Accounting for dispersal using simulated data improves understanding of species abundance patterns. Issue 2 (12th October 2021) - Feng, Xiao
Abstract: Aim: A long‐standing question in ecology and biogeography is how the population of a species is distributed across space. The highest abundance has been hypothesized to be in the geographical centre or the niche centre, although mixed patterns from empirical studies have triggered a recent debate. Here, we propose a conceptual framework based on environmental suitability and dispersal to interpret the mixed evidence. Location: Global. Time period: Present. Major taxa studied: Virtual species. Methods: We conducted a series of simulations to demonstrate how the abundance pattern would be affected by environmental suitability and dispersal ability. We simulated different combinations of environmental suitabilities and dispersal abilities in landscapes with varied heterogeneities. We also investigated how frequently the location of the niche centre overlapped with the geographical centre. Results: We demonstrated that the highest abundance could occur in the geographical centre, in the niche centre or somewhere in between the two centres, depending on the environmental set‐up and dispersal ability. We found that geographical and niche centres rarely overlapped, suggesting that a counteracting effect between the two factors, rather than reinforcement, is the norm in determining abundance patterns. Therefore, we would expect the highest abundance in the real world to occur between the two centres, in the niche centre, or in the geographical centre, in descending frequency. Main conclusions: Our proposed framework can be used to interpret the mixed patterns from empirical studies when testing the abundant‐centre and abundant niche‐centre hypotheses. Understanding the role of dispersal allows us to make predictions of the location with the highest abundance, as well as its location relative to the geographical centre and the niche centre. The varied locations of highest abundance mirror the mixed evidence in the literature, suggesting that the abundant‐centre and abundant niche‐centre hypotheses are not mutually exclusive. This highlights the importance of considering the underlying mechanisms for a better understanding of biogeographical patterns.