Browsing by Author "Castro, Sergio A."

Now showing 1 - 8 of 8
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    An island biogeography approach for understanding changes in compositional similarity at present scenario of biotic homogenization
    (ELSEVIER, 2011) Vergara, Pablo M.; Pizarro, Jaime; Castro, Sergio A.
    Local extinction of native species and colonization of non-native species are commonly invoked as responsible for changes in species similarity among biotas of different regions. In this study we used a model of species similarity between islands to assess the emergent, and unexplored, effects of changes in colonization by native species, extinction of non-native species, and propagule pressure on species similarity among insular communities. The model predicts that extinction probability of endemic species has a positive but asymptotic effect on species similarity, which is exacerbated by increasing colonization and reducing extinction of non-native species. Species similarity tends to increase with increasing colonization probability by non-native species, however this effect may be reduced, or even reverted, when the islands are exposed to an elevated number of non-native species that are prone to extinction, high levels of endemic species loss, and an initially large number of native species shared between islands. Species similarity was positively affected by the propagule pressure rate of non-native species only when their colonization and extinction probabilities were large and small enough, respectively. A negative effect of propagule pressure rate can be caused by an increase in the pool size of non-native species, which involves the introduction of different species into different islands, promoting biotic differentiation between islands. Our results indicate that the interactions between colonization, extinction and species pool lead to nonlinear responses and unexpected scenarios of biotic change. In order to validate model predictions, future research programs should focus on understanding the dynamics on such complex meta-communities where coexist native, non-native and endemic species. (C) 2011 Elsevier B.V. All rights reserved.
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    Diversity patterns and composition of native and exotic floras in central Chile
    (2011) Figueroa Ortiz, Javier Alejandro; Castro, Sergio A.
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    Floristic homogenization as a teleconnected trend in oceanic islands
    (2010) Castro, Sergio A.; Jaksic Andrade, Fabián
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    Partitioning beta-diversity reveals that invasions and extinctions promote the biotic homogenization of Chilean freshwater fish fauna
    (2020) Castro, Sergio A.; Rojas, P.; Vila, I.; Habit, E.; Pizarro-Konczak, J.; Abades T., Sebastián R.; Jaksic Andrade, Fabián
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    Régimen de incendios y expansión de plantas naturalizadas en Chile central
    (2011) Contreras, T.; Figueroa Ortiz, Javier Alejandro; Castro, Sergio A.
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    The identity of Fuegian and Patagonian "dogs" among indigenous peoples in southernmost South America
    (SOC BIOLGIA CHILE, 2023) Jaksic, Fabián; Castro, Sergio A.
    Background: By using a historical approach we attempt to answer the question of whether the "dogs" of Fuegian and Patagonian peoples are a domesticated dog (Canis lupus familiaris) or a tamed or domesticated Culpeo "fox" (Lycalopex culpaeus), or a cross breed. Methods and results: We reviewed historical chronicles and current scientific papers, and clarified several rather confusing concepts, providing disambiguation for terms such as Magellanic region, Patagonia, and Tierra del Fuego; Fuegian and Patagonian peoples; and Fuegian and Patagonian dogs. We conclude that these dogs belong to two different canid varieties: The smaller domestic dog typical of the "canoe-indians" (Chonos, Kawesqar, and Yahgan peoples) and the larger tamed or domesticated Culpeo "fox" typical of the "foot indians" (Aonikenk, Manek'enk, and Selk'nam peoples, thus proposing the use of Fuegian and Patagonian dog, respectively. Discussion: We think that the original Fuegian dog was indeed a Canis lupus familiaris brought along by the natives after the Bering's crossing and that the Patagonian dog was a tame Culpeo fox Lycalopex culpaeus, which was progressively replaced by the more gregarious, human friendly, and colorful domestic dogs brought by European explorers, adventurers, colonizers, and settlers of Patagonia and Tierra del Fuego during the mid to late 1800s. The possibility that the Patagonian dog was a cross between domestic dog and Culpeo "fox" cannot be ruled out, but the only specimen genetically analyzed was closest to being the latter and not a hybrid.
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    Vascular flora of Punta Arenas city: comparative analysis of composition, life forms, and biogeographic origins
    (2024) Castro, Sergio A.; Rojas, Gloria; Jaksic, Fabián M.
    The composition of the vascular flora in Punta Arenas city, found in the city’s public spaces, was studied. The species were identified and recorded in a database, which was supplemented with information on taxonomic classification, growth habit, Raunkiaer’s life form, origin status (native or exotic), and original continent-level distribution. These data were compared with studies conducted in five other cities in central Chile, together with an analysis of compositional similarity with these cities, by using the additive complement of Simpson’s index (1– βsim). In Punta Arenas, 119 species were identified, showing a higher proportion of Gymnosperms compared to central Chilean cities. The most represented families were Asteraceae (16 species), Fabaceae (14), Rosaceae (14), Poaceae (12), and Pinaceae (10), which together accounted for 55% of the floristic richness. The compositional similarity between Punta Arenas and the other central Chilean cities ranged from 0.187 to 0.315, showing lower similarity than expected by chance (Montecarlo randomization test; P < 0.05). The primary origin distribution of Punta Arenas’ vascular flora was European, unlike central Chilean cities where it was Asian. Finally, the proportion of exotic species (91.6%) and the number of exotic species per native species (16 exotics/native) were the highest documented for cities in Chile and higher than in other 114 cities worldwide. These results indicate that Punta Arenas’ urban flora differs from the flora in central Chilean cities, not only in taxonomic composition but also in growth habit, biogeographical origin, and high level of exoticism. These differences are likely due to the city’s territorial isolation and extreme southern location (53°S), leading to a unique urban flora configuration.