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Aim: Pinnipeds are thought to have evolved from a North Pacific ancestor, although some fossil evidence suggests a nonmarine Arctic origin and separate invasions into the North Pacific and North Atlantic. We here set out to test differing hypotheses about the origin of pinnipeds through identification and age estimation of pinniped marine invasions. Location: Arctic, North America, North Atlantic, North Pacific. Taxon: Pinnipeds (seals, sea lions, walruses and their fossil relatives). Methods: Because evidence indicates that taste loss in marine mammals and birds results from adaptation to the marine environment, we examined 16 representative pinnipeds for loss‐of‐function mutations in the TAS1R1, TAS1R2 and TAS1R3 genes encoding the sweet T1R2–T1R3 and umami (savory) T1R1–T1R3 receptors, and used the loss‐of‐function events of these receptors as indicators of marine invasion. Results: Numerous loss‐of‐function mutations were found in each pinniped TAS1R (22 in TAS1R1, 21 in TAS1R2 and 42 in TAS1R3). Six mutations were shared by all phocids and six other mutations by all otarioids (otariids and odobenids), but none by all phocids and all otarioids. Selective pressures on TAS1R1, TAS1R2 and TAS1R3 were estimated to have been relaxed, respectively, 16.3, 20.1 and 19.8 million years ago (Myra) in phocids, and 12.1, 18.1 and 18.2 Myra in otarioids. Main conclusions: All TAS1Rs, T1R1–T1R3 and T1R2–T1R3 are nonfunctional in all extant pinnipeds. Both receptors lost their function approximately 20 Myra in the Phocidae lineage and approximately 18 Myra in the Otarioidea lineage. Both lineages have colonized the marine realm independently, which entails nonmarine origins of both Pinnipedia and its stem lineage. Combined with fossil evidence, molecular findings here suggest an Arctic centre of long‐lasting (approximately 38–18 Myra) nonmarine pinniped evolution and at least five separate marine invasions, with the extinct (enaliarctid, Desmatophocidae, Kolponomos) and Otarioidea lineages entering the North Pacific and the Phocidae lineage the North Atlantic. [ABSTRACT FROM AUTHOR]

The spotted wing Drosophila, Drosophila suzukii , has emerged within the past decade as an invasive species on a global scale, and is one of the most economically important pests in fruit and berry production in Europe and North America. Insect ecology, to a strong degree, depends on the chemosensory modalities of smell and taste. Extensive research on the sensory receptors of the olfactory and gustatory systems in Drosophila melanogaster provide an excellent frame of reference to better understand the fundamentals of the chemosensory systems of D. suzukii. This knowledge may enhance the development of semiochemicals for sustainable management of D. suzukii , which is urgently needed. Here, using a transcriptomic approach we report the chemosensory receptor expression profiles in D. suzukii female and male antennae, and for the first time, in larval heads including the dorsal organ that houses larval olfactory sensory neurons. In D. suzukii adults, we generally observed a lack of sexually dimorphic expression levels in male and female antennae. While there was generally conservation of antennal expression of odorant and ionotropic receptor orthologues for D. melanogaster and D. suzukii , gustatory receptors showed more distinct species-specific profiles. In larval head tissues, for all three receptor gene families, there was also a greater degree of species-specific gene expression patterns. Analysis of chemosensory receptor repertoires in the pest species, D. suzukii relative to those of the genetic model D. melanogaster enables comparative studies of the chemosensory, physiology, and ecology of D. suzukii. [Display omitted] • Identification of chemosensory receptor genes expressed in D. suzukii larval heads • Scant evidence of sex-biased expression of chemosensory receptors in adult antennae • Comparison with D. melanogaster reveals greater conservation in adults than larvae. • In adults, gustatory receptors showed the most distinct expression profiles. • Larvae express fewer odorant receptors, many of which were not found in adults. [ABSTRACT FROM AUTHOR]