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Paulo A. V. Borges - One of the best experts on this subject based on the ideXlab platform.
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A roadmap for Island biology: 50 fundamental questions after 50 years of The Theory of Island Biogeography
Journal of Biogeography, 2017Co-Authors: Jairo Patiño, Robert J. Whittaker, Paulo A. V. Borges, José María Fernández-palacios, Claudine Ah-peng, Miguel B. Araújo, Sérgio P. Ávila, Pedro Cardoso, Josselin Cornuault, Erik J. De BoerAbstract: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.
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Oceanic Island Biogeography through the lens of the general dynamic model: assessment and prospect.
Biological reviews of the Cambridge Philosophical Society, 2016Co-Authors: Michael K. Borregaard, Thomas J. Matthews, Lawrence R. Heaney, Richard Field, Isabel R. Amorim, Paulo A. V. Borges, Juliano Sarmento Cabral, José María Fernández-palacios, Holger Kreft, Jens M. OlesenAbstract:The general dynamic model of oceanic Island Biogeography (GDM) has added a new dimension to theoretical Island Biogeography in recognizing that geological processes are key drivers of the evolutionary processes of diversification and extinction within remote Islands. It provides a dynamic and essentially non-equilibrium framework generating novel predictions for emergent diversity properties of oceanic Islands and archipelagos. Its publication in 2008 coincided with, and spurred on, renewed attention to the dynamics of remote Islands. We review progress, both in testing the GDM's predictions and in developing and enhancing ecological-evolutionary understanding of oceanic Island systems through the lens of the GDM. In particular, we focus on four main themes: (i) macroecological tests using a space-for-time rationale; (ii) extensions of theory to Islands following different patterns of ontogeny; (iii) the implications of GDM dynamics for lineage diversification and trait evolution; and (iv) the potential for downscaling GDM dynamics to local-scale ecological patterns and processes within Islands. We also consider the implications of the GDM for understanding patterns of non-native species diversity. We demonstrate the vitality of the field of Island Biogeography by identifying a range of potentially productive lines for future research. © 2016 Cambridge Philosophical Society.
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modeling directional spatio temporal processes in Island Biogeography
Ecology and Evolution, 2015Co-Authors: Kostas A. Triantis, Pedro Cardoso, F. Rigal, Jose Carvalho, Paulo A. V. BorgesAbstract:A key challenge in Island Biogeography is to quantity the role of dispersal in shaping biodiversity patterns among the Islands of a given archipelago. Here, we propose such a framework. Dispersal within oceanic archipelagos may be conceptualized as a spatio-temporal process dependent on: (1) the spatial distribution of Islands, because the probability of successful dispersal is inversely related to the spatial distance between Islands and (2) the chronological sequence of Island formation that determines the directional asymmetry of dispersal (hypothesized to be predominantly from older to younger Islands). From these premises, directional network models may be constructed, representing putative connections among Islands. These models may be translated to eigenfunctions in order to be incorporated into statistical analysis. The framework was tested with 12 datasets from the Hawaii, Azores, and Canaries. The explanatory power of directional network models for explaining species composition patterns, assessed by the Jaccard dissimilarity index, was compared with simpler time-isolation models. The amount of variation explained by the network models ranged from 5.5% (for Coleoptera in Hawaii) to 60.2% (for Pteridophytes in Canary Islands). In relation to the four studied taxa, the variation explained by network models was higher for Pteridophytes in the three archipelagos. By the contrary, small fractions of explained variation were observed for Coleoptera (5.5%) and Araneae (8.6%) in Hawaii. Time-isolation models were, in general, not statistical significant and explained less variation than the equivalent directional network models for all the datasets. Directional network models provide a way for evaluating the spatio-temporal signature of species dispersal. The method allows building scenarios against which hypotheses about dispersal within archipelagos may be tested. The new framework may help to uncover the pathways via which species have colonized the Islands of a given archipelago and to understand the origins of insular biodiversity.
