Islands have been the test bed of several theories in community ecology, biogeography, and evolutionary biology. Progress within these disciplines has given a more comprehensive and mechanistic understanding of the processes governing variation in species richness among islands. However, it remains unclear whether these same processes also explain variation in species and phylogenetic composition among islands. Integrating theory from ecology and biogeography, we infer the roles of dispersal, selection, and stochasticity on the composition of insular assemblages within archipelagos. We further assess the influence of source pool diversity and connectivity on the compositional uniqueness of insular assemblages. Island systems worldwide. We compiled data on species composition of non-volant mammals on ∼200 islands in nine archipelagos distributed worldwide from the literature. We used variation partitioning to quantify the relative influence of the environment (selection) and geographic distance (dispersal) relative to a null model (stochasticity, randomness) on taxonomic and phylogenetic compositional turnover within archipelagos. We then used a linear mixed model to gain further insight into the underlying mechanisms shaping variation in assemblage composition among islands at a global scale. Specifically, we assessed the influence of source pool diversity, isolation from the source pool, and island characteristics on compositional uniqueness. Our results suggest that within-archipelago variation in the composition of insular mammal assemblages is associated with stochastic or unmeasured processes rather than abiotic selection or dispersal limitation. The diversity and proximity of the source pool, as well as some island characteristics, explained variation in phylogenetic, but not taxonomic, compositional uniqueness globally. Within archipelagos, the largely unexplained variation in compositional turnover points to the overwhelming influence of extinction mediated by ecological drift or other stochastic processes, which obscures or overrides the signature of selection and/or dispersal. Globally, isolated islands associated with highly diverse source pools exhibit high phylogenetic uniqueness whereas well-connected islands associated with small source pools show the opposite trend. Phylogenetically unique assemblages also tend to occur on islands with a small elevational span and low annual temperature variation. Taken together, our results suggest that source pool diversity, along with the potential for colonization from those pools, plays an important role in shaping the composition of insular mammal assemblages worldwide. 

This dataset is a set of site by species matrices of the presence/absence of non-volant terrestrial mammals on a total of 204 islands in 9 different island groups. These island groups are as follows: Alexander Archipelago (Alx), Gulf of California (Clf), Mediterranean Land-bridge (MdtLB), Mediterranean Oceanic (MdtOC), Adriatic Sea (Adr), Philippines (Phl), Sundaland (Snd), Maluku islands (Mlk), Melanesia (Mln).

This data was compiled using published records in the primary literature, archipelago-wide checklists, and atlases, and cross-referenced community composition among multiple sources (Table S1 in the associated article). Domesticated and introduced species were omitted when indicated as non-native in the source data or the IUCN Red List.

Data and file overview

Each data file contains a site by species matrix of the presence/absence of non-volant terrestrial mammals. All data files are formatted as comma-separated values (.csv). In each data file, island names are in rows and species names are in columns. A value of 0 indicates absence, and a value of 1 indicates presence. Data files are named by island group as follows: Alexander Archipelago (Alx.csv), Gulf of California (Clf.csv), Mediterranean Land-bridge (MdtLB.csv), Mediterranean Oceanic (MdtOC.csv), Adriatic Sea (Adr.csv), Philippines (Phl.csv), Sundaland (Ind.csv), Maluku islands (Mlk.csv), Melanesia (Mln.csv).

All data files were created in 2016, and last updated in 2020.

Sharing and access information

This dataset is licensed under a CC0 1.0 Universal (CC0 1.0) Public Domain Dedication license.

This dataset is used in the article "Source pool diversity and proximity shape the compositional uniqueness of insular mammal assemblages worldwide" in the Journal of Biogeography, which is in press (DOI will be added when this article is published).

Methodological information

Species presences and absences was compiled using published records in the primary literature, archipelago-wide checklists, and atlases, and cross-referenced community composition among multiple sources (Table S1 in the associated article). Domesticated and introduced species were omitted when indicated as non-native in the source data or the IUCN Red List. 

Data sources per island group:

Alexander Archipelago (Alx.csv)

  Conroy, C.J., Demboski, J.R. & Cook, J.A. (1999). Mammalian biogeography of the Alexander Archipelago of Alaska: a north temperate nested fauna. Journal of Biogeography, 26, 343-352.
  Cook, J.A. & MacDonald, S. (2007). Mammals and amphibians of Southeast Alaska.

MacDonald, S.O. & Cook, J.A. (2010). Recent mammals of Alaska. University of Alaska Press.

Adriatic Sea (Adr.csv)

  Barun, A., Simberloff, D., Meiri, S., Tvrtković, N. & Tadić, Z. (2015). Possible character displacement of an introduced mongoose and     native marten on Adriatic Islands, Croatia. Journal of biogeography, 42, 2257-2269.
  Krystufek, B. & Kletecki, E. (2007). Biogeography of small terrestrial vertebrates on the Adriatic landbridge islands. Folia zoologica, 56, 225.
  Kryštufek, B., Murariu, D. & Kurtonur, C. (1997). Present distribution of the Golden Jackal Canis aureus in the Balkans and adjacent regions. Mammal Review, 27, 109-114.
  
