Articles de revues : « Robinson Crusoe Island (Juan Fernández Islands) »

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GOMES, LUCAS R. P., MÁRCIA S. COURI et CLAUDIO J. B. DE CARVALHO. « Anthomyiidae, Fanniidae and Muscidae (Diptera) from the Juan Fernández Archipelago (Chile) : 60 years after Willi Hennig’s contributions ». Zootaxa 4402, n^o 2 (28 mars 2018) : 373. http://dx.doi.org/10.11646/zootaxa.4402.2.9.

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Sixty years ago, Willi Hennig last catalogued the Anthomyiidae, Fanniidae and Muscidae fauna of the Juan Fernández Archipelago. This archipelago, composed of three main volcanic islands (Robinson Crusoe, Alejandro Selkirk and Santa Clara), has many endemic species. We describe Fannia hennigi sp. n. from the Robinson Crusoe Island, and record 11 species in 10 genera of Anthomyiidae, Fanniidae and Muscidae. A key to the identification of all species found in Juan Fernández Archipelago and a table with all species found in the Archipelago are presented, including four new records from Robinson Crusoe Island: Delia platura (Meigen, 1826); Fannia hennigi sp. n.; Lispoides insularis Hennig, 1957 and Schoenomyzina emdeni Hennig, 1955.

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Stuessy, Tod F., Daniel J. Crawford et Josef Greimler. « Human Impacts on the Vegetation of the Juan Fernández (Robinson Crusoe) Archipelago ». Plants 12, n^o 23 (30 novembre 2023) : 4038. http://dx.doi.org/10.3390/plants12234038.

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The human footprint on marine and terrestrial ecosystems of the planet has been substantial, largely due to the increase in the human population with associated activities and resource utilization. Oceanic islands have been particularly susceptible to such pressures, resulting in high levels of loss of biodiversity and reductions in the numbers and sizes of wild populations. One archipelago that has suffered from human impact has been the Juan Fernández (Robinson Crusoe) Archipelago, a Chilean national park located 667 km west of Valparaíso at 33° S. latitude. The park consists of three principal islands: Robinson Crusoe Island (48 km2); Santa Clara Island (2.2 km2); and Alejandro Selkirk Island (50 km2). The latter island lies 181 kms further west into the Pacific Ocean. No indigenous peoples ever visited or lived on any of these islands; they were first discovered by the Spanish navigator, Juan Fernández, in 1574. From that point onward, a series of European visitors arrived, especially to Robinson Crusoe Island. They began to cut the forests, and such activity increased with the establishment of a permanent colony in 1750 that has persisted to the present day. Pressures on the native and endemic flora increased due to the introduction of animals, such as goats, rats, dogs, cats, pigs, and rabbits. Numerous invasive plants also arrived, some deliberately introduced and others arriving inadvertently. At present, more than three-quarters of the endemic and native vascular species of the flora are either threatened or endangered. The loss of vegetation has also resulted in a loss of genetic variability in some species as populations are reduced in size or go extinct. It is critical that the remaining genetic diversity be conserved, and genomic markers would provide guidelines for the conservation of the diversity of the endemic flora. To preserve the unique flora of these islands, further conservation measures are needed, especially in education and phytosanitary monitoring.

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TRIAPITSYN, SERGUEI V. « Review of Cremnomymar species (Hymenoptera : Mymaridae) in mainland South America, with a new generic synonymy ». Zootaxa 5463, n^o 1 (4 juin 2024) : 25–46. http://dx.doi.org/10.11646/zootaxa.5463.1.2.

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Parapolynema Fidalgo syn. n. (Hymenopterea: Mymaridae) is synonymized under the Neotropical genus Cremnomymar Ogloblin, and its two described species, both from Argentina, are transferred to Cremnomymar as C. sagittifer (Fidalgo) comb. n. and C. tucumanum (Fidalgo) comb. n. These species are redescribed based on type and non-type specimens from Argentina and two new species are described and diagnosed, C. fidalgoi Triapitsyn sp. n. from Argentina and Chile and C. nahuelbutae Triapitsyn sp. n. from Chile. A key to females of the four known species of Cremnomymar in mainland South America outside of Chile’s Juan Fernández Islands, from where seven other, endemic Cremnomymar species are known, is provided. The male of C. fernandezi Ogloblin is redescribed based on a non-type specimen from Robinson Crusoe Island, Juan Fernández Islands, and a possibly conspecific female from the same collecting event is described. The male paratype of C. kuscheli (Ogloblin) from Juan Fernández Islands is redescribed and illustrated.

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Veliz, David, Noemi Rojas-Hernández, Pablo Fibla, Boris Dewitte, Sebastián Cornejo-Guzmán et Carolina Parada. « High levels of connectivity over large distances in the diadematid sea urchin Centrostephanus sylviae ». PLOS ONE 16, n^o 11 (4 novembre 2021) : e0259595. http://dx.doi.org/10.1371/journal.pone.0259595.

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Most benthic marine invertebrates with sedentary benthic adult phases have planktonic larvae that permit connectivity between geographically isolated populations. Planktonic larval duration and oceanographic processes are vital to connecting populations of species inhabiting remote and distant islands. In the present study, we analyzed the population genetic structure of the sea urchin Centrostephanus sylviae, which inhabits only the Juan Fernández Archipelago and the Desventuradas islands, separated by more than 800 km. For 92 individuals collected from Robinson Crusoe and Selkirk Islands (Juan Fernández Archipelago) and San Ambrosio Island (Desventuradas Islands), 7,067 single nucleotide polymorphisms (SNPs) were obtained. The results did not show a spatial genetic structure for C. sylviae; relative high migration rates were revealed between the islands. An analysis of the water circulation pattern in the area described a predominant northward water flow with periods of inverted flow, suggesting that larvae could move in both directions. Overall, this evidence suggests that C. sylviae comprises a single large population composed of individuals separated by more than 800 km.

