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The loss of large frugivores leads to seed dispersal loss and regeneration failure of numerous large-seeded trees near mother trees. Although Janzen–Connell effects are considered as the primary underlying cause, other factors remain understudied. Here, we used a field experiment to test the impact of flesh persistence on the recruitment of two large-seeded Sapotaceae species that lost their dispersers. In the rainforest of Mare Longue (Réunion), we sowed 3840 seeds in a four-factor design: seed treatment (seed cleaning; flesh persistence), canopy closure (understory; gap), year of sowing (01/2018; 11/2019) and species (Labourdonnaisia calophylloides, Mimusops balata). We also used camera traps to evaluate the impact of extant vertebrates. Seed treatment was by far the most influential factor: flesh persistence led to seedling recruitment divided by 3,2 on average, mainly due to failure of germination or seedling emergence. There were also significant variations in recruitment between species, years and canopy closure levels, notably due to the behaviour of the invasive fauna, especially giant snails that could unexpectedly restore recruitment by feeding on fruit flesh. Together, our results demonstrate strongly depleted recruitment due to flesh persistence and the importance of field experiments to understand the processes at work in complex ecosystems with novel plant–animal interactions.

Insular animals are thought to be under weak predation pressure and increased intraspecific competition compared with those on the mainland. Thus, insular populations are predicted to evolve ‘slow’ life histories characterized by fewer and smaller clutches of larger eggs, a pattern called the ‘island syndrome’. To test this pattern, we collected data on egg volume, clutch size and laying frequency of 31 Aegean Island populations of the closely related geckos of the Mediodactylus kotschyi species complex. We tested how predation pressure, resource abundance, island area and isolation influenced reproductive traits. Isolation and predation were the main drivers of variation in life-history traits. Higher predator richness seemed to promote faster life histories, perhaps owing to predation on adults, whereas the presence of boas promoted slower life histories, perhaps owing to release from predation by rats on the eggs of geckos. Insular geckos followed only some of the predictions of the ‘island syndrome’. Predation pressure seemed to be more complex than expected and drove life histories of species in two opposing directions. Our results highlight the importance of considering the identity of specific predators in ecological studies., The study was funded by an Israel Science Foundation (ISF) grant #1005/12.

International audience; Redonda is a small volcanic Caribbean island that is home to at least 4 endemic lizard species, including the Critically Endangered ground lizard (Pholidoscelis atratus). Black rats (Rattus rattus) and domestic goats (Capra hircus) were introduced to the island at some time after its discovery by Europeans in the late 1500s. They had a devastating effect on the island, resulting in the loss of nearly all trees and most of the ground vegetation. Point count surveys of P. atratus in 2012 indicated low densities, and the invasive rats were observed hunting and preying on the lizards. Both populations of rats and goats were successfully removed in 2017 as part of an ecological restoration program, and native vegetation and invertebrate populations have increased rapidly since. Population surveys in 2017, 2018, and 2019 show the lizard population has increased by more than sixfold. In 2017, as rats and goats were being removed, we evaluated the morphology and escape behavior of this species and repeated these measurements 1 year later. We observed that P. atratus had become bolder, with a reduced flight distance. We also detected changes in limb morphology related to locomotion and suggest possible explanations that will need to be further investigated in the future. These results show how the removal of invasive species can rapidly affect lizard population recovery and behavior, potentially restoring island ecosystems to their pre-human interference dynamics.

Feeding habits of snakes on Kinkasan Island, where potential food resources for snakes is limited, was investigated based on field surveys of six years. In total 280 snakes, which consisted of five species (Elaphe quadrivirgata, E. climacophora, Euprepiophis conspicillatus, Rhabdophis tigrinus, and Gloydius blomhoffii), were collected. A total of 168 prey items were recovered from the stomach contents of these snakes. The diet of R. tigrinus and G. blomhoffii exclusively consisted of a frog, Rana tagoi, which is the only amphibian species inhabiting Kinkasan Island. Diet of El. quadrivirgata was also predominantly comprised of Ra. tagoi ( 97.7%). O nly e ndothermic animals were found in the stomach contents of El. climacophora and Eu. conspicillatus. Direct observations of feeding behavior and a broad range of body temperature of El. quadrivirgata indicated that during the breeding season of Ra. tagoi, this snake forages for frogs hiding in crevices of rocks immersed in cold running water of mountain streams. Our study demonstrated that, given the limited prey fauna on Kinkasan Island, two dietary generalists, El. quadrivirgata and G. blomhoffii, and one amphibian specialist, R. tigrinus, largely rely on the single frog species as major diet. High exploitation of Ra. tagoi by El. quadrivirgata would be attained by its unique foraging tactics that are characterized by a shuttling movement between hot basking rocks and cold streams for foraging.

