Laurent Pouyaud

Cryptic Diversity in Indo-Australian Rainbowfishes Revealed by DNA Barcoding: Implications for Conservation in a Biodiversity Hotspot Candidate

The rainbowfishes of the family Melanotaeniidae represent one of the largest radiations of freshwater fishes from the Indo-Australian archipelago. A total of 75 nominal species have been described, among which several have become very popular among tropical fish hobbyists because of their tendency to form large schools of colourful individuals. Facing habitat loss and competition or predation by introduced species, this group has become a priority in the conservation of ornamental fishes in Indonesia. In this context, several expeditions have been conducted between 2007 and 2010 in Indonesian Papua with the aim to initiate a large-scale survey of the genetic resources in this group. We assessed the diversity of the Papua rainbowfishes with DNA barcoding. We sequenced the mitochondrial COI gene for 350 specimens belonging to 53 nominal species throughout the Indo-Australian archipelago. Unexpected levels of cryptic diversity and endemism were detected since additional cryptic lineages were detected in several watersheds from the Vogelkop and the Lengguru massif. DNA barcoding supports the presence of nearly 30 evolutionary lineages among the 15 nominal species sampled in the Vogelkop and all these lineages are endemic to a single lake or watershed. This result highlights that the diversity of the family has been largely underestimated and urges for the identification of conservation priorities in Papua.

Autosomal differences between males and females in hybrid zones: a first report from Barbus barbus and Barbus meridionalis (Cyprinidae).

Narrow hybrid zones are generally subjected to the action of two forces: dispersal, which tends to homogenise the hybridising taxa, and selection against hybrids, which, in contrast, produces steep clines of introgression for diagnostic markers. Although differences between sexes in dispersal abilities or in susceptibility to hybrid counterselection are common in hybrid zones, autosomal genetic differences between males and females have never been reported to our knowledge. Barbus barbus and Barbus meridionalis (Cyprinidae) form a hybrid zone along the Lergue river. By carrying out a genetic analysis of males and females in six samples from two central stations of the hybrid zone using codominant markers (six allozymes and four microsatellite loci), we revealed significant multilocus and monolocus differences between the sexes. This could reflect a genetic difference among sexes within a same cohort, caused either by a survival (or fertility) differential among sexes or by a sex-specific pattern of dispersal. Alternatively, this may be due to genetic differentiation between cohorts, since male and female barbel exhibit different maturation, growth and survival patterns leading to different age distributions among sexes, and particularly among reproducers.

Population genetic structure of the tropical eel Anguilla bicolor in Indonesian waters based on microsatellite markers

Abstract. The short-finned eel Anguilla bicolor is known to be subdivided in two distinct subspecies (i.e. A. bicolor bicolor and A. bicolor pacifica), each subspecies being geographically distributed in allopatry. The present survey intends to describe genetic differentiation, population structure, molecular variance and phylogeny of both subspecies of A. bicolor in Indonesian waters. The genotypes of seven microsatellite locus and sequences of the entire cytochrome b were analyzed on 180 specimens collected in 10 representative locations, where one of the two subspecies spend their freshwater life. The results showed high heterozygosity (0.767 < He < 0.891). Significant deviation from Hardy-Weinberg equilibrium were essentially detected on AjTR04 and Aro63 loci. No diagnostic microsatellite loci was observed between the subspecies which shared most of their alleles. Genetic Reynolds distances computed for each population ranged between 0.029 and 0.073 among A. bicolor pacifica populations, between 0.045 and 0.149 among A. bicolor bicolor populations and between 0.042 and 0.114 among populations of different subspecies. Both the mitochondrial and the microsatellite markers confirm the subdivision into two subspecies while microsatellite loci suggest a moderate differentiation between subspecies.