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This article was originally published as: Barrera, M.A, Janes, J.K, & Gorrell, J.C. (2022). Molecular phylogenetics and systematics of two enteric helminth parasites (Baylisascaris laevis and Diandrya vancouverensis) in the Vancouver Island marmot (Marmota vancouverensis). International Journal for Parasitology: Parasites and Wildlife, 19, 301-310. https://doi.org/10.1016/j.ijppaw.2022.11.006 Island biogeography can promote rapid diversification and speciation via geographic isolation and novel selection pressures. These same factors can threaten the persistence of island endemics by limiting gene flow and suitable habitat. Host-parasite interactions on islands introduce another dimension of complexity as both species must simultaneously adapt to exogenous and endogenous factors. One example of host-parasite island biogeography is the critically endangered Vancouver Island (VI) marmot (Marmota vancouverensis) which is endemic to VI, Canada, and hosts two enteric helminth parasites: Baylisascaris laevis, an ascarid nematode common in tribe Marmotini, and Diandrya vancouverensis, an anoplocephalid cestode endemic to the VI marmot. Here, we aligned novel sequences from B. laevis (six genes) and D. vancouverensis (two genes) with congeneric sequences from GenBank. Phylogenies reconstructed using Bayesian and maximum parsimony approaches consistently placed B. laevis in a morphoclade, and D. vancouverensis in a monophyletic clade sister to D. composita. Mean pairwise sequence divergence between D. vancouverensis and D. composita (9.06 ± 1.94%) surpassed commonly accepted thresholds for species delimitation, whereas divergence between VI and mainland populations of B. laevis (1.12 ± 0.78%) was comparable to (or sometimes greater than) pairwise divergence values between other Baylisascaris species. Disparity in the genetic divergence of each parasite may reflect differences in their life cycle, host specificity, virulence, and the chronological extent of their isolation. Detailed descriptions of the population genetic structure and effects of both parasites on their shared host are crucial next steps in understanding the history of B. laevis and D. vancouverensis on VI and informing conservation efforts for the VI marmot and its enteric helminth parasites. This research was funded by a Discovery Grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada (#RGPIN-2018-06764) and an Innovation HUB grant from Co-operative Education and Work-Integrated Learning Canada. https://viurrspace.ca/bitstream/handle/10613/26085/Gorrell2022IJPPW.pdf?sequence=3

This is a manuscript version of an article published as: Haines, J.A., Nason, S.E., Skurdal, A.M.M., Bourchier, T., Boutin, S., Taylor, R.W., McAdam, A.G., Lane, J.E., Kelley, A.D., Humphries, M.M., Gorrell, J.C., Dantzer, B., Coltman, D.W., & Hämäläinen, A. (2020). Sex- and context-specific associations between personality and a measure of fitness but no link with life history traits. Animal Behaviour, 167, 23-29. https://doi.org/10.1016/j.anbehav.2020.06.013 The pace-of-life syndrome hypothesis posits that personality traits (i.e. consistent individual differences in behaviour) are linked to life history and fitness. Specifically, fast-paced individuals are predicted to be proactive (i.e. active and aggressive) with an earlier age at first reproduction, a shorter life span and higher fecundity than slow-paced individuals. Environmental conditions and sex differences may be important in maintaining behavioural and life history variation in populations and may influence the covariance of personality with life history or lifetime fitness. However, these effects are rarely tested together. We investigated whether the occurrence of a resource pulse (called a mast year) during adulthood altered the associations between personality and life history traits or lifetime offspring production in adult North American red squirrels, Tamiasciurus hudsonicus. Despite accounting for environmental context during adulthood, we found no evidence of an overall pace-of-life syndrome in this population as personality was not associated with age at first reproduction or longevity in either sex. Males and females had similar activity levels, but females were more aggressive, potentially due to the fitness benefits of protecting their offspring from predation. In all females, regardless of mast experience, there was no association between activity and lifetime pup production, but there was a positive association between aggression and lifetime pup production. In males that experienced a mast, there was a positive association between lifetime pup production and both activity and aggression. In males that did not experience a mast, there was no association between activity and lifetime pup production, but there was a negative association between aggression and lifetime pup production. Lifetime recruit production (number of adult offspring recruited into the breeding population) in either sex was not influenced by activity or aggression regardless of mast experience. Overall, our results suggest that the infrequent occurrence of mast years may contribute to maintaining variation in personality traits in red squirrels. Pre-print version This is a manuscript version of an article published as: Haines, J.A., Nason, S.E., Skurdal, A.M.M., Bourchier, T., Boutin, S., Taylor, R.W., McAdam, A.G., Lane, J.E., Kelley, A.D., Humphries, M.M., Gorrell, J.C., Dantzer, B., Coltman, D.W., & Hämäläinen, A. (2020). Sex- and context-specific associations between personality and a measure of fitness but no link with life history traits. Animal Behaviour, 167, 23-29. https://doi.org/10.1016/j.anbehav.2020.06.013 https://viurrspace.ca/bitstream/handle/10613/23323/GorrellAB.pdf?sequence=3