Human activity has facilitated the introduction of a number of alien mammal species to the Galápagos Archipelago. Understanding the phylogeographic history and population genetics of invasive species on the Archipelago is an important step in predicting future spread and designing effective management strategies. In this study, we describe the invasion pathway of Rattus rattus across the Galápagos using microsatellite data, coupled with historical knowledge. Microsatellite genotypes were generated for 581 R. rattus sampled from 15 islands in the archipelago. The genetic data suggest that there are at least three genetic lineages of R. rattus present on the Galápagos Islands. The spatial distributions of these lineages correspond to the main centers of human settlement in the archipelago. There was limited admixture among these three lineages, and these finding coupled with low rates of gene flow among island populations suggests that interisland movement of R. rattus is rare. The low migration among islands recorded for the species will have a positive impact on future eradication efforts.

Successful island colonizations are key events to understand range dynamic processes, but studying a young population right after it reaches establishment is a rare opportunity in natural systems. The genetic structure of a recently established population may offer unique insights into its colonization history and demographic processes that are important for a successful colonization. Here, we studied the population genetics of a recently established island population of Eurasian blackbirds (Aves:Turdus merula) located on the island of Heligoland in the German North Sea. Using microsatellites, we genotyped the majority of the island population, including the nestlings, over a 4-year period between 2004 and 2007. We also genotyped high numbers of migrants on stopover and mainland individuals, as they are potential founders of the island population. We identified two genetic clusters that comply with the migrating and mainland birds. While most of the island birds belong to the mainland cluster, some breeding individuals and a low fraction of the offspring belong to the genetic cluster found in migrating individuals with almost no admixture between the two, pointing to assortative mating acting on the island population. We did not find any evidence for founder events and detected deviations from the Hardy–Weinberg equilibrium that disappeared in cohorts of older age that coincide with a lower number of siblings in older cohorts. The observed genetic patterns unravel a complex colonization history to which migratory and mainland birds have contributed and which is characterized by assortative mating. Further research will be directed towards habitat selection and phenotypic differences as potential drivers of assortative mating in this island population.

