Effects of Salinity on Development in the Ghost Shrimp Callichirus islagrande and Two Populations of C. major (Crustacea: Decapoda: Thalassinidea)

Salinity (S) was abruptly decreased from 35‰ to 25‰ at either the 4th zoeal (ZIV) or decapodid stage (D) in Callichirus islagrande (Schmitt) and 2 populations of C. major (Say). Other larvae were maintained at stable 35‰ or 25‰ S throughout development. In C. islagrande, duration of ZIV did not vary among the stable salinities. However, a decrease of salinity at ZIV reduced the duration of this stage, suggesting that the S decrease could be a possible cue for acceleration of larval development. In the Gulf population of C. major duration of ZIV was significantly longer at stable 35‰ S than at stable 25‰ S; the latter equaled duration for larvae transferred from 35 to 25‰ S at ZIV. Development in the Florida Atlantic population of C. major was variable but similar at stable 35 and 25‰ S. In 2 of 3 such comparisons, larvae reared at a stable 35‰ S more often molted to a 5th zoeal stage and became deformed at D than those reared at a stable 25‰ S. Callichirus islagrande and the Gulf population of C. major, both of which inhabit lower salinity waters on the Louisiana coast, were more similar in larval responses to salinity than were the 2 populations of C. major. Adult habitat was a better indicator of larval response to salinity than was phylogenetic proximity

Dark Energy from structure: a status report

The effective evolution of an inhomogeneous universe model in any theory of gravitation may be described in terms of spatially averaged variables. In Einstein's theory, restricting attention to scalar variables, this evolution can be modeled by solutions of a set of Friedmann equations for an effective volume scale factor, with matter and backreaction source terms. The latter can be represented by an effective scalar field (`morphon field') modeling Dark Energy. The present work provides an overview over the Dark Energy debate in connection with the impact of inhomogeneities, and formulates strategies for a comprehensive quantitative evaluation of backreaction effects both in theoretical and observational cosmology. We recall the basic steps of a description of backreaction effects in relativistic cosmology that lead to refurnishing the standard cosmological equations, but also lay down a number of challenges and unresolved issues in connection with their observational interpretation. The present status of this subject is intermediate: we have a good qualitative understanding of backreaction effects pointing to a global instability of the standard model of cosmology; exact solutions and perturbative results modeling this instability lie in the right sector to explain Dark Energy from inhomogeneities. It is fair to say that, even if backreaction effects turn out to be less important than anticipated by some researchers, the concordance high-precision cosmology, the architecture of current N-body simulations, as well as standard perturbative approaches may all fall short in correctly describing the Late Universe.Comment: Invited Review for a special Gen. Rel. Grav. issue on Dark Energy, 59 pages, 2 figures; matches published versio

Range extensions along western Atlantic for Epialtidae crabs (Brachyura, Majoidea) genera Acanthonyx Latreille, 1828 and Epialtus H. Milne Edwards, 1834

The present study provided information extending the known geographical distribution of three species of majoid crabs, the epialtids Acanthonyx dissimulatus Coelho, 1993, Epialtus bituberculatus H. Milne Edwards, 1834, and E. brasiliensis Dana, 1852. Specimens of both genera from different carcinological collections were studied by comparing morphological characters. We provide new data that extends the geographical distributions of E. bituberculatus to the coast of the states of Paraná and Santa Catarina (Brazil), and offer new records from Belize and Costa Rica. Epialtus brasiliensis is recorded for the first time in the state of Rio Grande do Sul (Brazil), and A. dissimulatus is reported from Quintana Roo, Mexico. The distribution of A. dissimulatus, previously known as endemic to Brazil, has a gap between the states of Espírito Santo and Rio de Janeiro. However, this restricted southern distribution is herein amplified by the Mexican specimens

Molecular phylogeny of mud crabs (Brachyura: Panopeidae) from the northwestern Atlantic and the role of morphological stasis and convergence

10.1007/s002270000325Marine Biology137111-18MBIO

Phylogeny of eriphioid crabs (Brachyura, Eriphioidea) inferred from molecular and morphological studies

10.1111/zsc.12030Zoologica Scripta43152-64ZLSC