Cryptic speciation and phylogeographic relationships in the elephant ear spongeIanthella basta(Porifera, Ianthellidae) from northern Australia

Abstract

Morphological delineation of sponge species is hindered by the narrow range of fixed diagnostic characters and our limited knowledge of how much phenotypic plasticity the sponge body plan assumes in response to environmental conditions. Here, we make use of the partial mitochondrial cytochrome c oxidase subunit I (COI) gene and the second internal transcribed spacer (ITS2) region to assess the taxonomic validity of colour morphotypes observed in the elephant ear sponge Ianthella basta (Pallas, 1776) across its distribution range in northern Australia, and explore levels and patterns of genetic diversity among populations of the species collected from both sides of the Torres Strait. Molecular phylogenetic analyses revealed congruent topologies consistent with three evolutionarily significant units (ESUs) that were independent of the morphology of the sponge. ESU I includes previously morphologically and genetically delineated western Pacific specimens of I. basta (Guam), and probably corresponds to the type specimen originally described from Indonesia. ESU I occurs in almost all sampling sites across northern Australia, suggesting considerable levels of connectivity among reefs throughout the Torres Strait. ESUs II and III are each exclusively associated with a geographic region of high sponge species richness separated by Torres Strait, and probably represent the result of historical population fragmentation.

Phylogeography of the Sponge Suberites diversicolor in Indonesia: Insights into the Evolution of Marine Lake Populations

“…This is consistent with phylogeographic studies of sponges and other invertebrates that show a barrier within the Torres Strait (e.g. [63], [64]). Dispersal potential and habitat specialization may determine how lineages are distributed and how fauna of different geographic regions are connected (e.g.…”

“…[55], [78], [79]). However, in some sponge taxa COI can provide low but sufficient genetic variation within species over relatively short geographic distances [63], [69], [80].…”

Discordance between morphological and molecular species boundaries among Caribbean species of the reef sponge Callyspongia

“…GenBank sequences: 1 Erpenbeck et al (2007), EF519624; 2 Kayal and Lavrov (2008) loci appear to evolve less slowly and have been used successfully to estimate population structure and phylogenies (Duran and R€ utzler 2006;L opez-Legentil and Pawlik 2009;DeBiasse et al 2010;Dailianis et al 2011;Escobar et al 2012). Variation in COI has also revealed cryptic species (Wulff 2006b;Blanquer and Uriz 2007;P€ oppe et al 2010;Xavier et al 2010;Andreakis et al 2012;de Paula et al 2012), including C. vaginalis (DeBiasse et al in review). Among the species examined here, COI genetic distances were up to 27% among taxa, suggesting variation at this locus is sufficient to distinguish among species in Callyspongia.…”

From the tropics to the pole and back again: Radiation in the flathead fishes (Platycephalidae) across Australia and the Indo‐West Pacific

“…The most pronounced divergence, coinciding with the mid-Miocene climate shift, splits the Indian and Pacific Ocean groups along the Sunda Arc and Torres Strait(Figure 3). Similar levels of intra-species divergence are known from other flathead species across similar geographical locations (e.g.,Figure 4and outlined in, as well as across other marine groups(Andreakis, Luter, & Webster, 2012;Poore & Andreakis, 2011;Puckridge, Last, White, & Andreakis, 2013). These observations hint at the potential magnitude of cryptic diversity across the region as well as suggest that processes creating diversification in the P. indicus cryptic species complex may be acting on whole suites of species.…”