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Calling for a new strategy to measure environmental (habitat) diversity in Island Biogeography: a case study of Mediterranean tenebrionids (Coleoptera: Tenebrionidae)
Fragmenta Entomologica, 2015Co-Authors: Simone Fattorini, Leonardo Dapporto, Giovanni Strona, Paulo A. V. BorgesAbstract:Many recent researches in Island Biogeography attempted to disentangle the effects of area per se and “habitat diversity” on species richness. However, the expression “habitat diversity” in this context should be avoided, because habitats can be only recognized by referring to the resources needed by a particular species. What is really measured in such researches is some form of “environmental heterogeneity”. Although habitat heterogeneity can be measured in various ways, most researches in Island Biogeography simply used the number of biotopes (typically classified as land cover categories). However, not all biotopes have the same surface. On the basis of the area occupied by each land cover category, it is possible to calculate indices of environmental diversity, evenness and dominance, as commonly done in community ecology research. These indices can be used to investigate the role of environmental diversity in determining species richness. We used the tenebrionid beetles inhabiting twenty-five small Islands around Sicily (Central Mediterranean) to illustrate these concepts. We found that both area per se and environmental heterogeneity contributed to determine species richness. Moreover, we found that the relationship between species richness and environmental homogeneity followed a power function model. This indicates that environmental homogenization may determine a rapid, non linear decline in species richness.
Jose Carvalho - One of the best experts on this subject based on the ideXlab platform.
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modeling directional spatio temporal processes in Island Biogeography
Ecology and Evolution, 2015Co-Authors: Kostas A. Triantis, Pedro Cardoso, F. Rigal, Jose Carvalho, Paulo A. V. BorgesAbstract:A key challenge in Island Biogeography is to quantity the role of dispersal in shaping biodiversity patterns among the Islands of a given archipelago. Here, we propose such a framework. Dispersal within oceanic archipelagos may be conceptualized as a spatio-temporal process dependent on: (1) the spatial distribution of Islands, because the probability of successful dispersal is inversely related to the spatial distance between Islands and (2) the chronological sequence of Island formation that determines the directional asymmetry of dispersal (hypothesized to be predominantly from older to younger Islands). From these premises, directional network models may be constructed, representing putative connections among Islands. These models may be translated to eigenfunctions in order to be incorporated into statistical analysis. The framework was tested with 12 datasets from the Hawaii, Azores, and Canaries. The explanatory power of directional network models for explaining species composition patterns, assessed by the Jaccard dissimilarity index, was compared with simpler time-isolation models. The amount of variation explained by the network models ranged from 5.5% (for Coleoptera in Hawaii) to 60.2% (for Pteridophytes in Canary Islands). In relation to the four studied taxa, the variation explained by network models was higher for Pteridophytes in the three archipelagos. By the contrary, small fractions of explained variation were observed for Coleoptera (5.5%) and Araneae (8.6%) in Hawaii. Time-isolation models were, in general, not statistical significant and explained less variation than the equivalent directional network models for all the datasets. Directional network models provide a way for evaluating the spatio-temporal signature of species dispersal. The method allows building scenarios against which hypotheses about dispersal within archipelagos may be tested. The new framework may help to uncover the pathways via which species have colonized the Islands of a given archipelago and to understand the origins of insular biodiversity.
Mark V. Lomolino - One of the best experts on this subject based on the ideXlab platform.
