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The family Ampullariidae includes both aquatic and amphibious apple snails. They are an emerging model for evolutionary studies due to the high diversity, ancient history, and wide geographical distribution. Insight into drivers of ampullariid evolution is hampered, however, by the lack of genomic resources. Here, we report the genomes of four ampullariids spanning the Old World (Lanistes nyassanus) and New World (Pomacea canaliculata, P. maculata, and Marisa cornuarietis) clades. The ampullariid genomes have conserved ancient bilaterial karyotype features and a novel Hox gene cluster rearrangement, making them valuable in comparative genomic studies. They have expanded gene families related to environmental sensing and cellulose digestion, which may have facilitated some ampullarids to become notorious invasive pests. In the amphibious Pomacea, novel acquisition of an egg neurotoxin and a protein for making the calcareous eggshell may have been key adaptations enabling their transition from underwater to terrestrial egg deposition.

Despite the increasing accessibility of high‐throughput sequencing, obtaining high‐quality genomic data on non‐model organisms without proximate well‐assembled and annotated genomes remains challenging. Here, we describe a workflow that takes advantage of distant genomic resources and ingroup transcriptomes to select and jointly enrich long open reading frames (ORFs) and ultraconserved elements (UCEs) from genomic samples for integrative studies of microevolutionary and macroevolutionary dynamics. This workflow is applied to samples of the African unionid bivalve tribe Coelaturini (Parreysiinae) at basin and continent‐wide scales. Our results indicate that ORFs are efficiently captured without prior identification of intron‐exon boundaries. The enrichment of UCEs was less successful, but nevertheless produced substantial data sets. Exploratory continent‐wide phylogenetic analyses with ORF supercontigs (>515,000 parsimony informative sites) resulted in a fully resolved phylogeny, the backbone of which was also retrieved with UCEs (>11,000 informative sites). Variant calling on ORFs and UCEs of Coelaturini from the Malawi Basin produced ~2000 SNPs per population pair. Estimates of nucleotide diversity and population differentiation were similar for ORFs and UCEs. They were low compared to previous estimates in molluscs, but comparable to those in recently diversifying Malawi cichlids and other taxa at an early stage of speciation. Skimming off‐target sequence data from the same enriched libraries of Coelaturini from the Malawi Basin, we reconstructed the maternally‐inherited mitogenome, which displays the gene order inferred for the most recent common ancestor of Unionidae. Overall, our workflow and results provide exciting perspectives for integrative genomic studies of microevolutionary and macroevolutionary dynamics in non‐model organisms. [ABSTRACT FROM AUTHOR]

Within Viviparidae, the systematic affinities of several genera are uncertain, with respect to one another, but also as to their subfamily attribution. From the genera that have been assigned unambiguously to one of the three subfamilies, a clear biogeographic pattern emerges that highlights a wide geographic separation of Bellamyinae from Viviparinae and Lioplacinae. Here we study Rivularia Heude, 1890, a genus previously assigned to Bellamyinae and largely restricted to the Hunan Province of China. We find that, although the taxon falls within the geographic range of Bellamyinae, comparative anatomical and genetic data reveal that it is a viviparine, tentatively the sister group of European Viviparus. Anatomical support includes the morphology of the radula and salivary glands, the presence of the testis in close association with the digestive gland in the viscera, rather than in the pallial cavity (Bellamyinae) and in females, the occurrence of the albumen gland and capsule gland ventral rather than posterior to the brood pouch, and proximal, rather than distal, to the last U-turn in the female reproductive tract. Greater differences are found when compared with Lioplacinae. Our finding represents the first record of natural co-occurrence of Viviparinae and Bellamyinae. Vicariance is the most likely cause for the strongly disjunct occurrence of Viviparinae in the Palearctic. [ABSTRACT FROM AUTHOR]

Background: Non-indigenous taxa currently represent a large fraction of the species and biomass of freshwater ecosystems. The accumulation of invasive taxa in combination with other stressors in these ecosystems may alter the habitats to which native taxa are adapted, which could elicit evolutionary changes in native populations and their ecological interactions. Assessing ecological and evolutionary consequences of invasions simultaneously may therefore be the most effective approach to study taxa with complex invasion histories. Here we apply such an integrated approach to the cerithioid gastropod Melanoides tuberculata, a model system in invasion biology. Results: Molecular phylogenetics and ancestral range reconstructions allowed us to identify several independent Asian invasions in Lakes Malawi and Tanganyika, the Congo River, Nigeria and Cameroon. Some invasive M. tuberculata populations display much variation in shell morphology, and overlap in morphospace with M. tuberculata populations native to Africa. Experiments confirmed great ecophenotyic plasticity in some invasive populations, which, in combination with the overlap in disparity with native populations, masks invaders and their dispersal through Africa. Finally, the results of geographic modeling indicate that cryptic M. tuberculata invasions occurred primarily in densely populated areas. Conclusions: We reveal the continental nature of invasions of Asian M. tuberculata to Africa. Several of the affected ecosystems have high endemicity in Cerithioidea: Lake Tanganyika has an unparalleled diversity in freshwater cerithioids (>10 endemic genera) and the Congo Basin and Lake Malawi are home to the two largest endemic species clusters of Melanoides in Africa (~12 and ~8 species, respectively). Cerithioids perform ecologically important functions in the benthic ecosystems of African freshwaters, but invaders and ecosystem change pose risks to their native diversity. We draw suggestions for more effective conservation strategies from our integrated approach. [ABSTRACT FROM AUTHOR]