Abstract
AbstractAimIdentifying niche shifts is key for forecasting future species distributions. Non‐indigenous species (NIS) are one of the greatest threats to biodiversity, and understanding how niche shifts affect the spread of NIS is fundamental. Here, we modelled the native and introduced niches, as well as the potential geographical extent of a widely distributed NIS, the Pacific oyster Magallana gigas. We then tested for niche shifts in environmental space and predicted spread under contemporary climate change (CCC) conditions.LocationGlobal.MethodsWe used: (1) the two‐dimensional Centroid shift, Overlap, Unfilling and Expansion (COUE) framework and (2) the n‐dimensional hypervolume framework (NDH) to quantify the niches in both analogue and total environmental spaces. Niches were tested for equivalency by comparing the observed and randomized overlaps. Ensemble ecological niche models (ENMs) were then used to predict habitat suitability for the present‐day and two future CCC scenarios.ResultsThe NDH framework indicated that the introduced niche of M. gigas has shifted into new environmental conditions compared to the native niche. In contrast, COUE framework implied no niche shift, but the first two dimensions only accounted for a small proportion of the overall environmental variability. Ensemble ENMs revealed suitable areas where M. gigas has yet to be recorded and predicted both a poleward expansion and a tropical contraction of suitable habitat for M. gigas by 2100.Main conclusionsWe found that M. gigas has rapidly shifted its niche in both analogue and non‐analogue environmental spaces since it was first recorded as introduced species over 50 years ago. Our results suggested that niche shifts facilitate both present‐day and future spread of NIS. Additionally, our study demonstrated the importance of modelling niche dynamics in multidimensional space for predicting range shifts of NIS under CCC.
Highlights
Non-indigenous species (NIS) are one of the biggest threats to global biodiversity (Bax et al, 2003; Molnar et al, 2008), and understanding their potential distributions in the near future is a priority for biodiversity managers (Guisan et al, 2013; Sinclair et al, 2010)
Ecological niche models (ENMs) are popular mathematical models used to increase our understanding of suitable habitats and predicting areas that may be at risk of invasion (Mainali et al, 2015; Thuiller et al, 2005; Václavík & Meentemeyer, 2012)
This study revealed rapid niche shifts in a highly successful marine NIS in its introduced range
Summary
Non-indigenous species (NIS) are one of the biggest threats to global biodiversity (Bax et al, 2003; Molnar et al, 2008), and understanding their potential distributions in the near future is a priority for biodiversity managers (Guisan et al, 2013; Sinclair et al, 2010). Ecological niche models (ENMs) are popular mathematical models used to increase our understanding of suitable habitats and predicting areas that may be at risk of invasion (Mainali et al, 2015; Thuiller et al, 2005; Václavík & Meentemeyer, 2012). Range shifts are an order of magnitude faster than terrestrial ecosystems (Sorte et al, 2010), and investigating potential marine NIS distributions and areas at risk of invasion with CCC is of high importance. An increasing number of studies using ENMs suggest that NIS will expand their ranges and/or shift their ranges poleward as a result of ocean warming (Goldsmit et al, 2018; de Rivera et al, 2011; Saupe et al, 2014), less is known about the stability of their niche space over time
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