Gulf of California (Clf.csv)

  Álvarez-Castañeda, S.T. & Ortega-Rubio, A. (2003). Current status of rodents on islands in the Gulf of California. Biological Conservation, 109, 157-163.
  Ceballos, G. (2014). Mammals of Mexico. JHU Press.
IUCN (2016). The IUCN Red List of Threatened Species. Version 2016-3. 
Millien, V. & Gonzalez, A. (2011). The maximal body mass–area relationship in island mammals. Journal of biogeography, 38, 2278-2285.

Sundaland (Ind.csv)

  Meijaard, E. (2003). Mammals of south‐east Asian islands and their Late Pleistocene environments. Journal of Biogeography, 30, 1245-1257.
  Millien, V. & Gonzalez, A. (2011). The maximal body mass–area relationship in island mammals. Journal of biogeography, 38, 2278-2285.
  Suyanto, A., Yoneda, M., Maryanto, I., Maharadatunkamsi, H. & Sugardjito, J. (1998). Checklist of the mammals of Indonesia. LIPI-JICA Joint Project for Biodiversity Conservation in Indonesia.

Maluku Islands (Mlk.csv)

  Meijaard, E. (2003). Mammals of south‐east Asian islands and their Late Pleistocene environments. Journal of Biogeography, 30, 1245-1257.
  Millien, V. & Gonzalez, A. (2011). The maximal body mass–area relationship in island mammals. Journal of biogeography, 38, 2278-2285.
  Suyanto, A., Yoneda, M., Maryanto, I., Maharadatunkamsi, H. & Sugardjito, J. (1998). Checklist of the mammals of Indonesia. LIPI-JICA Joint Project for Biodiversity Conservation in Indonesia.

Mediterranean (MdtLB.csv and MdtOC.csv)

  Angelici, F., Laurenti, A. & Nappi, A. (2009). A checklist of the mammals of small Italian islands. Hystrix, the Italian Journal of Mammalogy, 20.
  Millien, V. & Gonzalez, A. (2011). The maximal body mass–area relationship in island mammals. Journal of biogeography, 38, 2278-2285.
  Vigne, J.-D. (1992). Zooarchaeology and the biogeographical history of the mammals of Corsica and Sardinia since the last ice age. Mammal Review, 22, 87-96.
  
Melanesia (Mln.csv)

  Lavery, T.H., Olds, A.D., Seddon, J.M. & Leung, L.K.P. (2016). The mammals of northern Melanesia: speciation, ecology, and biogeography. Mammal Review, 46, 60-76.

Philippines (Phl.csv)

  Heaney, L.R., Balete, D.S., Duya, M.R.M., Duya, M.V., Jansa, S.A., Steppan, S.J. et al. (2016). Doubling diversity: a cautionary tale of previously unsuspected mammalian diversity on a tropical oceanic island. Frontiers of Biogeography, 8.
  Heaney, L.R., Dolar, M.L., Balete, D.S., Esselstyn, J.A., Rickart, E.A. & Sedlock, J.L. (2010). Synopsis of Philippine Mammals. The Field Museum of Natural History.
  Heaney, L.R., Dolar, M.L., Balete, D.S., Esselstyn, J.A., Rickart, E.A. & Sedlock, J.L. (2011). Supplement to the Synopsis of Philippine Mammals. The Field Museum of Natural History.
  Meijaard, E. (2003). Mammals of south‐east Asian islands and their Late Pleistocene environments. Journal of Biogeography, 30, 1245-1257.
  Millien, V. & Gonzalez, A. (2011). The maximal body mass–area relationship in island mammals. Journal of biogeography, 38, 2278-2285.

Data-specific information

Island names are in rows, and species names are in columns. A value of 0 indicates absence, and a value of 1 indicates presence. The dataset includes oceanic and land-bridge islands, though each island group consists of only one type of island. Gulf of California (Clf), Mediterranean Land-bridge (MdtLB), Adriatic Sea (Adr), and Sundaland (Snd) consist of land-bridge islands. Alexander Archipelago (Alx), Mediterranean Oceanic (MdtOC), Philippines (Phl), Maluku islands (Mlk), Melanesia (Mln) consist of oceanic islands. However, the Alexander Archipelago (Alx) islands were colonized via dispersal after emerging as a “blank slate” after deglaciation approximately 15,000 years ago, and can therefore be treated as land-bridge islands in this dataset. Access to complete species-level presence-absence data for the entire mammal fauna of individual islands limited the selection of island groups.