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THE RETICULATING PHYLOGENY OF Island Biogeography THEORY
The Quarterly review of biology, 2009Co-Authors: Mark V. Lomolino, James H. BrownAbstract:Biogeographers study all patterns in the geographic variation of life, from the spatial variation in genetic and physiological characteristics of cells and individuals, to the diversity and dynamics of biological communities among continental biotas or across oceanic archipelagoes. The field of Island Biogeography, in particular, has provided some genuinely transformative insights for the biological sciences, especially ecology and evolutionary biology. Our purpose here is to review the historical development of Island Biogeography theory during the 20th century by identifying the common threads that run through four sets of contributions made during this period, including those by Eugene Gordon Munroe (1948, 1953), Edward O. Wilson (1959, 1961), Frank W. Preston (1962a,b), and the seminal collaborations between Wilson and Robert H. MacArthur (1963, 1967), which revolutionized the field and served as its paradigm for nearly four decades. This epistemological account not only reviews the intriguing history of Island theory, but it also includes fundamental lessons for advancing science through transformative integrations. Indeed, as is likely the case with many disciplines, Island theory advanced not as a simple accumulation of facts and an orderly succession of theories and paradigms, but rather in fits and starts through a reticulating phylogeny of ideas and alternating periods of specialization and reintegration. We conclude this review with a summary of the salient features of this scientific revolution in the context of Kuhn’s structure, which strongly influenced theoretical advances during this period, and we then describe some of the fundamental assumptions and tenets of an emerging reintegration of Island Biogeography theory.
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Prairie dog towns as Islands: applications of Island Biogeography and landscape ecology for conserving nonvolant terrestrial vertebrates
Global Ecology and Biogeography, 2003Co-Authors: Mark V. Lomolino, Gregory A. SmithAbstract:Aim To evaluate the utility of Island Biogeography theory as a model for understanding and conserving native communities of nonvolant terrestrial vertebrates at prairie dog towns. Location Oklahoma Panhandle, USA. Methods We surveyed mammal, reptile and amphibian communities on 36 black-tailed prairie dog (Cynomys ludovicianus) towns during the summers and falls of 1997 to 1999. We used a Geographic Information System (GIS) to characterize the landscape within 10 km of each town. We used Principal Components Analysis (PCA), Correlation Analysis, and Linear Regression to test for patterns in species richness relative to area and isolation of towns, local habitat characteristics, and characteristics of the adjacent landscape. Results Species richness was not significantly correlated with town size, town isolation, or local habitat characteristics. On the other hand, species richness was significantly correlated with characteristics of the landscape within 10 km of the focal town. In addition, species richness of mammals at prairie dog towns during the summer increased in a northerly direction, while richness of mammals at towns during fall increased to the west. Main conclusions These results, albeit contrary to traditional Island Biogeography theory, are consistent with an emerging view that communities on relatively small Islands are strongly influenced by characteristics of the adjacent landscape (or seascape). We recommend that to the extent possible, networks of reserves for prairie dogs and their associated species should include clusters of large towns (i.e. larger than those studied here), as well as large but isolated towns, and that conservation efforts should include management of the intervening matrix of anthropogenic habitats.
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Concluding remarks: historical perspective and the future of Island Biogeography theory
Global Ecology and Biogeography, 2000Co-Authors: James H. Brown, Mark V. LomolinoAbstract:MacArthur and Wilson’s equilibrium theory revolutionized the field of Island Biogeography and, to a large degree, ecology as well. The theory, which quickly became the ruling paradigm of Island Biogeography, has changed little over the past three decades. It has not kept pace with relevant theory and our growing appreciation for the complexity of nature, especially with empirical findings that species diversity on many Islands: 1) is not in equilibrium; 2) is influenced by differences in speciation, colonization, and extinction among taxa; and 3) is influenced by differences among Islands in characteristics other than area and isolation. The discipline of Biogeography, itself, is in a state of disequilibrium. We may again be about to witness another paradigm shift, which will see the replacement of MacArthur and Wilson’s theory. Wherever this shift may take us, we are confident that the next generation of biogeographers will still look to Islands for insights into the forces that shape biological diversity.
