Population structure and gene flow in stomion: A species swarm of flightless beetles of the galápagos islands

Stomion is a swarm of 13 flightless tenebrionid beetle species endemic to the Galápagos Islands. Their distribution is patchy and largely restricted to the littoral and arid zones of the archipelago. Each taxon is found on one or a few geographically close islands. Thirty-five populations representing nine of the taxa were examined at eight polymorphic enzyme loci using cellulose acetate electrophoresis to measure patterns of gene flow and investigate models of dispersal in a relatively young species group exhibiting spatially isolated populations. Genetic subdivision is high, particularly among populations of taxa which inhabit more than one island, revealing restricted gene flow and confirming the high potential for reproductive isolation among subpopulations. The mean FST across taxa was 0.30. The genetic differentiation occurring between spatially isolated populations may explain the exuberant speciation of the genus in the Galápagos. Tests of gene flow models give support to the stepping-stone model of dispersal. Because of their lack of flight wings, interisland dispersal of Stomion probably occurred by oceanic drift as pleuston or on floating debris, with individuals colonizing nearby islands more frequently than ones at a greater distance

The Death Cap mushroom (Amanita phalloides) moves to a native tree in Victoria, British Columbia

Amanita phalloides (Vaill. ex Fr.) Link, the Death Cap mushroom, is an invasive ectomycorrhizal fungus in North America that was inadvertently introduced from Europe. Death Cap mushrooms are highly toxic and have caused three recorded poisonings in British Columbia, including one recent death. In British Columbia, these mushrooms fruit mostly in urban environments in the greater Vancouver and Victoria areas under planted exotic broadleaf trees. In California, A. phalloides was demonstrated to also form ectomycorrhizas with a native oak species. Here we report that A. phalloides forms ectomycorrhizas with Quercus garryana, BCâ s only native species of oak, and can fruit in association with this tree host. If Death Cap mushrooms spread in Q. garryana habitat, the risk for serious mushroom poisoning will increase and mushroom harvesters, the medical community, and park managers need to be aware of this increased risk.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Genetic differentiation and speciation in Stomion (Coleoptera: Tenebrionidae): Flightless beetles of the Galapagos Islands, ecuador

Stomion is a swarm of 13 tenebrionid beetle taxa endemic to the Galapagos Islands. The taxa show marked morphological variation, and all are flightless. They can be divided into three divergent morphological groups based on external sculpturing of the elytra. Eleven taxa were examined electrophoretically at 20 enzyme loci to measure the extent of genetic differentiation which accompanied morphological differentiation and speciation. Stomion are shown to be ideal candidates for allopatric and founder event speciation, with their limited dispersal ability, narrow distributions, and incidence of single-island endemics. Accordingly, individual heterozygosities were low in most taxa, and gene pool divergence was apparent among populations of single taxa occupying different islands. Both interspecific and intraspecific genetic identities were high, with an average I = 0.88 and I = 0.96, respectively. The relatively young age of the genus and the allopatric mode of speciation may account for high genetic relatedness. No clear relationship was found between allozyme phenotypes and the three morphological groups, thus, the evolution of these traits may have been facilitated by similar selection among islands of similar age and geography. The geographical distributions of the morphological groups can be used to suggest a general pattern of speciation for the group

A NEW GENUS AND SPECIES OF STYGOBITIC PARAMELITID AMPHIPOD FROM THE PILBARA, WESTERN AUSTRALIA

Volume: 24Start Page: 395End Page: 41

Chemical diversity in south-eastern Australian saline lakes II: biotic implications

This study explores how differences in ionic composition of south-eastern Australian saline lake waters, caused by path differentiation according to the Eugster-Jones-Hardie models of solute evolution and halite recycling, influence species composition of ostracod faunas. Ostracod occurrences are reported as physiologically important ionic ratios set in a marine-meteoric framework, with chemical boundaries determined by mixing and evaporation models. The occurrence of halophilous ostracods coincides with changes in the ionic structure of lake waters. Chemical diversity is found to be biologically important, with most ostracods preferring a specific pathway of the Eugster-Jones-Hardie models. Path preference predominantly reflects the different tolerance ranges of species to a combination of Na+/H+, Na+/Ca 2+ and alkalinity/Cl- activity ratios, which probably govern acid-base balance and Na+ and Ca2+ regulation. An alkalinity/Cl- activity ratio of ∼-2.3 corresponds to the main division in the ostracod data and reflects the abrupt change in alkalinity/Cl- ratios that occurs when a seawater-like solute matrix is diluted with a large amount of meteoric water (95%). Most halobiont ostracods occur in waters enriched with Na-Cl as a result of halite recycling. Evidence is presented that the same geochemical processes are relevant to other aquatic organisms (e.g. zooplankton, diatoms, insects) found in salt lakes