Patterns of habitat utilization of small rodents in an area of Araucaria forest in Southern Brazil

Abstract We investigated patterns of spatial distribution and microhabitat selection of rodents in a patch (26 ha) of mixed ombrophilous forest (or Araucaria forest), dominated by the Araucaria ‘pine’Araucaria angustifolia, in the National Park of Aparados da Serra, RS, in southern Brazil. We conducted monthly trapping sessions lasting 6 days (from June 2000 to June 2001) using a square grid of 121 trap stations, separated by 15 m (2.25 ha). We measured 10 microhabitat variables that could influence species distribution. These variables were related to the occurrence of mammals by using canonical correspondence analysis (CCA) and stepwise multiple regression. The distribution patterns of the three most common rodents differed significantly (χ² = 38.6; P < 0.002), with Delomys dorsalis being more clumped than the other two species. Both CCA and multiple regression analysis showed a significant effect of microhabitat variables on species occurrence. The multiple regression parameters for Oligoryzomys nigripes were R² = 0.142, P < 0.05, for Akodon montensis were R² = 0.222, P < 0.01, and for D. dorsalis R² = 0.323, P < 0.001. Variables that significantly influenced species distribution were vegetation density at 1 m height and length of fallen logs for O. nigripes, canopy cover for A. montensis, and vegetation density at 2 m height, quantity of leaves of Araucaria trees (negative relationship), tree density (except Araucaria trees), and number of potential shelters, for D. dorsalis. The results indicated that D. dorsalis is the most habitat specialist among the rodent species and that there are no apparent competitive interactions.     

Novel,panzootic and hybrid genotypes of amphibian chytridiomycosis associated with the bullfrog trade

Global amphibian declines are linked with the presence of specific, highly virulent genotypes of the emerging fungal disease chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) known as the global panzootic lineage (Bd‐GPL). The global trade in amphibians for human consumption is suspected to have facilitated emergence of the disease, but evidence to support this is largely lacking. Here, we investigated the role the Lithobates catesbeianus (North American bullfrog) trade in spreading Bd genotypes by comparing strains associated with L. catesbeianus to a global panel using 36 sequenced loci from multiple chromosomal regions. Most bullfrogs were infected with Bd‐GPL genotypes, but we also detected novel, highly divergent Bd genotypes (Bd‐Brazil) from a live bullfrog in a US market and from native Brazilian anurans in the Atlantic Forest where bullfrogs are widely farmed. Sexual reproduction was also detected for the first time in Bd in the form of a hybrid genotype between the Bd‐GPL and Bd‐Brazil lineages in the Atlantic Forest. Despite the demonstration that ribosomal RNA types in Bd fail to undergo concerted evolution (over 20 sequence types may be found in a single strain), the Bd‐GPL and Bd‐Brazil lineages form largely separate clusters of related internal transcribed spacer (ITS) RNA sequences. Using ITS sequences, we then demonstrate the presence of Bd‐Brazil in Japan, primarily on invasive L. catesbeianus. The finding that Bd is capable of sexual reproduction between panzootic and endemic genotypes emphasizes the risk of international wildlife trade as a source of additional Bd epizootics owing to hybridization.     

Isolation and characterization of microsatellite markers from the sweet passion fruit (Passiflora alata Curtis: Passifloraceae)

Passiflora alata is one of the commercialized species of the passion vines, grown for its edible fruits. It is found in South America, mainly Paraguay, Argentina, Peru and Brazil. The development of a set of microsatellite markers was proposed to provide tools for analysing both genetic structure of wild populations and the reproductive system of the species, which are poorly understood. Seven markers were developed from a P. alata‐genomic library enriched for simple sequence repeats (SSR). Twelve individuals were genotyped, and the levels of the expected heterozygosity (H_E) did show that those markers could be used to develop P. alata genetic studies.     

Food and humidity affect sex pheromone ratios in the stink bug, Euschistus heros

Abstract.  Male stink bugs, Euschistus heros , only produce the three-component sex pheromone blend consisting of methyl-(2 E ,4 Z )-decadienoate, methyl-2,4,6-trimethyldodecanoate and methyl-2,4,6-trimethyltridecanoate in a constant ratio of 53 : 3 : 44, respectively, when provided with a food source (green beans, Phaseolus vulgaris ). When volatiles are collected from insects with drinking water, humidified air, or under dry conditions, the insects stop producing two components (methyl-2,4,6-trimethyldodecanoate and methyl-2,4,6-trimethyltridecanoate) after 1 day and increase the amount of defensive compounds produced [e.g. ( E )-2-hexenal, decane]. Methyl-2,4,6-trimethyltridecanoate is able to change the behaviour of females but not males. Dual-choice olfactometer bioassays with synthetic standards of all three components, as well as the ternary mixture in the correct ratio, induce a response from females but not males, indicating that all three components have a role in sexual communication. Thus, the dietary conditions under which volatile collections are carried out are crucial for determination of the precise sex pheromone blend.     

