Browsing by Author "Burger, Joseph R."

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    Areas of global importance for conserving terrestrial biodiversity, carbon and water
    (2021) Jung, Martin; Arnell, Andy; de Lamo, Xavier; Garcia-Rangel, Shaenandhoa; Lewis, Matthew; Mark, Jennifer; Merow, Cory; Miles, Lera; Ondo, Ian; Pironon, Samuel; Ravilious, Corinna; Rivers, Malin; Schepashenko, Dmitry; Tallowin, Oliver; van Soesbergen, Arnout; Govaerts, Rafael; Boyle, Bradley L.; Enquist, Brian J.; Feng, Xiao; Gallagher, Rachael, V; Maitner, Brian; Meiri, Shai; Mulligan, Mark; Ofer, Gali; Roll, Uri; Hanson, Jeffrey O.; Jetz, Walter; Di Marco, Moreno; McGowan, Jennifer; Rinnan, D. Scott; Sachs, Jeffrey D.; Lesiv, Myroslava; Adams, Vanessa; Andrew, Samuel C.; Burger, Joseph R.; Hannah, Lee; Marquet, Pablo A.; McCarthy, James K.; Morueta-Holme, Naia; Newman, Erica A.; Park, Daniel S.; Roehrdanz, Patrick R.; Svenning, Jens-Christian; Violle, Cyrille; Wieringa, Jan J.; Wynne, Graham; Fritz, Steffen; Strassburg, Bernardo B. N.; Obersteiner, Michael; Kapos, Valerie; Burgess, Neil; Schmidt-Traub, Guido; Visconti, Piero
    To meet the ambitious objectives of biodiversity and climate conventions, the international community requires clarity on how these objectives can be operationalized spatially and how multiple targets can be pursued concurrently. To support goal setting and the implementation of international strategies and action plans, spatial guidance is needed to identify which land areas have the potential to generate the greatest synergies between conserving biodiversity and nature's contributions to people. Here we present results from a joint optimization that minimizes the number of threatened species, maximizes carbon retention and water quality regulation, and ranks terrestrial conservation priorities globally. We found that selecting the top-ranked 30% and 50% of terrestrial land area would conserve respectively 60.7% and 85.3% of the estimated total carbon stock and 66% and 89.8% of all clean water, in addition to meeting conservation targets for 57.9% and 79% of all species considered. Our data and prioritization further suggest that adequately conserving all species considered (vertebrates and plants) would require giving conservation attention to similar to 70% of the terrestrial land surface. If priority was given to biodiversity only, managing 30% of optimally located land area for conservation may be sufficient to meet conservation targets for 81.3% of the terrestrial plant and vertebrate species considered. Our results provide a global assessment of where land could be optimally managed for conservation. We discuss how such a spatial prioritization framework can support the implementation of the biodiversity and climate conventions.
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    Reproductive correlates of social network variation in plurally breeding degus (Octodon degus)
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2013) Wey, Tina W.; Burger, Joseph R.; Ebensperger, Luis A.; Hayes, Loren D.
    Studying the causes and reproductive consequences of social variation can provide insight into the evolutionary basis of sociality. Individuals are expected to behave adaptively to maximize reproductive success, but reproductive outcomes can also depend on group structure. Degus (Octodon degus) are plurally breeding rodents, in which females allonurse indiscriminately. However, communal rearing does not appear to enhance female reproductive success, and larger group sizes are correlated with decreasing per capita pup production. To further investigate mechanisms underlying these patterns, we asked how differences in sex, season and average group reproductive success are related to degu association networks. We hypothesized that if reproductive differences mirror social relationships, then females (core group members) should show stronger and more stable associations than males, and female association strength should be strongest during lactation. We also hypothesized that, at the group level, social cohesion would increase reproductive output, while social conflict would decrease it. Females did have higher association strength and more preferred partners than males, but only during lactation, when overall female associations increased. Females also had more stable preferred social partnerships between seasons. A measure of social cohesion (average association strength) was not related to per capita pup production of female group members, but potential social conflict (heterogeneity of association strengths) was negatively related to per capita pup production of female group members. Our results highlight temporal and multilevel patterns of social structure that may reflect reproductive costs and benefits to females. (C) 2013 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
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    Sociality, exotic ectoparasites, and fitness in the plural breeding rodent Octodon degus
    (2012) Burger, Joseph R.; Chesh, Adrian S.; Munoz, Pamela; Fredes, Fernando; Ebensperger, Luis A.; Hayes, Loren D.
    Social animals are susceptible to high infection levels by contact-transmitted parasites due to increased conspecific interaction. Exotic parasites are known to have adverse consequences on native hosts. We examined the relationship between social group size and exotic ectoparasite loads, and adult infection levels with per capita fitness and offspring survival in the plural breeding rodent Octodon degus in central Chile. Degus at our site were almost entirely infected by two exotic ectoparasites: the fleas Leptopsylla segnis and Xenopsylla cheopis. Neither group size nor number of females per group predicted the abundance of either exotic flea species. The per capita number of pups (per capita fitness) that emerged from burrow systems used by known social groups was negatively correlated with abundance of L. segnis but not X. cheopis. On adults, X. cheopis abundance was three times greater than L. segnis but was not significantly correlated with per capita fitness. In females, L. segnis abundance was negatively correlated with peak body mass during pregnancy. Adult ectoparasite load was not correlated with offspring survival. Based on these results, we hypothesize that high infection levels of L. segnis result in decreased reproductive fitness of adult female degus but are not a cost of sociality because parasite loads are not predicted by social group size. Further work is needed to experimentally test this hypothesis and to determine if L. segnis serves as a vector for a deleterious pathogen. Lastly, the lack of native ectoparasites may explain why a previous study at our site determined that behavioral adaptations needed to cope with high ectoparasite burdens (e. g., grooming) are not extensive in degus; they simply have not had the coevolutionary time needed for selection of these behaviors.
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    The influence of trap type on evaluating population structure of the semifossorial and social rodent Octodon degus
    (2009) Burger, Joseph R.; Chesh, Adrian S.; Castro, Rodrigo A.; Ortiz Tolhuysen, Liliana; Torre, Ignasi; Ebensperger, Luis A.; Hayes, Loren D.
    Trap type may influence captures of individuals in different age-sex categories in small mammal studies, resulting in biased population and demographic information. We deployed 4 live trap types at burrow systems of the rodent, Octodon degus Molina, 1782, in central Chile to determine trap efficacy in capturing individuals of 6 demographic categories. We captured 2672 individuals in 17 709 trap days (15.1% trapping success). Tomahawks were the most efficient trap capturing half of individuals during both years, followed by mesh Sherman traps, large Sherman traps, and medium Sherman traps in 2005. All trap types equally sampled sexes. Large and medium Sherman traps provided similar demographic structure, where half of the individuals captured were pups; Tomahawk traps sampled more adults than pups. Relative captures of pups were similar across different trap types, suggesting that pups are equally sampled by each of the deployed trap types. Relative captures of adults were lower in Sherman traps, suggesting that this age class avoided solid-walled traps. For Octodon degus, the sole use of Tomahawk traps may produce sufficient, unbiased demographic data. Only 4 trap mortalities occurred (0.15%). Researchers may minimize trap mortality without compromising sufficient demographic sampling by trapping during peak animal activity.
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    The influence of trap type on evaluating population structure of the semifossorial and social rodent Octodon degus
    (2009) Burger, Joseph R.; Castro Bustamante, Rodrigo Alfredo; Ortiz Tolhuysen, Liliana Patricia; Ebensperger Pesce, Luis Alberto