Effects of islanding on the genetics of Niviventer confucianus (Mamalia: Rodentia: Muridae) populations in the Thousand Island Lake region

The impact of islanding on the genetics of the dominant species, Niviventer confucianus, was analysed using 13 microsatellite markers. All 16 populations are of high genetic diversity with a total of 134 alleles. The average number of effective alleles (Ne) is 6; the average expected heterozygosity (H_E) and polymorphic information content (PIC) are 0.823 and 0.763, respectively. Landscape fragmentation might contribute to weak genetic differentiation among 13 island populations. Values of F_ST simulated by Structure 2.3.4 implied that the 16 populations could be assigned into three clusters, from which we postulated the possible dispersion history. Pairwise F_ST tests showed that genetic differences mainly occurred between small island populations and others. Currently, habitat area appears to be the main factor affecting the genetics of Niviventer confucianus, and not the distances between islands. Hence we suggest that more attention should be paid to habitat area in the future.     

Repeated sampling adds to the genetic diversity of Lepidochelys olivacea (Eschscholtz 1829) olive ridley sea turtle

ABSTRACT

First sampled in the late 1990s, Campamento Tortuguero La Gloria, in Jalisco, Mexico, was resampled for olive ridley sea turtle (Lepidochyles olivacea Eschscholtz) diversity 10 years later. A comparison with all previously reported mitochondrial sequences revealed that these new samples added to the known genetic diversity for this species, and revealed unexpectedly high genetic diversity among turtles nesting on this beach. The results highlight the importance of systematic resampling in known nesting rookeries to verify the genetic diversity of study populations. Three new olive ridley haplotypes are reported, all more closely related to Baja Californian haplotypes than to Australian haplotypes. Significant genetic divergence is reported within populations, within ocean basins (Atlantic, Pacific, Indian and Indo-Pacific), and between ocean basins. Furthermore, this is the first study that integrates satellite tagging data to demonstrate diverse post-nesting migration patterns of turtles with identical haplotypes, and it demonstrates flexibility in post-nesting migratory behaviour for olive ridley sea turtles of the same genetic provenance.     

Geographical distributions and host associations of larval parasitoids of frugivorous Drosophilidae in Japan

In Japan, dominant parasitoids attacking frugivorous Drosophilidae species were Asobara (Braconidae, Alysiinae), Leptopilina, and Ganaspis species (Figitidae, Eucoilinae). Asobara japonica was found throughout Japan, and its populations in the main islands of Japan were parthenogenetic whereas those in the subtropical islands were sexually reproducing. Other parasitoids showed rather restricted distributions; A.tabida, A. rossica, A. rufescens, and Leptopilina heterotoma occurred mainly in northern to central parts of the main islands, Ganaspis xanthopoda from central to southern parts of the main islands, A. leveri in a southern part of the main islands, and A. pleuralis, L. victoriae, and Ganaspis sp. mainly in the subtropical islands. Their major hosts were species of the D. melanogaster species group in the main islands, and species of the D. melanogaster, immigrans, and polychaeta species groups in the subtropical islands. Host use considerably varied among parasitoid species, especially in the subtropical islands.     

Traditional and geometric morphometric analyses reveal homogeneity in European Scutacarus acarorum Goeze, 1780 populations (Acari: Scutacaridae: Heterostigmatina)

The mite Scutacarus acarorum (Scutacaridae, Heterostigmatina) is one of the dominant bumblebee inquilines in the Holarctic. The wide distribution and the host generalist behaviour of S. acarorum suggest that it could be a group of multiple cryptic species. European S. acarorum populations and a small population from New York were studied using traditional and geometric morphometric methods to detect possible geographical or host-dependent variation. The analyses revealed homogeneity of all populations, suggesting that the species experienced a bottleneck during the last ice age and that gene flow between the populations is maintained. High variability within populations indicates a high genetic diversity. No host-related morphological differences were detected, suggesting that S. acarorum is a true generalist. Fresh mite samples from locations all over the Holarctic are needed to draw further conclusions on the species’ phylogeography and also on its population genetic structure.     

