Biology subjects

Arcese, P.

Publications and source records attributed to Arcese, P..

6 recordsLinked to original sources

bioRxiv2018

Prioritize diversity or declining species? Trade-offs and synergies in spatial planning for the conservation of migratory birds

Stemming biodiversity loss requires strategic conservation guided by well-articulated and achievable targets, whether they be proactive (e.g., protect diverse places) or reactive (e.g., protect threatened species). Both types of targets can be effective, but there are trade-offs, especially for broadly-distributed ecosystems or taxa, such as migratory species, a group for which conservation has been challenged by limited knowledge of distributions throughout the annual cycle. We combined novel spatiotemporal distribution models with population trend data to first examine focal areas for the conservation of Neotropical migratory birds (n=112 species) during the non-breeding period in the Western Hemisphere based on a proactive approach (highest diversity) versus a reactive approach (strongest declines) to conservation. For the focal areas, we then assessed the extent of recent anthropogenic impact, protected area status and projected future changes in land cover using three shared socioeconomic pathways (Sustainability=SSP1, Business-as-usual=SSP2, Regional nationalism=SSP3). Spatial priorities were strikingly different when targeting areas of high species diversity, emphasizing southern Mexico and northern Central America, versus areas with more severe declines across species, emphasizing the Andean cordilleras of South America. Only a fraction of the non-breeding region (1.4%) met targets for diversity and decline, mostly in southern Central America. Current levels of protection were similar for the two targets. Areas prioritized to conserve high species diversity have experienced less recent anthropogenic impact than areas prioritized for decline but are predicted to experience more rapid land conversion to less suitable open, agricultural landscapes in the next three decades under both an SSP1 and SSP2 scenario. Only the SSP3 scenario projected similar conversion rates for the two targets. Our findings indicate how even within taxa, efficient conservation efforts will depend on the careful consideration of desired targets combined with reliable predictions about the locations and types of land cover change under alternative socioeconomic futures.

ecology↗

bioRxiv2018

Biodiversity on Indigenous lands equals that in protected areas

Declines in global biodiversity due to land conversion and habitat loss are driving a \"Sixth Mass Extinction\" and many countries currently fall short of meeting even nominal land protection targets to mitigate this crisis. Here, we quantify the potential contribution of Indigenous lands to biodiversity conservation using case studies of Australia, Brazil and Canada. Indigenous lands in each country are slightly more species rich than existing protected areas and, in Brazil and Canada, support more threatened species than existing protected areas or random sites. These results indicate that Indigenous lands and existing protected areas are similar in biodiversity. Enhanced partnerships between Indigenous communities and federal or state governments could help ameliorate current shortfalls in global biodiversity protection by facilitating protection for native species, helping to stem global biodiversity loss.

ecology↗

bioRxiv2018

Sex-specific additive genetic variances and correlations for fitness in a song sparrow (Melospiza melodia) population subject to natural immigration and inbreeding

Quantifying sex-specific additive genetic variance (VA) in fitness, and the cross-sex genetic correlation (rA), is pre-requisite to predicting evolutionary dynamics and the magnitude of sexual conflict. Quantifying VA and rA in underlying fitness components, and multiple genetic consequences of immigration and resulting gene flow, is required to identify mechanisms that maintain VA in fitness. However, these key parameters have rarely been estimated in wild populations experiencing natural environmental variation and immigration. We used comprehensive pedigree and life-history data from song sparrows (Melospiza melodia) to estimate VA and rA in sex-specific fitness and underlying fitness components, and to estimate additive genetic effects of immigrants as well as inbreeding depression. We found substantial VA in female and male fitness, with a moderate positive cross-sex rA. There was also substantial VA in adult reproductive success in males but not females, and moderate VA in juvenile survival but not adult survival. Immigrants introduced alleles for which additive genetic effects on local fitness were negative, potentially reducing population mean fitness through migration load, yet alleviating expression of inbreeding depression. Substantial VA for fitness can consequently be maintained in the wild, and be concordant between the sexes despite marked sex-specific VA in reproductive success.

evolutionary biology↗

bioRxiv2018

Optimizing conservation of migratory species over their full annual cycle in the Western Hemisphere

Limited knowledge of the distribution, abundance, and habitat associations of migratory species introduces uncertainty about the most effective conservation actions. We used Neotropical migratory birds as a model group to evaluate contrasting approaches to land prioritization to support [≥]30% of the global abundances of 117 species throughout the annual cycle in the Western hemisphere. Conservation targets were achieved in 43% less land area in plans based on annual vs. weekly optimizations. Plans agnostic to population structure required comparatively less land area to meet targets, but at the expense of representation. Less land area was also needed to meet conservation targets when human-dominated lands were included rather than excluded from solutions. Our results point to key trade-offs between efforts minimizing the opportunity costs of conservation vs. those ensuring spatiotemporal representation of populations, and demonstrate a novel approach to the conservation of migratory species based on leading-edge abundance models and linear programming to identify portfolios of priority landscapes and inform conservation planners.

ecology↗

bioRxiv2017

Demographic consequences of invasion by a native, controphic competitor to an insular bird population

Species invasions and range shifts can lead to novel competitive interactions between historically resident and colonizing species, but the demographic consequences of such interactions remain controversial. We present results from field experiments and 45 yrs of demographic monitoring to test the hypothesis that the colonization of Mandarte Is., BC, Canada, by fox sparrows (Passerella iliaca) caused the long-term decline of the song sparrow (Melospiza melodia) population resident there. Several lines of evidence indicate that competition with fox sparrows for winter food reduced over-winter survival in juvenile song sparrows, enforcing population decline despite an increase in annual reproductive rate in song sparrows over the same period. In contrast, we found no evidence of interspecific competition for resources during the breeding season. Our results indicate that in the absence of a sufficient ecological or evolutionary shift in niche dimension, range expansions by dominant competitors have the potential to cause the extirpation of historically resident species when competitive interactions between them are strong and resources not equitably partitioned.

ecology↗

bioRxiv2017

The consequences of polyandry for sibship structures, distributions of relationships and relatedness, and potential for inbreeding in a wild population

The evolutionary benefits of simultaneous polyandry (female multiple mating within a single reproductive event) remain elusive. One potential benefit could arise if polyandry alters sibship structures and consequent relationships and relatedness among females descendants, and thereby intrinsically reduces future inbreeding risk (the indirect inbreeding avoidance hypothesis). However such effects have not been quantified in naturally complex reproductive systems that also encompass iteroparity, overlapping generations, sequential polyandry, and polygyny. We used long-term social and genetic pedigree data from song sparrows (Melospiza melodia) to quantify cross-generational consequences of simultaneous polyandry for offspring sibship structures and distributions of relationships and relatedness among possible mates. Simultaneous polyandry decreased full-sibships and increased half-sibships on average, but such effects varied among females and were smaller than would occur in the absence of sequential polyandry or polygyny. Further, while simultaneous polyandry decreased the overall frequencies of possible matings among adult full-sibs, it increased the frequencies of possible matings among adult half-sibs and more distant relatives. These results imply that the intrinsic consequences of simultaneous polyandry for inbreeding risk could cause weak indirect selection on polyandry, but the magnitude and direction of such effects will depend on complex interactions with other mating system components and the form of inbreeding depression.

evolutionary biology↗