The shape of things to come: linking developmental plasticity to post-metamorphic morphology in anurans

Development consists of growth and differentiation, which can be partially decoupled and can be affected by environmental factors to different extents. In amphibians, variation in the larval environment influences development and causes changes in post-metamorphic shape. We examined post-metamorphic consequences, both morphological and locomotory, of alterations in growth and development. We reared tadpoles of two phylogenetically and ecologically distant frog species (the red-eyed treefrog Agalychnis callidryas and the African clawed frog Xenopus laevis) under different temperatures with ad libitum food supply and under different food levels at a constant temperature. Low temperature and low food levels both resulted in similarly extended larval periods. However, low temperature yielded relatively long-legged frogs with a lower degree of ossification than warm temperature, whereas low food yielded relatively short-legged frogs with a higher degree of ossification than high food levels. Such allometric differences had no effect on locomotor performance of juveniles. Our results provide a basis for understanding the relationship between growth, differentiation and post-metamorphic shape in anurans and help explain many of the discrepancies reported in previous studies. © 2010 The Authors. Journal Compilation © 2010 European Society For Evolutionary Biology.Peer Reviewe

Paleoenvironmental changes in the western Mediterranean since the last glacial maximum: High resolution multiproxy record from the Algero-Balearic basin.

4 figures, 1 table.The present study uses a multiproxy approach in order to further understand the evolution of climate responses in the western Mediterranean as of the Last Glacial Maximum. Sediments from ODP Site 975 in the Algero–Balearic basin have been analysed at high resolution, both geochemically and mineralogicallly. The resulting data have been used as proxies to establish a sedimentary regime, primary marine productivity, the preservation of the proxies and oxygen conditions. Fluctuations in detrital element concentrations were mainly the consequence of wet/arid oscillations. Productivity has been established using Ba excess, according to which marine productivity appears to have been greatest during cold events Heinrich 1 and Younger Dryas. The S1 time interval was not as marked by increases in productivity as was the eastern Mediterranean. In contrast, the S1 interval was first characterized by a decreasing trend and then by a fall in productivity after the 8.2 ky BP dry-cold event. Since then productivity has remained low. Here we report that there was an important redox event in this basin, probably a consequence of the major oceanographic circulation change occurring in the western Mediterranean at 7.7 ky BP. This circulation change led to reventilation as well as to diagenetic remobilization of redox-sensitive elements and organic matter oxidation. Comparisons between our paleoceanographic reconstruction for this basin and those regarding other Mediterranean basins support the hypothesis that across the Mediterranean there were different types of responses to climate forcing mechanism. The Algero–Balearic basin is likely to be a key area for further understanding of the relationships between the North Atlantic and the eastern Mediterranean basins.We are grateful to the ODP Core Repository personnel (Bremen, Germany) for their assistance with sampling. Analyses were performed at the Analytical Facilities (CIC) and Department of Mineralogy and Petrology (University of Granada), and at the Japanese Agency for Marine–Earth Sciences and Technology (JAMSTEC). The authors are indebted to Dr. K.-C. Emeis for stimulating discussion and to Dr. T. Correge, as editor, and to Dr. N. Fagel and one anonymous reviewer for their invaluable comments and reviews. We are likewise grateful to project CSD2006-00041 and to E. Pinero, E. Abarca, E. Holanda, J. Montes, C. Niembro, D. Ortega for laboratory assistance. Editing of the original English manuscript was done by M. Bettini. This study was financed by Projects REN2003-09130-CO2-01 and CGL2006-13327-C04-04/CLI (MEC), Project RNM432 and Research Group RNM0179 (Junta de Andalucía).Peer reviewe

Climate forcing and Neanderthal extinction in Southern Iberia: insights from a multiproxy marine record.

6 figures, 1 tablePaleoclimate records from the western Mediterranean have been used to further understand the role of climatic changes in the replacement of archaic human populations inhabiting South Iberia. Marine sediments from the Balearic basin (ODP Site 975) was analysed at high resolution to obtain both geochemical and mineralogical data. These data were compared with climate records from nearby areas. Baexcces was used to characterize marine productivity and then related to climatic variability. Since variations in productivity were the consequence of climatic oscillations, climate/productivity events have been established. Sedimentary regime, primary marine productivity and oxygen conditions at the time of population replacement were reconstructed by means of a multiproxy approach. Climatic/oceanographic variations correlate well with Homo spatial and occupational patterns in Southern Iberia. It was found that low ventilation (U/Th), high river supply (Mg/Al), low aridity (Zr/Al) and low values of Baexcess coefficient of variation, may be linked with Neanderthal hospitable conditions. We attempt to support recent findings which claim that Neanderthals populations continued to inhabit southern Iberia between 30 and 28 ky cal BP and that this persistence was due to the specific characteristics of South Iberian climatic refugia. Comparisons of our data with other marine and continental records appear to indicate that conditions in South Iberia were highly inhospitable at 24 ky cal BP. Thus, it is proposed that the final disappearance of Neanderthals in this region could be linked with these extreme conditions.This work was financed by Projects REN2003-09130-CO2-01 and CGL2006-13327-C04-04 (MEC), project RNM 432 and Research Group RNM 179 (Junta de Andalucía). We also thank project CSD2006-00041 (TOPOIBERIA). We would like to thank the ODP Core Repository (Bremen, Germany) for their assistance with sampling, and the university of Bremen for the use of the XRF core scanner. Other geochemical analyses were performed at the “Centro de Instrumentación Científica” (University of Granada), the Department of Mineralogy and Petrology (University of Granada), and the Japan Agency for Marine–Earth and Science Technology (JAMSTEC) laboratories. Our thanks to E. Abarca, E. Holanda, J. Montes, C. Niembro and D. Ortega for their laboratory assistance. Dr. J.S. Carrion and one anonymous reviewer are greatly thanked for constructive comments and reviews. The authors also are grateful to P. González-Sampériz and A. Moreno for their stimulating suggestion. Thorough editing of the original English manuscript was done by M. Bettini.Peer reviewe