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The use of conservation translocations to mitigate human effects on biodiversity is increasing, but how these efforts are allocated remains unclear. Based on a comprehensive literature review and online author survey, we sought to determine the goals of translocation efforts, whether they focus on species and regions with high threat and likelihood of perceived success, and how success might be improved. We systematically searched the ISI Web of Knowledge and Academic Search Complete databases to determine the species and regions of conservation translocations and found 1863 articles on conservation translocations in the United States, Canada, Mexico, Central America, and Caribbean published from 1974 to 2013. We questioned 330 relevant authors to determine the motivation for translocations, how translocations were evaluated, and obstacles encountered. Conservation translocations in North America were geographically widespread (in 21 countries), increased in frequency over time for all animal classes (from 1 in 1974 to 84 in 2013), and included 279 different species. Reintroductions and reinforcements were more common in the United States than in Canada and Mexico, Central America, or the Caribbean, and their prevalence was correlated with the number of species at risk at national and state or provincial levels. Translocated species had a higher threat status at state and provincial levels than globally (International Union for Conservation of Nature Red List categorization), suggesting that translocations may have been motivated by regional priorities rather than global risk. Our survey of authors was consistent with these results; most translocations were requested, supported, or funded by government agencies and downlisting species at national or state or provincial levels was the main goal Nonetheless, downlisting was the least reported measure of success, whereas survival and reproduction of translocated individuals were the most reported. Reported barriers to success included biological factors such as animal mortality and nonbiological factors, such as financial constraints, which were less often considered in the selection of release sites. Our review thus highlights discrepancies between project goals and evaluation criteria and between risk factors considered and obstacles encountered, indicating room to further optimize translocation projects. El uso de las translocaciones para conservación y mitigar los efectos humanos sobre la biodiversidad está incrementando, pero aún no es claro cómo se asignan estos esfuerzos. Con base en una revisión integral de literatura y una encuesta de autor en línea buscamos determinar los objetivos de los esfuerzos de translocación, ya sea que se enfoquen en especies y regiones con una amenaza mayor y una probabilidad de éxito percibido y cómo el éxito puede mejorarse. Buscamos sistemáticamente las bases de datos completas de la Red de Conocimiento y Búsqueda Académica ISIpara determinar las especies y regiones de las translocaciones para conservación y encontramos 1,863 artículos sobre translocaciones para conservación en los Estados Unidos, Canadá, México, América Central y el Caribe, publicados entre 1974 y 2013 · Consultamos a 330 autores relevantes para determinar los motivos de las translocaciones, cómo fueron evaluadas y los obstáculos a los que se enfrentaron. Las translocaciones para conservación en América del Norte estaban dispersas geográficamente (en 21 países), incrementaron su frecuencia con el tiempo para todas las clases animales (de una en 1974 a 84 en 2013) e incluyeron a 279 especies diferentes. Las reintroducciones y los refuerzos fueron más comunes en los Estados Unidos que en Canadá, México, América Central o el Caribe, y su prevalencia estuvo correlacionada con el número de especies en riesgo a nivel nacional, estatal o provincial. Las especies reubicadas tenían un mayor estado de amenaza a nivel estatal y provincial que a nivel global (categorías de la Lista Roja de la Unión Internación para la Conservación de la Naturaleza), lo que sugiere que las reubicaciones podrían haber estado motivadas por prioridades regionales en lugar del riesgo global. Nuestra encuesta a los autores fue consistente con estos resultados ya que la mayoría de las reubicaciones fueron solicitadas, apoyadas o financiadas por agencias del gobierno y bajar la categoría de la especie a nivel nacional, estatal o provincial era el objetivo principal. Sin embargo, bajar la categoría fue la medida de éxito menos reportada. Los obstáculos para el éxito reportados incluyeron factores biológicos, como la mortalidad animal, y factores no biológicos, como las restricciones financieras, que fueron menos considerados en la selección de los sitios de liberación. Nuestra revisión resalta así las discrepancias entre los objetivos del proyecto y los criterios de evaluación y entre los factores de riesgo considerados y los obstáculos enfrentados, lo que indica que existe espacio para optimizar aún más los proyectos de reubicación.

