New findings of Hexalona-branch representatives in Brazil,with a description of Prenda gen. nov. (Crustacea: Anomopoda: Aloninae)

Altogether, Coronatella and Hexalona-branches are considered the main lineages of Aloninae – a subfamily of common bottom-dwelling microcrustaceans in freshwater environments. Although the taxonomic features of Brazilian members of the Hexalona-branch have been summarised for species from the costata-group and affinis-group, a revision of other widely distributed species in the world is still lacking in this country. The aim of this paper was to study the morphology of Brazilian populations from the guttata-group and intermedia-group, and to describe a new genus from the Hexalona-branch. The parthenogenetic females of Alona cf. guttata from Brazil have similar morphology when compared to data from the literature, but the armature of the terminal claw of its males seems to be different from those of Alona guttata sensu stricto, Alona barbulata and Alona werestschagini. The intermedia-group is formed by Alona elisae sp. nov., which seems to be endemic to the Cerrado of Brazil Central, and Alona isabellae sp. nov., which is widely distributed in Brazil; this species has a labral keel armed with 2–4 setulae, and postabdomen with setulae of lateral fascicles longer than the level of marginal denticles, morphological traits that differentiate it from Alona elisae sp. nov. Another endemic species from the Hexalona-branch is Prenda arvensis gen. nov. and sp. nov., which has two main head pores, a reduced seta on endite 1 of the first limb, sixth limb is a wide lobe. The potential of biodiversity from the Hexalona-branch from Brazil is still underestimated, and a global revision of the guttata-group and intermedia-group is very important for the progress of Aloninae taxonomy and systematics.

http://zoobank.org/urn:lsid:zoobank.org:pub:0A2E4A30-0C9C-43E8-8E72-1DEDA6AFF3C3     

Niche lability in the evolution of a Caribbean lizard community

Niche conservatism--the tendency for closely related species to be ecologically similar--is widespread. However, most studies compare closely related taxa that occur in allopatry; in sympatry, the stabilizing forces that promote niche conservatism, and thus inhibit niche shifts, may be countered by natural selection favouring ecological divergence to minimize the intensity of interspecific interactions. Consequently, the relative importance of niche conservatism versus niche divergence in determining community structure has received little attention. Here, we examine a tropical lizard community in which species have a long evolutionary history of ecological interaction. We find that evolutionary divergence overcomes niche conservatism: closely related species are no more ecologically similar than expected by random divergence and some distantly related species are ecologically similar, leading to a community in which the relationship between ecological similarity and phylogenetic relatedness is very weak. Despite this lack of niche conservatism, the ecological structuring of the community has a phylogenetic component: niche complementarity only occurs among distantly related species, which suggests that the strength of ecological interactions among species may be related to phylogeny, but it is not necessarily the most closely related species that interact most strongly.     

Inhibition of mTOR induces autophagy and reduces toxicity of polyglutamine expansions in fly and mouse models of Huntington disease

Huntington disease is one of nine inherited neurodegenerative disorders caused by a polyglutamine tract expansion. Expanded polyglutamine proteins accumulate abnormally in intracellular aggregates. Here we show that mammalian target of rapamycin (mTOR) is sequestered in polyglutamine aggregates in cell models, transgenic mice and human brains. Sequestration of mTOR impairs its kinase activity and induces autophagy, a key clearance pathway for mutant huntingtin fragments. This protects against polyglutamine toxicity, as the specific mTOR inhibitor rapamycin attenuates huntingtin accumulation and cell death in cell models of Huntington disease, and inhibition of autophagy has the converse effects. Furthermore, rapamycin protects against neurodegeneration in a fly model of Huntington disease, and the rapamycin analog CCI-779 improved performance on four different behavioral tasks and decreased aggregate formation in a mouse model of Huntington disease. Our data provide proof-of-principle for the potential of inducing autophagy to treat Huntington disease.     

Genetic variation increases during biological invasion by a Cuban lizard

A genetic paradox exists in invasion biology: how do introduced populations, whose genetic variation has probably been depleted by population bottlenecks, persist and adapt to new conditions? Lessons from conservation genetics show that reduced genetic variation due to genetic drift and founder effects limits the ability of a population to adapt, and small population size increases the risk of extinction. Nonetheless, many introduced species experiencing these same conditions during initial introductions persist, expand their ranges, evolve rapidly and become invasive. To address this issue, we studied the brown anole, a worldwide invasive lizard. Genetic analyses indicate that at least eight introductions have occurred in Florida from across this lizard's native range, blending genetic variation from different geographic source populations and producing populations that contain substantially more, not less, genetic variation than native populations. Moreover, recently introduced brown anole populations around the world originate from Florida, and some have maintained these elevated levels of genetic variation. Here we show that one key to invasion success may be the occurrence of multiple introductions that transform among-population variation in native ranges to within-population variation in introduced areas. Furthermore, these genetically variable populations may be particularly potent sources for introductions elsewhere. The growing problem of invasive species introductions brings considerable economic and biological costs. If these costs are to be mitigated, a greater understanding of the causes, progression and consequences of biological invasions is needed.