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Biology subjects

Mevel, L.

Publications and source records attributed to Mevel, L..

2 recordsLinked to original sources

Demographic responses to climatic changes during the Final Palaeolithic in Europe

The European Final Palaeolithic witnessed marked changes in almost all societal domains. Despite a rich body of evidence, our knowledge of palaeodemographic processes and regional population dynamics still needs to be improved. In this study, we present regionally differentiated estimates of absolute numbers and population densities for the Greenland Interstadial 1d-a (GI-1d-a; 14-12.7 ka BP) and the Greenland Stadial 1 (GS-1; 12.7-11.6 ka BP) for Southern, Western, Northern and Central Europe. The data were obtained by applying the Cologne Protocol, a geostatistical approach for estimating prehistoric population size and density, to a newly compiled dataset of Final Palaeolithic sites. On a large spatio-temporal scale, we observe a shift of the main areas of human occupation from the Franco-Cantabrian region, which was intensely occupied during most phases of the preceding Upper Palaeolithic, to regions north of the Alps. At smaller scales, we observe divergent regional trends in the Final Palaeolithic meta-population: during GI 1d-a, a decreasing population in southwestern Europe and an increasing population in north-eastern Central Europe. For the first time since the dispersal of anatomically modern humans into Europe, we see that Central Europe becomes the dominant demographic growth area. Subsequently, the climatic cooling of GS-1 coincides with a pronounced population decline in most parts of the study area. An apparent increase in population density occurs only in north-eastern Central Europe and north-eastern Italy. Our estimates suggest that the total population was reduced by half. Similar results, with a relationship between decreasing temperatures and decreasing populations, have already been observed for the late phase of the Gravettian, when populations were reduced to only one third of those estimated for the early phase. Yet, in contrast to the collapse of local populations during the late Gravettian, the increase in population densities in Central Europe during GS-1 indicates population movements eastwards, possibly in response to deteriorating climatic conditions, particularly in western regions during the Younger Dryas.

ecology↗

Drosophila glue evolved different adhesive and mechanical properties across 50 million years

Drosophila glue, a bioadhesive produced by fly larvae to attach themselves to a substrate for several days, has recently gained attention for its peculiar adhesive and mechanical properties. Although Drosophila glue production was described more than 50 years ago, a general survey of the adhesive and mechanical properties of this proteinaceous gel across Drosophila species is lacking. To measure adhesion, we present here a protocol that is robust to variations in protocol parameters, pupal age and calculation methods. We find that the glue, which covers the entire pupal surface, increases the animal rigidity and plasticity when bound to a glass slide. Our survey of pupal adhesion in 25 Drosophilidae species reveals la wide range of phenotypes, from species that produce no or little glue and adhere little, to species that produce high amounts of glue and adhere strongly. One species, D. hydei, stands out from the rest and emerges as a promising model for the development of future bioadhesives, as it has the highest detachment force per glue area and produces relatively large amounts of glue relative to its size. We also observe that species that invest more in glue tend to live in more windy and less rainy climates, suggesting that differences in pupal adhesion properties across species are shaped by ecological factors. Our present survey provides a basis for future biomimetic studies based on Drosophila glue.

biophysics↗