Some new and known species of Tylencholaimoidea (Nematoda: Dorylaimida) from Korea

A lineal “island” theory is proposed to account for the dispersal of marine/estuarine, supralittoral talitrid populations, both to and from isolated shore “islands” on continental and true oceanic islands. Evolution may occur following dispersal to shores that are contiguous with ecologically open habitats, inclusive of sub-tropical forest litter and caves. Specific hypotheses of the lineal “island” theory are therefore: the conventional wrack hypothesis 1 – direct from marine supralittoral wrack to subtropical forest litter; the driftwood hypothesis 2(a) – direct from marine supralittoral driftwood to subtropical forest litter; the driftwood hypothesis 2(b) – direct from the marine supralittoral driftwood to caves opening on a marine supralittoral; and the driftwood hypothesis 2(c) – direct from the marine supralittoral driftwood via caves to subtropical forest litter. Circumstantial evidence supporting each hypothesis is presented using the ecology and distribution data of the talitrid fauna of the northeast Atlantic islands, north of 25°N and south of 40°N, including the Canaries, Madeira and the Azores archipelagos. The currently known talitrid fauna of all these islands includes 15 species: seven endemic, subtropical landhoppers, two synanthropically introduced landhoppers, three wrack generalists, one sand-burrowing specialist, one specialist cavehopper, and one specialist driftwood hopper. Based on distributional data from the northeastern Atantic islands, specialist driftwood hoppers have a long distance dispersal capability, which makes them potential colonizers of distant oceanic islands. Talitrids provide an excellent model of dispersal and speciation, whose evolutionary pathways can be solved by modern genetic methods.     

Preliminary report on the genetic structure of Glyphoglossus molossus (Anura: Microhylidae) from the Khorat Plateau,north-eastern Thailand

Glyphoglossus molossus, is one of the most economically important amphibians in the Khorat Plateau, north-eastern Thailand. It is categorised as a near-threatened species by IUCN due to over-exploitation. Here, we examined the genetic structure of G. molossus using partial mitochondrial cytochrome-b gene sequences from specimens collected at 11 localities. The sequence analysis revealed the presence of 15 haplotypes, 5 of which are shared by 2 or more populations, and 10 haplotypes that are confined to a single population. The relatively low haplotype (h) and nucleotide (π) diversities suggest that the Phu Phan Mountain Range is not high enough to act as an effective dispersal barrier between the Sakon Nakhon and Khorat Basins. However, AMOVA and phylogenetic analyses based on Maximum likelihood (ML) and Bayesian inference (BI) strongly supported the presence of two genetically divergent clades, Sakon Nakhon Basin and the northern part of the Khorat Basin (clade A) and the southern part of the Khorat Basin (clade B). These two lineages are separated by substantial geographical distance, which has putatively resulted in a reduction of gene flow. Further studies, with more extensive genetic sampling, especially from throughout the species range will aid in better interpreting our results.     

Observations of water-flea Daphnia magna and avian fecalia in rock pools: is traditional natural history reporting still relevant for science?

Unexpected observation of freshwater invertebrate Daphnia magna in temporary rock pools on a small island off the Norwegian Atlantic coast confirms colonising ability, mediated through avian dispersal. Robust diapausal eggs of D. magna pass the gut of migrating geese and subsequently hatch in environments where such waterfowl forage and rest along migrating routes. The incubation experiment demonstrates that decomposing fecalia of geese constitute sufficient feed to support developing populations of D. magna in experimental oligotrophic conditions. The findings also show that D. magna is highly adapted for colonisation of temporary pools north of the Arctic Polar Circle, with excellent tolerance to low temperatures. Discussion part I relates the findings to published evidence on avian transport of invertebrate propagules, such as correlations between migration patterns of waterfowl and geographical patterns of aquatic invertebrate diversity. Discussion part II reflects on academic cultures, epistemological aspects of natural history reporting, the presence of a whale cadaver as an ecological indicator and the relevance of simple observation as a starting point for further discourse.     

Mapping aquatic faunal exchanges across the Sunda shelf,South-East Asia,using distributional and genetic data sets from the cyprinid fish Barbodes gonionotus (Bleeker, 1850)

The islands of Sumatra, Java and Borneo and mainland South-East Asia are encompassed by a shallow marine shelf, the Sunda shelf. The striking faunal similarities between countries bordering the Sunda shelf have been attributed to faunal exchanges across the shelf during Pleistocene glacial maxima when sea levels fell by up to 120 m and the shelf was exposed and drained by large river systems which connected many of today's rivers. The widespread distribution of fish species reflecting extensive faunal exchange across the area is predicted to be observed within species through the broad geographic distribution of genetic lineages. Here I report a discontinuous species distribution across the region for the cyprinid fish, Barbodes gonionotus. Mitochondrial DNA control region sequence and nuclear locus data from populations sampled across the species range, suggest that the present species distribution largely reflects faunal exchanges early in the Pleistocene and that these two regional population groupings have subsequently diverged in isolation. However, the mtDNA data present some evidence for limited genetic dispersal during more recent Pleistocene low sea levels. These results broadly confirm previous work from a catfish species and suggest that freshwater faunal exchanges may have been limited across the region during the Pleistocene despite extended periods during which the Sunda shelf was exposed.     

