Phylogeographic relationships and morphological evolution between cave and surface Astyanax mexicanus populations (De Filippi 1853) (Actinopterygii, Characidae).

The Astyanax mexicanus complex includes two different morphs, a surface- and a cave-adapted ecotype, found at three mountain ranges in Northeastern Mexico: Sierra de El Abra, Sierra de Guatemala and Sierra de la Colmena (Micos). Since their discovery, multiple studies have attempted to characterize the timing and the number of events that gave rise to the evolution of these cave-adapted ecotypes. Here, using RADseq and genome-wide sequencing, we assessed the phylogenetic relationships, genetic structure and gene flow events between the cave and surface Astyanax mexicanus populations, to estimate the tempo and mode of evolution of the cave-adapted ecotypes.

Mitochondrial phylogeography and molecular evolution of the rhodopsin visual pigment in troglobitic populations of (De Filippi, 1853).

Cave-adapted animals provide a unique opportunity to study the evolutionary mechanisms underlying phenotypic, metabolic, behavioral, and genetic evolution in response to cave environments. The Mexican tetra ( ) is considered a unique model system as it shows both surface and cave-dwelling morphs. To date, at least 33 different cave populations have been identified, with phylogenetic studies suggesting an origin from at least two independent surface lineages, thereby providing a unique opportunity to study parallel evolution.

Genetic and ecomorphological divergence between sympatric Astyanax morphs from Central America.

Intraspecific ecological and morphological polymorphism can promote ecological speciation and the build-up of reproductive isolation. Here, we evaluate correlations among morphology, trophic ecology and genetic differentiation between two divergent morphs (elongate and deep-body) of the fish genus Astyanax in the San Juan River basin in Central America, to infer the putative evolutionary mechanism shaping this system. We collected the two morphs from three water bodies and analysed: (1) the correlation between body shape and the shape of the premaxilla, a relevant trophic morphological structure, (2) the trophic level and niche width of each morph, (3) the correspondence between trophic level and body and premaxillary shape, and (4) the genetic differentiation between morphs using mitochondrial and nuclear markers.

Genetic diversity and structure of one of the most endangered freshwater fish species in Mexico: (Miller, 1950) and recognition of its evolutionarily significant units.

The endangered Chiapas killifish is an endemic freshwater species that lives in four subbasins of the Grijalva and Usumacinta basins, and one of the most geographically restricted species of the Produndulidae family. The species was originally described as endemic to springs in the high limestone plateau in San Cristóbal de Las Casas in the Río Amarillo subbasin (upper Grijalva basin). However, it was recently recorded in the Jataté and Tzaconejá subbasins in the upper Usumacinta basin, thereby expanding its known distribution range.

Species Delimitation of Scavenger Flies in the Valley of Mexico.

Identification of species involved in cadaveric decomposition, such as scavenger Diptera, is a fundamental step for the use of entomological evidence in court. Identification based on morphology is widely used in forensic cases; however, taxonomic knowledge of scavenger fauna is poor for many groups and for many countries, particularly Neotropical ones. A number of studies have documented the utility of a DNA barcoding strategy to assist in the identification of poorly known and diverse groups, particularly in cases involving immature states or fragmented organisms.