Mass of genes rather than master genes underlie the genomic architecture of amphibian speciation.

The genetic architecture of speciation, i.e., how intrinsic genomic incompatibilities promote reproductive isolation (RI) between diverging lineages, is one of the best-kept secrets of evolution. To directly assess whether incompatibilities arise in a limited set of large-effect speciation genes, or in a multitude of loci, we examined the geographic and genomic landscapes of introgression across the hybrid zones of 41 pairs of frog and toad lineages in the Western Palearctic region. As the divergence between lineages increases, phylogeographic transitions progressively become narrower, and larger parts of the genome resist introgression. This suggests that anuran speciation proceeds through a gradual accumulation of multiple barrier loci scattered across the genome, which ultimately deplete hybrid fitness by intrinsic postzygotic isolation, with behavioral isolation being achieved only at later stages. Moreover, these loci were disproportionately sex linked in one group (Hyla) but not in others (Rana and Bufotes), implying that large X-effects are not necessarily a rule of speciation with undifferentiated sex chromosomes. The highly polygenic nature of RI and the lack of hemizygous X/Z chromosomes could explain why the speciation clock ticks slower in amphibians compared to other vertebrates. The clock-like dynamics of speciation combined with the analytical focus on hybrid zones offer perspectives for more standardized practices of species delimitation

A rapid rate of sex-chromosome turnover and non-random transitions in true frogs.

The canonical model of sex-chromosome evolution predicts that, as recombination is suppressed along sex chromosomes, gametologs will progressively differentiate, eventually becoming heteromorphic. However, there are numerous examples of homomorphic sex chromosomes across the tree of life. This homomorphy has been suggested to result from frequent sex-chromosome turnovers, yet we know little about which forces drive them. Here, we describe an extremely fast rate of turnover among 28 species of Ranidae. Transitions are not random, but converge on several chromosomes, potentially due to genes they harbour. Transitions also preserve the ancestral pattern of male heterogamety, in line with the 'hot-potato' model of sex-chromosome transitions, suggesting a key role for mutation-load accumulation in non-recombining genomic regions. The importance of mutation-load selection in frogs might result from the extreme heterochiasmy they exhibit, making frog sex chromosomes differentiate immediately from emergence and across their entire length

New methodology for estimating the shear strength of layering in slate by using the Brazilian test

A new method is proposed in order to estimate the shear strength of schistosity planes in slate in terms of Mohr-Coulomb cohesion and internal friction angle. The procedure consists in carrying out the Brazilian method under different loading-foliation angles, for which experimental tests were achieved in slates from the northwest of the Iberian Peninsula (Spain). The experimental fracture patterns were analytically studied and justified by simulating the stress field in the discontinuity planes contained in the whole sample, taking into account the first failure registered in the tests. By combining experimental and analytical studies and a procedure based on the representation of the threshold state of stressesin the elastic regimein the failure plane, it is possible to estimate the foliation's strength envelope through a lineal adjustment according to the Mohr-Coulomb criterion and, thus, to characterize the layering. Finally, the proposed procedure was validated by the direct shear test. The cohesion and the internal friction angle obtained with this convenctional test were very close to that calculated by the proposed method, verifying the methodology developed by the authors. This procedure may be interesting in various engineering applications, either in the study of the properties of cleavage in slate, which is commonly used as an industrial rock, or in dam foundations, underground excavations and slope engineering, since one of the main failures in civil engineering is due to sliding along weak planes.The authors of this paper would like to acknowledge the financial support of the PhD fellowship Severo Ochoa Program of the Government of the Principality of Asturias (PA-14-PF-BP14-067). Also, the authors are grateful to editors and reviewers for their suggestions and help us to improve this manuscript

Impacts on Animal Biodiversity

Spain, possibly the EU s richest country with regard to animal species, has the highest number of endemisms. The number of new species described every year indicates that a high percentage of the fauna remains unknown. Greater effort is required in our country with regard to taxonomic research. There exists much evidence of climatic effects on the biology, abundance and distribution of vertebrates and of certain groups of insects of our fauna, and there are very little data on most of the invertebrates. There are two future scenarios of the effects of climate change on the biodiversity of vertebrates: 1) Ecosystems will be displaced jointly in accordance with climate, and 2) oEcosystems will adapt and change. The first scenario is unrealistic, due to the tremendous and growing fragmentation of habitats in Europe and the complexity of the responses by the different species and of the interactions between them. A possibility of displacement of the biocenoses only appears to exist in rivers. The second point does not allow for accurate predictions in most cases in view of the current level of knowledge. There is evidence of the direct effects of climate change to date, in spite of the scarcity of good temporal series. Thus, large phenological changes have been detected in populations of vertebrates and invertebrates, with advances (and in certain cases delays) in processes of initiation of activity, the arrival of migratory species or reproduction. The maladjustment between predators and their prey resulting from differential responses to climate is another detected consequence of recent changes. The distribution of certain species is being displaced towards the North or towards higher altitudes, which for certain mountain species is involving a clear reduction of their areas of distribution. Likewise, in rivers the displacement has been observed of thermophilous species upstream (particularly of molluscs), whereas the proportion of cold water species is diminishing (especially of insects). In lagoons and lakes it has been seen that altitude, latitude and depth have similar effects upon communities, which appears to be related to temperature. There is some evidence of greater virulence of parasites or of an increase in populations of invasive species, in general more adaptable to environmental change that may be dependent on climate change. The deterioration of fragile habitats such as small bodies of water, springs, small streams and isolated forests due to desiccation or fire or the disappearance of food plants of limited distribution could seriously affect animal populations and even lead to species disappearance, above all of invertebrates. Neither the displacement of distribution areas (hypothesis I) nor the rapid adaptation to new ecological conditions (hypothesis II) appear to be viable solutions for most of the species studied. Among the areas most vulnerable to the effects of climate change, we could include coastal areas, wetlands, permanent water courses that would become seasonal, seasonal ones that would have a more irregular flow or would even disappear, high mountain areas and humid pasturelands. The main adaptational solutions should include the design of reserves and nature parks to allow for the possibility of migration and changes in distribution by means of interconnecting biological corridors. The network of protected areas should incorporate latitudinal and altitudinal gradients to enable the protection of populations with geographic distributions undergoing processes of geographic displacement resulting from climate change. It would be interesting to promote the classification or creation of zones or areas especially sensitive to climatic change , for those areas with unique, original ecosystems or threatened or endemic species that cannot opt to change their habitat and that may become extinct. Examples of these zones are high-mountain areas or springs, streams or other water- courses containing endangered or vulnerable species. The conservation of biodiversity ought to pay attention not only to the protected areas, but also very particularly to the generalised promotion of land uses that are compatible with conservation and capable of counteracting the effects of climatic change. The increase in the demand for water for human use, due to temperature increase and in a possible context of prolonged droughts, might possibly determine an increase in technological solutions that do not take into consideration the impacts on the biodiversity of animals that depend on the maintenance of aquifers and of permanent water courses. Reforestation could have positive or adverse effects on faunistic diversity depending on how it is implemented. In any case, it will affect the taxonomic composition of the edaphic fauna. It is necessary to promote research into taxonomy and in relation to long temporal series, both at specific and community level, and to prevent the deterioration or progressive disappearance of sources of information such as the phenological database of plants and animals (birds and insects) initiated in 1940 by the Agricultural Meteorology Service, belonging to the National Meteorology Institute (INM).Peer reviewe

Coordinated Body Bending Improves Performance of a Salamander-like Robot

Annual Meeting of the Society-for-Integrative-and-Comparative-Biology (SICB) ( 2017. New Orleans