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Anderson, Gregory J., Daniel J. Crawford et Gabriel Bernardello. « The reproductive biology of island plants : the Juan Fernández and Canary Islands ». Vieraea Folia scientiarum biologicarum canariensium 41, Vieraea 41 (2013) : 115–27. http://dx.doi.org/10.31939/vieraea.2013.41.08.

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Knowledge of reproductive biology is fundamental to understanding successful colonization and subsequent evolution of island plants, to founding effective conservation programs for island biota, and for the insights provided from island studies to understanding the evolution of plants in general. We focus on the reproductive biology of plants of the Canary Islands via a comparison with that of plants from the Chilean Juan Fernández (Robinson Crusoe Islands). We focus on breeding systems (i.e., compatibility, ability to self pollinate) and pollination. The breeding system of the progenitors of island lineages are inferred to assess the usual interpretation: i.e., that successful colonists are self compatible, i.e., following ‘Baker’s Law’ vs. the alternative of a mixed breeding system (‘leaky’ self incompatibility). We briefly review the mechanisms promoting outcrossing in self compatible hermaphroditic species. We assess whether current floral forms reflect pollination features of the colonizing ancestors or whether they represent selection on islands in situ. . The limited range of pollinators available to new island colonists especially of younger archipelagoes, forces adaptation to new syndromes that are not always reflected in their floral morphology or nectar. Despite the broad interest in island plants, there are few comprehensive studies of either breeding systems or pollination biology. Thus, generalizations about island systems can lead to misunderstandings: as Baker exhorted nearly a half century ago, more studies of island plant reproductive biology are needed. Furthermore, conservation programs will not be effective without a knowledge of reproductive biology of island natives.

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Kim, Seon-Hee, JiYoung Yang, Myong-Suk Cho, Tod F. Stuessy, Daniel J. Crawford et Seung-Chul Kim. « Chloroplast Genome Provides Insights into Molecular Evolution and Species Relationship of Fleabanes (Erigeron : Tribe Astereae, Asteraceae) in the Juan Fernández Islands, Chile ». Plants 13, n^o 5 (23 février 2024) : 612. http://dx.doi.org/10.3390/plants13050612.

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Erigeron represents the third largest genus on the Juan Fernández Islands, with six endemic species, five of which occur exclusively on the younger Alejandro Selkirk Island with one species on both islands. While its continental sister species is unknown, Erigeron on the Juan Fernández Islands appears to be monophyletic and most likely evolved from South American progenitor species. We characterized the complete chloroplast genomes of five Erigeron species, including accessions of E. fernandezia and one each from Alejandro Selkirk and Robinson Crusoe Islands, with the purposes of elucidating molecular evolution and phylogenetic relationships. We found highly conserved chloroplast genomes in size, gene order and contents, and further identified several mutation hotspot regions. In addition, we found two positively selected chloroplast genes (ccsA and ndhF) among species in the islands. The complete plastome sequences confirmed the monophyly of Erigeron in the islands and corroborated previous phylogenetic relationships among species. New findings in the current study include (1) two major lineages, E. turricola–E. luteoviridis and E. fernandezia–E. ingae–E. rupicola, (2) the non-monophyly of E. fernandezia occurring on the two islands, and (3) the non-monophyly of the alpine species E. ingae complex.

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Bourne, W. R. P., M. L. de Brooke, G. S. Clark et T. Stone. « Wildlife conservation problems in the Juan Fernández Archipelago, Chile ». Oryx 26, n^o 1 (janvier 1992) : 43–51. http://dx.doi.org/10.1017/s003060530002322x.

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The rugged islands where the original Robinson Crusoe was marooned in the south-east Pacific are remarkable for the number and variety of endemic plants, some of which are pollinated by a beautiful endemic hummingbird. They are also the main breeding station of a fur seal, which once numbered millions but was later thought to be extinct, and several widespread seabirds. So far the only losses appear to be the endemic sandalwoods and widespread elephant seal, but the other wildlife is now threatened by deforestation, erosion and competition or predation from introduced species. There is a need for more support for local conservation measures, since the islands may soon start to undergo rapid development.

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Baeza, Carlos M., Tod F. Stuessy et Clodomiro Marticorena. « Notes on the Poaceae of the Robinson Crusoe (Juan Fernández) Islands, Chile ». Brittonia 54, n^o 3 (juillet 2002) : 154–63. http://dx.doi.org/10.1663/0007-196x(2002)054[0154:notpot]2.0.co;2.

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MARTÍNEZ, JAVIER, RODRIGO A. VÁSQUEZ, CRISTOBAL VENEGAS et SANTIAGO MERINO. « Molecular characterisation of haemoparasites in forest birds from Robinson Crusoe Island : Is the Austral Thrush a potential threat to endemic birds ? » Bird Conservation International 25, n^o 2 (19 août 2014) : 139–52. http://dx.doi.org/10.1017/s0959270914000227.

