Phylogenomic Discordance in the Eared Seals is best explained by Incomplete Lineage Sorting following Explosive Radiation in the Southern Hemisphere.

The phylogeny and systematics of fur seals and sea lions (Otariidae) have long been studied with diverse data types, including an increasing amount of molecular data. However, only a few phylogenetic relationships have reached acceptance because of strong gene-tree species tree discordance. Divergence times estimates in the group also vary largely between studies. These uncertainties impeded the understanding of the biogeographical history of the group, such as when and how trans-equatorial dispersal and subsequent speciation events occurred. Here, we used high-coverage genome-wide sequencing for 14 of the 15 species of Otariidae to elucidate the phylogeny of the family and its bearing on the taxonomy and biogeographical history. Despite extreme topological discordance among gene trees, we found a fully supported species tree that agrees with the few well-accepted relationships and establishes monophyly of the genus Arctocephalus. Our data support a relatively recent trans-hemispheric dispersal at the base of a southern clade, which rapidly diversified into six major lineages between 3 and 2.5 Ma. Otaria diverged first, followed by Phocarctos and then four major lineages within Arctocephalus. However, we found Zalophus to be nonmonophyletic, with California (Zalophus californianus) and Steller sea lions (Eumetopias jubatus) grouping closer than the Galapagos sea lion (Zalophus wollebaeki) with evidence for introgression between the two genera. Overall, the high degree of genealogical discordance was best explained by incomplete lineage sorting resulting from quasi-simultaneous speciation within the southern clade with introgresssion playing a subordinate role in explaining the incongruence among and within prior phylogenetic studies of the family. [Hybridization; ILS; phylogenomics; Pleistocene; Pliocene; monophyly.].

The Radiation of Darwin's Giant Daisies in the Galápagos Islands.

Evolutionary radiations on oceanic islands have fascinated biologists since Darwin's exploration of the Galápagos archipelago [1, 2]. Island radiations can provide key insights for understanding rapid speciation, including evolutionary patterns and the processes behind them. However, lack of resolution of species relationships has historically hindered their investigation, particularly in the plant kingdom [3-5]. Here, we report a time-calibrated phylogenomic analysis based on genotyping-by-sequencing data [6] of the 15 species of Scalesia (Darwin's giant daisies), an iconic and understudied plant radiation endemic to the Galápagos Islands and considered the plant counterpart to Darwin's finches [1, 7-9]. Results support a Pliocene to early Pleistocene divergence between Scalesia and the closest South American relatives, and rapid diversification of extant Scalesia species from a common ancestor dated to the Middle Pleistocene. Major evolutionary patterns in Scalesia include the following: (1) lack of compliance with the "progression rule" hypothesis, in which earlier diverging lineages are expected to occupy older islands; (2) a predominance of within-island speciation over between-island speciation; and (3) repeated convergent evolution of potentially adaptive traits and habitat preferences on different islands during the course of diversification. Massive sequencing provided the essential framework for investigating evolutionary and ecological processes in the complex natural laboratory of the Galápagos, thereby advancing our understanding of island plant radiations.

Knowledge of the consequences and use of drugs for CostaRica niversity students / Conhecimento das consequências e do uso de drogas em estudantes universitários costarriquenses / Conocimiento de las consecuencias y uso de drogas en estudiantes universitarios costarricenses

ABSTRACT Objective: to determine the relationship between knowledge of consequences and drug use in undergraduate students of a university in San José, Costa Rica. Method: the cross-sectional study examines the demographic profile of the sample and the relationship between knowledge of consequences, drug use and academic performance. The study focuses on three types of drugs: alcohol, marijuana and cocaine. Three variables will be analyzed: demographic data, knowledge of consequences and use of drugs. Results: the relationship between knowledge of consequences and use of drugs was made using of the T-test. The sample had 272 students, 28.2% (n=77) of them were men and 71.4% were women (n=195). They were selected from the areas of social sciences (n=137, 50.2%), and from the area of health sciences (n=136; 49.8%). Alcohol was the most used drug (n=217, 79.8%), followed by marijuana (n=72, 26.6%) and finally cocaine (n=3, 1.1%) in the last 12 months. Conclusion: the results shown indicate that there is no significant relationship between such variables. The findings are important at the level of drug policies to support the development of new preventive strategies for drug use.

RESUMO Objetivo: determinar a relação entre o conhecimento das consequências e o uso de drogas em estudantes de graduação de uma universidade em San José, Costa Rica. Método: este estudo, de corte transversal, examina o perfil demográfico da amostra e a relação entre o conhecimento das consequências, o uso de drogas e o desempenho acadêmico. A pesquisa centra-se em três tipos de drogas: álcool, maconha e cocaína. Três variáveis foram analisadas: os dados demográficos, o conhecimento das consequências e o uso de drogas. Resultados: a relação entre o conhecimento das consequências e o uso de drogas foi realizada através do uso do T-test. A amostra foi composta por 272 estudantes, sendo 28,2% (n=77) homens e 71,4% mulheres (n=195); selecionados da área de ciências sociais (n=137; 50,2%), e da área de ciências da saúde (n=136; 49,8%). O álcool foi a droga mais utilizada (n=217; 79,8%), seguida da maconha (n=72; 26,6%) e, finalmente, a cocaína (n=3; 1.1%) nos últimos 12 meses. Conclusão: os resultados demostram que não existe relação significativa entre tais variáveis, e são importantes no nível das políticas de drogas para apoiar o desenvolvimento de novas estratégias preventivas para o uso de drogas.

