Focusing on the theme of island biogeography, we read an experimental paper by Simberloff & Wilson as well as a synthesis paper from Patiño et al. that came out of working group discussions at the 2016 Island Biology Conference. Together, these two works span the wide breadth of topics foundational to island biogeography including dispersal dynamics, colonization patterns, and extinction rates. As my research may deal with thinking of patch dynamics between different habitats of various resources, clarification of island biogeography theory and its translatable application to non-island systems such as fragmented landscapes will be important.
Simberloff & Wilson’s goal is to test theory put forth by McArthur & Wilson’s Monograph in Population in Biology series. By fumigating mangrove islands off the coast of Florida, the authors are able to observe colonization and competition dynamics in action, until the islands reach equilibrium arthropod species richness levels. I was particularly impressed with the speed in which this equilibrium was reached, in less than a year. I think this may be in some ways do the methodology of the eradication, as resources and habitat were maintained unlike many natural experiments of island colonization after volcanic eruptions. However, this method may be appropriate for more targeted disturbances such as an invasive species or an epidemic that wipes out the arthropod community. With large scale manipulative projects like this, it seems inevitable that sampling and replication are issues. Across the six islands, the authors were not able to support that distance from the faunal source was indicative of time to equilibrium, despite clear distance patterns pre-defaunation on species compositions of islands. While species richness equilibriums were achieved, population abundances were not comparable to pre-defaunation. I think this exemplifies the more recent term of “immigration credit”, where colonizers can be counted for richness values before they are functionally fixed.
Patiño et al. ask 50 new questions from the context of island biogeography to drive future work. This genre of a “horizon scan” is an appealing synthesis piece that acts as a concrete product from conference discussions. To coordinate pre-conference surveys, during conference discussions, and post-conference editing certainly was a challenge, yet this paper exemplifies a model the type of planning necessary to optimize conference-based collaborations. I think in contrast to the methods used in the paper that spurred this reading group (Courchamp and Bradshaw 2018), this process seemed more iterative and with strategic inclusion of multiple perspectives. I also appreciated the ten questions that are heavily related to how island biogeography theory can inform conservation and management policies. This field seems to especially be influenced by cross-disciplines such as genetics, paleobiology, climatology and geology. I think similar to other areas of ecology, island biology studies will move to an increasingly ecosystem-level and function studies of multiple trophic level interactions, community dynamics, and global change.
Simberloff DS, Wilson EO. (1969) Experimental zoogeography of islands: the colonization of empty islands. Ecology 50, 278–296.
Patiño J, Whittaker RJ, Borges PA, Fernández‐Palacios JM, Ah‐Peng C, Araújo MB, Ávila SP, Cardoso P, Cornuault J, de Boer EJ, de Nascimento L. (2017) A roadmap for island biology: 50 fundamental questions after 50 years of The Theory of Island Biogeography. Journal of Biogeography 44(5):963-83.