Review

Island biogeography: Taking the long view of nature’s laboratories

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Science  01 Sep 2017:
Vol. 357, Issue 6354, eaam8326
DOI: 10.1126/science.aam8326

Figures

  • Islands provide model systems for the investigation of the fundamental biogeographical processes of migration, diversification, and extinction, as discussed herein with emphasis on long-term dynamics.

  • Fig. 1 Insular species extinctions since 1500 CE.

    (A) Comparison of insular and continental extinctions for birds, plants, and invertebrates [data source: (8)]. (Inset) Rodrigues solitaire (extinct flightless endemic; by Frederick William Frohawk, 1907). (B) Cumulative island endemic extinctions, for those species for which an estimate of date of loss is available [compiled from (8, 9, 94)].

  • Fig. 2 MacArthur and Wilson’s equilibrium theory of island biogeography.

    (A) The core model of how isolation-controlled immigration, I, and area-controlled extinction, E, respond to species richness (P, mainland species pool; dotted lines indicate combinations of richness and turnover rate for particular combinations of island area and isolation). (B) Hypothesized adjustments of initial equilibrium through community and evolutionary processes, leading to (C) predicted elevation of the island species–area relationship due to in situ diversification. The possible correspondence between time points in (B) and (C) is our addition. [(A) and (C) modified from (10), (B) modified from (95)]

  • Fig. 3 The implications of island geodynamics for island biogeographical processes.

    (A) The dynamics of a generalized hotspot archipelago: island emergence, building, erosion, and subsidence to become seamounts (guyots) drives phases where, in turn, immigration, diversification, and extinction dominate, generating island progression-rule patterns. (B) Trends in key process rates (I, immigration; S, speciation; E, extinction) (dashed lines), generating a realized species richness trajectory over time in relation to a hypothetical carrying capacity K, controlled by the island ontogeny, as formalized in the general dynamic model of oceanic island biogeography (20). (C) Alternative ontogenies, which can be used to generate alternative biogeographic models (20, 24, 96).

  • Fig. 4 Generalizations about island species–area relationships (ISARS) based on recent analyses of multiple data sets (5760).

    (A) As island isolation increases, the ISAR slope (z) increases, with intermediate isolation generating the highest rates of species turnover. (B) For remote archipelagos, the endemics subset produces steeper slopes and lower intercepts than non-endemic native species. (C) The slope of the archipelago species–area relationship (ASAR) should generally exceed the slopes of the constituent archipelago ISARs. Points A and B on the ASAR represent the archipelago diversity for archipelagos A and B, respectively.

  • Fig. 5 Contrasting directional movements of evolutionary lineages.

    (A) Wilson’s (62) taxon cycle describes the directional movement of ponerine ants from mainland to the Pacific islands, where derived forms evolve (inset: Diacamma sp., Sabah, by S. Shattuck, 2012, www.antwiki.org/wiki/Diacamma; license: https://creativecommons.org/licenses/by-sa/3.0/). (B) Fjeldså’s (66) interpretation of Oscine (songbird) evolution, as an insular radiation in the region of present-day New Guinea (using a reconstructed base map for ~34 million years ago), subsequently spreading throughout the globe to provide around half of the world’s birds (inset: Atrapia mayeri, New Guinea, by H. E. W. Cottee-Jones).

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