Bythinella Moquin-Tandon, 1856 (Gastropoda: Rissooidea: Bythinellidae) in Romania: species richness in a glacial refugium

The buff-throated partridge, Tetraophasis szechenyii Madarász, 1885, is a species endemic to west China. The complete mitochondrial genome of this species was sequenced. It was 16,706 base pairs (bp) in length and contained 13 protein-coding genes, 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a control region (CR). The phylogenetic relationships of the buff-throated partridge and 19 other Phasianidae species were inferred by Bayesian inference and maximum likelihood analyses based on 12 protein-coding genes. With the exception of a few nodes, most internal branches were supported by a high Bayesian posterior probability (BPP?=?1.0). The resulting trees clarified the phylogenetic position of T. szechenyii within Phasianidae. The genetic diversity and population structure of the Pamulin population of T. szechenyii were examined based on the mitochondrial DNA CR. Nucleotide sequence analysis defined 18 haplotypes in 24 individuals. Haplotype diversity (h) was 0.953 and nucleotide diversity (π) was 0.0044. The results revealed that the genetic diversity of this population was not particularly low. Combined with the field work conducted by our lab, we found that members of the Pamuling population are cooperative breeders and the population may contain individuals from neighbouring groups. Our work provided genetic background information for the conservation and management of this species.     

Molecular phylogeny of the Aplodactylidae (Perciformes: Cirrhitoidea), a group of Southern Hemisphere marine fishes

Aplodactylids are temperate marine nearshore fish of New Zealand, southern Australia, several south-west Pacific islands, and western South America. The molecular phylogeny of the five aplodactylid species was reconstructed from mitochondrial DNA sequences. The observed relationships and levels of genetic variation supports the most recent review of the Aplodactylidae in which the monotypic Crinodus is synonymized with Aplodactylus, the only genus presently recognized. Phylogenetic relationships indicate that the Aplodactylidae originated in the approximate region of Australia and New Zealand, with the majority of radiation occurring prior to this family achieving representation in South America. The disjunct trans-Pacific distribution of this family was the result of chance dispersal rather than vicariance accompanying Gondwana fragmentation. Such dispersal was most likely undertaken during the larval phase, mediated by the West Wind Drift current.     

The relation between species numbers and island characteristics for habitat islands in a volcanic landscape

Within the Craters of the Moon Lava Flow in southeastern Idaho are kipukas, islands of sagebrush habitat isolated by relatively barren lava. In 1979 I counted the number of species of plants, small mammals, and reptiles for a series of kipukas. The degree of isolation of a kipuka was not related to numbers of species found there; thus, these data do not support the equilibrium theory of island biogeography. For most of the study organisms lava is not a significant barrier to dispersal. Larger kipukas support larger numbers of species. For plants this relationship likely is a result of the increased topographic variety of larger kipukas, whereas for small mammal species minimum area requirements for maintaining populations are met only by larger kipukas. More distant kipukas showed increased density of small mammals possibly as a result of reduced predation. Patterns of distribution in this ecosystem are best explained, not by any all-inclusive community mechanism, but through the agglomerative contributions of a variety of population and community functions.     

A biogeographical analysis of the tenebrionid beetles (Coleoptera,Tenebrionidae) of the island of Thasos in the context of the Aegean Islands (Greece)

