Effect of distance, area, and climate on the frequency of introduction and extinction events on islands and archipelagos

Abstract

Abstract Change in community similarity (e.g., biotic homogenization) is regulated by different types of introduction and extinction events. However, the spatial patterns and potential drivers of these event types have not yet been addressed to date. Here, we used bird species occurrences on 152 oceanic islands worldwide in both historical (~1500 CE) and current periods with the aim to (1) elucidate the variations of these events among islands and archipelagos and (2) disentangle the effects of biogeographical and environmental factors (e.g., spatial distance, island area, climatic conditions, and/or inter‐island distance). We found that community similarity increased at both island and archipelago scales after species introductions and extinctions. The introduction and extinction of one species to/from only one island (unique introduction and extinction) comprise most events (>94%). Island area has a positive effect on nearly all event types at both island and archipelago scales, while climate difference generally has a negative effect on these events. Conversely, responses to spatial distance and inter‐island distance on different events are more complex than expected. Overall, biogeographical variables (area and distance) seem to explain most of the events followed by climate variables. Yet extinction events at the archipelago level were also highly associated with inter‐island distance as an indicator of dispersal limitation. Our findings provide a solid foundation for understanding the event‐mediated processes of homogenization and present essential insights into how biogeographical and environmental factors affect different events on islands.

Keywords

• biological invasion
• biotic homogenization
• community similarity
• island biogeography
• spatial scale
• species extinction