Interactions with conspecifics are an important aspect of an individual's environment. Although it is well known that the presence of conspecifics can have important effects on behaviour, in general it is also now acknowledged that the composition of the social environment can vary, and that this variation may have profound effects on individual behaviour and fitness. Using a wild population of North American red squirrels, Tamiasciurus hudsonicus, we investigated the importance of the composition of the social environment in a territorial species by assessing whether the risk of intrusion faced by territory owners varied with the degree of relatedness and familiarity in their social neighbourhoods. To test this, we conducted temporary removals of territory owners and observed the time until intrusion and the identity of intruding individuals. We found that individuals in neighbourhoods with low average familiarity faced a higher risk of intrusion and that unfamiliar neighbours were more likely to intrude. Surprisingly, we found that related neighbours also posed a higher risk of intrusion. The results from our study suggest that familiarity with neighbours may be an ecologically and evolutionarily relevant measure of the social environment, even in a species considered to be ‘asocial’. Future studies should consider the potential importance of the social environment, which has heretofore been mostly overlooked, as a relevant selective pressure in asocial, territorial species.

The ability to discriminate among individuals, or among classes of individuals, can provide animals with important fitness benefits. Although several mechanisms for discrimination are possible, most require animals to show stable phenotypic variation that reflects their identity or their membership in a particular class (e.g. sex, mate, kin). For territorial animals that rarely interact physically, vocalizations could serve as long-distance signals that facilitate discrimination. In this study, we tested whether the territorial rattle vocalizations of North American red squirrels, Tamiasciurus hudsonicus, are repeatable, and whether they could hence provide the basis for multiple types of discrimination. We measured four structural features from two rattles from each of 76 marked squirrels. All four features were repeatable, which is consistent with territorial rattles being individually distinctive. We then conducted a playback experiment to determine whether squirrels use rattles for discrimination. Specifically, we tested whether squirrels discriminate between the rattles of neighbours and non-neighbours, and kin (coefficient of relatedness, r ≥ 0.25) and non-kin (r

Parasites can negatively affect their host’s physiology and morphology and render host individuals less attractive as mating partners. The energetic requirements of defending against parasites have to be traded off against other needs such as feeding activity, territoriality, thermoregulation or reproduction. Parasites can affect mating patterns, with females preferentially mating with parasite-resistant or parasite-free partners. We tested experimentally whether removal of both ectoparasites and endoparasites on free-living, male Columbian ground squirrels, Urocitellus columbianus, affected male mating behaviour, reproductive success and seasonal and posthibernation weight gain compared to control males. We predicted that experimental males would lose less body mass and mate more often than control males. In addition, we predicted experimental males would copulate earlier than control males in the mating sequences of receptive females and sire more offspring, because this species exhibits a strong first-male paternity advantage. Parasite treatment significantly reduced the parasite loads of experimental males. None of these males had ectoparasites at the end of the season, compared to 70% infestation of the control males. However, contrary to our expectations, the experimental treatment did not affect male reproductive behaviour (mating frequency, mating position, consort duration and mate-guarding duration), did not increase male reproductive success, and did not influence male body mass. We conclude that parasite infestation plays a minor role in affecting male reproductive behaviour, maybe because of the overall low infestation rates. Alternatively, males may be able to compensate for any costs associated with moderate loads of parasites.