Asexual species are thought to suffer more from coevolving parasites than related sexuals. Yet a variety of studies do not find the patterns predicted by theory. Here, to shine light on this conundrum, we investigate one such case of an asexual advantage in the presence of parasites. We follow the frequency dynamics of sexual and asexual Daphnia pulex in a natural pond that was initially dominated by sexuals. Coinciding with an epidemic of a microsporidian parasite infecting both sexuals and asexuals, the pond was rapidly taken over by the initially rare asexuals. With experiments comparing multiple sexual and asexual clones from across the local metapopulation, we confirm that asexuals are less susceptible and also suffer less from the parasite once infected. These results are consistent with the parasite-driven, ecological replacement of dominant sexuals by closely related, but more resistant asexuals, ultimately leading to the extinction of the formerly superior sexual competitor. Our study is one of the clearest examples from nature, backed up by experimental verification, showing a parasite-mediated reversal of competition dynamics. The experiments show that, across the metapopulation, asexuals have an advantage in the presence of parasites. In this metapopulation, asexuals are relatively rare, likely due to their recent invasion. While we cannot rule out other reasons for the observed patterns, the results are consistent with a temporary parasite-mediated advantage of asexuals due to the fact that they are rare, which is an underappreciated aspect of the Red Queen Hypothesis.

Large herbivores play key roles in terrestrial ecosystems. Continuous defaunation processes have produced cascade effects on plant community composition, vegetation structure, and even climate. Wood-pastures were created by traditional management practices that have maintained open structures and biodiversity for millennia. In Europe, despite the broad recognition of their biological importance, such landscapes are declining due to land-use changes. This calls for finding urgent solutions for wood-pasture conservation. To test whether introducing an ecological replacement of an extinct wild horse could have positive effects on woodpasture restoration, we designed a 3-year rewilding experiment. Horses created a more open wood-pasture structure by browsing on seedlings and saplings, affected tree composition via selective browsing and controlled the colonization of woody vegetation in grassland-dominated areas. Thus, rewilding could be a potential avenue for wood-pasture restoration and biodiversity conservation. However, such benefits may not materialize without a necessary paradigm and political shift.

Translocations, the human‐mediated movement and free‐release of living organisms, are increasingly used as conservation tools in imperiled terrestrial ecosystems. Marine ecosystems, too, are increasingly threatened, and marine restoration efforts are escalating. But the methods and motivations for marine restoration are varied, so the extent to which they involve conservation‐motivated translocations is unclear. Because translocations involve considerable risks, building on previous experience to establish and implement best practice guidelines for policy application is imperative. We conducted a global literature review to determine what marine conservation translocation experience exists. Our review indicates marine conservation translocations are widespread and increasingly common. Reinforcements and reintroductions predominate, but precedent for assisted colonizations and ecological replacements also exists. In 39 years, 487 translocation projects were conducted to conserve over 242 marine species or their ecosystems. Most projects involved coastal invertebrates (44%) or plants (30%). Few species were of conservation concern according to the IUCN Red List, likely reflecting the leading objective for most (60%) marine conservation translocations, which was ecosystem rather than species recovery. With currently no standard metrics for evaluating translocation success or ecosystem function, we recommend future projects follow the relevant IUCN guidelines and identify specific targets to measure the efficacy of translocations.

