Conceptual and empirical advances in Neotropical biodiversity research.

The unparalleled biodiversity found in the American tropics (the Neotropics) has attracted the attention of naturalists for centuries. Despite major advances in recent years in our understanding of the origin and diversification of many Neotropical taxa and biotic regions, many questions remain to be answered. Additional biological and geological data are still needed, as well as methodological advances that are capable of bridging these research fields. In this review, aimed primarily at advanced students and early-career scientists, we introduce the concept of "trans-disciplinary biogeography," which refers to the integration of data from multiple areas of research in biology (e.g., community ecology, phylogeography, systematics, historical biogeography) and Earth and the physical sciences (e.g., geology, climatology, palaeontology), as a means to reconstruct the giant puzzle of Neotropical biodiversity and evolution in space and time. We caution against extrapolating results derived from the study of one or a few taxa to convey general scenarios of Neotropical evolution and landscape formation. We urge more coordination and integration of data and ideas among disciplines, transcending their traditional boundaries, as a basis for advancing tomorrow's ground-breaking research. Our review highlights the great opportunities for studying the Neotropical biota to understand the evolution of life

Conceptual and empirical advances in Neotropical biodiversity research

The outstanding biodiversity found in the American tropics (the Neotropics) has attracted the attention of naturalists for centuries. Despite major advances in the generation of biodiversity data, many questions remain to be answered. In this review, we first summarize some of the knowns and unknowns about Neotropical biodiversity, and discuss how human impact may have drastically affected some of the patterns observed today. We then link biodiversity to landscape, and outline major advances in biogeographical research. In particular, we argue that it is crucial to test the effect of landscape and climatic evolution to biotic diversification and distribution in order to achieve a comprehensive understanding of current patterns. In this context, it is also important to consider extant and extinct taxa, as well as to use probabilistic and parametric methods that explicitly include landscape evolution models. We subsequently explore different scales in Neotropical biogeography, focusing on the intersection between biogeography and community ecology, both of which often address similar questions from different angles. The concepts of community assembly, island biogeography, neutral processes, and ecological interactions are then discussed as important components of the complex processes that determine the patterns observed today. Single-taxon and cross-taxonomic studies are complementary and greatly needed, but achieving synthesis remains challenging. Finally, we argue that phylogenetic approaches hold great potential to connect across taxonomic, spatial and temporal scales, despite current difficulties to generate and cross-analyze large volumes of molecular data. We conclude by outlining major prospects and hindrances for further advancing our knowledge on the rich Neotropical biodiversity.</p

Current and Historical Drivers of Landscape Genetic Structure Differ in Core and Peripheral Salamander Populations

With predicted decreases in genetic diversity and greater genetic differentiation at range peripheries relative to their cores, it can be difficult to distinguish between the roles of current disturbance versus historic processes in shaping contemporary genetic patterns. To address this problem, we test for differences in historic demography and landscape genetic structure of coastal giant salamanders (Dicamptodon tenebrosus) in two core regions (Washington State, United States) versus the species' northern peripheral region (British Columbia, Canada) where the species is listed as threatened. Coalescent-based demographic simulations were consistent with a pattern of post-glacial range expansion, with both ancestral and current estimates of effective population size being much larger within the core region relative to the periphery. However, contrary to predictions of recent human-induced population decline in the less genetically diverse peripheral region, there was no genetic signature of population size change. Effects of current demographic processes on genetic structure were evident using a resistance-based landscape genetics approach. Among core populations, genetic structure was best explained by length of the growing season and isolation by resistance (i.e. a ‘flat’ landscape), but at the periphery, topography (slope and elevation) had the greatest influence on genetic structure. Although reduced genetic variation at the range periphery of D. tenebrosus appears to be largely the result of biogeographical history rather than recent impacts, our analyses suggest that inherent landscape features act to alter dispersal pathways uniquely in different parts of the species' geographic range, with implications for habitat management

Life history, climate and biogeography interactively affect worldwide genetic diversity of plant and animal populations.

Understanding how biological and environmental factors interactively shape the global distribution of plant and animal genetic diversity is fundamental to biodiversity conservation. Genetic diversity measured in local populations (GDP) is correspondingly assumed representative for population fitness and eco-evolutionary dynamics. For 8356 populations across the globe, we report that plants systematically display much lower GDP than animals, and that life history traits shape GDP patterns both directly (animal longevity and size), and indirectly by mediating core-periphery patterns (animal fecundity and plant dispersal). Particularly in some plant groups, peripheral populations can sustain similar GDP as core populations, emphasizing their potential conservation value. We further find surprisingly weak support for general latitudinal GDP trends. Finally, contemporary rather than past climate contributes to the spatial distribution of GDP, suggesting that contemporary environmental changes affect global patterns of GDP. Our findings generate new perspectives for the conservation of genetic resources at worldwide and taxonomic-wide scales

Variation in anhydrobiotic survival of two eutardigrade morphospecies: a story of cryptic species and their dispersal

Studies of geographic variation in anhydrobiosis may increase our understanding of the population dynamics of terrestrial meiofauna and the relative importance of local adaptation and microhabitat niche separation. Alltough anhydrobiosis in tardigrades has been studied intensively, few studies have dealt with intraspecific variation in survival and none of these included genetic data, which are necessary when working with meiofauna as cryptic species are common. We analyzed the anhydrobiotic survival and genetic variation in COI of two eutardigrades (Richtersius coronifer and Ramazzottius oberhaeuseri) from Italy and Sweden to detect possible local adaptation. Survival was analyzed as a multidimensional contingency table and showed that anhydrobiotic survival was higher in Sweden for R. oberhaeuseri whereas no geographic variation was found for R. coronifer. Our genetic analysis indicated the coexistence of two cryptic species of R. oberhaeuseri in Italy, of which only one was found in Sweden. It could not be determined if the variation in Ramazzottius is intra- or interspecific due to the presence of these cryptic species. We suggest that geographic variation in anhydrobiotic survival may be a general phenomenon in tardigrades but further research is necessary to determine the degree of intraspecific variation. Our analysis showed indications of long term isolation of the individual populations of R. coronifer but recent dispersal in one of the cryptic species of Ramazzottius. We found higher survival in R. oberhaeuseri than in R. coronifer and suggest that these results can be explained by a coupling between anhydrobiotic survival and dispersal rate

The difference between trivial and scientific names: There were never any true cheetahs in North America

© 2016 Faurby et al.Dobrynin et al. (Genome Biol 16:277, 2015) recently published the complete genome of the cheetah (Acinonyx jubatus) and provided an exhaustive set of analyses supporting the famously low genetic variation in the species, known for several decades. Their genetic analyses represent state-of-the-art and we do not criticize them. However, their interpretation of the results is inconsistent with current knowledge of cheetah evolution. Dobrynin et al. suggest that the causes of the two inferred bottlenecks at 100,000 and 10,000 years ago were immigration by cheetahs from North America and end-Pleistocene megafauna extinction, respectively, but the first explanation is impossible and the second implausible.Peer Reviewe