Invasive species represent a major challenge through their consequences on biodiversity, human health and economy. Their effects are especially important on fragile and unique insular biotas such as the Galápagos Islands. Ants in particular are keystone species implicated in ecosystem functioning and biodiversity and they can be dramatic invaders. In the Galápagos Islands, the tropical fire ant Solenopsis geminata is considered a high-impact invasive species, though it remains surprisingly poorly studied. The objectives of this work are to document the invasion of S. geminata in the Galápagos Islands by 1) updating its distribution; 2) determining its reproduction and dispersal strategies and reconstruct its invasion history throughout the archipelago and 3) evaluating its impact on the native fauna (focusing on ants and arthropods communities and endemic land tortoises). First, we added 66 new records of S. geminata in the Galápagos since 2008. It has now been recorded on seven islands and 11 islets in a wide range of habitats, including nesting sites of 24 endemic and/or endangered vertebrate species, for which it constitutes a potential threat. Secondly, by combining Bayesian clustering methods, coalescent-based scenario testing using microsatellite data and historical records, we determined that genetic diversity of populations of S. geminata collected in Galápagos Islands is significantly lower than the genetic diversity of populations from native areas (Costa Rica). The Galápagos populations form three clusters corresponding to an island or groups of islands. They appear to be the result of a single introduction in the first half of the 19th century, probably from mainland Ecuador, which acted as a bridgehead population to two subsequent introductions within the archipelago, corresponding human colonization fluxes in the archipelago. We sampled ants in all main habitats of Santa Cruz Island. Introduced ant species were largely prevalent, and S. geminata was the dominant species and was associated with low evenness of ant communties and lower abundance of native ants. We found that Galápagos’ ant communities are determined by the vegetation type and altitude, but found only little evidence for competitively structured assemblages, except in disturbed areas. The arthropod diversity was investigated in two agricultural sites of Santa Cruz Island by combining three complementary sampling techniques. More than half of the species were either endemic or native, but introduced species constituted the majority of the catches. Solenopsis geminata was by far the most abundant and common species. Finally, we investigated the mortality of Cheloidis land tortoise’s eggs and hatchlings in an area infested by S. geminata on Santa Cruz Island with regard to the abundance of fire ants and the duration of incubation. Egg survival was negatively associated with longer incubation times but we found no direct relation between ant density and tortoise mortality despite a high abundances of fire ants in the vicinity of the majority of the tortoise burrows. Our work allows addressing ecological and genetical aspects of the invasion of S. geminata in the Galápagos Islands. We analyzed our results in the light of an ecoevolutionary framework presenting different invasion scenarios and discussed S. geminata as an invasive ant. This provided us with information useful for the study and management of this invasive species in the Galápagos Islands. / Les espèces invasives constituent un défi majeur à cause de leur impact sur la biodiversité, la santé humaine et l’économie. Leurs effets sont particulièrement importants sur les environnements insulaires fragiles et uniques comme les île Galápagos. Les fourmis en particulièr sont des espèces clé de voûte du fonctionnement des écosystèmes et de la biodiversité. Elles peuvent de ce fait devenir des envahisseurs spectaculaires. Dans les îles Galápagos, la fourmi de feu tropicale Solenopsis geminata fait partie des espèces invasives à haut impact et cependant elle a été étonnamment peu étudiée. Les objectifs de ce travail consistent à documenter l’invasion de S. geminata dans l’archipel des Galápagos: 1) en mettant à jour sa distribution; 2) en déterminant ses stratégies de reproduction et de dispersion et en reconstruisant l’histoire de son invasion dans l’archipel et 3) en évaluant son impact sur la faune native (particulièrement sur les communautés de fourmis et d’arthropodes et sur les tortues terrestres endémiques). Tout d’abord, nous avons ajouté 66 nouveaux relevés de S.geminata aux Galápagos depuis 2008. À ce jour, la fourmi a été observée sur 7 îles et 11 îlots, et ce dans une grande variété d’habitats. On la trouve également sur les sites de ponte de 24 espèces de vertébrés endémiques ou en voie de disparition, qu’elle menace ainsi potentiellement. Ensuite, en combinant des méthodes bayésiennes de regroupement et des comparaisons de scénarios en se basant sur des séquences microsatellites et des données historiques, nous avons montré que la diversité génétique des populations de S. geminata des Galápagos est significativement inférieure à celle des populations des zones d’indigénat (Costa Rica). Les populations des Galápagos - réparties en 3 groupes correspondant à une île ou un groupe d’îles – sont le résultat d’une introduction unique ayant eu lieu dans la première moitié du 19ème siècle. Elles proviennent vraisemblablement de l’Equateur continental et constituent une population “tête de pont” pour deux introductions ultérieures au sein de l’archipel. Ces mouvements correspondent aux flux de populations humaines. Nous avons échantillonné les fourmis dans tous les principaux habitats de l’île de Santa Cruz. Les fourmis introduites sont largement prévalentes. Solenopsis geminata constitue l’espèce dominante et se trouve associée avec une faible équitabilité des communautés de fourmis ainsi qu’avec une diminution de l’abondance des fourmis natives. Nos résultats indiquent que les communautés de fourmis des Galápagos sont structurées par le type de végétation et l’altitude, alors que les assemblages de fourmis ne sont pas structurés compétitivement, à l’exception des zones perturbées. Nous avons investigué la diversité arthropodienne de deux sites agricoles de l’île de Santa Cruz en combinant trois méthodes d’échantillonnage complémentaires. Plus de la moitié des espèces collectées étaient soit endémiques, soit natives. Les espèces introduites ont toutefois constitué la majorité des individus collectés. Solenopsis geminata était de loin la plus abondante et la plus commune des espèces récoltées. Enfin, dans une zones infestées par S. geminata sur l’île de Santa Cruz, nous avons mis en relation la mortalité des oeufs et juvéniles de tortues terrestres Chelonoidis avec l’abondance des fourmis de feu et la durée d’incubation des oeufs. Le taux de survie des oeufs est négativement corrélé à leur durée d’incubation. Cependant, malgré de très hautes abondances de fourmis de feu à proximité des nids de tortues, nous n’avons pas trouvé de relation directe avec leur mortalité. Pour conclure, ce travail aborde les aspects génétiques et écologiques de l’invasion de la fourmi de feu tropicale dans les îles Galápagos. Nos résultats sont analysés au sein d’un cadre éco-évolutif présentant différents scénarios d’invasion. Nous discutons également de S. geminata en tant qu’espèce invasive. Nous espérons apporter des informations utiles dans le cadre de l’étude et du contrôle de cette espèce invasive aux Galápagos., Doctorat en Sciences, info:eu-repo/semantics/published

