Multigene phylogeny supports diversification of four-eyed fishes and one-sided livebearers (Cyprinodontiformes: Anablepidae) related to major South American geological events

Phylogeny and historical biogeography of neotropical catfishes Trichomycterus (Siluriformes: Trichomycteridae) from eastern Brazil

The catfish subfamily Trichomycterinae is widely distributed in South America inhabiting several habitats, but specially mountain streams. Trichomycterus is the most speciose trichomycterid genus and recently due to his paraphyletic condition has been restricted to a clade from eastern Brazil called Trichomycterus sensu stricto comprising around 80 valid species distributed in seven areas of endemism of eastern Brazil. This paper aims to analyse the biogeographical events responsible for the distribution of Trichomycterus s.s., by reconstructing the ancestral data based on a time-calibrated multigene phylogeny. A multi-gene phylogeny was generated using 61 species of Trichomycterus s.s. and 30 outgroups, with divergence events calculated based on the estimated origin of Trichomycteridae. Two event-based analyses were applied to investigate the biogeographical events responsible the present distribution of Trichomycterus s.s. and suggest that the modern distribution of the group is a result of different vicariance and dispersal events. The diversification of Trichomycterus s.s. subgenera occurred in the Miocene, except for Megacambeva, with different biogeographical events shaping its distribution in eastern Brazil. An initial vicariant event split up the Fluminense ecoregion from the Northeastern Mata Atlantica + Paraíba do Sul + Fluminense + Ribeira do Iguape + Upper Paraná ecoregions. Dispersal events occurred mainly between Paraíba do Sul and neighboring river basins, with additional dispersal events from Northeastern Mata Atlantica to Paraíba do Sul, from São Francisco to Northeastern Mata Atlântica, and from Upper Paraná to São Francisco.

Investigating the utility of Anchored Hybrid Enrichment data to investigate the relationships among the Killifishes (Actinopterygii: Cyprinodontiformes), a globally distributed group of fishes

The Killifishes (Cyprinodontiformes) are a diverse and well-known group of fishes that contains sixteen families inclusive of Anablepidae, Aphaniidae Aplocheilidae, Cubanichthyidae, Cyprinodontidae, Fluviphylacidae, Fundulidae, Goodeidae, Nothobranchiidae, Orestiidae, Pantanodontidae, Poeciliidae, Procatopodidae, Profundulidae, Rivulidae, and Valenciidae and more than 1,200 species that are globally distributed in tropical and temperate, freshwater and estuarine habitats. The evolutionary relationships among the families within the group, based on different molecular and morphological data sets, have remained uncertain. Therefore, the objective of this study was to use a targeted approach, anchored hybrid enrichment, to investigate the phylogenetic relationships among the families within the Cyprindontiformes. This study included more than 100 individuals, representing all sixteen families within the Cyprinodontiformes, including many recently diagnosed families. We recovered an average of 244 loci per individual. These data were submitted to phylogenetic analyses (RaxML and ASTRAL) and although we recovered many of the same relationships as in previous studies of the group, several novel sets of relationships for other families also were recovered. In addition, two well-established clades (Suborders Cyprinodontoidei and Aplocheilodei) were recovered as monophyletic and are in agreement with most previous studies. We also assessed the degree of gene tree discordance in our dataset to evaluate support for alternative topological hypotheses for interfamilial relationships within the Cyprinodontiformes using a variety of different analyses. The results from this study will provide a robust, historical framework needed to investigate a plethora of biogeographic, taxonomic, ecological, and physiological questions for this group of fishes.

