Mechanistic and Correlative Models of Ecological Niches

The suite of factors that drives where and under what conditions a species occurs has become the focus of intense research interest. Three general categories of methods have emerged by which researchers address questions in this area: mechanistic models of species’ requirements in terms of environmental conditions that are based on first principles of biophysics and physiology, correlational models based on environmental associations derived from analyses of geographic occurrences of species, and process-based simulations that estimate occupied distributional areas and associated environments from assumptions about niche dimensions and dispersal abilities. We review strengths and weaknesses of these sets of approaches, and identify significant advantages and disadvantages of each. Rather than identifying one or the other as ‘better,’ we suggest that researchers take great care to use the method best-suited to each specific research question, and be conscious of the weaknesses of any method, such that inappropriate interpretations are avoided

Uses and Requirements of Ecological Niche Models and Related Distributional Models

Abstract.—Modeling approaches that relate known occurrences of species to landscape features to discover ecological properties and predict geographic occurrences have seen extensive recent application in ecology, systematics, and conservation. A key component in this process is estimation or characterization of species’ distributions in ecological space, which can then be useful in understanding their potential distributions in geographic space. Hence, this process is often termed ecological niche modeling or (less boldly) species distribution modeling. Applications of this approach vary widely in their aims, products, and requirements; this variety is reviewed herein, examples are provided, and differences in data needs and possible interpretations are discussed

Predicting the geography of species' invasions via ecological niche modeling

Species’ invasions have long been regarded as enormously complex processes, so complex as to defy predictivity. Phases of this process, however, are emerging as highly predictable: the potential geographic course of an invasion can be anticipated with high precision based on the ecological niche characteristics of a species in its native geographic distributional area. This predictivity depends on the premise that ecological niches constitute long-term stable constraints on the potential geographic distributions of species, for which a sizeable body of evidence is accumulating. Hence, although the entire invasion process is indeed complex, the geographic course that invasions are able to take can be anticipated with considerable confidence

Type specimens in modern ornithology are necessary and irreplaceable.

Recent years have seen a series of new species descriptions in which no type specimen or fragmentary type specimen material was provided as documentation. These descriptions have been controversial, but the Code of Zoological Nomenclature makes clear that such nondiagnostic types are not acceptable specimen documentation. A more appropriate approach is documentation of the discovery, but without formal naming of the species, until suitable specimen documentation can be assembled

Good and Bad News about Ebola

No Abstract see PDF.The author received no specific funding for this work

Phylogeny and Rates of Molecular Evolution in the Aphelocoma Jays (Corvidae)

I examined hypotheses of Aphelocoma jay phylogeny derived from allozyme data. Results from various algorithms differ in details, but the overall patterns are consistent: Scrub Jays (A. coerulescens) and Unicolored Jays (A. unicolor) were derived independently from different populations of Gray-breasted Jays (A. ultramarina). Within Scrub Jays, the californica subspecies group was derived from the populations of interior North America (woodhouseii group). One Unicolored Jay population and two Scrub Jay populations, all strongly differentiated, are placed consistently at the base of the phylogeny, but phenotypic, biogeographic, and theoretical evidence suggests that these populations represent rapidly evolving populations derived from within populations of their respective species. Because analyses of rates of molecular evolution demonstrate significant rate heterogeneity, I suggest that the application of a molecular clock to date-splitting events in the Aphelocoma jays is not a valid approach

Taxonomy is important in conservation: a preliminary reassessment of Philippine species-level bird taxonomy

Alpha taxonomy involves delineation of the basic unit of biology: the species. The concepts by which we define species, however, have been controversial, with several alternatives competing at present, some creating fewer and some more species units, depending on interpretation of species limits. Although it is tempting to assume that species concepts would have little interaction with the geographic foci of species richness and endemism — and some have so argued — this assumption does not withstand careful analysis. In this paper, I develop a first-pass assessment of Philippine bird taxonomy under an alternative species concept, and compare the results with the traditional biological species concept lists. Differences between the two lists were dramatic, but not just in numbers of species; rather, new, previously unrecognized or previously underappreciated foci of endemism were noted. A thorough understanding of the taxonomic basis of species lists is therefore critical to conservation planning

Gene Flow in Scrub Jays: Frequency and Direction of Movement

Based on strong differences in plumage coloration between coastal California (californica subspecies group) and Great Basin (woodhousesii subspecies group) populations of Scrub Jays (Aphelocoma coerulescens), museum specimens representing gene flow between the two forms are identified. A total of 27 examples of apparent genetic exchange between two forms (individuals of one subspecies group taken within the range of the other) is documented. Immigration rates are on the order of one per hundred or one per thousand individuals, a rate sufficient to prevent differentiation by genetic drift alone if effective population sizes are in the range of 100-550 individuals. Gene flow east-to-west across the Mojave Desert is two to seven times stronger than west-to-east movement. This directional bias has theoretical implications because an important assumption (symmetry of gene flow patterns) of most theoretical treatments of the effects of gene flow is violated. If effective population sizes are comparable in the two forms, then the bias in gene flow should lead to an overall greater rate of differentiation in the genetically more isolated woodhouseii populations

New Species and New Species Limits in Birds

No abstract is available for this item

Ecologic niche modeling and spatial patterns of disease transmission

Centers for Disease Control and Prevention http://www.cdc.gov/ncidod/eid/index.htmEcologic niche modeling (ENM) is a growing field with many potential applications to questions regarding the geography and ecology of disease transmission. Specifically, ENM has the potential to inform investigations concerned with the geography, or potential geography, of vectors, hosts, pathogens, or human cases, and it can achieve fine spatial resolution without the loss of information inherent in many other techniques. Potential applications and current frontiers and challenges are reviewed