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A call for a new paradigm of Island Biogeography
Global Ecology and Biogeography, 2000Co-Authors: Mark V. LomolinoAbstract:MacArthur and Wilson's equilibrium theory of Island Biogeography quickly became the paradigm of the field in the 1960s and has strongly influenced this and other disciplines of ecology and conservation biology for the past three decades. Recently, however, a growing number of ecologists have begun to question whether the theory remains a useful paradigm for modern ecology. We now have a much better appreciation for the complexity of nature and we study patterns that span a very broad range in spatial, temporal and ecological scales. At such scales, assumptions that communities are in equilibrium, that species, Islands and intervening landscapes or seascapes are equivalent or homogeneous with respect to factors influencing immigration and extinction, and that in situ speciation can be overlooked become very tenuous. With this in mind, this and other papers of this special feature discuss the principal, conceptual shortcomings of the equilibrium theory and offer some modifications or alternatives to the theory that we hope will eventually lead to a more comprehensive understanding of the forces structuring insular communities.
Pedro Cardoso - One of the best experts on this subject based on the ideXlab platform.
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A roadmap for Island biology: 50 fundamental questions after 50 years of The Theory of Island Biogeography
Journal of Biogeography, 2017Co-Authors: Jairo Patiño, Robert J. Whittaker, Paulo A. V. Borges, José María Fernández-palacios, Claudine Ah-peng, Miguel B. Araújo, Sérgio P. Ávila, Pedro Cardoso, Josselin Cornuault, Erik J. De BoerAbstract: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.
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modeling directional spatio temporal processes in Island Biogeography
Ecology and Evolution, 2015Co-Authors: Kostas A. Triantis, Pedro Cardoso, F. Rigal, Jose Carvalho, Paulo A. V. BorgesAbstract:A key challenge in Island Biogeography is to quantity the role of dispersal in shaping biodiversity patterns among the Islands of a given archipelago. Here, we propose such a framework. Dispersal within oceanic archipelagos may be conceptualized as a spatio-temporal process dependent on: (1) the spatial distribution of Islands, because the probability of successful dispersal is inversely related to the spatial distance between Islands and (2) the chronological sequence of Island formation that determines the directional asymmetry of dispersal (hypothesized to be predominantly from older to younger Islands). From these premises, directional network models may be constructed, representing putative connections among Islands. These models may be translated to eigenfunctions in order to be incorporated into statistical analysis. The framework was tested with 12 datasets from the Hawaii, Azores, and Canaries. The explanatory power of directional network models for explaining species composition patterns, assessed by the Jaccard dissimilarity index, was compared with simpler time-isolation models. The amount of variation explained by the network models ranged from 5.5% (for Coleoptera in Hawaii) to 60.2% (for Pteridophytes in Canary Islands). In relation to the four studied taxa, the variation explained by network models was higher for Pteridophytes in the three archipelagos. By the contrary, small fractions of explained variation were observed for Coleoptera (5.5%) and Araneae (8.6%) in Hawaii. Time-isolation models were, in general, not statistical significant and explained less variation than the equivalent directional network models for all the datasets. Directional network models provide a way for evaluating the spatio-temporal signature of species dispersal. The method allows building scenarios against which hypotheses about dispersal within archipelagos may be tested. The new framework may help to uncover the pathways via which species have colonized the Islands of a given archipelago and to understand the origins of insular biodiversity.
Kostas A. Triantis - One of the best experts on this subject based on the ideXlab platform.
