Mitochondrial phylogeny of Arvicolinae using comprehensive taxonomic sampling yields new insights

Comprehensive taxonomic sampling can vastly improve the accuracy of phylogenetic reconstruction. Here, we present the most inclusive phylogenetic analysis of Arvicolinae (Mammalia, Rodentia) to date, combining all published cytochrome  b gene sequences of greater than 1097 bp and new sequences from two monotypic genera. Overall, the phylogenetic relationships between 69 species of voles and lemmings, representing 18 genera and 10 tribes, were studied. By applying powerful modern approaches to phylogenetic reconstruction, such as maximum likelihood and Bayesian analysis, we provide new information on the early pulse of evolution within the Arvicolinae. While the position of two highly divergent lineages, Phenacomys and Ondatra , could not be resolved, the tribe Lemmini, appeared as the most basal group of voles. The collared lemmings (Dicrostonychini) grouped together with all of the remaining tribes. The two previously unstudied monotypic genera Dinaromys and Prometheomys form a moderately well-supported monophyletic clade, possibly a sister group to Ellobius (Ellobiusini). Furthermore, with one exception, all tribes ( sensu Musser & Carleton, 2005) proved to be monophyletic and can thus be regarded as meaningful evolutionary entities. Only the tribe Arvicolini emerged as paraphyletic in both analyses because of the unresolved phylogenetic position of Arvicola terrestris . Steppe voles of the genus Lagurus were solidly supported as a sister group to the Microtus and allies clade.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 825–835.     

Phylogeography of the last surviving populations of Rhodian and Anatolian fallow deer (Dama dama dama L., 1758)

The European fallow deer ( Dama dama dama ) is one of the most widespread cervids, and its distribution has been heavily affected by man. At present, only one wild autochthonous population is reputed to survive in Anatolia, but its census size is dramatically decreasing. This means that a significant portion of the ancestral genetic diversity of this taxon is seriously threatened. In the present study, a portion of the mitochondrial DNA (D-loop) in 37 D. d. dama specimens from three Mediterranean sites, Turkey, the island of Rhodes (Greece), and the Italian Peninsula, and seven individuals of the Persian fallow deer, Dama dama mesopotamica , was sequenced, and the results from the data analysis are interpreted in light of current archaeozoological and biogeographical knowledge. We conclude that: (1) D. d. mesopotamica is strongly differentiated from D. d. dama , confirming the results of previous genetic studies and (2) the Rhodian populations of D. d. dama , founded by humans in Neolithic times, possess a set of mitochondrial lineages, found in no other study populations. The persistence of these haplotypes is particularly significant because human-mediated processes (e.g. domestication) usually result in genetic depletion and erosion of an ancestral genetic pool. In the case of the Rhodes' population of fallow deer, we hypothesize that, during the foundation of this population, humans unknowingly preserved a remarkable portion of the original genetic diversity of the source population(s).  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 835–844.     

Human dorsal root ganglion neurons from embryonic donors extend axons into the host rat spinal cord along laminin-rich peripheral surroundings of the dorsal root transitional zone

Following dorsal root crush, the lesioned axons regenerate in the peripheral compartment of the dorsal root, but stop at the boundary between the peripheral and the central nervous system, the dorsal root transitional zone. We have previously shown that fibres from human fetal dorsal root ganglia grafted to adult rat hosts are able to grow into the spinal cord, but were not able to specify the route taken by the ingrowing fibres. In this study we have challenged the dorsal root transitional zone astrocyte boundary with human dorsal root ganglion transplants from 5–8-week-old embryos. By tracing immunolabelled human fibres in serial sections, we found that fibres consistently grow around the dorsal root transitional zone astrocytes in laminin-rich peripheral surroundings, and extend into the host rat spinal cord along blood vessels, either into deep or superficial laminae of the dorsal horn, or into the dorsal funiculus. Human fibres that did not have access to blood vessels grew on the spinal cord surface. These findings indicate, that in spite of a substantial growth capacity by axons from human embryonic dorsal root ganglion cells as well as their tolerance to non-permissive factors in the mature mammalian CNS, these axons are still sensitive to the repellent effects of astrocytes of the mature dorsal root transitional zone. Furthermore, this axonal ingrowth is consistently associated with laminin-expressing structures until the axons reach the host spinal cord.     

Monteiro's Storm‐petrel Oceanodroma monteiroi: a new species from the Azores

The existence of two seasonally distinct breeding populations of Oceanodroma storm‐petrels in the Azores islands was first documented in 1996. The discovery of morphological differences between the populations led to the suggestion that they may represent cryptic sibling species. Recent mtDNA and microsatellite analysis from storm‐petrel populations has considerably advanced our understanding of their taxonomic relationships. Here we present new information on the timing of breeding and moult of the two Azores populations, the extent of exchange of individuals between seasons, and diet from feather isotopes. We conclude that the hot‐season Azores population should be considered a new species for which we propose the name Oceanodroma monteiroi, Monteiro's Storm‐petrel. The species is both genetically distinct and genetically isolated from the sympatric cool‐season population of Madeiran Storm‐petrel Oceanodroma castro, and from all other populations of Oceanodroma castro in the Atlantic and Pacific Oceans examined to date. Differences in the vocalizations permit species recognition, and the extent of primary feather wear and stage of moult aids separation of the two species in the Azores, which is especially valuable during August when both attend the breeding colonies in large numbers. Feather carbon and nitrogen isotopes reveal that the diet of Monteiro's Storm‐petrel differs from that of the sympatric Madeiran Storm‐petrel during both breeding and non‐breeding seasons, and unlike the Madeiran Storm‐petrel, Monteiro's Storm‐petrel appears to maintain the same foraging environment during the summer and winter months, though it shows a dietary shift to higher trophic levels during the non‐breeding season. Monteiro's Storm‐petrel is thought to be confined to the Azores archipelago, where it is currently known to nest on just two small neighbouring islets. The total population size was estimated at 250–300 pairs in 1999.     

Effect of fragmentation on predation pressure of insect herbivores in a north temperate deciduous forest ecosystem

1. Forest fragmentation affects many ecosystem processes by spatially altering relationships among organisms. Herbivory by arthropods is an important ecosystem processes in forests that fragmentation alters by changing relationships among herbivores, their predators, and their hosts. The relative importance of these factors remains unclear. 2. It was tested whether the exclusion of vertebrate predators affected the arthropod abundance or amounts of herbivory in a fragmented, deciduous forest landscape in southern Quebec. Differences in the abundance of arthropod herbivores and amounts of herbivory in forest patches with different landscape characteristics (small isolated patches versus large connected ones), on sugar maple saplings with or without exclosures that restricted access by large vertebrate predators were measured. 3. Saplings protected from predators with exclosures had greater abundances of all arthropods (herbivores and invertebrate predators) than those without, indicating potential top‐down effects of vertebrate predators on arthropods. Analysis of effect sizes between exclosure treatments and controls suggests the magnitude of predation effects may be affected by fragmentation. 4. Strong top‐down effects of predators on arthropods, and weak effects of fragmentation on predation or amounts of herbivory were found. As a result, herbivory may be regulated by factors other than vertebrate predation in this system.