1
|
Llorente-Culebras S, Carmona CP, Carvalho WD, Menegotto A, Molina-Venegas R, Ladle RJ, Santos AMC. Island biodiversity in peril: Anticipating a loss of mammals' functional diversity with future species extinctions. GLOBAL CHANGE BIOLOGY 2024; 30:e17375. [PMID: 38895806 DOI: 10.1111/gcb.17375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/10/2024] [Accepted: 05/16/2024] [Indexed: 06/21/2024]
Abstract
Islands are biodiversity hotspots that host unique assemblages. However, a substantial proportion of island species are threatened and their long-term survival is uncertain. Identifying and preserving vulnerable species has become a priority, but it is also essential to combine this information with other facets of biodiversity like functional diversity, to understand how future extinctions might affect ecosystem stability and functioning. Focusing on mammals, we (i) assessed how much functional space would be lost if threatened species go extinct, (ii) determined the minimum number of extinctions that would cause a significant functional loss, (iii) identified the characteristics (e.g., biotic, climatic, geographic, or orographic) of the islands most vulnerable to future changes in the functional space, and (iv) quantified how much of that potential functional loss would be offset by introduced species. Using trait information for 1474 mammal species occurring in 318 islands worldwide, we built trait probability density functions to quantify changes in functional richness and functional redundancy in each island if the mammals categorized by IUCN as threatened disappeared. We found that the extinction of threatened mammals would reduce the functional space in 63% of the assessed islands, although these extinctions in general would cause a reduction of less than 15% of their overall functional space. Also, on most islands, the extinction of just a few species would be sufficient to cause a significant loss of functional diversity. The potential functional loss would be higher on small, isolated, and/or species-rich islands, and, in general, the functional space lost would not be offset by introduced species. Our results show that the preservation of native species and their ecological roles remains crucial for maintaining the current functioning of island ecosystems. Therefore, conservation measures considering functional diversity are imperative to safeguard the unique functional roles of threatened mammal species on islands.
Collapse
Affiliation(s)
- Sonia Llorente-Culebras
- Terrestrial Ecology Group (TEG-UAM), Departamento de Ecología, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Carlos P Carmona
- Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
| | - William D Carvalho
- Terrestrial Ecology Group (TEG-UAM), Departamento de Ecología, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
- Programa de Pós-Graduação em Biodiversidade Tropical, Universidade Federal do Amapá, Macapá, Brazil
| | - André Menegotto
- Terrestrial Ecology Group (TEG-UAM), Departamento de Ecología, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Rafael Molina-Venegas
- Terrestrial Ecology Group (TEG-UAM), Departamento de Ecología, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| | - Richard J Ladle
- Institute of Biological and Health Sciences, Federal University of Alagoas, Maceió, Brazil
| | - Ana M C Santos
- Terrestrial Ecology Group (TEG-UAM), Departamento de Ecología, Universidad Autónoma de Madrid, Madrid, Spain
- Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, Madrid, Spain
| |
Collapse
|
2
|
Maki T, Sannomiya N, Hirao T, Fukui D. Scale-dependent influences of environmental, historical, and spatial processes on taxonomic and functional beta diversity of Japanese bat assemblages. Ecol Evol 2024; 14:e11277. [PMID: 38628917 PMCID: PMC11019122 DOI: 10.1002/ece3.11277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/14/2024] [Accepted: 04/02/2024] [Indexed: 04/19/2024] Open
Abstract
This study investigated the relative influences of environmental, spatial, and historical factors, including the island-specific history of land connectivity, on bat assemblages in the Japanese Archipelago. We collected bat distribution data from 1408 studies and assigned them to Japan's First Standard Grid (approximately 6400 km2). Japanese bat assemblages were analyzed at two scales: the entire Japanese Archipelago comprised 16 islands and exclusively the four main islands. At first, we calculated taxonomic and functional total beta diversity (β total) by Jaccard pairwise dissimilarity and then divided this into turnover (β repl) and richness-difference (β rich) components. We conducted hierarchical clustering of taxonomic beta diversity to examine the influence of the two representative sea straits, Tsugaru and Tokara, which are considered biogeographical borders. Variation partitioning was conducted to evaluate the relative effects of the three factors on the beta diversity. Clustering revealed that the Tokara Strait bordered the two major clades; however, the Tsugaru Strait did not act as a biogeographical border for bats. In the variation partitioning, shared fraction between spatial and historical factors significantly explained taxonomic and functional β total and taxonomic β repl at the entire archipelago scale, but not at the four main islands scale extending only Tsugaru Strait but not Tokara Strait. Pure environmental factors significantly explained functional β total at both scales and taxonomic β total only at the four main islands scale. These results suggest that spatial and historical factors are more pronounced in biogeographical borders, primarily structuring assemblage composition at the entire archipelago scale, especially in taxonomic dimension. However, current environmental factors primarily shape the assemblage composition of Japanese bats at the main island scale. The difference in results between the two scales highlights that the primary processes governing assemblages of both dimensions depend on the quality of the dispersal barriers between terrestrial and aquatic barriers for bats.