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SummaryThe Juan Fernández Firecrown Sephanoides fernandensis and Juan Fernández Tit-Tyrant Anairetes fernandezianus are two endemic forest birds inhabiting Robinson Crusoe Island and are classified as ‘Critically Endangered’ and ‘Near Threatened’ respectively by IUCN. Previous research concluded that the two main factors involved in the decline of these birds were habitat degradation and the introduction of predator / competitor species. However, the potential role of parasitic diseases has not yet been explored. In order to explore hypothetical host-switching phenomena, we genetically identified the haemoparasites present in four bird species, the two endemic species mentioned above and two recent colonisers, Green-Backed Firecrown Sephanoides sephaniodes and Austral Thrush Turdus falcklandii. We failed to find infections by different blood parasites (Plasmodium, Haemoproteus, Leucocytozoon, Trypanosoma, Babesia and Isospora) in the endangered Juan Fernández Firecrown. However, the Juan Fernández Tit-Tyrant was infected with some parasites shared with the Austral Thrush. The latter species may function as a key-host species on the island as it showed both the higher hemoparaasitic diversity and prevalence. The role of Green-Backed Firecrowns is apparently of lower importance because only one individual was found parasitized. The Austral Thrush could be responsible of the introduction of some parasites also isolated from the Juan Fernández Tit-Tyrant and represent a potential threat to the endemic firecrown due to its role as a reservoir. The spread of Austral Thrushes could increase the contact between species, increasing the probability of a switching event.

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SOTO, EDUARDO M., et MARTÍN J. RAMÍREZ. « Revision and phylogenetic analysis of the spider genus Philisca Simon (Araneae : Anyphaenidae, Amaurobioidinae) ». Zootaxa 3443, n^o 1 (29 août 2012) : 1. http://dx.doi.org/10.11646/zootaxa.3443.1.1.

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We review the spider genus Philisca Simon, an endemic of the southern forests in Chile and Argentina, and present aphylogenetic analysis including 15 species, of which five are newly described (P. atrata, P. robinson, P. viernes, P. pizarroiand P. robusta), together with other 98 representatives of the family Anyphaenidae. Four species names are considerednomina dubia (Clubiona gayi Nicolet, Drassus mirandus Nicolet, Clubiona altiformis Nicolet, P. obscura Simon). Cluiliuschilensis Mello-Leitão is newly synonymized with P. accentifera Simon. The phylogenetic analysis resulted in P.puconensis Ramírez branching off basally in the genus, because of its numerous leg spines and unmodified malechelicerae, all plesiomorphic for the group; the remaining species form two clear groups. The first one, formed by P. hahniSimon, P. tripunctata (Nicolet), P. amoena (Simon), P. hyadesi (Simon) and P. doilu (Ramírez), are grouped by the lossof spines on legs I and II. The second, formed by P. huapi Ramírez, P. ingens Berland, P. ornata Berland, P. accentiferaSimon, P. atrata and four new species endemic to the Robinson Crusoe Island in the Juan Fernández Archipelago, havethe male chelicerae, and in most cases also the endites, modified. In total, six species of Philisca are endemic to JuanFernández, but our dataset is not conclusive for the distinction of alternative colonization scenarios. We analyze theevolution of leg macrosetae, and show two independent instances of reduction of spination, one on the continent and another on the Juan Fernández islands.

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Sepúlveda, P., J. P. Le Roux, L. E. Lara, G. Orozco et V. Astudillo. « Biostratigraphic evidence for dramatic Holocene uplift of Robinson Crusoe Island, Juan Fernández Ridge, SE Pacific Ocean ». Biogeosciences 12, n^o 6 (27 mars 2015) : 1993–2001. http://dx.doi.org/10.5194/bg-12-1993-2015.

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Abstract. Hotspot oceanic islands typically experience subsidence due to several processes related to migration of the oceanic plate away from the mantle plume and surface flexural loading. However, many other processes can interrupt subsidence, some of which may be associated with catastrophic events. A study of the biostratigraphy and sedimentology of Holocene deposits on Robinson Crusoe Island (RCI) on the Juan Fernández Ridge (JFR) indicated that dramatic uplift has occurred since 8000 years BP, at a rate of about 8.5mm yr-1. This is evidenced by supratidal flats with tepee structures and sand layers containing marine gastropods (mostly Nerita sp.) that are now exposed ca. 70 m a.s.l. The active hotspot is located 280 km further west and the last volcanic activity on RCI occurred at ca. 800 000 years BP. Long-term subsidence is evidenced by deep submerged marine abrasion terraces at RCI. As no direct evidence was found for the existence of a compensating bulge generated by the present hotspot upon which RCI would be situated, it must be concluded that subsidence in the wake of the mantle plume beneath the migrating plate was interrupted by very rapid uplift, but on a scale that did not fully compensate for the previous subsidence. This can be attributed to large-scale landslides followed by isostatic rebound, although this is only vaguely reflected in the low-resolution bathymetry of the area. To determine if this mechanism produced the uplift, a detailed bathymetric survey of the area will be required. If such a survey confirms this hypothesis, it may have implications for the short-term dynamics of vertical variations of oceanic edifices and their related effects on ecosystems and human population.

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Carle, Ryan David, Abram B. Fleishman, Tiare Varela, Pablo Manríquez Angulo, Guillermo De Rodt, Peter Hodum, Valentina Colodro, Verónica López et Héctor Gutiérrez-Guzmán. « Introduced and native vertebrates in pink-footed shearwater (Ardenna creatopus) breeding colonies in Chile ». PLOS ONE 16, n^o 7 (29 juillet 2021) : e0254416. http://dx.doi.org/10.1371/journal.pone.0254416.

