Molecular species delimitation methods and population genetics data reveal extensive lineage diversity and cryptic species in Aglaopheniidae (Hydrozoa)

Abstract

A comprehensive inventory of global biodiversity would be greatly improved by automating methods for species delimitation. The Automatic Barcode Gap Discovery method, the Poisson tree processes algorithm and the Generalized mixed Yule-coalescent model have been proposed as means of increasing the rate of biodiversity description using single locus data. We applied these methods to explore the diversity within the Aglaopheniidae, a hydrozoan family with many species widely distributed across tropical and temperate oceans. Our analyses revealed widespread cryptic diversity in this family, almost half of the morpho-species presenting several independent evolutionary lineages, as well as support for cases of synonymy. For two common species of this family, Lytocarpia brevirostris and Macrorhynchia phoenicea, we compared the outputs to clustering analyses based on microsatellite data and to nuclear gene phylogenies. For L. brevirostris, microsatellite data were congruent with results of the species delimitation methods, revealing the existence of two cryptic species with Indo-Pacific distribution. For M. phoenicea, all analyses confirmed the presence of two cryptic species within the South-Western Indian Ocean. Our study suggests that the diversity of Aglaopheniidae might be much higher than assumed, likely related to low dispersal capacities. Sequence-based species delimitation methods seem highly valuable to reveal cryptic diversity in hydrozoans; their application in an integrative framework will be very useful in describing the phyletic diversity of these organisms.

One species for one island? Unexpected diversity and weak connectivity in a widely distributed tropical hydrozoan

“…We investigated the genetic structure and connectivity among populations of a widely distributed hydrozoan species, L. brevirostris α (sensu Postaire et al, 2016b) across three spatial scales in the IndoPacific region using a set of 16 microsatellite loci. The study revealed that populations of this brooding hydrozoan were characterized by low connectivity even at the smallest spatial scale (a few kilometres), presented an IBD pattern, and that the detected genetic clusters correspond to the sampled islands.…”

“…Larger individuals (3-10 cm high) with visible reproductive structures were preferentially collected to avoid misidentification with other species from the genus Lytocarpia. A total of 593 collected L. brevirostris α individuals ( Figure 1 and Table 1) were primarily identified using morphological characters (Millard, 1975) and verified using microsatellite data (Postaire et al, 2016b). L. brevirostris was relatively rare in New Caledonia compared with the WIO and only 3 sites presented more than 5 individuals ( Figure 1 and Table 1) among 18 explored sites all around the island.…”

“…Lytocarpia brevirostris (Busk, 1852) is a typical tropical Aglaopheniidae brooding species, found on coral reefs throughout the Indo-Pacific region (Millard, 1975;GravierBonnet, 2006;Gravier-Bonnet and Bourmaud, 2006, 2012Di Camillo et al, 2011). This orange feather-like colonial hydrozoan is composed of two sympatric cryptic species, which can be identified using molecular markers (either typical barcoding markers or microsatellites; Postaire et al, 2016b). In this study, we focus on one of these cryptic species, named L. brevirostris α in Postaire et al (2016b).…”

“…This orange feather-like colonial hydrozoan is composed of two sympatric cryptic species, which can be identified using molecular markers (either typical barcoding markers or microsatellites; Postaire et al, 2016b). In this study, we focus on one of these cryptic species, named L. brevirostris α in Postaire et al (2016b). Hydrozoans are among the least studied cnidarians for population genetics, but the few studies available to date (Darling and Folino-Rorem, 2009;Schuchert, 2014) highlighted the high genetic differentiation among individuals sampled from different regions.…”

From population connectivity to the art of striping Russian dolls: the lessons from Pocillopora corals

“…Similarly, Souter, Henriksson, Olsson, and Grahn (2009) studied the connectivity pattern in the coral Pocillopora damicornis in East Africa and, after identifying two cryptic lineages using mitochondrial markers, chose to analyze them separately. Also, exploring the species diversity of the hydrozoans from the Aglaopheniidae family, Postaire, Magalon, Bourmaud, and Bruggemann (2016) revealed extensive lineage diversity and cryptic species in two common species, Lytocarpia brevirostris and Macrorhynchia phoenicea . Then, studying the connectivity of one of the cryptic species within the L. brevirostris complex using microsatellites, Postaire, Gélin, Bruggemann, and Magalon (2017) found a high genetic differentiation among populations, each island housing an independent evolutionary lineage, probably representing different species.…”