Diversification in the use of resources by Idarnes species: bypassing functional constraints in the fig–fig wasp interaction

Mutualisms such as the fig–fig wasp mutualism are generally exploited by parasites. We demonstrate that amongst nonpollinating fig wasps (NPFWs) parasitic on Ficus citrifolia, a species of Idarnes galls flowers and another species feeds on galls induced by other wasps killing their larvae. The galling wasp inserts its ovipositor through the fig wall into the fig cavity. The ovipositor then follows a sinuous path and is introduced through the stigma and style of the flower. The egg is deposited between the integument and nucellus, in the exact location where the pollinating mutualistic wasp would have laid its egg. Gall induction is a complex process. In contrast, the path followed by the ovipositor of the other species is straightforward: attacking a larva within a developed gall poses different constraints. Shifts in feeding regime have occurred repeatedly in NPFWs. Monitoring traits associated with such repeated evolutionary shifts may help understand underlying functional constraints. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 114–122.     

Total evidence phylogenetic analysis and reclassification of Euschistus Dallas within Carpocorini (Hemiptera: Pentatomidae: Pentatominae)

Robust phylogenetic hypotheses have become key for studies addressing the evolutionary biology and ecology of various groups of organisms. In the species‐rich heteropteran superfamily Pentatomoidea, phylogenies at lower taxonomic levels are still scarce and mostly employ exclusively morphological data. In this study, we conducted a total evidence phylogeny focusing on the tribe Carpocorini (Pentatomidae), using morphological data and four DNA markers (COI, Cytb, 16S and 28S rDNA; ～2330 bp; 32 taxa) in order to investigate the relationships within Euschistus Dallas, one of the most speciose pentatomid genera, and between Euschistus and related genera. Our hypotheses generated by maximum likelihood and Bayesian inference show that the current taxonomic composition and classification of Euschistus and allied genera are in need of revision. Euschistus was recovered as nonmonophyletic, with the subgenera forming four independent lineages: Euschistus (Euschistus) and Euschistus (Lycipta) Stål are sister groups; Euschistus (Euschistomorphus) Jensen‐Haarup is more closely related to Dichelops Spinola and Agroecus Dallas; and Mitripus Rolston is divided into two clades closely related to Sibaria Stål and Ladeaschistus Rolston. We chose not to change the classification of E. (Euschistomorphus) until further data become available, and propose to split Euschistus into three genera with the exclusion of Euschistus (Mitripus) and all of its species. Here we elevate Mitripus to genus rank to include M. acutus comb.n. , M. convergens comb.n. and M. legionarius comb.n. , and propose Adustonotus Bianchi gen.n. to include A. anticus comb.n. , A. latus comb.n. , A. tauricornis comb.n. , A. grandis comb.n. , A. hansi comb.n. , A. paranticus comb.n. , A. irroratus comb.n. and A. saramagoi comb.n. We also provide identification keys to the genera Adustonotus gen.n. , Ladeaschistus, Mitripus n. rank and Sibaria, here defined as the Mitripus genus group, and to the species of Mitripus and Adustonotus gen.n. Our results provide insights into the current status of the classification of the Pentatomidae, suggesting the need for phylogenetic analyses at different taxonomic levels within stink bugs. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:E09D2675‐0F2B‐4AAE‐9837‐257E0B18BC52 .     

Does seed germination contribute to ecological breadth and geographic range? A test with sympatric Diplusodon (Lythraceae) species from rupestrian fields

We tested the regeneration niche hypothesis by comparing the germination ecology of two sympatric Diplusodon species differing in their geographic range and microhabitat. Diplusodon orbicularis is an endemic shrub achieving high densities on sandy soils, whereas Diplusodon hirsutus has a wider geographic range and establishes on rocky outcrops. Seeds were set to germinate under constant temperatures of 15, 20, 25, 30 and 35°C under 12 h light/12 h dark conditions. Light induced germination in both species, but germination under darkness was also observed. Optimum conditions for germination were 25°C/light for both species. The lack of differences in soil temperatures between rocky outcrops and sandy soils provides evidence of no temperature‐dependent microhabitat selection. Unexpectedly, germinability of the more widespread species was lower than that of the endemic congener. Higher germinability of D. orbicularis may account for higher densities when compared with D. hirsutus. Our results provide limited support for the role of germination in contributing to ecological breadth and geographic range.