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Biodiversity conservation planning requires accurate, current information about species status and threats. Although introduced mammals are the greatest threat to seabirds globally, data on introduced species is lacking for many seabird breeding islands. To inform conservation planning, we used trail cameras to document the presence, relative abundance, and seasonal and diel attendance of introduced and native vertebrates within pink-footed shearwater (Ardenna creatopus) breeding colonies on Isla Mocha (five colonies, 2015–2020) and Isla Robinson Crusoe (Juan Fernández Archipelago), Chile (one colony, 2019–2020). The most commonly detected species were pink-footed shearwaters and introduced rats (Rattus spp.) on Isla Mocha, and European rabbits (Oryctolagus cuniculus) and pink-footed shearwaters on Isla Robinson Crusoe. Introduced mammals observed, in order of greatest catch-per-unit-effort, were rats, cats (Felis catus), dogs (Canis lupus familiaris), and European hares (Lepus europaeus) on Isla Mocha and European rabbits, cats, cattle (Bos taurus), rats, dogs, mice (Mus musculus), and southern coati (Nasua nasua) on Isla Robinson Crusoe. Especially noteworthy results for pink-footed shearwater conservation were the presence of cats during all monitoring months in shearwater colonies on both islands, that catch-per-unit-effort of rabbits was greater than shearwaters on Isla Robinson Crusoe, and that rats were the most observed vertebrates after shearwaters on Isla Mocha. Pink-footed shearwaters were regularly present on the islands from October through May. Presence and relative catch-per-unit-effort of pink-footed shearwaters qualitatively matched the species’ known breeding phenology. The regular presence and temporal overlap with shearwaters of cats, rats, rabbits, and cattle within shearwater colonies, coupled with the irregular presence of dogs, coati, hares, and mice, indicated a serious conservation threat for pink-footed shearwaters and other native insular fauna and flora. Finally, our study provides a widely applicable model for analysis of multi-year trail camera data collected with unstandardized settings.

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Paule, Juraj, Roswitha Schmickl, Tomáš Fér, Sabine Matuszak-Renger, Heidemarie Halbritter et Georg Zizka. « Phylogenomic insights into the Fascicularia-Ochagavia group (Bromelioideae, Bromeliaceae) ». Botanical Journal of the Linnean Society 192, n^o 4 (21 décembre 2019) : 642–55. http://dx.doi.org/10.1093/botlinnean/boz085.

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Abstract Ochagavia (four species) and Fascicularia (one species) form a well-supported clade of the early-diverging Bromelioideae. The two genera are morphologically similar, but they can be easily discerned on the basis of generative characters. Besides the species distributed on the Chilean mainland, the group includes O. elegans, endemic to the Robinson Crusoe Island of the Juan Fernández Islands. In previous molecular phylogenetic studies, O. elegans formed a sister clade to the remainder of Fascicularia and Ochagavia. A phylogenomic approach, including nearly complete and, in five cases, full plastomes (c. 160 kbp) and the nuclear rDNA cistron (c. 6 kbp), and scanning electron microscope (SEM) images of pollen were used to analyse relationships in the Fascicularia-Ochagavia group. Plastome and nuclear trees were largely congruent and supported previous phylogenetic analyses of O. elegans being sister to the remainder of the group. A divergent phylogenetic position was suggested for O. carnea using different organellar trees. SEM analysis of pollen supported the division of Fascicularia and Ochagavia. Evolutionary and taxonomic implications of our results are discussed.

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Rejmánek, Marcel. « Pittosporum undulatum Vent. is an invasive tree on Robinson Crusoe Island (Juan Fernández Archipelago), Chile ». Gayana. Botánica 78, n^o 1 (juin 2021) : 99–103. http://dx.doi.org/10.4067/s0717-66432021000100099.

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Morinière, Jérôme, Mariano C. Michat, Manfred A. Jäch, Johannes Bergsten, Lars Hendrich et Michael Balke. « Anisomeriini diving beetles-an Atlantic-Pacific Island disjunction on Tristan da Cunha and Robinson Crusoe Island, Juan Fernández ? » Cladistics 31, n^o 2 (17 avril 2014) : 166–76. http://dx.doi.org/10.1111/cla.12074.

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ŠVIHLA, VLADIMÍR, et FRANCISCO RAMÍREZ FISCHER. « Parisopalpus defoei sp. nov. from Robinson Crusoe Island, Chile, the first known species of the genus from the Neotropical Region (Coleoptera : Oedemeridae) ». Zootaxa 3394, n^o 1 (20 juillet 2012) : 31. http://dx.doi.org/10.11646/zootaxa.3394.1.3.

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The genus Parisopalpus Hudson, 1975 originally included three species occurring in Australia and New Zealand. Another hitherto unknown species was collected in Juan Fernández Archipiélago: Isla Robinson Crusoe, which belongs administratively to Chile. It was identified as a member of this genus by the first author of this paper and is described below. No other member of the genus Parisopalpus was hitherto known from South America, although Parisopalpus nigronotatus (Boheman, 1858) has been intercepted in the cargo compartments of airplanes by Chilean biosecurity and identified by the second author of this paper, it is not established in the Chilean fauna.