Loss of key plant-animal interactions (e.g., disturbance, seed dispersal, and herbivory) due to extinctions of large herbivores has diminished ecosystem functioning nearly worldwide. Mitigating for the ecological consequences of large herbivore losses through the use of ecological replacements to fill extinct species' niches and thereby replicate missing ecological functions has been proposed. It is unknown how different morphologically and ecologically a replacement can be from the extinct species and still provide similar functions. We studied niche equivalency between 2 phenotypes of Galápagos giant tortoises (domed and saddlebacked) that were translocated to Pinta Island in the Galápagos Archipelago as ecological replacements for the extinct saddlebacked giant tortoise (Chelonoidis abingdonii). Thirty-nine adult, nonreproductive tortoises were introduced to Pinta Island in May 2010, and we observed tortoise resource use in relation to phenotype during the first year following release. Domed tortoises settled in higher, moister elevations than saddlebacked tortoises, which favored lower elevation arid zones. The areas where the tortoises settled are consistent with the ecological conditions each phenotype occupies in its native range. Saddlebacked tortoises selected areas with high densities of the arboreal prickly pear cactus (Opuntia galapageia) and mostly foraged on the cactus, which likely relied on the extinct saddlebacked Pinta tortoise for seed dispersal. In contrast, domed tortoises did not select areas with cactus and therefore would not provide the same seed-dispersal functions for the cactus as the introduced or the original, now extinct, saddlebacked tortoises. Interchangeability of extant megaherbivores as replacements for extinct forms therefore should be scrutinized given the lack of equivalency we observed in closely related forms of giant tortoises. Our results also demonstrate the value of trial introductions of sterilized individuals to test niche equivalency among candidate analog species. La pérdida de interacciones clave planta-animal (p.ej., perturbación, dispersión de semillas y herbivoría) causados por la extinción de grandes herbívoros ha disminuido el funcionamiento de los ecosistemas casi a nivel mundial. Se ha propuesto la mitigación para las consecuencias ecológicas de la pérdida de grandes herbívoros a través del uso de reemplazos ecológicos para ocupar el nicho de especies extintas y por lo tanto replicar las funciones ecológicas ausentes. Se desconoce que tan diferente morfológica y ecológicamente puede ser un sustituto de la especie extinta y todavía poder proveer funciones similares. Estudiamos la equivalencia de nichos entre 2 fenotipos de tortugas gigantes de las Galápagos (abovedado y ensillado) que fueron llevadas como reemplazos ecológicos de la tortuga ensillada extinta (Chelonoidis abingdonii) a la Isla Pinta en el archipiélago de las Galápagos. Se introdujeron 39 tortugas adultas, no-reproductivas a la Isla Pinta en mayo de 2010 y observamos el uso de recursos por las Tortugas en relación con el fenotipo durante el primer año después de la liberación. Las tortugas abovedadas se asentaron en elevaciones más altas y más húmedas que las ensilladas, que favorecieron a las zonas áridas con bajas elevaciones. Las áreas en las que se asentaron las tortugas son consistentes con las condiciones ecológicas que cada fenotipo ocupa en su zona nativa. Las tortugas ensilladas seleccionaron áreas con altas densidades de cactos arbóreos (Opuntia galapageia) y generalmente forrajeaban en el cactus, que probablemente dependía de la especia extinta para la dispersión de sus semillas. En contraste, las tortugas abovedadas no seleccionaron áreas con cactos y por lo tanto no proveyeron las mismas funciones de dispersión de semillas del cactus como lo hicieron las tortugas introducidas o las originales, y ahora extintas, tortugas ensilladas. El intercambio de megaherbívoros existentes como sustitutos de formas extintas debería ser analizado debido a que observamos la falta de equivalencias en formas de tortugas gigantes cercanamente relacionadas. Nuestros resultados también demuestran el valor de introducciones piloto de individuos esterilizados para probar la equivalencia de nichos entre especies candidatas análogas.

South America was isolated from other continents during most of the Cenozoic, developing a singular mammalian fauna. In contrast to North America, Europe, Asia, and Africa, up to the late Neogene, the carnivore adaptive zone in South America was populated by crocodiles (Sebecidae), large snakes (Madtsoiidae), large birds (Phorusrhacidae), and metatherian mammals (Sparassodonta). Sparassodonta were varied and comprised a wide range of body masses (≈ 2–50 kg) and food habits. Their diversity decreased towards the late Miocene (Huayquerian Stage/Age) and the group became extinct in the “middle” Pliocene (≈ 3 Ma, Chapadmalalan Stage/Age). Several authors have suggested that the cause of this decline and extinction was the ingression of carnivorans to South America (about 6–7 Ma ago), because they competed with the Sparassodonta; although this hypothesis has been criticized in recent years. With the intention of testing the hypothesis of “competitive displacement,” we review the fossil record of South American Sparassodonta and Carnivora, collect data about diversity, estimate size and diet, and determine first and last appearances. The diversity of Sparassodonta is low relative to that of Carnivora throughout the Cenozoic with the early Miocene (Santacrucian Stage/Age) showing the greatest diversity with 11 species. In the late Miocene-middle Pliocene (Huayquerian Stage/Age), the fossil record shows overlap of groups, and the Sparassodonta’s richness curve begins to decline with the first record of Carnivora. Despite this overlap, carnivorans diversity ranged from four or fewer species in the late Miocene-Pliocene to a peak of around 20 species in the early Pleistocene (Ensenadan Stage/Age). Carnivora was initially represented by small-sized, omnivorous species, with large omnivores first appearing in the Chapadmalalan Stage/Age. Over this period, Sparassodonta was represented by large and small hypercarnivores and a single large omnivorous species. From this review of the fossil record, it is suggested that factors other than competitive displacement may have caused the extinction of the Sparassodonta.

