Origins and introductions of the Caribbean frog, Eleutherodactylus johnstonei (Leptodactylidae): management and conservation concerns

Johnstone's Whistling Frog, Eleutherodactylus johnstonei, is a highly successful colonizer that has become widely distributed throughout the Caribbean region. It has been introduced both purposefully and unintentionally by humans, and it continues to expand its range locally and regionally. Its current distribution and recent expansion do not support the hypothesis that E. johnstonei is expanding into new habitats exclusively by outcompeting native species. Instead, its range expansion progresses mainly parallel to human expansion (habitat disturbance through land development) and extreme climatic events (habitat disturbance through hurricanes and volcanism). Once a habitat has been disturbed and E. johnstonei has arrived, any previously existing endemic Eleutherodactylus species tend not to be found again at their previous ranges or population densities. The most probable explanation for this is that the broader physiological tolerance of the ecological generalist E. johnstonei allows it to become permanently established in a disturbed biota, whereas ecologically specialized endemics are prevented from recolonizing such habitats. Invasion of E. johnstonei can result in a parapatric distribution with endemics (e.g. E. euphronides, E. shrevei) or in sympatry (e.g. E. martinicensis), and habitats include areas with widely divergent climatic conditions (e.g. xeric: Anguilla, Barbuda; mesic: Grenada, St Vincent). Management for this species includes prevention of further or repeat introductions, close monitoring of ranges, and preservation of native habitats to ensure survival of local endemics.     

THE SHELL-FORMING MANTLE EPITHELIUM OF BIOPHALARIA GLABRATA (PULMONATA): ULTRASTRUCTURE, PERMEABILITY AND CYTOCHEMISTRY

In the freshwater snail Biomphalaria glabrata, the outer mantleepithelium and the transitional epithelium from the outer mantleepithelium to the belt are characterized by apical vesiclesof different electron density and vacuoles including lipid dropletsand fibrillar structures. Wide intercellular spaces predominatein the transitional epithelium. In addition to belt desmosomes,freeze fracture studies detect septate junctions as apical intercellularjunctions. The permeability of the septate junctions is testedby injecting anaesthetized snails with solutions containingperoxidase and lanthanum-nitrate. The septate junctions appearto be impermeable for the protein and inhibit permeation ofthe ion. Alkaline phosphatase is detected at the light microscope levelin the transitional and outer mantle epithelium. At the electronmicroscope level localization of alkaline phosphatase is restrictedto the apical and basal cell membranes of the same epithelia.An ATPase with low affinity to Ca²⁺ and Mg²⁺ ions is observedin the lumen of vacuoles in the proximal belt, the transitionaland the outer mantle epithelium. The possible role of the vacuolesas a site of synthesis or modification of the intercrystallinematrix is discussed. A high affinity Ca²⁺/Mg²⁺ ATPase is detectedwith the help of Electron Spectroscopic Imaging in the cellmembranes and in membranes of the rER. A model for solute transport through the epithelia to the extrapallialspace is proposed. (Received 18 August 1992; accepted 4 January 1993)     

Development and characterization of novel microsatellite markers for the common earthworm (Lumbricus terrestris L.)

We developed and characterized 10 highly polymorphic microsatellite loci from an SSR‐enriched genomic DNA library of the common earthworm (Lumbricus terrestris L). Characterization of these loci using 32 individuals revealed high levels of genetic diversity, five to 18 alleles per locus and a high observed and expected heterozygosity. These loci will be used for paternity analysis and population genetic studies of the co‐evolution between L. terrestris and its parasites.     

Analysis of the mitochondrial genome of Schistocerca gregaria gregaria (Orthoptera: Acrididae)

In the present study, we present the full sequence of the mitochondrial genome of the African desert locust Schistocerca gregaria gregaria. The size of 15625 bp reported matches very well with mitochondrial genomes of other Orthopteriodea. The mitochondrial genome comprises 13 protein‐coding genes, two ribosomal RNAs and 22 t‐RNAs with two t‐RNA (trnD and trnK) rearrangements that are typical for the taxon Caelifera. We compared the sequence with 12 mitochondrial genes of Schistocerca gregaria flaviventris and Schistocerca americana and used some of these data to construct phylogenetic trees, which confirm the close relationship between the two subspecies S. g. flaviventris and S. g. gregaria. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 296–305.