Dataset Information

Cryptic genetic diversity in the mottled rabbitfish Siganus fuscescens with mitochondrial introgression at a contact zone in the South China Sea.

ABSTRACT: The taxonomy of the mottled rabbitfish Siganus fuscescens species complex has long been challenging. In this study, we analyzed microsatellite genotypes, mitochondrial lineages, and morphometric data from 373 S. fuscescens individuals sampled from the northern Philippines and Hong Kong (South China Sea, Philippine Sea and Sulu Sea basins), to examine putative species boundaries in samples comprising three co-occurring mitochondrial lineages previously reported to characterize S. fuscescens (Clade A and Clade B) or S. canaliculatus (Clade C). We report the existence of two cryptic species within S. fuscescens in the northeast region of the South China Sea and northern Philippine Sea, supported by genetic and morphological differences. Individual-based assignment methods recovered concordant groupings of individuals into two nuclear genotype clusters (Cluster 1, Cluster 2) with (1) limited gene flow, if any, between them (FST = 0.241; P < 0.001); (2) low frequency of later-generation hybrids; (3) significant association with mitochondrial Clade A and Clade B, respectively; and (4) subtle yet significant body shape differences as inferred from geometric morphometric analysis. The divergence between mitochondrial Clade C and the two other clades was not matched by genetic differences at microsatellite marker loci. The occurrence of discordant mitonuclear combinations (20.5% of the total number of individuals) is thought to result from mitochondrial introgression, consistent with a scenario of demographic, and presumably spatial, post-Pleistocene expansion of populations from northern regions into a secondary contact zone in the South China Sea. Mitonuclear discordance due to introgression obscures phylogenetic relationships for recently-diverged lineages, and cautions against the use of mitochondrial markers alone for species identification within the mottled rabbitfish species complex in the South China Sea region.

SUBMITTER: Ravago-Gotanco R

PROVIDER: S-EPMC5821360 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Cryptic genetic diversity in the mottled rabbitfish Siganus fuscescens with mitochondrial introgression at a contact zone in the South China Sea.

Ravago-Gotanco Rachel R de la Cruz Talna Lorena TL Pante Ma Josefa MJ Borsa Philippe P

PloS one 20180221 2

The taxonomy of the mottled rabbitfish Siganus fuscescens species complex has long been challenging. In this study, we analyzed microsatellite genotypes, mitochondrial lineages, and morphometric data from 373 S. fuscescens individuals sampled from the northern Philippines and Hong Kong (South China Sea, Philippine Sea and Sulu Sea basins), to examine putative species boundaries in samples comprising three co-occurring mitochondrial lineages previously reported to characterize S. fuscescens (Clad ...[more]

PMID: 29466431

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Project description:Clarifying the underlying mechanisms that enable closely related species to coexist in a particular environment is a fundamental aspect of ecology. Coral reefs support a high diversity of marine organisms, among which rabbitfishes (family Siganidae) are a major component The present study aimed to reveal the mechanism that allows rabbitfishes to coexist on coral reefs in Okinawa, Japan, by investigating the spatial distributions, feeding ecologies, and behavioral interactions of four species: Siganus unimaculatus, S. virgatus, S. corallinus, and S. puellus. All four species had a size-specific spatial distribution, whereby small individuals were found in sheltered areas that were covered by branching and bottlebrush Acropora spp. and large individuals were found in both sheltered and exposed rocky areas. However, no clear species-specific spatial distribution was observed. There was some variation in the food items taken, with S. unimaculatus primarily feeding on brown foliose algae, red foliose algae, and red styloid algae, and S. virgatus and S. puellus preferring brown foliose algae and sponges, respectively. However, S. corallinus did not show any clear differences in food preferences from S. virgatus or S. unimaculatus, mainly feeding on brown foliose algae and red styloid algae. The four species exhibited differences in foraging substrate use, which was probably related to differences in their body shape characteristics: S. unimaculatus has a slender body with a remarkably protruding snout and mainly used concave substrates for feeding, whereas S. virgatus has a deeper body with a low degree of snout protrusion and mainly used convex substrates. The other two species have a low degree of snout protrusion combined with a deeper body in the case of S. corallinus and a slender body in the case of S. puellus and used concave, flat, and convex substrates to an equal degree for feeding. Behavioral interactions were categorized into "agonistic behaviors" (attack and agonistic displays) and "no interactions." For all four species, a greater frequency of agonistic behaviors was observed when two conspecific pairs approached each other than when two heterospecific individuals encountered each other. Together, these results suggest that food item partitioning is one of the main factors enabling the coexistence of these four syntopic rabbitfish species, which is enhanced by species-specific differences in feeding substrates as a result of their different body shape and behavioral characteristics.

Dataset Information

Cryptic genetic diversity in the mottled rabbitfish Siganus fuscescens with mitochondrial introgression at a contact zone in the South China Sea.

Publications

Cryptic genetic diversity in the mottled rabbitfish Siganus fuscescens with mitochondrial introgression at a contact zone in the South China Sea.

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