The extinction of large herbivores, often keystone species, can dramatically modify plant communities and impose key biotic thresholds that may prevent an ecosystem returning to its previous state and threaten native biodiversity. A potentially innovative, yet controversial, landscape-based long-term restoration approach is to replace missing plant-herbivore interactions with non-native herbivores. Aldabran giant (Aldabrachelys gigantea) and Madagascan radiated (Astrochelys radiata) tortoises, taxonomically and functionally similar to the extinct Mauritian giant tortoises (Cylindraspis spp.), were introduced to Round Island, Mauritius, in 2007 to control the non-native plants that were threatening persistence of native species. We monitored the response of the plant community to tortoise grazing for 11 months in enclosures before the tortoises were released and, compared the cost of using tortoises as weeders with the cost of using manual labor. At the end of this period, plant biomass; vegetation height and cover; and adult, seedling, flower, and seed abundance were 3-136 times greater in adjacent control plots than in the tortoise enclosures. After their release, the free-roaming tortoises grazed on most non-native plants and significantly reduced vegetation cover, height, and seed production, reflecting findings from the enclosure study. The tortoises generally did not eat native species, although they consumed those native species that increased in abundance following the eradication of mammalian herbivores. Our results suggest that introduced non-native tortoises are a more cost-effective approach to control non-native vegetation than manual weeding. Numerous long-term outcomes (e.g., change in species composition and soil seed bank) are possible following tortoise releases. Monitoring and adaptive management are needed to ensure that the replacement herbivores promote the recovery of native plants. La extinción de grandes herbívoros, casi siempre especies clave, puede modificar dramáticamente a las comunidades de plantas e imponer umbrales bióticos claves que pueden impedir que un ecosistema regrese a su estado previo y que amenacen a la biodiversidad nativa. Una aproximación potencialmente innovadora, a largo plazo basada en el paisaje, pero controversial, consiste en reemplazar las interacciones herbívoro-planta faltantes con herbívoros no-nativos. Aldabrachelys gigantea y Astrochelys radiata son tortugas terrestres similares funcional y taxonómicamente a la especie extinta Cylindraspis spp., que fueron introducidas a Round Island, Mauricio, en 2007 para controlar a las plantas no-nativas que estaban amenazando la persistencia de especies nativas. Monitoreamos la respuesta de la comunidad vegetal al forrajeo de las tortugas durante 11 meses en encierros antes de que las tortugas fueran liberadas y comparamos el costo de usar a las tortugas como eliminadores de hierbas con el costo de usar labor manual. Al final de este periodo la biomasa vegetal, la altura y cobertura de la vegetación, y la abundancia de adultos, plántulas, flores y semillas eran entre 3-316 veces más grandes en terrenos control adyacentes que en los encierros con tortugas. Después de su liberación, las tortugas forrajearon a casi todas las plantas no-nativas y redujeron significativamente la cobertura de la vegetación, altura y producción de semilla, igualando los resultados del estudio de los encierros. Las tortugas en general no comieron especies nativas aunque sí consumieron aquellas especies nativas cuya abundancia incrementó después de la erradicación de mamíferos herbívoros. Nuestros resultados sugieren que las tortugas no-nativas introducidas son una aproximación más económica que el deshierbe manual para controlar a la vegetación no-nativa. Numerosos resultados a largo plazo (e.g., cambios en la composición de especies y el banco de semillas en el suelo) son posibles una vez liberadas las tortugas. Se requiere de monitoreo y manejo adaptativo para asegurar que los herbívoros de reemplazo promuevan la recuperación de las plantas nativas.

Conservation introductions, translocating species beyond their native range, are increasingly necessary. Because genetic diversity is essential for species to respond to novel environments, understanding whether establishing populations can maintain genetic diversity is crucial to the long‐term success of conservation introductions. Using a systematic review, we quantified conservation introductions globally and assessed whether genetic monitoring is occurring. We found that, despite extensive discussion, conservation introductions were rare. Of 167 examples, most were performed in North America, Australia, and China, with megadiverse developing nations underrepresented. Plants were disproportionately represented (74%), and climate change was the primary motivator of conservation introductions (40%). Survival and reproduction were the most frequently measured outcomes (71% and 37%, respectively). Ten works (5.9%) reported genetic monitoring, of which only two considered temporal genetic data and showed a worrying trend of rapid negative genetic change post‐establishment. With limited genetic evidence, it remains unclear whether conservation introductions can establish self‐sustaining populations. As these translocations may be the only option for some species, we recommend conservation practitioners trial conservation introductions with temporal genetic monitoring to assess the maintenance of founding genetic diversity and inbreeding. Only through scientifically derived applications of conservation introductions will we learn how to establish self‐sustaining populations in an uncertain future. Systematic review revealed temporal genetic monitoring is rarely performed for conservation introductions. Two works that did assess genetic data over time showed a worrying trend of negative genetic changes including loss of founding diversity and inbreeding. Temporal genetic monitoring should be prioritised for conservation introductions to ensure we understand how to create self‐sustaining populations into an uncertain future.

