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Allometric analyses of sexually selected structures have revealed many patterns of evolutionary and behavioural significance, for example, in weapons, ornaments, and genitalia. We investigated allometry of the baculum (penis bone) relative to body size in post-growth adults of three large mustelids: wolverine (Gulo gulo (Linnaeus, 1758)), northern river otter (Lontra canadensis (Linnaeus, 1758)), and sea otter (Enhydra lutris (Linnaeus, 1758)). The baculum grew over a longer period than did body size. Correlations among bacular variables were positive in post-growth adults. No regression slopes expressed positive allometry (i.e., slope > 1 for linear variables). These trends point to the possibility that bacular size is adapted to the average size of the reproductive tract of sexually mature female northern river otters and possibly sea otters, and that pre-ejaculatory ("pre-copulatory") selection is highest in those species. Bacular size varied more than skull or limb-bone size, and bacular shape also varied greatly. Species differed in size and complexity of the urethral groove and bacular apex, suggesting functional differences in intromission. Substantial variation in bacular shape resulted from healed fractures, especially in sea otter. Knowledge of copulatory behaviour, age of breeding, female reproductive anatomy, and genitalic interactions during intromission is needed for comprehensive understanding of bacular anatomy, allometry, and variation for these species. [ABSTRACT FROM AUTHOR]

The distribution of small mammals is constrained by extreme environmental demands and variable food supplies that are commonly incurred at northern latitudes. Little brown bats (Myotis lucifugus (Le Conte, 1831)) are at the northwestern limits of their range in Alaska (USA), where environmental demands are higher and prey availability is more seasonal than elsewhere in their range. We hypothesized that the little brown bat in interior Alaska has adjusted to these constraints by broadening its foraging niche, relative to that of southern conspecifics. We analyzed arthropod fragments (microhistology) in guano to describe prey composition to order. We compared the efficacy of evaluating diet by microhistology with DNA analysis and stable isotope analysis on guano and hair. Bats consumed aerial prey such as Lepidoptera (moths) and Diptera (true flies and mosquitoes), as well as terrestrial arthropods including Araneae (spiders). Shifts in the proportion of aerial prey in the diet were closely linked to ordinal day. Values for [delta][.sup.15]N in hair indicated that bats were generalists in interior Alaska, coastal Alaska, and the Yukon (Canada), but significant outliers indicated that some individuals have distinct diets. The little brown bat's flexibility in feeding strategies likely allows this species to sustain populations in arctic and subarctic regions. Key words: Alaska, arthropods, diet analysis, foraging, bat guano, fecal DNA, generalists, little brown bat, microhistology, Myotis lucifugus, niche. La repartition des petits mammiferes est limitee par les demandes environnementales extremes et la disponibilite variable de nourriture qui caracterisent souvent les latitudes septentrionales. Les vespertilions bruns (Myotis lucifugus (Le Conte, 1831)) sont a la limite nord-ouest de leur aire de repartition en Alaska (Etats-Unis), ou les demandes environnementales sont plus fortes et la disponibilite des proies est plus saisonniere qu'ailleurs dans leur aire. Nous avons postule que les vespertilions bruns dans l'interieur de l'Alaska se sont ajustes a ces contraintes en elargissant leur niche d'approvisionnement par rapport a celle de leurs conspecifiques meridionaux. Nous avons analyse les fragments d'arthropodes (microhistologie) dans le guano pour decrire la composition des proies selon leurs ordres. Nous avons compare l'efficacite d'evaluer le regime alimentaire par microhistologie avec analyse d'ADN et analyse d'isotopes stables dans le guano et les poils. Les vespertilions consommaient des proies aeriennes comme des lepidopteres (papillons nocturnes) et des dipteres (mouches et moustiques), ainsi que des arthropodes terrestres comme des aranees (araignees). Les variations de la proportion des proies aeriennes dans le regime alimentaire etaient etroitement reliees a la date julienne. Les valeurs de [delta][.sup.15]N dans les poils indiquent que les vespertilions sont des generalistes dans l'interieur et le long des cotes de l'Alaska et au Yukon (Canada), mais des valeurs aberrantes significatives indiquent que certains individus ont des regimes alimentaires particuliers. La souplesse des strategies d'alimentation des vespertilions bruns permet vraisemblablement a cette espece de maintenir des populations en regions arctiques et subarctiques. [Traduit par la Redaction] Mots-cles: Alaska, arthropodes, analyse du regime alimentaire, approvisionnement, guano de chauve-souris, ADN fecal, generalistes, vespertilion brun, microhistologie, Myotis lucifugus, niche., Introduction Generalist predators present a challenge for dietary analysis because they consume a variety of species that often includes multiple trophic levels. Small predators such as birds and bats may [...]

We report the first Canadian record of the Holarctic least shrew (Sorex minutissimus Zimmermann, 1780) and associated helminth worms, collected along the Dempster Highway in central Yukon in 2014. We identify the specimen based on morphological characters, characterize the habitat, report other mammals and helminth species associated with this specimen, and use mitochondrial DNA sequences to place the specimen within a phylogenetic context and address Pleistocene refugial hypotheses. Although long considered an Eurasian endemic, the diminutive least shrew was first reported from Alaska in 1994. Our new record for Canada indicates that the species may occur at least as far east as the MacKenzie River and DNA variation suggests this species persisted only in the Beringian refugium in North America during the Last Glacial Maximum. The discovery of a new mammal and associated parasites for Canada points to the urgent need for more detailed information on high-latitude biotas in North America, data that are best obtained through museum-based field surveys, particularly for small, cryptic species. Key words: distribution, helminth, museum collections, Sorex minutissimus, Holarctic least shrew, Yukon. Nous signalons la premiere observation au Canada d'une musaraigne naine (Sorex minutissimus Zimmermann, 1780) holarctique et d'helminthes associes, preleves le long de la route de Dempster, dans le centre du Yukon, en 2014. Nous identifions le specimen sur la base de caracteres morphologiques, en caracterisons l'habitat, rendons compte d'autres mammiferes et especes d'helminthes associes a ce specimen et utilisons des sequences d'ADN mitochondrial pour le placer dans un contexte phylogenetique et examiner des hypotheses concernant les refuges au Pleistocene. Bien qu'elle ait longtemps ete consideree comme etant une espece endemique d'Eurasie, la musaraigne naine a ete signalee en Alaska pour la premiere fois en 1994. Notre observation de sa presence au Canada indique que l'aire de l'espece pourrait s'etendre vers l'Est au moins jusqu'au fleuve Mackenzie, et les variations d'ADN donnent a penser que cette espece n'a persiste que dans le refuge beringien en Amerique du Nord, durant le dernier maximum glaciaire. Cette decouverte d'un nouveau mammifere et de parasites associes au Canada souligne le besoin pressant de renseignements plus detailles sur les biotes de haute latitude en Amerique du Nord, des donnees qu'il est preferable d'obtenir dans le cadre d'etudes museales sur le terrain, particulierement en ce qui concerne les petites especes cryptiques. [Traduit par la Redaction] Mots-cles: repartition, helminthe, collections museales, Sorex minutissimus, musaraigne naine holarctique, Yukon., Introduction From a continental perspective, shrew (Soricomorpha: Soricidae) assemblages at high latitudes in northwestern North America are relatively species rich (Berman et al. 2007) and these assemblages have yielded a [...]