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Sepúlveda, P., J. P. Le Roux, L. E. Lara, G. Orozco et V. Astudillo. « Biostratigraphic evidence of dramatic Holocene uplift of Robinson Crusoe Island, Juan Fernández Ridge, SE Pacific Ocean ». Biogeosciences Discussions 11, n^o 9 (19 septembre 2014) : 13605–22. http://dx.doi.org/10.5194/bgd-11-13605-2014.

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Abstract. A study of the biostratigraphy and sedimentology of Holocene deposits on Robinson Crusoe Island (RCI) on the Juan Fernández Ridge (JFR) indicates that a~dramatic but localized uplift occurred since 8000 BP, at a rate of about 8.5 mm yr−1. In fact, supratidal flats and sand layers with marine gastropods (mostly Nerita sp.) are now exposed ca. 70 m a.s.l., and covered by transitional dunes. The last volcanic activity on RCI occurred at ca. 0.8 Ma (active hotspot located 280 km further west) and there is no sign of a compensating bulge that explains this uplift, isobaths of the sea floor instead suggesting general subsidence. However, modeling indicates that large-scale landslides followed by isostatic rebound are a viable explanation, partially reflected in the low-resolution bathymetry of the area.

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Díaz-Díaz, Oscar, Nicolás Rozbaczylo et Rodrigo A. Moreno. « Leocrates ernstehlersi n. sp. (Polychaeta : Hesionidae), a new species from Juan Fernández Archipelago, Chile ». Latin American Journal of Aquatic Research 50, n^o 5 (1 novembre 2022) : 714–22. http://dx.doi.org/10.3856/vol50-issue5-fulltext-2948.

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The genus Leocrates is currently made up of 11 nominal species, of which Leocrates chinensis Kinberg, 1866 is the type species. Kinberg's original description is brief, and the diagnostic morphological characters are poorly defined. Therefore, numerous subsequent records in different world regions have been considered doubtful. Numerous specimens of Leocrates collected by SCUBA diving in various locations of Robinson Crusoe Island (33°37'S, 78°51'W) in the Juan Fernández Archipelago, between 4 and 10 m depth were examined and determined as a new species herein named Leocrates ernstehlersi n. sp. It is characterized by the size of anterior and posterior eyes, the median chaetigers with scarce notochaetae and neurochaetae per bundle; neurochaetal blades are 4-14 times longer than wide and neuracicular lobes slightly longer than wide. A key to identifying species of Leocrates having large anterior eyes and anterior eyes/prostomial width ratio between 1/4 to 1/8 is also included.

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Bernardello, Gabriel, Leonardo Galetto et Gregory J. Anderson. « Floral nectary structure and nectar chemical composition of some species from Robinson Crusoe Island (Chile) ». Canadian Journal of Botany 78, n^o 7 (1 juillet 2000) : 862–71. http://dx.doi.org/10.1139/b00-055.

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Floral nectary structure and nectar composition of 12 species, including 11 endemics, are reported from Robinson Crusoe Island (Juan Fernández Archipelago, Chile). These species are mostly hummingbird pollinated. Nectary morphology follows the general pattern within each of the families, suggesting it is an ancestral feature. The mean nectar concentration (± SD) as a percentage of weight (weight/total weight of solution) was 28.3 ± 20.7. Sucrose, fructose, and glucose were identified in most samples. In Nicotiana cordifolia, an unknown monosaccharide was also detected. When more than one sample per species was examined, there was usually variability in sugar ratios. Statistical tests indicated that population size does not influence this variability. However, there were differences when the pollinator type was compared, with a trend of a higher sucrose proportion and a lower coefficient of variation of sucrose in the species pollinated by hummingbirds. This would indicate a specialization in the nectar composition of the hummingbird-pollinated species. Cuminia eriantha, N. cordifolia, and Rhaphithamnus venustus also possess amino acids in their nectar. In the non-hummingbird-pollinated species, the presence of nectaries and nectar serves as an indication of the ancestral pollination system of the first colonizers rather than the current condition, which is wind pollination or self-compatibility for most of the species. Thus, the presence of nectar in flowers does not necessarily indicate extant biotic pollination.Key words: angiosperms, Robinson Crusoe Island, nectary structure, nectar sugar composition, sugar concentration, hummingbird pollination.

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Reyes, Julio C., Koen Van Waerebeek, Juan C. Cárdenas et José L. Yáñez. « Mesoplodon bahamondi sp. n. (Cetacea, Ziphiidae), a new living beaked whale from the Juan Fernández Archipelago, Chile ». Boletín Museo Nacional de Historia Natural 45 (28 décembre 1995) : 31–44. http://dx.doi.org/10.54830/bmnhn.v45.1995.381.

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Mesoplodon bahamondi sp.n. is described from a calvarium collected at Playa Blanca, Robinson Crusoe Island (33°37'S, 78°53'W), off Chile. Cranial characters which differentiate this new species from all congeners include: 1) unique arrangement and shape of bones in the antorbital region, in particular the large size of the jugale; 2) widest known rostrum base, relative to zygomatic width, of any known Mesoplodon skull; 3) the extremely short distance between the premaxillary foramina. Comparisons are made with other species of Mesoplodon, in particular with M. bowdoini, its closest morphological relative, confirming its distinctness. The antorbital region is proposed as useful aid in the identification of Mesoplodon skulls. The possible relationship between M. bahamondi with an unidentified Mesoplodon repeatedly sighted in the eastern tropical Pacific is suggested.

