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Creators/Authors contains: "Galbreath, Kurt E."

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  1. Abstract

    Across eastern North America, glacial cycles of the Pleistocene drove episodic latitudinal range shifts by temperate species. Isolation of populations within low-latitude refugia during glacial maxima was enhanced by physiographic barriers, leading to patterns of phylogeographic differentiation that are shared across diverse taxa. Postglacial population expansion created opportunities for differentiated lineages to come into contact, with various potential population-genetic outcomes. Northern short-tailed shrews (Blarina brevicauda) exhibit three mitochondrial phylogroups that probably originated via glacial-age range restriction and isolation. We investigate the history of postglacial expansion and interlineage contact between historically isolated regional populations of B. brevicauda. Morphological differences between skulls of shrews representing a Western lineage and those representing Central and Eastern lineages are consistent with past subspecies delineations. However, we demonstrate broad range overlap between neighboring phylogroups across the Upper Peninsula and Lower Peninsula in Michigan. Further, incongruence between phylogroup association and morphology among individuals in Upper Peninsula populations suggests that genetic admixture between shrews representing the Western and Central groups has occurred in the past and may be ongoing. We show that across most cranial measurements, shrews within the contact zone are morphologically most similar to the Central group regardless of mitochondrial identity, but one measurement in these contact zone shrews (depth of skull) is more similar to that seen in the Western group. These results suggest that hybridization between historically isolated populations has resulted in the origin of a novel skull phenotype that is proportionally deeper, narrower, and shorter than those seen in core Western and Central populations.

     
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  2. Free, publicly-accessible full text available June 1, 2024
  3. Abstract Citellinema Hall, 1918 includes 6 valid species of gastrointestinal nematodes of sciurids. Two species occur in the Palearctic and 4 in the Nearctic, 3 of which occur minimally across Colorado, Idaho and Oregon and 1, Citellinema bifurcatum , has a wide distribution across North America. Members of the genus are didelphic, possess a cephalic vesicle, a terminal spine-like process in females and feature robust spicules, consisting of a proximal end fused and semicylindrical shaft connected to a lamina supported by 2 terminal filiform processes. Typically, the size of the spicules is used to differentiate species. As part of the Beringian Coevolution Project, specimens provisionally identified as C. bifurcatum were collected through intensive field sampling of mammals and associated parasites from across localities spanning the Holarctic. These specimens revealed considerable genetic variability at both mitochondrial and nuclear loci, supporting the identification of deeply divergent clades. Examination of these new specimens, along with the holotypes of C. bifurcatum and Citellinema quadrivittati indicates that Citellinema monacis (previously synonymized with C . bifurcatum ) should be resurrected and 3 additional species described. We suggest that the apparent bifurcated nature of the spicule should be considered a generic diagnostic trait, while the proportional length of the lamina relative to that of the spicule is used as a specific character. We demonstrate the critical need for continued inventory of often poorly known assemblages of hosts and parasites, contributing to a growing baseline of archival specimens, collections and information that make explorations of faunal structure and diversity possible. 
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  4. Abstract Aim

    We test the predictions of the Stockholm Paradigm, a synthesis of eco‐evolutionary theory explaining the nature of faunal assembly, host range and parasite diversification. Faunal diversification and assembly, manifested in patterns of host colonization, co‐adaptation and parasite speciation, are predicted to emerge as a consequence of alternating episodes of ecological disruption and stability. Specifically, for a diverse cestode genus (Arostrilepis), we evaluate the number and direction of Pleistocene dispersal events across Beringia, the number and relative timing of host colonization events and the relationship between host and parasite biogeographic histories and associations through time.

    Location

    Beringia and adjacent temperate to arctic biomes in North America and Eurasia.

    Taxon

    Arostrilepis(Cyclophyllidea: Hymenolepididae) and its rodent hosts.

    Methods

    Multi‐locus phylogenetic reconstruction and biogeographic ancestral range estimation.

    Results

    Arostrilepislineages crossed Beringia eastward into North America a minimum of four times and westward into Asia twice in association with temporally disjunct geographic expansions of three major tribes of cricetid rodents (Arvicolini, Myodini, Lemmini). Inferences of ancestral host associations support at least nine instances of host colonization involving shifts from one rodent tribe or family to another. Several previously unrecognized lineages ofArostrilepisare revealed.

    Main conclusions

    Consistent with expectations of the Stockholm Paradigm, episodes of intercontinental dispersal were both frequent in the history ofArostrilepisand preceded a majority of inferred host‐colonization events. Events of historical geographic expansion created numerous opportunities for development of novel host–parasite associations through ecological fitting, as parasites tracked historically conserved resources available across diverse host taxa. Beringia played a major role in shaping rodent/parasite assemblages by mediating dispersal between the northern continents during glacial episodes of the Pleistocene, rather than by serving as a zone of refugial isolation.

     
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  5. Abstract

    The Cyclophyllidea is the most diverse order of tapeworms, encompassing species that infect all classes of terrestrial tetrapods including humans and domesticated animals. Available phylogenetic reconstructions based either on morphology or molecular data lack the resolution to allow scientists to either propose a solid taxonomy or infer evolutionary associations. Molecular markers available for the Cyclophyllidea mostly include ribosomalDNAand mitochondrial loci. In this study, we identified 3641 single‐copy nuclear coding loci by comparing the genomes ofHymenolepis microstoma,Echinococcus granulosusandTaenia solium. We designedRNAbaits based on the sequence ofH. microstoma, and applied target enrichment and Illumina sequencing to test the utility of those baits to recover loci useful for phylogenetic analyses. We capturedDNAfrom five species of tapeworms representing two families of cyclophyllideans. We obtained an average of 3284 (90%) of the targets from the test samples and then used captured sequences (2 181 361 bp in total; fragment size ranging from 301 to 6969 bp) to reconstruct a phylogeny for the five test species plus the three species for which genomic data are available. The results were consistent with the current consensus regarding cyclophyllidean relationships. To assess the potential for our method to yield informative genetic variation at intraspecific scales, we extracted 14 074 single nucleotide polymorphisms (SNPs) from alignments of fourArostrilepis macrocirrosaand twoA. cookiand successfully inferred their relationships. The results showed that our target gene tools yield data sets that provide robust inferences at a range of taxonomic scales in the Cyclophyllidea.

     
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