Background Ecosystem degradation, mainly through overexploitation and destruction of natural habitats, is a well-known threat to the viability and persistence of many species’ populations worldwide. The use of translocations as a viable conservation tool in conjunction with protected areas has been rapidly increasing over the last few decades. Protected areas such as strict nature reserves, national parks, and species management areas continue to be central tools for biodiversity conservation as they provide vital habitats set aside from various human pressures. Because action consistently runs ahead of policy, the need for a clearer evidence base on the outcomes of wildlife translocations undertaken at a global scale is becoming increasingly urgent for scientific and decision-making communities, in order to build clear strategy frameworks around conservation translocations. We therefore conducted a systematic mapping exercise to provide an overview of the existing evidence on the outcomes of wildlife translocations in protected areas. Methods We searched two bibliographic databases, four web-based search engines with search-by-key-words capacity, 5 specialist websites, and conducted a grey literature call through two project stakeholders. We screened articles by title, abstract, and full text using pre-defined inclusion criteria all the while assessing the consistency of the reviewers. All relevant translocations were coded from retained publications. Key variables of interest were extracted and coded for each translocation event. The quantity and characteristics of the available evidence and knowledge gaps/clusters are summarised. The distribution and frequency of translocations are presented in heat- and geographical maps. Review findings A total of 613 articles were considered eligible for coding bibliometric data. Metapopulation management and review articles were not coded for quantitative and qualitative variables. Linked data (duplicated translocations) were also excluded. Finally, 841 studies of different translocation events were fully coded from 498 articles. Most of these translocations were carried out in North America and Oceania. The most commonly undertaken intervention types were one-off supplementations and “supplemented reintroductions”. Mammals were by far the most transferred group among animals. Magnoliopsida was the most translocated plant group. Survival, space use, and demography metrics were the most studied outcomes on translocated species. Conclusions This systematic map provides an up-to-date global catalogue of the available evidence on wildlife translocations to, from, or within protected areas. It should enable protected area managers to better understand their role in the global network of protected areas, regarding translocation practice, both as suppliers or recipients of translocated species. It may help managers and practitioners make their own choices by comparing previous experiences, regarding both the species concerned and the precise translocation modalities (number of individuals, etc . ). Finally, it constitutes a decision-making tool for managers as well as for policy makers for future translocations.

Climate change poses a particular threat to species with fragmented distributions and little or no capacity to migrate. Assisted colonization, moving species into regions where they have not previously occurred, aims to establish populations where they are expected to survive as climatic envelopes shift. However, adaptation to the source environment may affect whether species successfully establish in new regions. Assisted colonization has spurred debate among conservation biologists and ecologists over whether the potential benefits to the threatened species outweigh the potential disruption to recipient communities. In our opinion, the debate has been distracted by controversial examples, rather than cases where assisted colonization may be a viable strategy. We present a strategic plan for the assisted migration of tuatara (Sphenodon punctatus), an endemic New Zealand reptile. The plan includes use of extant populations as reference points for comparisons with assisted-colonization populations with respect to demography, phenotypic plasticity, and phenology; optimization of genetic variation; research to fill knowledge gaps; consideration of host and recipient communities; and inclusion of stakeholders in the planning stage. When strategically planned and monitored, assisted colonization could meet conservation and research goals and ultimately result in the establishment of long-term sustainable populations capable of persisting during rapid changes in climate. El cambio climático representa una amenaza particular para especies con distribución fragmentada y con poca o ninguna capacidad para migrar. La colonización asistida, mover especies hacia regiones donde no ocurrían previamente, trata de establecer poblaciones donde se espera que sobrevivan a medida que el clima cambia. Sin embargo, la adaptación al ambiente original puede afectar si la especie se establece exitosamente en regiones nuevas. La colonización asistida ha estimulado el debate entre biólogos de la conservación y ecólogos sobre si los beneficios potenciales para las especies amenazadas tienen más peso que la disrupción potencial a las comunidades receptoras. En nuestra opinión, el debate ha sido distraído por ejemplos controversiales, en lugar de casos en los que la colonización asistida puede ser una estrategia viable. Presentamos un plan estratégico para la migración asistida de la tuatara (Sphenodon punctatus), un reptil endémico de Nueva Zelanda. El plan incluye el uso de poblaciones existentes como referencia para comparaciones con poblaciones de colonización asistida con respecto a la demografía, plasticidad fenotípica y fenología; optimización de variación genética; investigación para llenar vacíos de conocimiento; consideración de comunidades huésped y recipientes; e inclusión de diversos actores en la etapa de planificación. Cuando es planeada y monitoreada estratégicamente, la colonización asistida podría alcanzar metas de conservación e investigación y finalmente resultar en el establecimiento de poblaciones sustentables a largo plazo, capaces de persistir durante cambios rápidos en el clima.