Browsing by Author "Santos, Ana C."
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- Are species-area relationships from entire archipelagos congruent with those of their constituent islands?Publication . Santos, Ana C.; Whittaker, Robert J.; Triantis, Kostas A.; Borges, Paulo A. V.; Jones, Owen R.; Quicke, Donald L. J.; Hortal, JoaquínAIM To establish the extent to which archipelagos follow the same species–area relationship as their constituent islands and to explore the factors that may explain departures from the relationship. LOCATION Thirty-eight archipelagos distributed worldwide. METHODS We used ninety-seven published datasets to create island species–area relationships (ISARs) using the Arrhenius logarithmic form of the power model. Observed and predicted species richness of an archipelago and of each of its islands were used to calculate two indices that determined whether the archipelago followed the ISAR. Archipelagic residuals (ArcRes) were calculated as the residual of the prediction provided by the ISAR using the total area of the archipelago, standardized by the total richness observed in the archipelago. We also tested whether any characteristic of the archipelago (geological origin and isolation) and/or taxon accounts for whether an archipelago fits into the ISAR or not. Finally, we explored the relationship between ArcRes and two metrics of nestedness. RESULTS The archipelago was close to the ISAR of its constituent islands in most of the cases analysed. Exceptions arose for archipelagos where (i) the slopes of the ISAR are low, (ii) observed species richness is higher than expected by the ISAR and/or (iii) distance to the mainland is small. The archipelago's geological origin was also important; a higher percentage of oceanic archipelagos fit into their ISAR than continental ones. ArcRes indicated that the ISAR underpredicts archipelagic richness in the least isolated archipelagos. Different types of taxon showed no differences in ArcRes. Nestedness and ArcRes appear to be related, although the form of the relationship varies between metrics. MAIN CONCLUSIONS Archipelagos, as a rule, follow the same ISAR as their constituent islands. Therefore, they can be used as distinct units themselves in large-scale biogeographical and macroecological studies. Departure from the ISAR can be used as a crude indicator of richness-ordered nestedness, responsive to factors such as isolation, environmental heterogeneity, number and age of islands.
- A roadmap for island biology : 50 fundamental questions after 50 years of The Theory of Island BiogeographyPublication . Patiño, Jairo; Whittaker, Robert J.; Borges, Paulo A. V.; Fernández-Palacios, José María; Ah-Peng, Claudine; Araújo, Miguel B.; Ávila, Sérgio P.; Cardoso, Pedro; Cornuault, Josselin; Boer, Erik J.; Nascimento, Lea; Gil, Artur José Freire; González-Castro, Aarón; Gruner, Daniel S.; Heleno, Ruben; Hortal, Joaquín; Illera, Juan Carlos; Kaiser-Bunbury, Christopher N.; Matthews, Thomas J.; Papadopoulou, Anna; Pettorelli, Nathalie; Price, Jonathan; Santos, Ana C.; Steinbauer, Manuel J.; Triantis, Kostas A.; Valente, Luis; Vargas, Pablo; Weigelt, Patrick; Emerson, Brent C.AIMS The 50th anniversary of the publication of the seminal book, The Theory of Island Biogeography, by Robert H. MacArthur and Edward O. Wilson, is a timely moment to review and identify key research foci that could advance island biology. Here, we take a collaborative horizon-scanning approach to identify 50 fundamental questions for the continued development of the field. LOCATION: Worldwide. METHODS: We adapted a well-established methodology of horizon scanning to identify priority research questions in island biology, and initiated it during the Island Biology 2016 conference held in the Azores. A multidisciplinary working group prepared an initial pool of 187 questions. A series of online surveys was then used to refine a list of the 50 top priority questions. The final shortlist was restricted to questions with a broad conceptual scope, and which should be answerable through achievable research approaches. RESULTS: Questions were structured around four broad and partially overlapping island topics, including: (Macro)Ecology and Biogeography, (Macro)Evolution, Community Ecology, and Conservation and Management. These topics were then subdivided according to the following subject areas: global diversity patterns (five questions in total); island ontogeny and past climate change (4); island rules and syndromes (3); island biogeography theory (4); immigration–speciation–extinction dynamics (5); speciation and diversification (4); dispersal and colonization (3); community assembly (6); biotic interactions (2); global change (5); conservation and management policies (5); and invasive alien species (4). MAIN CONCLUSIONS: Collectively, this cross-disciplinary set of topics covering the 50 fundamental questions has the potential to stimulate and guide future research in island biology. By covering fields ranging from biogeography, community ecology and evolution to global change, this horizon scan may help to foster the formation of interdisciplinary research networks, enhancing joint efforts to better understand the past, present and future of island biotas.
- The role of plant fidelity and land-use changes on island exotic and indigenous canopy spiders at local and regional scalesPublication . Florencio, Margarita; Rigal, François; Borges, Paulo A. V.; Cardoso, Pedro; Santos, Ana C.; Lobo, Jorge M.Understanding the processes that lead to successful invasions is essential for the management of exotic species. We aimed to assess the comparative relevance of habitat (both at local and at regional scale) and plant features on the species richness of local canopy spiders of both indigenous and exotic species. In an oceanic island, Azores archipelago, we collected spiders in 97 transects belonging to four habitat types according to the degree of habitat disturbance, four types of plants with different colonisation origin (indigenous vs. exotic), and four types of plants according to the complexity of the vegetation structure. Generalised linear mixed models and linear regressions were performed separately for indigenous and exotic species at the local and regional landscape scales. At the local scale, habitat and plant origin explained the variation in the species richness of indigenous spiders, whereas exotic spider richness was poorly correlated to habitat and plant structure. The surrounding landscape matrix substantially affected indigenous spiders, but did not affect exotic spiders, with the exception of the negative effect exerted by native forests on the richness of exotic species. Our results revealed that the local effect of habitat type, plant origin and plant structure explain variations in the species richness observed at a regional scale. These results shed light on the mechanistic processes behind the role of habitat types in invasions, i.e., plant fidelity and plant structure are revealed as key factors, suggesting that native forests may act as physical barriers to the colonisation of exotic spiders.
- The molluscs of the intertidal algal turf in the AzoresPublication . Ávila, Sérgio P.; Santos, Ana C.; Penteado, Ana M.; Rodrigues, Ana M.; Quintino, Inês; Machado, Maria I.The molluscan fauna of the high intertidal algal turf on the island of Pico (Azores) was studied in order to complement existing descriptions of the intertidal biota on these islands. A total of 15,275 specimens belonging to 19 species were found. Five species, the gastropods Alvania mediolittoralis Gofas, 1989, Omalogyra atomus (Philippi, 1841), Pisinna glabrata (Megerle von Muhlfeld, 1824) and Skeneopsis planorbis (Fabricius 0., 1780), and the bivalve Lasaea adansoni (Gmelin, 1791), account for 98% of the total number of specimens, P. glabrata itself being responsible for 46% of all specimens. In places where patellid limpets are absent, Ihe algal turf extends higher in the intertidal zone. In such places, three very abundant molluscan species characterize molluscan assemblages in the algal turf: Lasaea adansoni, Skeneopsis planorbis and Pisinna glabrata, Lasaeo adansoni and Skeneopsis planorbis virtually disappear in the transition from algal lurf to algal fronds, the only (very) abundant species being P. glabrata and, with less importance, Omalogyra atomus and Sinezona cingulata (Costa O.G., 1861).