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Reyes, Javier, Luis E. Lara et Diego Morata. « Contrasting P-T paths of shield and rejuvenated volcanism at Robinson Crusoe Island, Juan Fernández Ridge, SE Pacific ». Journal of Volcanology and Geothermal Research 341 (juillet 2017) : 242–54. http://dx.doi.org/10.1016/j.jvolgeores.2017.05.035.

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Reyes, Javier, Luis E. Lara, Vanessa Sutherland, Nicolás Aguirre, Carlos Orellana, Folkmar Hauff et Kaj Hoernle. « Tracing the Origin and Magmatic Evolution of the Rejuvenated Volcanism in Santa Clara Island, Juan Fernández Ridge, SE Pacific ». Minerals 14, n^o 5 (19 mai 2024) : 524. http://dx.doi.org/10.3390/min14050524.

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Oceanic intraplate volcanoes sometimes experience late-stage eruptive activity known as rejuvenated volcanism, and contrasting interpretations for its petrogenesis depend on the compositional characteristics. In the Juan Fernández Ridge (JFR), a volcanic chain approximately 800 km in length emplaced on the Nazca Plate, some subaerial occurrences of rejuvenated volcanism have been recognized on the Robinson Crusoe and Santa Clara Islands, both part of the same deeply eroded shield volcano complex. This study aims to understand the origin and magmatic evolution of rejuvenated volcanism on Santa Clara Island, emplaced after ~2.15 Ma of quiescence above the shield sequence, mainly via the analysis of unpublished geochemical and isotopic data. Field reconnaissance identified two nearly coeval rejuvenated sequences on Santa Clara Island: Bahía W (BW) and Morro Spartan (MS), both formed by basanitic and picro-basaltic lava flows with brecciated levels and local intercalations of sedimentary and pyroclastic deposits. In comparison to the chemical signature of the preceding shield-building stage (comprised mainly of basalts and picrites), the two rejuvenated sequences exhibit a notable enrichment in incompatible elements, but the Sr, Nd, and Pb isotopes are very similar to the FOZO mantle endmember, with an apparent additional contribution of HIMU and EM1 components. The geochemistry of lavas revealed the involvement of various processes, including contamination by ultramafic xenoliths, high-pressure fractional crystallization of olivine and clinopyroxene, and potential partial assimilation of oceanic lithospheric components. While the oceanic lithosphere has been considered as a potential source, the isotopic data from Santa Clara lies outside of the mixing curve between depleted mantle (DM, here represented by the North Chile Rise and the East Pacific Rise) and the previous shield stage, suggesting that a lithospheric mantle is not the primary source for the rejuvenated stage volcanism. Therefore, we favor an origin of the rejuvenated volcanism from the mantle plume forming the JFR, supported by similarities in isotopic signatures with the shield stage and high values of 208Pb/204Pb (only comparable to San Félix—San Ambrosio in the vicinity of JFR), implying the presence of a regional source with radiogenic 208Pb/204Pb isotope ratios. In addition, isotopic variations are subparallel to the mixing line between HIMU and EM1 components, whose participation in different proportions might explain the observed trends. In conclusion, we propose that the source of the rejuvenated volcanism on Santa Clara Island is a heterogeneous mantle plume, the same one that fed the shield stage. The rejuvenated volcanism is derived from a secondary melting zone away from the main axis of the plume.

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Ernst, Billy, Pablo Rivara, Braulio Tapia, Stephane Gauthier, Francisco Santa Cruz et Esteban Molina. « Use of acoustic and stereo camera systems for assessing demersal fish of Robinson Crusoe Island (Juan Fernández Archipelago, off central Chile) ». Journal of the Acoustical Society of America 141, n^o 5 (mai 2017) : 3865. http://dx.doi.org/10.1121/1.4988640.

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Córdova, Pablo, et Raúl P. Flores. « Hydrodynamic and Particle Drift Modeling as a Support System for Maritime Search and Rescue (SAR) Emergencies : Application to the C-212 Aircraft Accident on 2 September, 2011, in the Juan Fernández Archipelago, Chile ». Journal of Marine Science and Engineering 10, n^o 11 (3 novembre 2022) : 1649. http://dx.doi.org/10.3390/jmse10111649.

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Search and rescue (SAR) refers to every operation aiming to find someone presumed lost, sick, or injured in remote or hard-to-access areas. This study presents the design of an operational system that supports maritime SAR emergencies by combining information from global hydrodynamic models (GHM) and a local hydrodynamic model (LHM) implemented in FVCOM. The output of these hydrodynamic models is used as input in a multiple particle drift estimator (MPDE) to estimate the trajectories of the floating elements derived from accidents in the ocean. The MPDE also includes trajectory estimates using the empirical LEEWAY formulation. The modeling system is validated with data collected during a SAR emergency that occurred on 2 September 2011, where a C-212 aircraft from the Chilean Air Force destined to the Juan Fernández Archipelago crashed in the ocean between the islands of Santa Clara and Robinson Crusoe. Trajectories were assessed in terms of the commonly used NCLS (normalized cumulative Lagrangian separation) performance indicator and a modified version, NCLSmod, which considers both the movement and orientation of the trajectories. The LHM was executed in three scenarios: forced only with tide, forced with tide and wind combined, and forced only with wind. The performance of the different models varied in response to the ocean–atmosphere conditions and their local variations at the time of the accident. In times of calm wind, models with tidal influence performed better, while wind-forced models performed better when winds were greater than 7 km h−1. The use of FVCOM (LHM) solved the coastal circulation and accounted for bathymetric effects in the Juan Fernández Archipelago area. This resulted in an improved variability and distribution of the modeled trajectories compared to the observed drifter trajectories. This work is the first study related to cases of maritime SAR emergencies in Chile, and provides a fast tool to estimate search areas based on an ensemble of particle drift and trajectory forecasts using multiple publicly available data sources.

