Body size increase in insular rodent populations: a role for predators?

Insular mammalian populations living in areas of small size are often characterized by a drastic change in body mass compared to related continental populations or species. Generally, small mammals (less than 100 g) evolve into giant forms while large mammals (up to 100 g) evolve into dwarf forms. These changes, coupled with changes in other life, behavioural, physiological or demographic traits are referred to generally as the insular syndrome. We tested in this study the relative contribution of three factors — area of island, numbers of competitor species and number of predator species — to changes in body size of the woodmouse (Apodemus sylvaticus) in the Western Mediterranean Sea. Our results, based on a comparative analysis using the phylogenetic independent contrasts method, indicate that the increase in body size is related both to the decrease of island size and to the lower number of predator species. A decrease of competitor species does not seem to have an important effect.     

Influence of environment upon the life history of gudgeon, Gobio gobio (L.): a recent and successful colonizer of the Iberian Peninsula

The growth and the reproductive tactics of gudgeon, Gobio gobio (L.) were assessed in three contrasting streams of the Iberian Peninsula: the Rivers Moros and Ucero, tributaries of the R. Duero, and the R. MatarrańGa, a tributary of the R. Ebro. The R. Duero gudgeon have spread in the last 50 years while their presence in the lower tributaries of the R. Ebro followed the construction of reservoirs in the mid 1960s. The life histories of the Moros and MatarrańnGa gudgeon are very similar; rapid growth in spring, early reproduction (1 -year-old), high reproductive cost, short life-span and trend to semelparity. Both populations are strongly influenced by the severe summer droughts that result in (I) reduction in the condition coefficient, (2) reduction in the growth rate (particularly in the River MatarrańGa), (3) single spawning and (4) no gonad development in the summer. The gudgeon in the Ucero delay maturity, grow slower, are multi-spawners and have a longer life span. All the Duero populations come from the same genetic pool and they are actually connected through the populations living along this river basin, whereas the MatarrańGa population is not genetically linked, we hypothesize that the differences between these populations are environmentally induced.     

Delimitation of morphologically similar sponge crab species of the genus Pseudodromia (Crustacea, Decapoda, Dromiidae) from South Africa

Stewart, B. A., Gouws, G., Daniels, S. R. & Matthee, C. A. (2004). Delimitation of morphologically similar sponge crab species of the genus Pseudodromia (Crustacea, Decapoda, Dromiidae) from South Africa. — Zoologica Scripta , 33 , 45–55.
Presently, three Pseudodromia sponge crab species are recognized, all of which are endemic to the continental shelf off the coast of South Africa. Two of these differ only in the morphology of their rostral teeth, making them difficult to distinguish, and can thus be considered as cryptic species. In addition they have very similar distribution ranges, thus raising doubts as to their specific status. Discriminant function analysis of morphometric data, differentiation at 10 allozyme loci, and sequence data derived from the 12S rRNA mitochondrial gene were used to test whether specimens identified as P. latens and P. rotunda are morphological forms of a single, widespread species, or represent two, distinct, reproductively isolated species, and to establish whether these two taxa are sister species, and thus form a monophyletic entity. The presence of fixed allele differences at three, and strong genetic heterogeneity at five other allozyme loci, indicating no gene flow occurring between sympatric populations, as well as the relatively high degree of 12S rRNA and allozyme genetic differentiation observed, supported the recognition of P. latens and P. rotunda as separate species. The 12S rRNA topology suggested that the genus Pseudodromia , as presently constituted, is paraphyletic, thus inferring that the morphological characters used to define this taxon might not be useful for phylogenetic inferences. It was concluded that in view of the uncertainties raised regarding the designation and composition of certain genera within the family Dromiidae, further rigorous analyses of morphological and genetic data are needed to further our understanding of the taxonomy of the sponge crabs.     

Exopolysaccharide-producing strains of thermophilic lactic acid bacteria cluster into groups according to their EPS structure

AIMS: To compare galactose-negative strains of Streptococcus thermophilus and Lactobacillus delbrueckii subspecies bulgaricus isolated from fermented milk products and known to produce exopolysaccharides (EPSs). METHODS AND RESULTS: The structures of the EPSs were determined using nuclear magnetic resonance (NMR) and their genetic relationships determined using restriction endonuclease analysis (REA) and random amplification of polymorphic DNA (RAPD). Similar groupings were apparent by REA and RAPD, and each group produced an EPS with a particular subunit structure. CONCLUSION: Although none of the strains assimilated galactose, all inserted a high proportion of galactose into their EPS when grown in skimmed milk, and fell into three distinct groups. Significance and Impact of the Study: This information should help in an understanding of genetic exchanges in lactic acid bacteria.     

A homeobox-containing marker of posterior neural differentiation shows the importance of predetermination in neural induction

A homeobox sequence has been used to isolate a new Xenopus cDNA, named XIHbox6. A short probe from this gene serves as an early marker of posterior neural differentiation in the Xenopus nervous system. The gene recognized by this cDNA sequence is first transcribed at the late gastrula stage and solely in the posterior neural cells. The gene is expressed when ectodermal and mesodermal tissues of an early gastrula are placed in contact, but not by either tissue cultured on its own. However, gene expression is most easily inducible in ectoderm from the dorsal region, i.e., in ectoderm normally destined to form neural structures. This establishes the principle, in contrast to previous belief, that the induction of the embryonic nervous system involves a predisposition of the ectoderm and does not depend entirely on an interaction with inducing mesoderm.     

Private Financing Options for Long-term Care

Private financing for long-term care now comes almost exclusively from out-of-pocket payments. Long-term-care costs quickly impoverish most elderly, resulting in Medicaid dependency. The consequences are profound for the western Sun Belt with its rapidly growing elderly population. Key private financing options are long-term-care individual retirement accounts (LTC/IRAs), home equity conversion, social-health maintenance organizations and long-term-care insurance. Study of data from the past half century suggests that the LTC/IRA approach would prove unsatisfactory for the purpose despite the intuitive appeal of this mechanism. Experience with home equity conversions is still very limited, and unresolved questions limit this approach to the role of a reserve option for now. While promising, social-health maintenance organizations are still in the experimental stages and not yet commercially available. Long-term-care insurance is currently sold on a thin market and emphasizes nursing home coverage. New approaches to private financing through long-term-care insurance seem to offer the best approach for immediate implementation.