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Island Biogeography taking the long view of nature s laboratories
Science, 2017Co-Authors: Michael K. Borregaard, Thomas J. Matthews, Robert J. Whittaker, Jose Maria Fernandezpalacios, Kostas A. TriantisAbstract:BACKGROUND Ever since Darwin, natural scientists have turned to Islands for inspiration and for model systems. For the past half century, they have done so largely within the paradigm established by Robert H. MacArthur and Edward O. Wilson’s Theory of Island Biogeography , which provided a quantitative, dynamic framework, based upon assumptions of geographically predictable patterns of immigration, extinction, and speciation. Although this approach has proven productive, its application to remote archipelagos and evolutionary time scales has been hampered by a rather static view of Islands themselves, despite mounting evidence of their dynamism as platforms. We review recent progress in integrating the largely ecological thinking of their theory with insights on the longer-term dynamics of both the Islands and their biotas. ADVANCES Classification and analysis of marine Islands by their geophysical dynamics, and of their species by how they colonized, provides a step toward a more nuanced Biogeography out of which new insights are already emerging. This perspective is exemplified by the general dynamic model of oceanic Island Biogeography, which predicts how immigration, speciation, and extinction respond to the typical life cycle of hotspot Islands, with phases of emergence, development, and submergence. The model successfully predicts such emergent patterns as the occurrence of peak diversification on youthful, expanding Islands with maximum vacant niche space. Diversity patterns analyzed for large numbers of data sets have confirmed the importance of in situ evolutionary dynamics on remote archipelagos, which typically possess steep Island species–area relationships, especially for endemic taxa. We may infer that variations in propagule flow among Islands within archipelagos are important in modulating these emergent diversity patterns. There is, for example, good support for an “Island progression rule” in which older land masses donate colonists to younger Islands (consistent with the generalization of Islands as “sinks”), but there is also increasing evidence of “reverse colonization,” including from Islands to continental regions. Advances are also being made in linking such Island biogeographical models with the classic traits and syndromes of insular species, although this first demands that previous generalizations are rigorously reexamined using expanded data sets and modern techniques of analysis. A classic insular syndrome is the loss of dispersability of formerly dispersive species following Island colonization, for which there is now good evidence for several taxa, including many genera of land birds. Yet, paradoxically, and perhaps controversially, it has also been inferred that many species of plants lacking specialized dispersal adaptations can colonize quite remote Islands, often by nonstandard means of transport. Unfortunately, Island evolutionary syndromes, such as loss of flight in birds, frequently predispose species to heightened extinction risk when Islands are colonized and transformed by humans, as we also document. OUTLOOK Developments in theory and in analytical and modeling capabilities within biological and Earth system science, and the pooling of large numbers of data sets, enhancing statistical power, collectively hold the promise of a new synthesis in Island Biogeography. This synthesis will need to accommodate evidence of the long-term dynamics of remote Island systems, whereby some lineages persist far longer than any particular Island platform, while others founder as their sole Island home sinks under the waves. The promise is of a Biogeography in the tradition of the MacArthur–Wilson theory, generating and testing predictive models, but extended to accommodate a more sophisticated suite of insular geological and environmental dynamics, combined with a fuller understanding of patterns and processes of gene flow within and between archipelagos.
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Island Biogeography: Taking the long view of nature’s laboratories
Science (New York N.Y.), 2017Co-Authors: Robert J. Whittaker, Michael K. Borregaard, Thomas J. Matthews, José María Fernández-palacios, Kostas A. TriantisAbstract:BACKGROUND Ever since Darwin, natural scientists have turned to Islands for inspiration and for model systems. For the past half century, they have done so largely within the paradigm established by Robert H. MacArthur and Edward O. Wilson’s Theory of Island Biogeography , which provided a quantitative, dynamic framework, based upon assumptions of geographically predictable patterns of immigration, extinction, and speciation. Although this approach has proven productive, its application to remote archipelagos and evolutionary time scales has been hampered by a rather static view of Islands themselves, despite mounting evidence of their dynamism as platforms. We review recent progress in integrating the largely ecological thinking of their theory with insights on the longer-term dynamics of both the Islands and their biotas. ADVANCES Classification and analysis of marine Islands by their geophysical dynamics, and of their species by how they colonized, provides a step toward a more nuanced Biogeography out of which new insights are already emerging. This perspective is exemplified by the general dynamic model of oceanic Island Biogeography, which predicts how