A mathematical model for ion transport across a multilaminate barrier is presented which satisfactorily describes the exponentially nonlinear and slightly asymmetric current-voltage properties of skin subjected to an applied DC potential. This is accomplished using rate equations, analogous to the Butler-Volmer theory of electrode reaction rates, in which voltage-dependent potential energy barriers govern ion transport. In skin, the physical location of these barriers may be lipid lamellae in the stratum corneum and/or the walls of the epithelial cells lining skin appendages. Model parameters for the number of barriers, n , the symmetry of the barriers, α, and rate constants for sodium and chloride ion, K Na and K Cl , are calculated based on the current-voltage characteristic of excised human skin immersed in saline solutions and the sodium ion transference number for this tissue obtained during constant current iontophoresis. The ratio K Na / n is found to be equal, within experimental error, to the sodium ion permeability coefficient, P Na , obtained by measuring the passive diffusion of 22 Na + through the same skin samples, as predicted by the theory. Using the parameter values developed in this paper in conjunction with the kinetic model, it should be possible to obtain a prediction of iontophoretic delivery rates for other ions based on the passive diffusion of these ions through skin.

The problem of optimizing ocular bioavailability of topically applied ophthalmic drugs is discussed. A formula for drug concentration in the tear film is derived using well-known pharmacokinetic relationships and a first-order drug decay model for the tear film. The time integral of the tear film concentration is then related to ocular bioavailability. The results of this analysis show that: (1) high corneal permeability (corresponding to lipophilic compounds) produces the highest bioavailability; (2) the bioavailability of drugs with high corneal permeability is relatively unaffected by drug volume; and (3) by making the dosage volume sufficiently small, a bioavailability improvement factor of approximately 4 can be obtained for drugs with low corneal permeability.

The theoretical solution of the lag time in a general, multilayered membrane (including both binding and partitioning effects) is derived. Comparison of this lag time formula is made to standard lag time formulas derived when only partitioning is taken into account. The special case of the corneal membrane and a single membrane with binding are discussed. It was found that the ratio of low concentration lag times to high concentration lag times is directly proportional to the binding constant of the drug to the membrane. Therefore, the measurement of concentrationdependent lag times can be used to determine binding properties of a membrane with respect to a given drug.

A recent analysis of total mass transport through a homogeneous membrane is generalized to the case of membrane nonuniformity as well as the presence of irreversible, firstorder degradation or hydrolysis. The results show that for initial conditions where none of the transported mass is present in the membrane, the total mass transported is just the ratio of the time integral of the mass concentration on the donor side of the membrane to the effective steady-state resistance of the membrane. Four specific cases are considered which can be applied to the transport analysis of biological membranes such as the skin and the cornea.

The time-dependent theoretical solution to ionic mass transport through a uniform membrane under the influence of a uniform electric field is derived. Equivalent lag times and steady-state fluxes are then determined. The enhancement ratio of ionic flow (at a given voltage) to passive flow is shown to be proportional to the voltage for large augmenting voltages, and to decrease exponentially for large retarding voltages. Positive enhancement factors can be as large as 120 for triply charged ions, with one volt imposed across a membrane. The lag times decrease with increasing voltage magnitudes, and can (for triply charged ions, with one volt imposed across a membrane) be as small as 1/20 of the passive lag time.

Two simple models for ionic mass transport across membranes are discussed in the context of iontophoretic delivery of drugs through skin. The constant field model is mathematically the most tractable and offers some insights into the time dependence of iontophoretic transport. However, for thick membranes or for systems in which the total ion concentrations on opposite sides of the membrane differ appreciably, the electroneutrality approximation is more appropriate. Since both of these conditions are likely to be found in skin iontophoresis studies, the electroneutrality model should provide a better starting point for analyzing the details of iontophoresis experiments than does the constant field model. Equations for the diffusion potential, ion transference numbers and partition coefficients and the current-voltage characteristic of the membrane are given, enabling one to calculate ionic fluxes and active/passive flux ratios for a given applied current or voltage. As an example, the flux and transference number of a monovalent drug ion driven across a membrane in the presence of sodium chloride are calculated. Finally, known discrepancies between the predictions of the homogeneous membrane models and available experimental data are examined, and suggestions are made for modifying the theory to resolve these differences.