RESUMEN Objetivo: determinar la relación entre conocimiento de consecuencias y uso de drogas en estudiantes de pregrado de una universidad en San José, Costa Rica. Método: el estudio, de corte transversal, examina el perfil demográfico de la muestra y la relación entre conocimiento de consecuencias, uso de drogas y rendimiento académico. El estudio se enfoca en tres tipos de droga: alcohol, marihuana y cocaína. Se analizarán tres variables: datos demográficos, conocimiento de consecuencias y uso de drogas. Resultados: la relación entre conocimiento de consecuencias y uso de drogas se realizó mediante el uso de la prueba T-test. La muestra fue de 272 estudiantes, con un 28.2% (n=77) de hombres y 71.4% de mujeres (n=195); seleccionados de las áreas de ciencias sociales (n=137; 50.2%), y del área de ciencias de la salud (n=136; 49.8%). El alcohol fue la droga más utilizada (n=217; 79.8%), seguida por marihuana (n=72; 26.6%) y finalmente la cocaína (n=3; 1.1%) en los últimos 12 meses. Conclusion: los resultados mostrados indican que no hay una relación significativa entre tales variables. Los hallazgos son importantes a nivel de políticas de drogas para apoyar el desarrollar de nuevas estrategias preventivas de uso de drogas.

Species delimitation and biogeography of the gnatcatchers and gnatwrens (Aves: Polioptilidae).

The New World avian family Polioptilidae (gnatcatchers and gnatwrens) is distributed from Argentina to Canada and includes 15 species and more than 60 subspecies. No study to date has evaluated phylogenetic relationships within this family and the historical pattern of diversification within the group remains unknown. Moreover, species limits, particularly in widespread taxa that show geographic variation, remain unclear. In this study, we delimited species and estimated phylogenetic relationships using multilocus data for the entire family. We then used the inferred diversity along with alternative taxonomic classification schemes to evaluate how lumping and splitting of both taxa and geographical areas influenced biogeographic inference. Species-tree analyses grouped Polioptilidae into four main clades: Microbates, Ramphocaenus, a Polioptila guianensis complex, and the remaining members of Polioptila. Ramphocaenus melanurus was sister to the clade containing M. cinereiventris and M. collaris, which formed a clade sister to all species within Polioptila. Polioptila was composed of two clades, the first of which included the P. guianensis complex; the other contained all remaining species in the genus. Using multispecies coalescent modeling, we inferred a more than 3-fold increase in species diversity, of which 87% represent currently recognized species or subspecies. Much of this diversity corresponded to subspecies that occur in the Neotropics. We identified three polyphyletic species, and delimited 4-6 previously undescribed candidate taxa. Probabilistic modeling of geographic ranges on the species tree indicated that the family likely had an ancestral origin in South America, with all three genera independently colonizing North America. Support for this hypothesis, however, was sensitive to the taxonomic classification scheme used and the number of geographical areas allowed. Our study proposes the first phylogenetic hypothesis for Polioptilidae and provides genealogical support for the reclassification of species limits. Species limits and the resolution of geographical areas that taxa inhabit influence the inferred spatial diversification history.

Genomic variation at the tips of the adaptive radiation of Darwin's finches.

Adaptive radiation unfolds as selection acts on the genetic variation underlying functional traits. The nature of this variation can be revealed by studying the tips of an ongoing adaptive radiation. We studied genomic variation at the tips of the Darwin's finch radiation; specifically focusing on polymorphism within, and variation among, three sympatric species of the genus Geospiza. Using restriction site-associated DNA (RAD-seq), we characterized 32 569 single-nucleotide polymorphisms (SNPs), from which 11 outlier SNPs for beak and body size were uncovered by a genomewide association study (GWAS). Principal component analysis revealed that these 11 SNPs formed four statistically linked groups. Stepwise regression then revealed that the first PC score, which included 6 of the 11 top SNPs, explained over 80% of the variation in beak size, suggesting that selection on these traits influences multiple correlated loci. The two SNPs most strongly associated with beak size were near genes associated with beak morphology across deeper branches of the radiation: delta-like 1 homologue (DLK1) and high-mobility group AT-hook 2 (HMGA2). Our results suggest that (i) key adaptive traits are associated with a small fraction of the genome (11 of 32 569 SNPs), (ii) SNPs linked to the candidate genes are dispersed throughout the genome (on several chromosomes), and (iii) micro- and macro-evolutionary variation (roots and tips of the radiation) involve some shared and some unique genomic regions.

A comprehensive multilocus assessment of sparrow (Aves: Passerellidae) relationships.

The New World sparrows (Emberizidae) are among the best known of songbird groups and have long-been recognized as one of the prominent components of the New World nine-primaried oscine assemblage. Despite receiving much attention from taxonomists over the years, and only recently using molecular methods, was a "core" sparrow clade established allowing the reconstruction of a phylogenetic hypothesis that includes the full sampling of sparrow species diversity. In this paper, we use mitochondrial DNA gene sequences from all 129 putative species of sparrow and four additional (nuclear) loci for a subset of these taxa to resolve both generic and species level relationships. Hypotheses derived from our mitochondrial (2184 base pairs) and nuclear (5705 base pairs) DNA data sets were generally in agreement with respect to clade constituency but differed somewhat with respect to among-clade relationships. Sparrow diversity is defined predominantly by eight well-supported clades that indicate a lack of monophyly for at least three currently recognized genera. Ammodramus is polyphyletic and requires the naming of two additional genera. Spizella is also polyphyletic with Tree Sparrow (Spizella arborea) as a taxonomic "outlier". Pselliophorus is embedded within a larger Atlapetes assemblage and should be merged with that group. This new hypothesis of sparrow relationships will form the basis for future comparative analyses of variation within songbirds.