Phylogeography of Diadophis punctatus: extensive lineage diversity and repeated patterns of historical demography in a trans-continental snake

Dynamic climatic oscillations during the Pleistocene had profound effects on the distributions of species across North America. Although the role of historical climate change on speciation remains controversial, the impact on genetic variation within species has been well documented. We examined mtDNA sequences from the cytochrome b gene (1117 bp) and a portion of the NADH-4 gene (659 bp) for 286 individuals of Diadophis punctatus to infer phylogeographic patterns and population structure and to examine historical demographic patterns in both glaciated and unglaciated regions of North America. We inferred 14 lineages that replace each other geographically across the United States. Several of these lineages appear to be confined to specific habitats (floodplains, grasslands, montane environments) and traverse previously identified genetic barriers for terrestrial vertebrates including the Mississippi and Apalachicola Rivers, the Appalachian Mountains, and the western continental divide. We also observed overlapping ranges between some haplotype groups and several instances of secondary contact associated with ecological transition zones in eastern South Carolina, southern Oklahoma and central California. Within the US, diversification began during the late Miocene and continued into the mid-Pleistocene, suggesting these lineages pre-dated the last glacial maximum. Coalescent and non-coalescent demographic analyses indicate that independent lineages currently occupying previously glaciated or unsuitable areas in eastern, central and western US underwent post-glacial population expansion likely from southern refugia during the late Pleistocene/early Holocene. Conversely, southern lineages display patterns consistent with long-term population stability. Such long-term persistence of genetic structure may be due to the competitive effects between lineages or ecosystem stability in more southern latitudes.     

Large-scale identification of polymorphic microsatellites using an <Emphasis Type="Italic">in silico</Emphasis> approach

Background  

Simple Sequence Repeat (SSR) or microsatellite markers are valuable for genetic research. Experimental methods to develop SSR markers are laborious, time consuming and expensive. In silico approaches have become a practicable and relatively inexpensive alternative during the last decade, although testing putative SSR markers still is time consuming and expensive. In many species only a relatively small percentage of SSR markers turn out to be polymorphic. This is particularly true for markers derived from expressed sequence tags (ESTs). In EST databases a large redundancy of sequences is present, which may contain information on length-polymorphisms in the SSR they contain, and whether they have been derived from heterozygotes or from different genotypes. Up to now, although a number of programs have been developed to identify SSRs in EST sequences, no software can detect putatively polymorphic SSRs.     

Ecologically heterogeneous populations of the invasive ant Wasmannia auropunctata within its native and introduced ranges

Abstract 1. The biology of most invasive species in their native geographical areas remains largely unknown. Such studies are, however, crucial in shedding light on the ecological and evolutionary processes underlying biological invasions. 2. The present study focuses on the little fire ant Wasmannia auropunctata, a species native to Central and South America that has been widely introduced and which has become invasive throughout the tropics. We characterise and compare several ecological traits of native populations in French Guiana with those in one of its introduced ranges, New Caledonia. 3. We found ecologically heterogeneous populations of W. auropunctata coexisting in the species’ native geographical area. First, we found populations restricted to naturally perturbed areas (particularly floodplains) within the primary forest, and absent from the surrounding forest areas. These populations were characterised by low nest and worker densities. Second, we found dominant populations in recent anthropogenic areas (e.g. secondary forest or forest edge along road) characterised by high nest and worker densities, and associated with low ant species richness. The local dominance of W. auropunctata in such areas can be due to the displacement of other species (cause) or the filling‐up of empty habitats unsuitable to other ants (effect). With respect to their demographic features and ant species richness, the populations of native anthropogenic habitats were to a large extent similar to the invasive populations introduced into remote areas. 4. The results point to the need for greater research efforts to better understand the ecological and demographic features of invasive species within their native ranges.     

Parasites as accumulation indicators of heavy metal pollution

Parasites are attracting increasing interest from parasite ecologists as potential indicators of environmental quality because of the variety of ways in which they respond to anthropogenic pollution. However, until recently, little was known about the accumulation of toxins within parasites. Certain parasites, particularly intestinal acanthocephalans and cestodes of fish, can accumulate heavy metals at concentrations that are orders of magnitude higher than those in the host tissues or the environment. In this review, Bernd Sures, Roy Siddall and Horst Taraschewski discuss the recently described phenomenon of conspicuous metal accumulation by parasites and how this might be applied to environmental monitoring. They also suggest how environmental science and parasitology might profit from each other in the near future.     