This research aimed to study the origin and the biogeographical relationships of the tenebrionid beetle (Coleoptera, Tenebrionidae) fauna of the island of Thasos, with reference to the other Aegean Islands. A total of 32 Aegean Islands and 170 taxa (species and subspecies), 23 of which occur on Thasos, were included in this study. Nine tenebrionid species are here reported for the first time from Thasos, including the first records of Platydema europaeum and Nalassus plebejus from the Aegean Islands. Several models (linear, exponential, power, logistic, Gompertz, Weibull and Lomolino functions) were used to test the species–area relationship. The power function appeared to be the most appropriate model and the parameters of the curve suggest a possible relict character for this fauna. The proportion of Balkan taxa on the islands sharply decreases from west to east, whereas the Anatolian taxa follow an opposite trend. Multi‐dimensional scaling, Parsimony Analysis of Endemicity and discriminant function analysis revealed a clear faunal discontinuity between the western and central Aegean Islands on one side, and the islands close to the Anatolian coast on the other. This discontinuity, consistent with the persistence (from Messinian to Pleistocene) of a sea barrier between these two groups of islands, strongly supports the importance of Pleistocene island configurations in determining present distributional patterns. The comparative richness of the tenebrionid fauna on Thasos is enhanced by the proximity of the island to the mainland and the diversity of its surviving habitats.     

Geographic distribution,host plants,and morphological variation of the currently radiating phytophagous ladybird beetle Henosepilachna diekei

To overview the morphological and ecological diversification within a species of phytophagous ladybird beetle Henosepilachna diekei, information concerning its distribution and host plant use was studied. This species was found widely in South East and South Asia from the Philippines through the Greater Sunda islands, a western part of Lesser Sundas, the Malay Peninsula to Sri Lanka. Mikania species (Asteraceae), Mikania micrantha in particular, were the most frequently used host plants, but some other plants belonging to Lamiaceae or Acanthaceae were also used by some local populations. Each population is possibly monophagous. According to morphological analyses, seven populations from four host plants at six sites on four Indonesian islands were grouped into two, one occurring on Java and Kalimantan (Borneo) and another on Sulawesi and Lombok, indicating that they were separated by the Wallace line. This morphological distinction was not correlated with the host plant use.     

Distributions of two ectosymbionts,branchiobdellidans (Annelida: Clitellata) and scutariellids (Platyhelminthes: “Turbellaria”: Temnocephalida), on atyid shrimp (Arthropoda: Crustacea) in southeast China

Distribution of two ecologically similar but usually spatially separate ectosymbionts, branchiobdellidans (Annelida) and scutariellids (Platyhelminthes), on atyid shrimp (Neocaridina spp.) is reported from 18 localities in five Provinces of southeastern China. Prevalence was determined for the branchiobdellidan, Holtodrilus truncatus, found at seven locations, the scutariellid, Scutariella japonica, present at every site, and where cohabitation occurred. Both ectosymbionts showed a microhabitat predilection for the host's branchial chambers and instances of cohabitation occurred at all seven locations where H. truncatus were collected, although not on every shrimp. On-site observations of live hosts supporting both ectosymbionts showed that neither H. truncatus nor S. japonica reacted aggressively or defensively towards the other when in close proximity. Instances of imported Chinese Neocaridina spp. into central Honshu Island, Japan, almost certainly came from areas in southeast China identified in this study. These imported populations are predicted to spread northwards into the area where endemic Japanese branchiobdellidans occur.     

Mitochondrial DNA genetic variation and phylogeography of the recently described vole species Proedromys liangshanensis Liu,Sun, Zeng and Zhao, 2007 (Rodentia: Arvicolinae)

A vole species, Proedromys liangshanensis Liu, Sun, Zeng and Zhao, 2007 Liu, SY, Sun, ZY, Zeng, ZY and Zhao, EM. 2007. A new vole (Cricetidae: Arvicolinae: proedromys) from the Liangshan Mountains of Sichuan province. China. J Mammal., 88(5): 1170–1178.  [Google Scholar] (Rodentia: Arvicolinae), which is endemic to the Liangshan Mountains, Sichuan, China, was reported in 2007. The species is restricted to a narrow range because of its weak dispersal ability and habitat specificity, and only lives in fir and spruce forests with abundant grass. In this study, the genetic diversity and phylogeographical structure of 42 P. liangshanensis were examined based on analysis of a partial mitochondrial DNA control region. The results revealed low genetic diversity in the P. liangshanensis populations. Twelve nucleotide haplotypes were defined in the 42 collected individuals, and were divided into two major phylogenetic clades, which were obviously related to geographic pattern. Estimates of gene flow (Nm?=?0.09) also revealed a genetic divergence between the Jinyang and Meigu populations. Species-specific traits, habitat specificity and geographic events contributed to the genetic divergence of the new vole. ?These authors contributed equally to this work.      

