Multiple pathways for invasion of anurans on a Pacific island

Since 1937, thirteen species of non-indigenous anurans have made their way to Guam. Of these, at least six have established breeding populations. Various pathways led to the introduction of these species to the island. The only anuran intentionally introduced was Chaunus marinus (formerly Bufo marinus ), which was brought to Guam as a biocontrol agent. Kaloula picta, K. pulchra, Polypedates leucomystax , and probably Litoria fallax arrived as stowaways via maritime or air-transport vessels. Eleutherodactylus coqui and Euhyas (formerly Eleutherodactylus ) planirostris appear to have entered Guam through the horticultural trade. Specimens of Pseudacris regilla were found among agricultural products and Christmas trees. Five species have been transported to Guam via the aquacultural trade. The importation of tilapia, milkfish, and white shrimp from China, Hong Kong, Taiwan, and the Philippines was associated with the introduction to Guam of Fejervarya cancrivora, F. limnocharis sensu lato, Microhyla pulchra, Polypedates megacephalus , and Sylvirana guentheri (formerly Rana guentheri ). Presently, no quarantine or containment guidelines have been established for Guam's aquacultural industry.     

Global analysis of reptile elevational diversity

Aim Latitudinal‐ and regional‐scale studies of reptile diversity suggest a predominant temperature effect, unlike many other vertebrate richness patterns which tend to be highly correlated with both temperature and water variables. Here I examine montane gradients in reptile species richness with separate analyses of snakes and lizards from mountains around the world to assess a predominant temperature effect and three additional theories of diversity, including a temperature–water effect, the species–area effect and the mid‐domain effect (MDE). Location Twenty‐five elevational gradients of reptile diversity from temperate, tropical and desert mountains in both hemispheres, spanning 10.3° N to 46.1° N. Methods Elevational gradients in reptile diversity are based on data from the literature. Of the 63 data sets found or compiled, only those with a high, unbiased sampling effort were used in analyses. Twelve predictions and three interactions of diversity theory were tested using nonparametric statistics, linear regressions and multiple regression with the Akaike information criterion (AIC). Results Reptile richness and, individually, snake and lizard richness on mountains followed four distinct patterns: decreasing, low‐elevation plateaus, low‐elevation plateaus with mid‐elevation peaks, and mid‐elevation peaks. Elevational reptile richness was most strongly correlated with temperature. The temperature effect was mediated by precipitation; reptile richness was more strongly tied to temperature on wet gradients than on arid gradients. Area was a secondary factor of importance, whereas the MDE was not strongly associated with reptile diversity on mountains. Main conclusions Reptile diversity patterns on mountains did not follow the predicted temperature–water effect, as all diversity patterns were found on both wet and dry mountains. But the influence of precipitation on the temperature effect most likely reflects reptiles' use of radiant heat sources (sunning opportunities) that are more widespread on arid mountains than wet mountains due to lower humidity, sparser vegetation and less cloud cover across low and intermediate elevations.     

THE DESIGN OF A BEAUTIFUL WEAPON: COMPENSATION FOR OPPOSING SEXUAL SELECTION ON A TRAIT WITH TWO FUNCTIONS

Male fiddler crabs, genus Uca, have one greatly enlarged claw with which they court females and threaten and fight other males. Longer claws are more effective signals but are thought to be less effective weapons because the relative closing force at the tip of the claw decreases with claw length. We studied claw morphology and fighting in Uca terpsichores and Uca beebei and found a mechanism that may resolve opposing selection for signaling and fighting ability. When males fought they delivered gripping forces not at the tips but at the tubercles on the inner margins of their claws’ fingers. As claws grow, these tubercles remain relatively close to the apex of the gape. Consequently, the mechanical advantage that governs the forces that can be delivered at these tubercles decreases only slightly with increasing claw length allowing the claw to be an effective signal and a powerful weapon. Animal weapons are exceptionally diverse in form and detail of armature and the causes of this diversity are poorly understood. We suggest that the designs of weapons may often reflect compensatory patterns of growth and placement of armature that enhances the weapon's overall utility for multiple uses in competition for mates.     

COMPARATIVE ANALYSIS OF METHODS FOR THE PURIFICATION OF DNA FROM LOW-BIOMASS SAMPLES BASED ON TOTAL YIELD AND CONSERVED MICROBIAL DIVERSITY

Despite advances in the specificity and sensitivity of molecular biological technologies, the efficient recovery of DNA from low-biomass samples remains extremely challenging. Optimal methods to purify biomolecules from such environments should (1) achieve the greatest total yield and (2) reflect the true microbial diversity of the sample. These attributes were assessed from five DNA purification regimes: a standard-manual procedure, MoBio Ultraclean and Promega Wizard kits, and an automated Axcyte AutoLyser method with and without bead-beating agitation. A homogenous mixture of known concentrations of nine distinct bacterial lineages isolated from low-biomass environments was prepared and suitable aliquots of subsamples were processed in parallel. DNA products from each of these methods were then subjected to polymerase chain reaction (PCR), quantitative PCR and 16S rRNA clone-library analysis. The Axcyte AutoLyser outperformed all other purification regimes examined. This automated method consistently both yielded the highest concentration of PCR-amplifiable DNA, and reported species composition most consistent with the starting solution.