Carbon accumulation in agricultural soils after afforestation: a meta-analysis

Deforestation usually results in significant losses of soil organic carbon (SOC). The rate and factors determining the recovery of this C pool with afforestation are still poorly understood. This paper provides a review of the influence of afforestation on SOC stocks based on a meta-analysis of 33 recent publications (totaling 120 sites and 189 observations), with the aim of determining the factors responsible for the restoration of SOC following afforestation. Based on a mixed linear model, the meta-analysis indicates that the main factors that contribute to restoring SOC stocks after afforestation are: previous land use, tree species planted, soil clay content, preplanting disturbance and, to a lesser extent, climatic zone. Specifically, this meta-analysis (1) indicates that the positive impact of afforestation on SOC stocks is more pronounced in cropland soils than in pastures or natural grasslands; (2) suggests that broadleaf tree species have a greater capacity to accumulate SOC than coniferous species; (3) underscores that afforestation using pine species does not result in a net loss of the whole soil-profile carbon stocks compared with initial values (agricultural soil) when the surface organic layer is included in the accounting; (4) demonstrates that clay-rich soils (> 33%) have a greater capacity to accumulate SOC than soils with a lower clay content (< 33%); (5) indicates that minimizing preplanting disturbances may increase the rate at which SOC stocks are replenished; and (6) suggests that afforestation carried out in the boreal climate zone results in small SOC losses compared with other climate zones, probably because trees grow more slowly under these conditions, although this does not rule out gains over time after the conversion. This study also highlights the importance of the methodological approach used when developing the sampling design, especially the inclusion of the organic layer in the accounting.     

Tyrannobdella rex N. Gen. N. Sp. and the Evolutionary Origins of Mucosal Leech Infestations

Background

Leeches have gained a fearsome reputation by feeding externally on blood, often from human hosts. Orificial hirudiniasis is a condition in which a leech enters a body orifice, most often the nasopharyngeal region, but there are many cases of leeches infesting the eyes, urethra, vagina, or rectum. Several leech species particularly in Africa and Asia are well-known for their propensity to afflict humans. Because there has not previously been any data suggesting a close relationship for such geographically disparate species, this unnerving tendency to be invasive has been regarded only as a loathsome oddity and not a unifying character for a group of related organisms.

Principal Findings

A new genus and species of leech from Perú was found feeding from the nasopharynx of humans. Unlike any other leech previously described, this new taxon has but a single jaw with very large teeth. Phylogenetic analyses of nuclear and mitochondrial genes using parsimony and Bayesian inference demonstrate that the new species belongs among a larger, global clade of leeches, all of which feed from the mucosal surfaces of mammals.

Conclusions

This new species, found feeding from the upper respiratory tract of humans in Perú, clarifies an expansion of the family Praobdellidae to include the new species Tyrannobdella rex n. gen. n.sp., along with others in the genera Dinobdella, Myxobdella, Praobdella and Pintobdella. Moreover, the results clarify a single evolutionary origin of a group of leeches that specializes on mucous membranes, thus, posing a distinct threat to human health.     

Barcoding, types and the Hirudo files: using information content to critically evaluate the identity of DNA barcodes

Species identifications based on DNA barcoding rely on the correct identity of previously barcoded specimens, but little attention has been given to whether deposited barcodes include correspondence to the species' name-bearing type. The information content associated with COX1 sequences in the two most commonly used repositories of barcodes, GenBank and the Barcode of Life Data System (BOLD), is often insufficient for subsequent evaluation of the robustness of the identification procedure. We argue that DNA barcoding and taxonomy alike will benefit from more information content in the annotations of barcoded specimens as this will allow for validation and re-evaluation of the initial specimen identification. The aim should be to closely connect specimens from which reference barcodes are generated with the holotype through straight-forward taxonomy, and geographical and genetic correlations. Annotated information should also include voucher specimens and collector/identifier information. We examine two case studies based on empirical data, in which barcoding and taxonomy benefit from increased information content. On the basis of data from the first case study, we designate a barcoded neotype of the European medicinal leech, Hirudo medicinalis, on morphological and geographical grounds.     

A minor role for lipocalin 2 in high-fat diet-induced glucose intolerance

Adipose tissue controls energy homeostasis and systemic insulin sensitivity through the elaboration of a series of cytokines and hormones, collectively termed "adipokines." We and others have identified Lcn2 as a novel adipokine, but its exact role in obesity-induced insulin resistance remains controversial. The aim of this study was to examine the metabolic phenotype of Lcn2(-/-) mice to clarify the role of Lcn2 in metabolism. Male and female Lcn2(-/-) and wild-type (WT) littermates were placed on either chow or high-fat diet (HFD) to characterize their metabolic phenotype. Studies included body weight and body composition, glucose and insulin tolerance tests, and adipokine expression studies in serum and in white adipose tissue (WAT). Neither chow nor HFD cohorts showed any differences in body weight or body composition. Chow-fed Lcn2(-/-) mice did not exhibit any difference in glucose homeostasis compared with WT mice. Fasting serum glucose levels were lower in the chow-fed Lcn2(-/-) mice, but this finding was not seen in the HFD cohort. Serum adiponectin, leptin, resistin, and RBP4 levels were not different between WT and Lcn2(-/-) on chow diet. HFD-fed male Lcn2(-/-) mice did display a small improvement in glucose tolerance, but no difference in insulin sensitivity was seen in either male or female Lcn2(-/-) mice on HFD. We conclude that the global ablation of Lcn2 has a minimal effect on obesity-associated glucose intolerance but does not appear to affect either age- or obesity-mediated insulin resistance in vivo.