Browsing by Author "Taper, Mark L."

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Evidence of an Absence of Inbreeding Depression in a Wild Population of Weddell Seals (Leptonychotes weddellii)
(MDPI AG, 2023-02) Powell, John H.; Kalinowski, Steven T.; Taper, Mark L.; Rotella, Jay J.; Davis, Corey S.; Garrott, Robert A.
Inbreeding depression can reduce the viability of wild populations. Detecting inbreeding depression in the wild is difficult; developing accurate estimates of inbreeding can be time and labor intensive. In this study, we used a two-step modeling procedure to incorporate uncertainty inherent in estimating individual inbreeding coefficients from multilocus genotypes into estimates of inbreeding depression in a population of Weddell seals (Leptonychotes weddellii). The two-step modeling procedure presented in this paper provides a method for estimating the magnitude of a known source of error, which is assumed absent in classic regression models, and incorporating this error into inferences about inbreeding depression. The method is essentially an errors-in-variables regression with non-normal errors in both the dependent and independent variables. These models, therefore, allow for a better evaluation of the uncertainty surrounding the biological importance of inbreeding depression in non-pedigreed wild populations. For this study we genotyped 154 adult female seals from the population in Erebus Bay, Antarctica, at 29 microsatellite loci, 12 of which are novel. We used a statistical evidence approach to inference rather than hypothesis testing because the discovery of both low and high levels of inbreeding are of scientific interest. We found evidence for an absence of inbreeding depression in lifetime reproductive success, adult survival, age at maturity, and the reproductive interval of female seals in this population.
Hitching a ride: Seed accrual rates on different types of vehicles
(2017-12) Rew, Lisa J.; Brummer, Tyler J.; Pollnac, Fredric W.; Larson, Christian D.; Taylor, Kimberley T.; Taper, Mark L.; Fleming, Joseph D.; Balbach, Harold E.
Human activities, from resource extraction to recreation, are increasing global connectivity, especially to less-disturbed and previously inaccessible places. Such activities necessitate road networks and vehicles. Vehicles can transport reproductive plant propagules long distances, thereby increasing the risk of invasive plant species transport and dispersal. Subsequent invasions by less desirable species have significant implications for the future of threatened species and habitats. The goal of this study was to understand vehicle seed accrual by different vehicle types and under different driving conditions, and to evaluate different mitigation strategies. Using studies and experiments at four sites in the western USA we addressed three questions: How many seeds and species accumulate and are transported on vehicles? Does this differ with vehicle type, driving surface, surface conditions, and season? What is our ability to mitigate seed dispersal risk by cleaning vehicles? Our results demonstrated that vehicles accrue plant propagules, and driving surface, surface conditions, and season affect the rate of accrual: on- and off-trail summer seed accrual on all-terrain vehicles was 13 and 3508 seeds km-1, respectively, and was higher in the fall than in the summer. Early season seed accrual on 4-wheel drive vehicles averaged 7 and 36 seeds km-1 on paved and unpaved roads respectively, under dry conditions. Furthermore, seed accrual on unpaved roads differed by vehicle type, with tracked vehicles accruing more than small and large 4-wheel drives; and small 4-wheel drives more than large. Rates were dramatically increased under wet surface conditions. Vehicles indiscriminately accrue a wide diversity of seeds (different life histories, forms and seed lengths); total richness, richness of annuals, biennials, forbs and shrubs, and seed length didn't differ among vehicle types, or additional seed bank samples. Our evaluation of portable vehicle wash units showed that approximately 80% of soil and seed was removed from dirty vehicles. This suggests that interception programs to reduce vehicular seed transportation risk are feasible and should be developed for areas of high conservation value, or where the spread of invasive species is of special concern.
Performance of Juvenile Cutthroat Trout Translocated as Embryos from Five Populations into a Common Habitat
(2016-07) Andrews, Tessa; Shepard, Bradley B.; Litt, Andrea R.; Kruse, Carter G.; Nelson, M. Lee; Clancey, Patrick; Zale, Alexander V.; Taper, Mark L.; Kalinowski, Steven T.
The distributions of most native trout species in western North America have been severely reduced, and conservation of many of these species will require translocation into vacant habitats following removal of nonnative species. A critical question managers have is \Does it matter which donor sources are used for these translocations?\" We present a case study that addressed this question for a large native trout translocation project in Montana. We introduced embryos from five source populations of Westslope Cutthroat Trout Oncorhynchus clarkii lewisi to a large, fishless watershed in Montana following removal of nonnative fish with piscicides. Source populations providing embryos for translocations were three nearby (< 120 km) wild populations, the state of Montana\'s captive Westslope Cutthroat Trout hatchery conservation population (initiated 32 years ago using fish from wild populations located > 350 km from the translocation site), and a population in captivity for one generation comprised of individuals from the three wild populations used as single sources for this project, which were variably crossed (59% within populations and 41% between populations) to provide embryos. We used remote-site incubators at six different sites to introduce approximately 35,000 embryos from 400 genotyped parents. We later resampled and genotyped 1,450 of these individuals at age 1 and age 2. Juvenile survival for the more genetically diverse Montana Westslope Cutthroat Trout conservation population was twice as high as for other source populations, even though these other source populations were geographically closer to the translocation site than populations used to make the Montana Westslope Cutthroat Trout conservation population. Body weight for progeny from the two captive populations was higher than for progeny from wild source populations, and some differences were observed in body condition among source populations. Continued monitoring over several generations will be necessary to determine the eventual contributions of each source population and the relevance of these initial findings."