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PALMA, ÁLVARO T., ISMAEL CÁCERES-MONTENEGRO, RICHARD S. BENNETT, SPARTACO MAGNOLFI, LUIS A. HENRÍQUEZ, JORGE F. GUERRA, KAREN MANRÍQUEZ et R. EDUARDO PALMA. « Near-shore distribution of phyllosomas of the two only lobster species (Decapoda : Achelata) present in Robinson Crusoe Island and endemic to the Juan Fernández archipelago ». Revista chilena de historia natural 84, n^o 3 (septembre 2011) : 379–90. http://dx.doi.org/10.4067/s0716-078x2011000300006.

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Roy, Michael S., Juan Carlos Torres-Mura, Fritz Hertel, Marina Lemus et Renate Sponer. « Conservation of the Juan Fernandez firecrown and its island habitat ». Oryx 33, n^o 3 (juillet 1999) : 223–32. http://dx.doi.org/10.1046/j.1365-3008.1999.00067.x.

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AbstractThe Juan Fernandez Islands constitute two distantly separated (182 km) major islands, of which Isla Robinson Crusoe is the closest (667 km) to the Chilean mainland, and a number of smaller surrounding islets. The endemic Juan Fernandez firecrown Sephanoides fernandensis once inhabited both major islands and numbered many thousands. Today it exists only on Isla Robinson Crusoe and numbers just a few hundred. Another hummingbird, the green-backed firecrown S. sephaniodes, inhabits this island but also occurs on the mainland. The islands are in ecological meltdown as a result of the removal of much of the native (largely endemic) biota. This degradation has been exacerbated by introduced herbivorous and carnivorous mammals, which are extirpating all that remains. In a previous investigation the authors assessed the evolutionary relationships and genetic variation in the Juan Fernandez firecrown population. They showed that the species: (i) is a relative of the high Andean hummingbirds; (ii) is a close sister species of the green-backed firecrown; (iii) dispersed to the islands approximately 0.5–1 million years ago, unlike the green-backed firecrown, which is probably a very recent invader; (iv) maintains some genetic variation, although significantly lower than that found in the green-backed firecrown island population. Because of their relatively recent divergence the authors aimed to find out if the two species compete for resources. In addition, they assessed the conservation options for the Juan Fernandez firecrown and provided recommendations for its management. They concluded that the survival of the Juan Fernandez firecrown is inextricably linked to the holistic restoration of ecosystem/ community function of the island. The initial step must involve the removal of introduced mammals, followed by replanting of native flora. Although the authors do not support the use of captive propagation as a general conservation tool, they believe that, because the Juan Fernandez firecrown is composed of only one small population that is under extreme threat of extinction, a captive population should be established.

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Hahn, Ingo, Uwe Römer, Pablo Vergara et Hartmut Walter. « Biogeography, diversity, and conservation of the birds of the Juan Fernández Islands, Chile ». Vertebrate Zoology 59, n^o 1 (15 mai 2009) : 103–14. http://dx.doi.org/10.3897/vz.59.e30961.

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The Avifauna fernandeziana is described and analysed according to species richness, habitat choice, and breeding status. Taxonomic composition and biogeographical origin are identifi ed. Finally the current conservation status of birds is analysed from a geographical point of view using WALTER’s eigenplace index. The avifauna is represented by only 55 recorded species, one third regular breeders and two thirds visitors. Most species records come from the island Robinson Crusoe (41), followed by Alejandro Selkirk (26) and small Santa Clara (8). Eleven species breed on Crusoe and seven on Selkirk, but they share no endemics. In total 14 bird orders, 29 families and 41 genera are present. Richest orders are Procellariiformes (18 species) followed by Passeriformes (7) and Charadriiformes (7). On average 1.3 species are found per genus, 2.0 genera per family, and 1.7 families per order. Most seabirds originate from Subantarctic/Temperate zones, most landbirds from the Neotropis (together 65 %). Using the eigenplace index, all endemics appear in the two highest scored conservation classes. The six endemic landbird taxa are highly threatened, especially Sephanoides fernandensis and Aphrastura masafuerae. For the low species richness diverse factors may be responsible: low observation intensity, low immigration rates by isolation, competition for limited resources, and predation without retreat areas. The findings support the theoretical suggestion that on islands closely related taxa tend to reduce each other and that one generalist tends to replace several specialists.

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Carrasco, Sebastián, Sergio Ruiz et Miguel Sáez. « Earthquakes Felt in the Juan Fernandez Islands : Where Are They Coming from ? » Seismological Research Letters 91, n^o 1 (13 novembre 2019) : 262–71. http://dx.doi.org/10.1785/0220190151.

