Prey preference follows phylogeny: evolutionary dietary patterns within the marine gastropod group Cladobranchia (Gastropoda: Heterobranchia: Nudibranchia)

Abstract

BackgroundThe impact of predator-prey interactions on the evolution of many marine invertebrates is poorly understood. Since barriers to genetic exchange are less obvious in the marine realm than in terrestrial or freshwater systems, non-allopatric divergence may play a fundamental role in the generation of biodiversity. In this context, shifts between major prey types could constitute important factors explaining the biodiversity of marine taxa, particularly in groups with highly specialized diets. However, the scarcity of marine specialized consumers for which reliable phylogenies exist hampers attempts to test the role of trophic specialization in evolution. In this study, RNA-Seq data is used to produce a phylogeny of Cladobranchia, a group of marine invertebrates that feed on a diverse array of prey taxa but mostly specialize on cnidarians. The broad range of prey type preferences allegedly present in two major groups within Cladobranchia suggest that prey type shifts are relatively common over evolutionary timescales.ResultsIn the present study, we generated a well-supported phylogeny of the major lineages within Cladobranchia using RNA-Seq data, and used ancestral state reconstruction analyses to better understand the evolution of prey preference. These analyses answered several fundamental questions regarding the evolutionary relationships within Cladobranchia, including support for a clade of species from Arminidae as sister to Tritoniidae (which both preferentially prey on Octocorallia). Ancestral state reconstruction analyses supported a cladobranchian ancestor with a preference for Hydrozoa and show that the few transitions identified only occur from lineages that prey on Hydrozoa to those that feed on other types of prey.ConclusionsThere is strong phylogenetic correlation with prey preference within Cladobranchia, suggesting that prey type specialization within this group has inertia. Shifts between different types of prey have occurred rarely throughout the evolution of Cladobranchia, indicating that this may not have been an important driver of the diversity within this group.Electronic supplementary materialThe online version of this article (10.1186/s12862-017-1066-0) contains supplementary material, which is available to authorized users.

Transcriptomics provides a robust framework for the relationships of the major clades of cladobranch sea slugs (Mollusca, Gastropoda, Heterobranchia), but fails to resolve the position of the enigmatic genusEmbletonia

“…Quartet sampling, on the other hand, showed only medium support (split 4 in Fig. 1, Supplementary Table S11 Within Aeolidioidea, the families Myrrhinidae and Aeolidiidae form a monophyletic sister group relationship in our study, thus confirming the results of [28] and [18]. This is also consistent with recent morphological and molecular analyses [53].…”

“…The majority of the family Facelinidae is inferred as being monophyletic, but the facelinid species Noumeaella rubrofasciata groups with Myrrhinidae in published analyses [18,28] as well as in our study with nearly maximal 'classical' statistical support. However, quartet puzzling only shows weak support for this relationship (38% of the non-uncertain quartets; see split 6 in Fig.…”

“…Recent analyses, using a large transcriptomic data set, provided the first robust cladobranch tree that enabled the study of evolution of food preferences [27,28]. In a subsequent study, a broader data set with nearly 90 taxa was used to examine the evolution of the cnidosac [18], which is the main defence system of Aeolidida [29].…”

Multiple paedomorphic lineages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella

“…A subgroup of nudibranchs, treated here as suborder Aeolidacea, has evolved a defensive system for the secondary usage of cnidocysts from cnidarian prey [17,18]. While the phylogeny of Aeolidacea is currently actively studied [18][19][20][21], a majority of these nudibranchs as defined within the previously established broad-scope aeolidacean nudibranch phylogenetic framework [19], are complex animals with numerous dorsal papillae (cerata) (Figs 1-3). However, there is a single exclusively infaunal family, Pseudovermidae, with evident paedomorphic features such as vermiform shape and reduced dorsal papillae, which strongly matches early ontogenetic stages of complex aeolidaceans [22].…”

Description of a new Moridilla species from North Sulawesi, Indonesia (Mollusca: Nudibranchia: Aeolidioidea)—based on MicroCT, histological and molecular analyses

“…Moridilla brockii (included only in one study on Aeolidiidae) clusters with facelinid species but not with Noumeaella (Carmona et al 2013). In the available genomic studies (Goodheart 2017;Goodheart et al 2017Goodheart et al , 2018Martynov et al 2019) Moridilla was not included; however, Palisa groups with genera that also show a closer relationship to Moridilla (see Carmona et al 2013) than to Noumeaella. The description of the monotypic genus Moridilla with Moridilla brockii was based on a single individual from Pulau Dapur, Java, Indonesia (Bergh 1888).…”