Is the Great Barracuda (Sphyraena barracuda) a reef fish or a pelagic fish? The phylogeographic perspective

Structure and phylogeography of two tropical predators, spinner (Stenella longirostris) and pantropical spotted (S. attenuata) dolphins, from SNP data

Little is known about global patterns of genetic connectivity in pelagic dolphins, including how circumtropical pelagic dolphins spread globally following the rapid and recent radiation of the subfamily delphininae. In this study, we tested phylogeographic hypotheses for two circumtropical species, the spinner dolphin (Stenella longirostris) and the pantropical spotted dolphin (Stenella attenuata), using more than 3000 nuclear DNA single nucleotide polymorphisms (SNPs) in each species. Analyses for population structure indicated significant genetic differentiation between almost all subspecies and populations in both species. Bayesian phylogeographic analyses of spinner dolphins showed deep divergence between Indo-Pacific, Atlantic and eastern tropical Pacific Ocean (ETP) lineages. Despite high morphological variation, our results show very close relationships between endemic ETP spinner subspecies in relation to global diversity. The dwarf spinner dolphin is a monophyletic subspecies nested within a major clade of pantropical spinner dolphins from the Indian and western Pacific Ocean populations. Population-level division among the dwarf spinner dolphins was detected-with the northern Australia population being very different from that in Indonesia. In contrast to spinner dolphins, the major boundary for spotted dolphins is between offshore and coastal habitats in the ETP, supporting the current subspecies-level taxonomy. Comparing these species underscores the different scale at which population structure can arise, even in species that are similar in habitat (i.e. pelagic) and distribution.

New evidence indicates the presence of barracuda (Sphyraenidae) and supports a tropical marine environment in the Miocene of Madagascar

Recent exploration of Miocene-age deposits at Nosy Makamby, a small island ~50 km southwest of Mahajanga city in northwestern Madagascar, has led to the recovery of a large sample [82] of isolated barracuda teeth (Sphyraena sp.). in a tropical marine fauna that also includes diverse marine invertebrates, chondrichthyans, bony fishes, turtles, crocodylians, and sirenians. Characteristically for barracudas, the teeth are labiolingually flattened and fang-like with a broadly triangular and blade-like acuminate outline and sharply edged but unserrated cutting margins. These barracudas inhabited an environment that included coral reefs (based on fossil scleractinians) and seagrass beds (evidenced by the epiphytic benthic foraminifera Elphidium sp.). The relatively common occurrence of Miocene barracuda at Nosy Makamby corroborates the presence of a tropical marine ecosystem encircling Madagascar by the Miocene, likely similar overall to the environment found there today.

17 novel polymorphic microsatellite markers for the giant water bug, Abedus herberti (Belostomatidae)

The giant water bug (Abedus herberti) is a large flightless insect that is a keystone predator in aridland aquatic habitats. Extended droughts, possibly due to climate change and groundwater pumping, are causing once-perennial aquatic habitats to dry, resulting in serious conservation concern for some populations. A. herberti also exhibits exclusive male parental care, which has made it a model organism for studying mating systems evolution. Here we describe 17 novel polymorphic microsatellite loci developed for A. herberti. Number of alleles per locus ranged from 2 to 15, and average observed and expected heterozygosities were 0.579 and 0.697, respectively. These loci can successfully resolve both population genetic structure among sites separated by 3-100 km (F_ST = 0.08-0.21, P < 0.0001), and divergent mating strategies within local populations, making them highly useful for conservation genetics studies of this vulnerable species.