PRACTICAL APPLICATIONS

This communication carefully examines the effectiveness of common DNA purification regimes as well as an automated method. Comparative analyses convincingly demonstrate that the different methods not only result in different recovery of genomic DNA, but more importantly, different estimations of microbial diversity in the sample. This report will hopefully inspire investigators from various industries (pharmaceutical, ecological, medical, semiconductor, etc.) who find themselves in the initial phases of large-scale studies to devote a significant effort into optimizing sample extraction protocols to achieve the most accurate information.     

Continued misuse of multiple testing correction methods in population genetics‐A wake‐up call?

Population geneticists often use multiple independent hypothesis tests of Hardy–Weinberg Equilibrium (HWE), Linkage Disequilibrium (LD), and population differentiation, to make broad inferences about their systems of choice. However, correcting for Family‐Wise Error Rates (FWER) that are inflated due to multiple comparisons, is sparingly reported in our current literature. In this issue of Molecular Ecology Resources, perform a meta‐analysis of 215 population genetics studies published between 2011 and 2013 to show (i) scarce use of FWER corrections across all three classes of tests, and (ii) when used, inconsistent application of correction methods with a clear bias towards less‐conservative corrections for tests of population differentiation, than for tests of HWE, and LD. Here we replicate this meta‐analysis using 205 population genetics studies published between 2013 and 2018, to show the same continued disuse, and inconsistencies. We hope that both studies serve as a wake‐up call to population geneticists, reviewers, and editors to be rigorous about consistently correcting for FWER inflation.     

Disparate fisheries: Problems for the law of the sea conference and beyond

Abstract

The search for a uniform international fisheries regime at the United Nations Conference on the Law of the Sea will be impeded by the fact that the conditions between different fisheries and different fishery regions are greatly dissimilar. This is one of the conclusions emerging from a series of working papers produced by the Program of International Studies of Fisheries Arrangements undertaken by Resources for the Future, Inc. The working paper on the North Pacific shows that there are only a handful of States with an interest in the fisheries; that most of the States are highly developed; and that there has been a long history of fishery agreements. For the West African region, however, there are about forty. States involved, about half of which are local, developing States and the other half are mostly developed States from distant waters. Here the fisheries have been subjected to considerable recent pressures, with catches by the distant‐water States increasing about five‐fold in the past decade. In the Indian Ocean, with the exception of tuna, most of the fish stocks are still not fully utilized and have attracted almost no attention from States outside the region. Tuna fisheries, both in the Indian Ocean and elsewhere throughout the world, are approaching the limits of maximum sustainable yields, but the number and size of vessels continues to increase at a rapid rate. The global mobility of tuna vessels creates particularly difficult problems for the UN conferees. The disparity among these situations is likely to provide severe restrictions on the uniformity of general rules and principles that might be acceptable at the Conference.     

Detection and genetic characterisation of Toxoplasma gondii circulating in free-range chickens,pigs and seropositive pregnant women in Benue state,Nigeria

Toxoplasma gondii parasites present strong but geographically varied signatures of population structure. Populations sampled from Europe and North America have commonly been defined by over-representation of a small number of clonal types, in contrast to greater diversity in South America. The occurrence and extent of genetic diversity in African T. gondii populations remains understudied, undermining assessments of risk and transmission. The present study was designed to establish the occurrence, genotype and phylogeny of T. gondii in meat samples collected from livestock produced for human consumption (free-range chickens, n = 173; pigs, n = 211), comparing with T. gondii detected in blood samples collected from seropositive pregnant women (n = 91) in Benue state, Nigeria. The presence of T. gondii DNA was determined using a published nested polymerase chain reaction, targeting the 529 bp multicopy gene element. Samples with the highest parasite load (assessed using quantitative PCR) were selected for PCR-restriction fragment length polymorphism (PCR-RFLP) targeting the surface antigen 3 (SAG3), SAG2 (5’ and 3’), beta-tubulin (BTUB) and dense granule protein 6 (GRA6) loci, and the apicoplast genome (Apico). Toxoplasma gondii DNA was detected in all three of the populations sampled, presenting 30.6, 31.3 and 25.3% occurrence in free-range chickens, pigs and seropositive pregnant women, respectively. Quantitative-PCR indicated low parasite occurrence in most positive samples, limiting some further molecular analyses. PCR-RFLP results suggested that T. gondii circulating in the sampled populations presented with a type II genetic background, although all included a hybrid type I/II or II/III haplotype. Concatenation of aligned RFLP amplicon sequences revealed limited diversity with nine haplotypes and little indication of host species-specific or spatially distributed sub-populations. Samples collected from humans shared haplotypes with free-range chickens and/or pigs. Africa remains under-explored for T. gondii genetic diversity and this study provides the first detailed definition of haplotypes circulating in human and animal populations in Nigeria.