Biology

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Subject: search.filters.subject.Nudibranchia

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    Identification guide to the heterobranch sea slugs (Mollusca: Gastropoda) from Bocas del Toro, Panama
    (Springer Nature, 2016-07-15) Goodheart, Jessica A.; Ellingson, Ryan A.; Vital, Xochitl G.; Filho, Hilton C. Galvão; McCarthy, Jennifer B.; Medrano, Sabrina M.; Bhave, Vishal J.; García-Méndez, Kimberly; Jiménez, Lina M.; López, Gina; Hoover, Craig A.; Awbrey, Jaymes D.; De Jesus, Jessika M.; Gowacki, William; Krug, Patrick J.; Valdés, Ángel
    The Bocas del Toro Archipelago is located off the Caribbean coast of Panama. Until now, only 19 species of heterobranch sea slugs have been formally reported from this area; this number constitutes a fraction of total diversity in the Caribbean region. The Bocas del Toro Archipelago is located off the Caribbean coast of Panama. Until now, only 19 species of heterobranch sea slugs have been formally reported from this area; this number constitutes a fraction of total diversity in the Caribbean region. This increase in known diversity strongly suggests that the distribution of species within the Caribbean is still poorly known and species ranges may need to be modified as more surveys are conducted.
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    Phylogenomics, Systematics, and Evolution within the Nudibranch Group Cladobranchia (Mollusca: Gastropoda)
    (2017) Goodheart, Jessica Ann Marie; Cummings, Michael P; Collins, Allen G; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    To truly understand evolution, we must document patterns of variation in traits – ranging from anatomical features of individuals to geographic ranges of species – to gain insights into the mechanisms that lead to changes in diversity through time. This type of work requires a robust historical context of evolutionary relationships in order to make comparisons across taxa and inferences about past events. My dissertation provides a thorough phylogenetic analysis of the marine gastropod group Cladobranchia (Mollusca) to better understand the evolution of defensive capabilities within the clade. In the absence of a protective shell, lineages within Cladobranchia have evolved a diverse array of alternative defense mechanisms, including the use of stinging organelles (nematocysts) acquired from their cnidarian prey. It has been hypothesized that incorporation of nematocysts as a defensive strategy may have been an evolutionarily important event that led to large-scale diversification within this group. As such, understanding the steps involved in the evolution of this ability is necessary for evaluating this hypothesis. A major objective for my dissertation has been to use transcriptome (RNA-Seq) data from 37 species in Cladobranchia in order to generate a well-supported phylogenetic hypothesis of Cladobranchia. This research has produced the most highly supported phylogenetic tree of Cladobranchia thus far and contributes to confidence in the efficacy of genomic data to resolve relationships among gastropod lineages. As I have been able to expand this phylogenetic hypothesis with additional taxon sampling, including molecular data from a further 60 species, I have been able to provide context for understanding the evolutionary steps that led to the ability to sequester nematocysts. This phylogeny was then combined with morphological data from 50 nematocyst sequestering species within Cladobranchia to allow for a more detailed reconstruction of the evolution of nematocyst sequestration and prey preference within this clade. Overall, this work builds knowledge of the relationships among major lineages within Cladobranchia, and has substantially increased understanding of the evolution of morphological and ecological characters in this group.
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    Phylogeny of Cladobranchia (Gastropoda: Nudibranchia): a total evidence analysis using DNA sequence data from public databases
    (2015-07) Goodheart, Jessica A.; Bazinet, Adam L.; Collins, Allen G.; Cummings, Michael P.
    Cladobranchia is a clade of charismatic and exclusively marine slugs (Gastropoda: Nudibranchia). Though Cladobranchia and its sister taxon, Anthobranchia, have been supported by molecular data, little resolution among the higher-level groups within these two clades has emerged from previous analyses. Cladobranchia is traditionally divided into three taxa (Dendronotida, Euarminida, and Aeolidida), none of which have been supported by molecular phylogenetic studies. Reconstructions of the evolutionary relationships within Cladobranchia have resulted in poorly supported phylogenies, rife with polytomies and non-monophyletic groups contradicting previous taxonomic hypotheses. In this study, we present a working hypothesis for the evolutionary history of Cladobranchia, utilizing publicly available data that have been generated since the last attempt at a detailed phylogeny for this group (we include approximately 200 more taxa and a total of five genes). Our results resolve Cladobranchia as monophyletic and provide support for a small proportion of genera and families, but it is clear that the presently available data are insufficient to provide a robust and well-resolved phylogeny of these taxa as a whole.