Biological Journal of the Linnean Society

The authors adopt the name bonairensis for the Central Clade because the island of Bonaire has been sampled. 

Abstract

We use extensive geographical sampling and surveys of nuclear microsatellite and mitochondrial DNA loci to investigate the phylogeographic structure of the only recognized self-fertilizing vertebrates, the mangrove killifishes, currently thought to comprise two cryptic species, Kryptolebias marmoratus and Kryptolebias hermaphroditus. All genetic markers revealed three concordant main clades. The Northern clade includes populations from Florida, northern Cuba, Bahamas, Belize and Honduras and corresponds to K. marmoratus. The Southern clade encompasses populations from Brazil and corresponds to K. hermaphroditus. This species was considered endemic to southeastern Brazil, but molecular data corroborate its occurrence in northeastern Brazil. The Central clade, not previously resolved with genetic data, includes populations from Panama and Antilles. Despite the geographic proximity of the Northern and Central clades, the latter is genetically closer to the Southern clade. The discovery of the Central clade raises some taxonomic issues – it can either be considered a distinct species or united with the Southern clade into a single species with two subspecies. Another possible taxonomic solution is a single selfing species, K. marmoratus, with three subspecies. We show that the Central and Southern clades are highly selfing (97–100%), whereas selfing rates of the Northern clade populations vary geographically (39–99%). Genetic patterns indicate that populations in SE Brazil are recent, contrary to expectations based on the known distributions of related species.

We use extensive geographical sampling and surveys of nuclear microsatellite and mitochondrial DNA loci to investigate the phylogeographic structure of the only recognized self-fertilizing vertebrates, the mangrove killifishes, currently thought to comprise two cryptic species, Kryptolebias marmoratus and Kryptolebias hermaphroditus. All genetic markers revealed three concordant main clades. The Northern clade includes populations from Florida, northern Cuba, Bahamas, Belize and Honduras and corresponds to K. marmoratus. The Southern clade encompasses populations from Brazil and corresponds to K. hermaphroditus. This species was considered endemic to southeastern Brazil, but molecular data corroborate its occurrence in northeastern Brazil. The Central clade, not previously resolved with genetic data, includes populations from Panama and Antilles. Despite the geographic proximity of the Northern and Central clades, the latter is genetically closer to the Southern clade. The discovery of the Central clade raises some taxonomic issues – it can either be considered a distinct species or united with the Southern clade into a single species with two subspecies. Another possible taxonomic solution is a single selfing species, K. marmoratus, with three subspecies. We show that the Central and Southern clades are highly selfing (97–100%), whereas selfing rates of the Northern clade populations vary geographically (39–99%). Genetic patterns indicate that populations in SE Brazil are recent, contrary to expectations based on the known distributions of related species.

Abstract

Camouflage is a common tactic to avoid detection or recognition by predators and prey. Flounders have adaptive camouflage but a limited body pattern repertoire. We tested whether peacock flounders actively select or avoid certain substrates to more effectively use their limited camouflaging ability. We acquired and analyzed ten 30-min videos of individual flounders on a coral reef in Bonaire, Dutch Caribbean. Using Manly’s beta resource selection indices, we were able to confirm that peacock flounders at this location preferred to settle on neutral-coloured substrates, such as sand and dead coral. Moreover, they avoided live coral, cyanobacteria, and sponges, which are often brightly coloured (e.g. yellow, orange, and purple). Quantitative analyses of photographs of settled flounders indicate that they use uniform and mottled camouflage patterns, and that the small-to-moderate spatial scale of their physiologically controlled light and dark skin components limits their camouflage capabilities to substrates with similar colour and spatial frequencies. These fishes changed their body pattern very fast. We did not observe disruptive body patterns, which are generally characterized by large-scale skin components and higher contrast. The results suggest that flounders are using visual information to actively choose substrates on which they can achieve general background resemblance.