulls between habitats. Gulls nesting in the least preferred habitat (i.e. mainly bare) had smaller clutches than those nesting in the other two habitats, possibly as a result of their later seasonal laying. Despite the similar breeding success in different habitats, gulls did not seem to distribute according to the ideal free model reported for Herring Gulls Larus argentatus since the density in the preferred habitat (i.e. shrubs) was never higher than in the other two. We suggest that the habitat selection by Yellow-legged Gulls within the colony could follow an ideal despotic distribution.     

Comparative phylogeography and the identification of genetically divergent areas for conservation

Genetic diversity is recognized as a fundamental component of biodiversity and its protection is incorporated in several conventions and policies. However, neither the concepts nor the methods for assessing conservation value of the spatial distribution of genetic diversity have been resolved. Comparative phylogeography can identify suites of species that have a common history of vicariance. In this study we explore the strengths and limitations of Faith's measure of 'Phylogenetic Diversity' (PD) as a method for predicting from multiple intraspecific phylogeographies the underlying feature diversity represented by combinations of areas. An advantage of the PD approach is that information on the spatial distribution of genetic diversity can be combined across species and expressed in a form that allows direct comparison with patterns of species distributions. It also seeks to estimate the same parameter, feature diversity, regardless of the level of biological organization. We extend the PD approach by using Venn diagrams to identify the components of PD, including those unique to or shared among areas and those which represent homoplasy on an area tree or which are shared across all areas. PD estimation should be complemented by analysis of these components and inspection of the contributing phylogeographies. We illustrate the application of the approach using mtDNA phylogeographies from vertebrates resident in the wet tropical rainforests of north-east Queensland and compare the results to biodiversity assessments based on the distribution of endemic vertebrate species. The genetic vs. species approaches produce different assessments of conservation value, perhaps reflecting differences in the temporal and spatial scale of the determining processes. The two approaches should be seen as complementary and, in this case, conservation planning should incorporate information on both dimensions of biodiversity.     

Extensive intraspecific genetic diversity of a freshwater crayfish in a biodiversity hotspot

1. The freshwater crayfish Cherax dispar (Decapoda: Parastacidae) inhabits coastal regions and islands of South East Queensland, Australia. We hypothesised that populations of C. dispar on different islands would be more genetically divergent from each other than populations from different drainages within the same island or on the mainland. 2. Phylogenetic and phylogeographic analyses were conducted on two mitochondrial genes (cytochrome oxidase subunit I & 16S ribosomal DNA) and one nuclear gene (Internal Transcribed Spacer region 2). Phylogeographic patterns were compared with those for other freshwater organisms in the area. 3. Deep genetic divergences were found within C. dispar, including four highly divergent (up to 20%) clades. The geographic distribution of each of the clades revealed strong latitudinal structuring along the coast rather than structuring among the islands. The high genetic divergence observed among the C. dispar clades was estimated to have pre‐dated island formation and may represent ancient river drainage patterns. 4. A restricted distribution was observed for the most divergent clade, which was discovered only on two of the sand islands (North Stradbroke Island and Moreton Island). Furthermore, strong phylogeographic structuring was observed within this clade on North Stradbroke Island, where no haplotypes were shared between samples from opposite sides of the island. This low connectivity within the island supports the idea that C. dispar rarely disperse terrestrially (i.e. across watersheds).     

Climate‐driven increases in storm frequency simplify kelp forest food webs

Climate models predict a dramatic increase in the annual frequency and severity of extreme weather events during the next century. Here we show that increases in the annual frequency of severe storms lead to a decrease in the diversity and complexity of food webs of giant kelp forests, one of the most productive habitats on Earth. We demonstrate this by linking natural variation in storms with measured changes in kelp forest food web structure in the Santa Barbara Channel using structural equation modeling (SEM). We then match predictions from statistical models to results from a multiyear kelp removal experiment designed to simulate frequent large storms. Both SEM models and experiments agree: if large storms remain at their current annual frequency (roughly one major kelp‐removing storm every 3.5 years), periodic storms help maintain the complexity of kelp forest food webs. However, if large storms increase in annual frequency and begin to occur year after year, kelp forest food webs become less diverse and complex as species go locally extinct. The loss of complexity occurs primarily due to decreases in the diversity and complexity of higher trophic levels. Our findings demonstrate that shifts in climate‐driven disturbances that affect foundation species are likely to have impacts that cascade through entire ecosystems.