immigration, speciation, and extinction respond to the typical life cycle of hotspot Islands, with phases of emergence, development, and submergence. The model successfully predicts such emergent patterns as the occurrence of peak diversification on youthful, expanding Islands with maximum vacant niche space. Diversity patterns analyzed for large numbers of data sets have confirmed the importance of in situ evolutionary dynamics on remote archipelagos, which typically possess steep Island species–area relationships, especially for endemic taxa. We may infer that variations in propagule flow among Islands within archipelagos are important in modulating these emergent diversity patterns. There is, for example, good support for an “Island progression rule” in which older land masses donate colonists to younger Islands (consistent with the generalization of Islands as “sinks”), but there is also increasing evidence of “reverse colonization,” including from Islands to continental regions. Advances are also being made in linking such Island biogeographical models with the classic traits and syndromes of insular species, although this first demands that previous generalizations are rigorously reexamined using expanded data sets and modern techniques of analysis. A classic insular syndrome is the loss of dispersability of formerly dispersive species following Island colonization, for which there is now good evidence for several taxa, including many genera of land birds. Yet, paradoxically, and perhaps controversially, it has also been inferred that many species of plants lacking specialized dispersal adaptations can colonize quite remote Islands, often by nonstandard means of transport. Unfortunately, Island evolutionary syndromes, such as loss of flight in birds, frequently predispose species to heightened extinction risk when Islands are colonized and transformed by humans, as we also document. OUTLOOK Developments in theory and in analytical and modeling capabilities within biological and Earth system science, and the pooling of large numbers of data sets, enhancing statistical power, collectively hold the promise of a new synthesis in Island Biogeography. This synthesis will need to accommodate evidence of the long-term dynamics of remote Island systems, whereby some lineages persist far longer than any particular Island platform, while others founder as their sole Island home sinks under the waves. The promise is of a Biogeography in the tradition of the MacArthur–Wilson theory, generating and testing predictive models, but extended to accommodate a more sophisticated suite of insular geological and environmental dynamics, combined with a fuller understanding of patterns and processes of gene flow within and between archipelagos.
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modeling directional spatio temporal processes in Island Biogeography
Ecology and Evolution, 2015Co-Authors: Kostas A. Triantis, Pedro Cardoso, F. Rigal, Jose Carvalho, Paulo A. V. BorgesAbstract:A key challenge in Island Biogeography is to quantity the role of dispersal in shaping biodiversity patterns among the Islands of a given archipelago. Here, we propose such a framework. Dispersal within oceanic archipelagos may be conceptualized as a spatio-temporal process dependent on: (1) the spatial distribution of Islands, because the probability of successful dispersal is inversely related to the spatial distance between Islands and (2) the chronological sequence of Island formation that determines the directional asymmetry of dispersal (hypothesized to be predominantly from older to younger Islands). From these premises, directional network models may be constructed, representing putative connections among Islands. These models may be translated to eigenfunctions in order to be incorporated into statistical analysis. The framework was tested with 12 datasets from the Hawaii, Azores, and Canaries. The explanatory power of directional network models for explaining species composition patterns, assessed by the Jaccard dissimilarity index, was compared with simpler time-isolation models. The amount of variation explained by the network models ranged from 5.5% (for Coleoptera in Hawaii) to 60.2% (for Pteridophytes in Canary Islands). In relation to the four studied taxa, the variation explained by network models was higher for Pteridophytes in the three archipelagos. By the contrary, small fractions of explained variation were observed for Coleoptera (5.5%) and Araneae (8.6%) in Hawaii. Time-isolation models were, in general, not statistical significant and explained less variation than the equivalent directional network models for all the datasets. Directional network models provide a way for evaluating the spatio-temporal signature of species dispersal. The method allows building scenarios against which hypotheses about dispersal within archipelagos may be tested. The new framework may help to uncover the pathways via which species have colonized the Islands of a given archipelago and to understand the origins of insular biodiversity.
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general dynamic model of oceanic Island Biogeography using linear mixed effect models
2013Co-Authors: Robert A. D. Cameron, Kostas A. Triantis, Christine E. Parent, R. Alonso, Richard J. Ladle, Robert J. WhittakerAbstract:Aim We collate and analyse data for land snail diversity and endemism, as a means of testing the explanatory power of the general dynamic model of oceanic Island Biogeography (GDM): a theoretical model linking trends in species immigration, speciation and extinction to a generalized Island ontogeny.