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Abstract The Juan Fernandez Islands (JFI) are located in the Pacific Ocean 675 km west of the Chilean coast. This archipelago has historically been affected by large tsunamis. Robinson Crusoe Island (RCI), the main island of the JFI, was first inhabited in 1749. Since then, several tsunamis have destroyed RCI port structures and sometimes caused deaths. Ground shaking perceived by the inhabitants has preceded some tsunami arrivals. Seismological instrumentation was temporarily deployed on RCI in 1999, and a permanent station has been operating since 2014. Here, we use these data to characterize the seismic waves that arrive at the JFI and to determine whether shaking perception could be used as a tsunami early warning system. We compute peak ground accelerations (PGAs) from P, S, and T waves generated by Peruvian and Chilean earthquakes and find that the largest ground shakings are mostly related to T‐wave arrivals, which correlate with macroseismic modified Mercalli intensities lower than III. From the analysis of PGAs and macroseismic intensities, we conclude that shaking perception can be associated with large megathrust earthquakes, subduction events generated in the deep zone of seismogenic contact, and local seismicity. Unfortunately, potential tsunami earthquakes that occur on the Chilean coast will not be felt on RCI. Consequently, ground shaking in the JFI would not be a good proxy for tsunami warning, and a robust tsunami early warning system is necessary for RCI.

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Ramírez, Fabián, Alejandro Pérez-Matus, Tyler D. Eddy et Mauricio F. Landaeta. « Trophic ecology of abundant reef fish in a remote oceanic island : coupling diet and feeding morphology at the Juan Fernandez Archipelago, Chile ». Journal of the Marine Biological Association of the United Kingdom 93, n^o 6 (3 avril 2013) : 1457–69. http://dx.doi.org/10.1017/s0025315413000192.

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The trophic structure of organisms is an important aspect of the ecosystem as it describes how energy is transferred between different trophic levels. Here, we studied the diet and foraging ecology of 144 individuals belonging to five abundant fish species of subtidal habitats at Isla Robinson Crusoe. Sampling was conducted during the austral spring and summer of 2007 and 2008, respectively. The shallow subtidal habitat is mainly characterized by the abundance of two types of habitat: foliose algae and encrusting invertebrates. Diet and trophic characteristic of fishes were obtained by volumetric contribution and frequency of occurrence of each prey item. Of the five species studied, one is herbivorous (juvenile Scorpis chilensis), four are omnivores (Nemadactylus gayi, Malapterus reticulatus, Pseudocaranx chilensis and Scorpis chilensis adult), and one carnivore (Hypoplectrodes semicinctum). The dietary diversity index was relatively low compared to other temperate reef systems, which could indicate a low availability of prey items for coastal fishes. The morphological parameters indicated that cranial structures and pairs of pectoral fins influence the foraging behaviour. Differences in fin aspect ratio among species provided insight about fish depth distribution and feeding behaviour. These results suggest important adaptive changes in the depth gradient of fishes in the subtidal environments of this island. According to our records, this is the first attempt to characterize the trophic ecology of the subtidal fish assemblages at Juan Fernandez Archipelago, revealing the need for testing hypotheses related to selective traits that may enhance species coexistence in oceanic islands.

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Stuessy, Tod F., Daniel J. Crawford, Josef Greimler, Patricio López-Sepúlveda, Eduardo A. Ruiz, Carlos M. Baeza et Koji Takayama. « Metamorphosis of flora and vegetation during ontogeny of the Juan Fernández (Robinson Crusoe) Islands ». Botanical Journal of the Linnean Society, 5 février 2022. http://dx.doi.org/10.1093/botlinnean/boab090.

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Abstract Colonization, levels of speciation and vegetational metamorphosis during ontogeny of oceanic islands over geological time are central evolutionary and biogeographic concerns. A suitable archipelago in which to examine such events is the Juan Fernández (Robinson Crusoe) Archipelago, located at 33° S latitude off the coast of continental Chile and consisting of three major islands: Robinson Crusoe Island, 667 km west of the coastline; Santa Clara Island, 1.6 km off the south-western end of the former island and Alejandro Selkirk Island, 181 km directly further west into the Pacific Ocean. The two largest islands are c. 50 km2, with Santa Clara Island being only 2.1 km2. Radiometric dating for the three islands reveals the ages of Robinson Crusoe Island and Santa Clara Island to be c. 4 My, whereas that of Alejandro Selkirk Island is c. 1 My. Molecular clock estimates of crown-group divergences of endemic taxa fall mostly in these geological ages. Recent investigations have brought together a detailed inventory of the vascular flora of the archipelago with biological, evolutionary and biogeographic information that now supports examining metamorphosis of the vegetation and flora during the 4 My of island ontogeny. Geological dating and geomorphological models are used to infer changes in the landscape on both major islands. It is suggested that the original Robinson Crusoe Island may have been substantially larger and higher than at present (3000 vs. 915 m). Subsidence and erosion of the island led to loss of vegetation zones, especially impacting plants between 1000 and 3000 m. Some species may have adapted to this restructuring, but many would have gone extinct. Alejandro Selkirk Island, now 1 My, is only slightly smaller and lower than the original island (1319 vs. 2000 m), but it has probably lost some higher elevation habitats. The present vegetation of the two islands correlates with these suggestions, with Alejandro Selkirk Island retaining broad zones, but Robinson Crusoe Island having a flora that has been compacted and substantially intermixed with invasive species in recent centuries. Floristic inventory reveals 11 endemic genera, but most of these occur only on Robinson Crusoe Island, which has been the centre of cladogenesis in contrast to greater levels of anagenesis on Alejandro Selkirk Island. The ferns, due to their high dispersability, show almost no cladogenesis. Total endemic species diversity is higher on Robinson Crusoe Island (87) than on Alejandro Selkirk Island (62), and this difference is probably due to the greater age of the island and initial environmental heterogeneity. It is also probable that during this ontogeny, numbers of endemic species on Robinson Crusoe Island have been lost through island subsidence and erosion, loss of habitat and human impact.

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