1,720,987 research outputs found
Genetic Divergence Across Glacial Refugia Despite Interglacial Gene Flow in a Crested Newt
Full text linkMtDNA-based phylogeography has illuminated the impact of the Pleistocene Ice Age on species distribution dynamics and the build-up of genetic divergence. The well-known shortcomings of mtDNA in biogeographical inference can be compensated by integrating multilocus data and species distribution modelling into phylogeography. We re-visit the phylogeography of the Italian crested newt (Triturus carnifex), a species distributed in two of Europe’s main glacial refugia, the Balkan and Italian Peninsulas. While a new 51 nuclear DNA marker dataset supports the existence of three lineages previously suggested by mtDNA (Balkan, northern Italy and southern Italy), the nuclear DNA dataset also provides improved resolution where these lineages have obtained secondary contact. We observe geographically restricted admixture at the contact between the Balkan and northern Italy gene pools and identify a potential mtDNA ghost lineage here. At the contact between the northern and southern Italy gene pools we find admixture over a broader area, as well as asymmetric mtDNA introgression. Our species distribution model is in agreement with a distribution restricted to distinct refugia during Pleistocene glacial cycles and postglacial expansion with secondary contact. Our study supports: (1) the relevance of the north-western Balkan Peninsula as a discrete glacial refugium; (2) the importance of north-eastern Italy and the northern Apennine as suture zones; and (3) the applicability of a refugia-within-refugia scenario within the Italian Peninsula
Conserving the terecay (Podocnemis unifilis, Testudines: Pelomedusidae) through a community-based sustainable harvest of its eggs.
No full textGoing west: Range expansion for loggerhead sea turtles in the Mediterranean Sea under climate change
Full text linkGlobal changes represent possibly the greatest threat to the future of biodiversity, and this is especially true for species using very different habitats during their life cycle. The problem is even greater when dealing with human dominated landscapes (e.g., the Mediterranean basin) where climate change and habitat destruction and degradation often interact synergistically. We explored this synergy focusing on loggerhead sea turtles (Caretta caretta) in the Mediterranean Sea. Sea turtles depend on both marine and terrestrial environments and are influenced at the same time by changes occurring in both realms. To explore the changes of nesting grounds in the last decades, we first analysed the changes in the 10-year geographical centers of gravity for all nests from 1960 to 2020. By focusing only of the last 20 years, we incorporated both terrestrial and marine variables into a species distribution model (SDM), while accounting for temporal variability by using a multi-temporal calibration approach. The center of gravity for all nesting grounds shifted roughly of 1300 km to the northwest, and the climate suitability model (with the lowest AICc value and a mean AUC = 0.919 ± 0.047; p-value ≤ 0.001) highlighted a sharp increase over time in the northwest Mediterranean Sea. In the same time frame, the southeast Mediterranean showed a very limited increase in climate suitability for nesting. The most important variables were anthropogenic variables, which negatively influence nesting probability, and sea surface temperature, with an increase up to a maximum probability of nesting around 24–25 °C, but a rapid decrease at higher temperatures. The potential importance of the North-western Mediterranean beaches as possible nesting range for sea turtles highlights the relevance of proactive efforts to assist sea turtles’ conservation during their range expansion. More in general, our analyses demonstrate the importance of considering variables from multiple realms when modeling the distribution of species with complex life cycles
The ecological importance of hybridization
No full textHybridization as an evolutionary process has been studied in depth over the past few decades. Research has focused on its role in shaping reproductive barriers, its adaptive value, and its genomic consequences. In contrast, our knowledge of ecological dimensions of hybridization is still in its infancy, despite hybridization being an inherently ecological interaction. Using examples from various organisms, we show that hybridization can affect and be affected by non-reproductive interactions, including predation, competition, parasitism, mutualism, commensalism, and organism-environment interactions, with significant implications for community structure and ecosystem functioning. However, since these dimensions of hybridization have mostly been revealed from studies designed to decipher other evolutionary processes, we argue that much of the eco-evolutionary importance of hybridization is yet to be discovered
Mass of genes rather than master genes underlie the genomic architecture of amphibian speciation
Full text linkDufresnes, C; Brelsford, A; Jeffries, DL; Mazepa, G; Suchan, T; Canestrelli, D; Nicieza, A; Fumagalli, L; Dubey, S; Martinez-Solano, I; Litvinchuk, SN; Vences, M; Perrin, N; Crochet, P
New Avenues for old travellers. Phenotypic evolutionary trends meet morphodynamics, and both enter the global change biology era
Full text linkEvolutionary trends (ETs) are traditionally defined as substantial changes in the state of traits through time produced by a persistent condition of directional evolution. ETs might also include directional responses to ecological, climatic or biological gradients and represent the primary evolutionary pattern at high taxonomic levels and over long-time scales. The absence of a well-supported operative definition of ETs blurred the definition of conceptual differences between ETs and other key concepts in evolution such as convergence, parallel evolution, and divergence. Also, it prevented the formulation of modern guidelines for studying ETs and evolutionary dynamics related to them. In phenotypic evolution, the theory of morphodynamics states that the interplay between evolutionary factors such as phylogeny, evo-devo constraints, environment, and biological function determines morphological evolution. After introducing a new operative definition, here we provide a morphodynamics-based framework for studying phenotypic ETs, discussing how understanding the impact of these factors on ETs improves the explanation of links between biological patterns and processes underpinning directional evolution. We envisage that adopting a quantitative, pattern-based, and multifactorial approach will pave the way to new potential applications for this field of evolutionary biology. In this framework, by exploiting the catalysing effect of climate change on evolution, research on ETs induced by global change might represent an ideal arena for validating hypotheses about the predictability of evolution
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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