Mesozoic origin of coleoid cephalopods and their abrupt shifts of diversification patterns

Coleoids are the most diverse group of cephalopod mollusks. While their origin is date during the Mesozoic, the diversification pattern is unknown. However, two hypotheses have been proposed. The first suggests an increasing diversification rate after the Cretaceous-Paleogene extinction event (K-Pg) as consequence of empty habitats left by the ammonites and belemnites. The second hypothesis proposes a mid-Cenozoic increase in diversification rate related to distributional changes during ice ages and biotic interactions. To test these hypotheses, we estimated a lineage through time (LTT) and the gamma-statistic along with model-based diversification rates. These analyses were conducted on a dated molecular phylogeny for coleoids that we reconstructed using five molecular markers (cytochrome b, 16S rRNA, cytochrome oxidase I, rhodopsin, and PAX-6). Our divergence time estimation suggests that coleoids originated in the Mesozoic Era (Middle Triassic) and that both main clades (Decapodiformes and Octopodiformes) diverged in the Cretaceous/Jurassic Period. The LTT, gamma statistic, and diversification rates inferred with the Bayesian Analysis of Macro-evolutionary Mixtures (BAMM), indicate an acceleration in diversification rate over time since the origin of coleoids. Additionally, BAMM allowed us to detect abrupt increases in diversification rate before and after the K-Pg boundary. Our results partially support both hypotheses as all analyses indicate that the coleoid diversification rate was increasing during the Cenozoic. However, our results also indicate increasing diversification rates before the K-Pg boundary. We propose that the radiation of coleoids has been shaped by an acceleration in diversification rate over time, including exceptional episodes of abrupt increases before and after the K-Pg boundary.

First record sheds light on the distribution of the cyprinodontiform genus Jenynsia (Günther, 1866) in the High Andean Plateau

This is the first record of the genus Jenynsia in the High Andean Plateau (HAP). It has been found at elevations between 3400 and 3900 m in three endorreheic systems: Salar Antofalla, Antofagasta de la Sierra and El Peñón, northwestern Argentina, South America. This finding increases the number of known HAP fish genera to five. Furthermore, in contrast to the old Andean species-rich genus Orestias, the presence of Jenynsia obscura populations in young high-altitude, non-marine saline wetlands reported here supports a recent dispersal into the HAP.

Origins of Afrotropical freshwater fishes

The Afrotropics house a diverse freshwater ichthyofauna with > 3000 species, almost all of which are endemic. Recent progress in dated phylogenetics and palaeontology of several groups of Afrotropical freshwater fishes (AFFs) has allowed the testing of palaeoecology- and palaeogeography-based hypotheses explaining their early presence in Africa. Seven hypotheses were tested for 37 most-inclusive monophyletic groups of AFFs. Results indicated that ten lineages originated from direct, but asynchronous, marine-to-freshwater shifts. These lineages contribute < 2% to the current AFF species richness. Eleven lineages colonized the Afrotropics from the Orient after the Afro-Arabian plate collided with Eurasia in the early Oligocene. These lineages contribute ~20% to the total diversity. There are seven sister relationships between Afrotropical and Neotropical taxa. For only three of them (4% of the species diversity), the continental drift vicariance hypothesis was not rejected. Distributions of the other four younger trans-Atlantic lineages are better explained by post-drifting long-distance dispersal. In those cases, I discuss the possibility of dispersal through the Northern Hemisphere as an alternative to direct trans-Atlantic dispersal. The origins of ten AFF lineages, including the most species-rich Pseudocrenilabrinae (> 1100 species), are not yet established with confidence.

Frequent nonrandom shifts in the temporal sequence of developmental landmark events during teleost evolutionary diversification

Morphological transformations can be generated by evolutionary changes in the sequence of developmental events. In this study, we examined the evolutionary dynamics of the developmental sequence on a macroevolutionary scale in teleosts. Using the information from previous reports describing the development of 31 species, we extracted the developmental sequences of 19 landmark events involving the formation of phylogenetically conserved body parts; we then inferred ancestral developmental sequences by two different parsimony-based methods-event-pairing and continuous analysis. The phylogenetic comparisons of these sequences revealed event-dependent heterogeneity in the frequency of sequence changes. Most of the sequence changes occurred as exchanges of temporally neighboring events. These heterochronic changes in developmental sequences accumulated along evolutionary time, but the precise distribution of the changes over the teleostean phylogeny remains unclear due to technical limitations.