This is the third compilation of imperiled (i.e., endangered, threatened, vulnerable) plus extinct freshwater and diadromous fishes of North America prepared by the American Fisheries Society'S Endangered Species Committee. Since the last revision in 1989, imperilment of inland fishes has increased substantially. This list includes 700 extant taxa representing 133 genera and 36 families, a 92% increase over the 364 listed in 1989. The increase reflects the addition of distinct populations, previously non‐imperiled fishes, and recently described or discovered taxa. Approximately 39% of described fish species of the continent are imperiled. There are 230 vulnerable, 190 thretened, and 280 endangered extant taxa, and 61 taxa presumed extinct or extirpated from nature. Of those that were imperiled in 1989, most (89%) are the same or worse in conservation status; only 6% have improved in status, and 5% were delisted for various reasons. Habitat degradation and nonindigenous species are the main threats to at‐risk fishes, many of which are restricted to small ranges. Documenting the diversity and status of rare fishes is a critical step in identifying and implementing appropriate actions necessary for their protection and management.

No abstract

Building trust in science and evidence-based decision-making depends heavily on the credibility of studies and their findings. Researchers employ many different study designs that vary in their risk of bias to evaluate the true effect of interventions or impacts. Here, we empirically quantify, on a large scale, the prevalence of different study designs and the magnitude of bias in their estimates. Randomised designs and controlled observational designs with pre-intervention sampling were used by just 23% of intervention studies in biodiversity conservation, and 36% of intervention studies in social science. We demonstrate, through pairwise within-study comparisons across 49 environmental datasets, that these types of designs usually give less biased estimates than simpler observational designs. We propose a model-based approach to combine study estimates that may suffer from different levels of study design bias, discuss the implications for evidence synthesis, and how to facilitate the use of more credible study designs.

A phylogeny is presented for 34 species of Astyanax, 27 of them once included within A. aeneus or A. fasciatus in Central America and Mexico, based on 52 morphological characters (mostly osteological, but also pigmentation and meristics), with three outgroups. Monophyly is not supported for A. aeneus s. lat., as Brazilian species such as A. fasciatus s. str. and others occur also within that clade. There were only five resolved clades, three of them including both Brazilian and Central American species, one purely Nicaraguan, and one for central-northern Mexico and Texas. Coincidence with previous cladistic hypotheses is only partial. The genus Bramocharax Gill is not recovered, and thus confirmed as a synonym of Astyanax Baird & Girard. The findings point at a more complex biogeographic history of the region than usually recognized.

This study examined the patterns of morphological variation both between species, and between sexes and among populations within each species of the Mexican sailfin mollies, Poecilia velifera and Poecilia petenensis, using geometric morphometrics and linear measurements of morphological traits. While sexes within each species differed in characteristics that may be important in sexual selection, such as length of the dorsal fin, species differed in traits, such as body depth, that may also be influenced by natural selection due to differences in habitats. Within each species, many morphological traits were similar among populations, but important differences, including caudal peduncle depth in P. petenensis (but not in P. velifera), suggested that habitat differences may also be important in shaping population divergence independently within each species. Indeed, the evolutionary vectors of male morphological population divergence for each species differed by an angle of 98Á5 , representing nearly orthogonal vectors and suggesting independent shape divergence between these two molly species. Finally, geographic isolation did not explain the morphological differentiation seen among populations, suggesting that natural and sexual selection were strong forces promoting morphological diversification within these two species, despite the potential for a high degree of population connectivity and gene flow.

The cichlid genus Archocentrus has been considered one of the most promising (i.e., possibly natural) genera resurrected to receive some of the species formerly included in Cichlasoma. Evidence is presented to justify generic recognition of Archocentrus, as well as eight other closely related genera (Caquetaia, Hypsophrys, Parachromis, Amphilophus, Archocentrus, Cryptoheros, Amatitlania, and Rocio). Of these, Amatitlania (type species, A. nigrofasciata) and Rocio (type species, R. octofasciata) are described as new. The present revision treats all nominal species ever assigned to Archocentrus, as well as species that have been included in or near the same clade as Archocentrus centrarchus (type species of the genus) in available phylogenetic analyses. Geographical variation in morphology of the more widespread species was examined, which has resulted in the description of six new species (Cryptoheros chetumalensis, Amatitlania coatepeque, A. kanna, A. siquia, Rocio gemmata, and R. ocotal) with a seventh resurrected from synonymy (Cryptoheros cutteri). Archocentrus includes the type species (Ar. centrarchus), plus Ar. spinosissimus and Ar. multispinosus. Cryptoheros is restricted to the species complexes of Cr. spilurus (= subgenus Cryptoheros, including also Cr. chetumalensis and Cr. cutteri) and Cr. septemfasciatus (= Bussingius n. subgen., including also Cryptoheros altoflavus, Cr. nanoluteus, Cr. myrnae, and Cr. sajica); Cryptoheros panamensis is placed in Panamius n. subgen. Herotilapia is synonymized with Archocentrus, and Neetroplus is synonymized with Hypsophrys, which now includes the type species H. nicaraguensis and H. nematopus. Lectotypes are designated for Amatitlania nigrofasciata, Archocentrus spinosissimus, Cryptoheros septemfasciatus, Cr. spilurus, and Rocio octofasciata. Cichlasoma immaculatum is considered to be a synonym of Archocentrus spilurus, not of Ar. spinosissimus.

No abstract

No abstract