Insular biogeography of mammals in the Great Salt Lake

The distribution of 21 species of nonvolant mammals among nine islands in the Great Salt Lake was analyzed for biogeographic patterns. The number of species inhabiting an island is closely correlated with island area That the slope of the regression line describing this relationship (z or b) is relatively shallow compared to (1) totally isolated island systems or (2) island systems where an equilibrium between rates of colonization and extinction have been attained suggests that isolation plays little role in accounting for the variation in mammalian species diversity among islands. Stepwise multiple regression confirms this, while demonstrating that area alone accounts for 88 percent of the variation in species diversity among islands. However, endemic subspecies comprise a significant proportion of the insular mammalian fauna, suggesting that isolation for small mammals restricted to certain habitats may be substantial. A general scenario of the processes determining insular mammalian diversity and endemism is discussed for the Great Salt Lake, where the dynamic lake level creates a potential for different biogeographic processes over time.     

Heleobia maltzani (Westerlund, 1886) (Caenogastropoda: Truncatelloidea: Cochliopidae) from Crete and species-level diversity of Heleobia Stimpson, 1865 in Europe

Morphological characters and partial cytochrome oxidase (COI) DNA sequences were used to investigate intra- and interpopulation differences among three Cretan brackish-water populations of Heleobia maltzani snails. The morphology of male and female reproductive organs of H. maltzani did not differ within studied populations or in comparison with closely related species. In contrast, analysis of shell morphology revealed substantial variation not supported by the genetic data. Genetics results showed surprisingly low differentiation between all Cretan populations and also mainland populations of Heleobia. They also showed that H. maltzani is conspecific with four other European species of Heleobia, thus implying that there is only one species of brackish-water Heleobia in Europe. Such a low level of genotypic differentiation is unusual for typical island species and is most probably the consequence of recent colonization of Crete. Possible scenarios of such processes are discussed.     

Phylogeography of the Eurasian red squirrel (Sciurus vulgaris orientis) on the boreal island of Hokkaido,Japan

To test postglacial population expansion in small arboreal mammals dependent on boreal and subboreal forests, we used complete mitochondrial cytochrome b gene sequences (1140 bases) to investigate the phylogeography of the Eurasian red squirrel (Sciurus vulgaris orientis) on the Hokkaido Island of Japan. This subspecies is common in the boreal and subboreal forests of Hokkaido. We examined 61 specimens from 27 localities in Hokkaido. Phylogenetic relationships among 29 haplotypes found in the Hokkaido populations were not associated with geographic distribution of sampling localities. There were four mitochondrial DNA phylogroups. Phylogeographic analyses support sudden expansion of S. vulgaris orientis from restricted refugium in the southern part of Hokkaido during the last glacial period. The phylogeographic structure of this subspecies directly reflects the boreal and subboreal forest dynamics occurring in Hokkaido.     

Integrative taxonomy at the nexus of population divergence and speciation in insular speckled rattlesnakes

ABSTRACT

We describe two diminutive species of rattlesnakes (genus Crotalus) from small nearshore islands off the coast of Baja California in the western Gulf of California, Mexico. In order to test the hypothesis that some island populations represent cohesive species entities, we applied linear discriminant analysis and uniform validation procedures to multiple classes of intrinsic trait data. By using previously recognised species to establish a threshold for species recognition, we found that assignment of specimens to either new species was as probable as with other established rattlesnake species within the speckled rattlesnake (Crotalus mitchellii) complex. We also found that assignment of specimens from other island populations was not as probable as for the established species, and these populations are referable to C. pyrrhus. The species endemic to Piojo Island is most closely related to other island and mainland populations of C. pyrrhus whereas the species endemic to Cabeza de Caballo Island is apparently most closely related to C. angelensis, a nearby island endemic of large body size. However, patterns from both mitochondrial and nuclear phylogenies, and phenotypic variation, indicate that evolutionary trajectories of both of these species have been influenced by introgression from C. angelensis. We speculate that collective evidence based on contrasting patterns of nuclear and mitochondrial evolution supports a hybrid origin of the species from Cabeza de Caballo Island followed by exceptionally rapid mitochondrial evolution. Consistent with small body size, both species show a reduction in various scale counts relative to other species of the C. mitchellii species complex, suggesting that dwarfism is not simply a plastic response to insular conditions.

http://www.zoobank.org/urn.lsid:zoobank.org:pub:FBC8A11B-04A3-4231-85CA-3972DF5A42FF