Poco despues de su retorno del archipielago Malayo, Alfred Russel Wallace publico uno de sus trabajos mas relevante. En este usaba mariposas de la familia Papilionidae como modelos para poner a prueba hipotesis evolutivas, e incluia una revision de los Papilionidae de la region y la descripcion de 20 nuevas especies. Wallace argumento que los Papilionidae representaban las mariposas mas avanzadas, opinion contraria a la sostenida por sus colegas, incluyendo Bates y Trimen, quienes pensaban que los Nymphalidae eran mas avanzados debido a su posesion de patas vestigiales. En una seccion muy importante, Wallace formulo lo que quizas constituye la mas clara defnicion darwiniana de las diferencias entre especies, subespecies geografcas y “variedades” locales. Tambien discutio la relacion de estas categorias taxonomicas con lo que hoy se denomina “aislamiento reproductivo”. Mientras aceptaba el aislamiento reproductivo como una de las causas del origen de especies, lo rechazo como una defnicion de especie. Por el contrario, las especies se reconocian como formas que se sobreponen espacialmente y carecen de intermedios. Sin embargo, este argumento basado en distincion morfologica falla ante la presencia de polimorfsmos discretos. No obstante, basandose en continuidad reproductiva, Wallace claramente enfatizo la conespecifcidad en Papilio polytes de machos no mimeticos, hembras no mimeticas y hembras mimeticas batesianas; el mismo escenario planteo en P. memnon. Por ultimo, Wallace detallo como la seleccion natural explica varias formas de evolucion paralela, incluyendo el mimetismo.

Loulu palms (Pritchardia spp.) once dominated many lowland ecosystems in Hawai'i, and non-native rats (Rattus spp.), ungulates (e.g., pigs Sus scrofa), and humans have been proposed as major causes of their decline. Using field and captive feeding trials, we experimentally determined the vulnerability of seeds and seedlings of two species of Pritchardia. Our findings are consistent with the hypothesis generated from palaeoecological studies indicating that introduced rats may have assisted in the demise of native insular palm forests. Future conservation efforts involving Pritchardia should prioritize the reduction of rat predation on the plant recruitment stages preceding seedling establishment., Mammalian herbivores can limit plant recruitment and affect forest composition. Loulu palms (Pritchardia spp.) once dominated many lowland ecosystems in Hawai‘i, and non-native rats (Rattus spp.), ungulates (e.g. pigs Sus scrofa, goats Capra hircus) and humans have been proposed as major causes of their decline. In lowland wet forest, we experimentally determined the vulnerability of seeds and seedlings of two species of Pritchardia, P. maideniana and P. hillebrandii, by measuring their removal by introduced vertebrates; we also used motion-sensing cameras to identify the animals responsible for Pritchardia removal. We assessed potential seed dispersal of P. maideniana by spool-and-line tracking, and conducted captive-feeding trials with R. rattus and seeds and seedlings of both Pritchardia species. Seed removal from the forest floor occurred rapidly for both species: >50 % of Pritchardia seeds were removed from the vertebrate-accessible stations within 6 days and >80 % were removed within 22 days. Although rats and pigs were both common to the study area, motion-sensing cameras detected only rats (probably R. rattus) removing Pritchardia seeds from the forest floor. Captive-feeding trials and spool-and-line tracking revealed that vertebrate seed dispersal is rare; rats moved seeds up to 8 m upon collection and subsequently destroyed them (100 % mortality in 24–48 h in captivity). Surprisingly, seedlings did not suffer vertebrate damage in field trials, and although rats damaged seedlings in captivity, they rarely consumed them. Our findings are consistent with the hypothesis generated from palaeoecological studies, indicating that introduced rats may have assisted in the demise of native insular palm forests. These findings also imply that the seed stage of species in this Pacific genus is particularly vulnerable to rats; therefore, future conservation efforts involving Pritchardia should prioritize the reduction of rat predation on the plant recruitment stages preceding seedling establishment.

Species traits are thought to predict feeding specialization and the vulnerability of a species to extinctions of interaction partners, but the context in which a species evolved and currently inhabits may also matter. Notably, the predictive power of traits may require that traits evolved to fit interaction partners. Furthermore, local abiotic and biotic conditions may be important. On islands, for instance, specialized and vulnerable species are predicted to be found mainly in mountains, whereas species in lowlands should be generalized and less vulnerable. We evaluated these predictions for hummingbirds and their nectar-food plants on Antillean islands. Our results suggest that the rates of hummingbird trait divergence were higher among ancestral mainland forms before the colonization of the Antilles. In correspondence with the limited trait evolution that occurred within the Antilles, local abiotic and biotic conditions—not species traits—correlate with hummingbird resource specialization and the vulnerability of hummingbirds to extinctions of their floral resources. Specifically, hummingbirds were more specialized and vulnerable in conditions with high topographical complexity, high rainfall, low temperatures and high floral resource richness, which characterize the Antillean Mountains. These findings show that resource specialization and species vulnerability to extinctions of interaction partners are highly context-dependent.