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symposium summary: Island Biogeography
Frontiers of Biogeography, 2012Co-Authors: Kostas A. TriantisAbstract:ISSN 1948‐6596 news and update symposium summary Island Biogeography A contributed session at the 5th International Biogeography Society Conference – Heraklion, Greece, 7–11 January 2011 It is now almost 50 years since the publication of Robert H. MacArthur and Edward O. Wilson’s 1963 paper, An Equilibrium Theory of Insular Zo‐ ogeography which led to their famous book, The Theory of Island Biogeography (MacArthur and Wilson 1967). These publications were instrumen‐ tal in a switch from a static, historically oriented Biogeography, based in the direct interpretation of the data collected in the field, to a ‘dynamic’ equilibrium paradigm, based on a synthetic ap‐ proach to biogeographical processes. By their nature, the processes underlying biogeographic distributions and evolution on (remote) Islands occur on large scales of time and space and remain among the most difficult to study and understand. Although some of the top‐ ics emphasized by MacArthur and Wilson still re‐ main relatively unexplored, recent advances in Island theory demonstrate that we are moving towards a new synthesis, identifying and incorpo‐ rating aspects of the Island systems that were not considered in the past. All the talks in the Island Biogeography session pointed in this direction. One of the first lessons taught to us by Wal‐ lace, decades before MacArthur and Wilson, is that comparisons among different archipelagos and biogeographic regions of the globe can offer significant insights and increase our understand‐ ing of the processes regulating biodiversity across time and space (see Wallace 1887). Daniel Car‐ stensen and colleagues compared the bio‐ geographical patterns of birds in Wallacea and the West Indies, adopting a network approach to detect biogeographical modules (i.e. sub‐regions of Islands compartmentalized on the basis of a common avifauna) and the roles of each Island according to its spatial location and the topology of the geographical network. They discussed the relative importance of Island features and species richness on the local and regional fauna of the two biogeographical regions. Similarly, Silvia Aranda and co‐workers compared, within the framework of the Theory of Island Biogeography, the effects of area, isolation, geological age and climate on bryophyte species richness on Macaronesian Is‐ lands. They provided evidence that, in addition to area, it is necessary to quantify other variables that are also critical for the establishment of bio‐ diversity and at the same time have high explana‐ tory power (such as Island age and climate), if we are to build up a more predictive science of spe‐ cies richness variation across Island systems. However, Island area remains the most powerful single variable in explaining variation in the number of species occupying an Island and the species–area relationship (SAR) is one of ecology’s few laws. Even and Kathleen Tjorve showed that we should consider with caution the common assumption that the power law of Arrhenius is appropriate for both sample‐area (mainland) SARs and isolate (Island) SARs. Especially regarding iso‐ late SARs, they argue that the form of the rela‐ tionship is actually sigmoid when the finest scales are included. Based on this assumption, they pro‐ posed a new species–area model and presented results from different archipelagos and taxa. Fifty years ago E.O Wilson, studying Mela‐ nesian ants, coined the term ‘taxon cycle’ to de‐ scribe ‘the inferred cyclical evolution of species [of Melanesian ants], from the ability to live in mar‐ ginal habitats and disperse widely, to preference for more central, species‐rich habitats with an as‐ sociated loss of dispersal ability, and back again’ (Wilson 1961). However, the taxon cycle has, until recently, been difficult to test (see Rick‐ lefs and Bermingham 2002). Evan Economo and Eli Sarnat evaluated taxon cycle predictions with a new dataset on habitat distributions of the entire Fijian ant fauna and a community phylogeny for one of the genera present in that archipelago. They provided evidence that as lineages progress to higher levels of endemism, they undergo shifts from marginal to interior primary habitats, from ecological generalism to specialization, and from frontiers of Biogeography 3.1, 2011 — © 2011 the authors; journal compilation © 2011 The International Biogeography Society
