In the Light of Evolution Volume X: Comparative Phylogeography (2017) / Chapter Skim
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4 Comparative Phylogeography of Oceanic Archipelagos: Hotspots for Inferences of Evolutionary Process - Kerry L. Shaw and Rosemary G. Gillespie
4 Comparative Phylogeography of Oceanic Archipelagos: Hotspots for Inferences of Evolutionary Process - Kerry L. Shaw and Rosemary G. Gillespie
Pages 67-86
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From page 67... ...
‡ AND ROSEMARY G GILLESPIE† Remote island archipelagos offer superb opportunities to study the evolu tion of community assembly because of their relatively young and simple communities where speciation contributes to the origin and evolution of community structure.
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From page 68... ...
in particular because they are often formed with a full complement of species and have more frequent connections with source pools. Along with the effects of small size, spatial isolation, and dispersal origins on community assembly of remote islands, common phylogeographic
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From page 69... ...
In this paper, we examine the progression rule to gain insight into the process of community assembly. In the following sections, we first present a brief overview of the progression rule from exemplar remote oceanic archipelagos.
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From page 70... ...
Simple progression B Clades and grades FIGURE 4.1 Hypothetical progression patterns.
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From page 71... ...
THE PROGRESSION RULE IN COMPARATIVE ISLAND PHYLOGEOGRAPHY In the context of islands, a progression rule (or pattern) refers to a phenomenon of phylogeographic concordance with island age, whereby older lineages map to older islands within an archipelago, and younger lineages map to progressively younger islands in that system (Fig.
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From page 72... ...
than others, resulting in repeated colonizations by the same lineages, producing conditions for either biotic turnover or anagenesis, rather than the within- rchipelago a cladogenesis associated with the progression pattern (Rosindell and Phillimore, 2011)
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From page 73... ...
. This progression pattern would arise when the interisland colonists from an older island migrate early in the history of the extant, older island clade.
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From page 74... ...
Thus, despite the modest extent and topography of the Austral islands and the widespread and generalist nature of their taxa, all studies to date show strong support for a progression rule in this archipelago. Society Islands Age progression within the Society Islands is in good agreement with the fixed hotspot hypothesis (Clouard and Bonneville, 2005)
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From page 75... ...
. A progression pattern has been inferred for Galapagos bulimulid land snails (Parent and Crespi, 2009)
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From page 76... ...
. Older islands in the Canaries may show loss of old resident species due to aridification and orographic simplification; in some lineages, this may have been compensated by colonization and subsequent diversification of new, better-adapted organisms that could take advantage of empty niches and new opportunities.
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From page 77... ...
The history of community assembly over evolutionary time also may be informed by the geographical polarity evident in the progression pattern of a lineage. In an archipelago with a linear spatial and chronological sequence, like those often present in hotspot regions, a simple progression pattern is coincident with a unidirectional path of colonization from older to younger islands.
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From page 78... ...
Gillespie sequence of the archipelago landscape promotes a progression pattern because a probable source of colonists is available to establish the next stepping stone in the series once the next island habitat emerges. Thus, the initial progression arising from older to younger island colonizations seems relatively easy to explain.
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From page 79... ...
Curiously, although the consequences of priority effects are well understood over evolutionary timescales, the opposite appears to be true at ecological timescales. Biotic Turnover on an Ecological Timescale MacArthur and Wilson (1967)
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From page 80... ...
give way to the biotic resistance and community "lockup" dynamics that might sustain a progression pattern over evolutionary timescales? Possible hypotheses to explain community lockup dynamics that maintain progression patterns might be as follows.
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From page 81... ...
Whether sufficient data exist to mark these separate histories is an empirical issue, but to be sure, if we combine data across data partitions that represent distinctive histories, we will lose insights into these complexities. In a recent phylogeographic context, it is possible for different gene partitions to reveal conflicting but true histories that manifest more than one of these progression patterns within the same lineage.
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From page 82... ...
. Bootstrap values are shown for 1,000 parsimony replicates below branches.
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From page 83... ...
. The promise of these new genetic data technologies is that the heterogeneity of progression patterns can be fully investigated, and potentially lead to an understanding of the causes of such heterogeneous genetic signatures.
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From page 84... ...
The community might be resistant to subsequent invasion due to the monopolization of resources by the numerically dominant resident species; the more similar late colonists are to resident species, the less likely they are to successfully invade.
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From page 85... ...
Better characterization of ecological traits, reproductive behaviors, divergence times, and genetic admixture among lineages of island radiations should allow for more rigorous evaluation of priority effects on the development of progression within a phylogenetic context. The study of community assembly in and beyond the radiation zone is exciting in part because it brings together two fairly disparate disciplines: the ecological study of community structure and the evolutionary study of the origin of species.
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From page 86... ...
Gillespie ing, over a similar time frame that plays out over extended evolutionary time. Thus, we can measure ecological metrics at different time slices of the community assembly process to find how properties (species diversity, abundance, body size distributions, trophic interactions)
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