Collapse
Affiliation(s)
- Takahiro Maki
- Amami Station, International Center for Island StudiesKagoshima UniversityKagoshimaJapan
- The University of Tokyo Forests, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Nozomi Sannomiya
- The University of Tokyo Forests, Graduate School of Agricultural and Life SciencesThe University of TokyoTokyoJapan
| | - Toshihide Hirao
- The University of Tokyo Chichibu Forest, Graduate School of Agricultural and Life SciencesThe University of TokyoSaitamaJapan
| | - Dai Fukui
- Fuji Iyashinomori Woodland Study Center, Graduate School of Agricultural and Life SciencesThe University of TokyoYamanashiJapan
| |
Collapse
|
3
|
Kennedy S, Calaor J, Zurápiti Y, Hans J, Yoshimura M, Choo J, Andersen JC, Callaghan J, Roderick GK, Krehenwinkel H, Rogers H, Gillespie RG, Economo EP. Richness and resilience in the Pacific: DNA metabarcoding enables parallelized evaluation of biogeographic patterns. Mol Ecol 2023; 32:6710-6723. [PMID: 35729790 DOI: 10.1111/mec.16575] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/04/2022] [Accepted: 06/09/2022] [Indexed: 11/29/2022]
Abstract
Islands make up a large proportion of Earth's biodiversity, yet are also some of the most sensitive systems to environmental perturbation. Biogeographic theory predicts that geologic age, area, and isolation typically drive islands' diversity patterns, and thus potentially impact non-native spread and community homogenization across island systems. One limitation in testing such predictions has been the difficulty of performing comprehensive inventories of island biotas and distinguishing native from introduced taxa. Here, we use DNA metabarcoding and statistical modelling as a high throughput method to survey community-wide arthropod richness, the proportion of native and non-native species, and the incursion of non-natives into primary habitats on three archipelagos in the Pacific - the Ryukyus, the Marianas and Hawaii - which vary in age, isolation and area. Diversity patterns largely match expectations based on island biogeography theory, with the oldest and most geographically connected archipelago, the Ryukyus, showing the highest taxonomic richness and lowest proportion of introduced species. Moreover, we find evidence that forest habitats are more resilient to incursions of non-natives in the Ryukyus than in the less taxonomically rich archipelagos. Surprisingly, we do not find evidence for biotic homogenization across these three archipelagos: the assemblage of non-native species on each island is highly distinct. Our study demonstrates the potential of DNA metabarcoding to facilitate rapid estimation of biogeographic patterns, the spread of non-native species, and the resilience of ecosystems.
Collapse
Affiliation(s)
- Susan Kennedy
- Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- Department of Biogeography, Trier University, Trier, Germany
| | - Jerilyn Calaor
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, USA
| | - Yazmín Zurápiti
- Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Julian Hans
- Department of Biogeography, Trier University, Trier, Germany
| | - Masashi Yoshimura
- Environmental Research Support Section, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Juanita Choo
- Science and Technology Group, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Jeremy C Andersen
- Department of Environmental Conservation, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Jackson Callaghan
- Department of Integrative, Structural and Computational Biology, The Scripps Research Institute, La Jolla, California, USA
| | - George K Roderick
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, USA
| | | | - Haldre Rogers
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa, USA
| | - Rosemary G Gillespie
- Department of Environmental Science, Policy and Management, University of California, Berkeley, California, USA
| | - Evan P Economo
- Biodiversity and Biocomplexity Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- Radcliffe Institute for Advanced Study, Harvard University, Cambridge, Massachusetts, USA
| |
Collapse
|
4
|
Barreto E, Rangel TF, Pellissier L, Graham CH. Area, isolation and climate explain the diversity of mammals on islands worldwide. Proc Biol Sci 2021; 288:20211879. [PMID: 34905709 PMCID: PMC8670959 DOI: 10.1098/rspb.2021.1879] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Insular biodiversity is expected to be regulated differently than continental biota, but their determinants remain to be quantified at a global scale. We evaluated the importance of physical, environmental and historical factors on mammal richness and endemism across 5592 islands worldwide. We fitted generalized linear and mixed models to accommodate variation among biogeographic realms and performed analyses separately for bats and non-volants. Richness on islands ranged from one to 234 species, with up to 177 single island endemics. Diversity patterns were most consistently influenced by the islands' physical characteristics. Area positively affected mammal diversity, in particular the number of non-volant endemics. Island isolation, both current and past, was associated with lower richness but greater endemism. Flight capacity modified the relative importance of past versus current isolation, with bats responding more strongly to current and non-volant mammals to past isolation. Biodiversity relationships with environmental factors were idiosyncratic, with a tendency for greater effects sizes with endemism than richness. The historical climatic change was positively associated with endemism. In line with theory, we found that area and isolation were among the strongest drivers of mammalian biodiversity. Our results support the importance of past conditions on current patterns, particularly of non-volant species.
Collapse
Affiliation(s)
- Elisa Barreto
- Programa de pósgraduação em Ecologia e Evolução, Universidade Federal de Goiás, Goiânia, Brazil.,Swiss Federal Institute for Forest, Snow and Landscape, Birmensdorf, Switzerland
| | - Thiago F Rangel
- Departamento de Ecologia, Universidade Federal de Goiás, Goiânia, Brazil
| | - Loïc Pellissier
- Swiss Federal Institute for Forest, Snow and Landscape, Birmensdorf, Switzerland.,Landscape Ecology, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, Switzerland
| | - Catherine H Graham
- Swiss Federal Institute for Forest, Snow and Landscape, Birmensdorf, Switzerland
| |
Collapse
|