Comparing spatial diversification and meta-population models in the Indo-Australian Archipelago.

Loïc Chalmandrier,Jens-Christian Svenning,Brody Sandel,Soren Faurby,Niklaus E Zimmermann,Camille Albouy,Loïc Pellissier,Patrice Descombes

doi:10.1098/rsos.171366

Abstract

Reconstructing the processes that have shaped the emergence of biodiversity gradients is critical to understand the dynamics of diversification of life on Earth. Islands have traditionally been used as model systems to unravel the processes shaping biological diversity. MacArthur and Wilson's island biogeographic model predicts diversity to be based on dynamic interactions between colonization and extinction rates, while treating islands themselves as geologically static entities. The current spatial configuration of islands should influence meta-population dynamics, but long-term geological changes within archipelagos are also expected to have shaped island biodiversity, in part by driving diversification. Here, we compare two mechanistic models providing inferences on species richness at a biogeographic scale: a mechanistic spatial-temporal model of species diversification and a spatial meta-population model. While the meta-population model operates over a static landscape, the diversification model is driven by changes in the size and spatial configuration of islands through time. We compare the inferences of both models to floristic diversity patterns among land patches of the Indo-Australian Archipelago. Simulation results from the diversification model better matched observed diversity than a meta-population model constrained only by the contemporary landscape. The diversification model suggests that the dynamic re-positioning of islands promoting land disconnection and reconnection induced an accumulation of particularly high species diversity on Borneo, which is central within the island network. By contrast, the meta-population model predicts a higher diversity on the mainlands, which is less compatible with empirical data. Our analyses highlight that, by comparing models with contrasting assumptions, we can pinpoint the processes that are most compatible with extant biodiversity patterns.

Highlights

Understanding mechanisms of speciation and colonization throughout Earth’s history is fundamental to reconstruct how life has diversified and produced biodiversity gradients [1]
We further evaluated whether the simulation results of the diversification and meta-population models matched the empirical distribution data for 14 plant families
The diversification model predicted that the Southeast Asia Archipelago is a hotspot of diversity with more species than continental Southeast Asia and Australia, while the meta-population model predicted the inverse pattern, with the Archipelago having a lower diversity than the continents

Summary

Introduction

Understanding mechanisms of speciation and colonization throughout Earth’s history is fundamental to reconstruct how life has diversified and produced biodiversity gradients [1]. Since the spatial distribution of ecological conditions has changed over geological time [3,4], and because those shifts have modulated speciation and extinction [5], it is important to consider palaeoenvironmental conditions to understand extant biodiversity gradients [4,6,7]. Studies investigating biodiversity gradients related to current environmental patterns are almost always spatially explicit [8,9]. Novel approaches are needed to couple reconstructions of the palaeo-environment with spatially explicit models of speciation and extinction [15,16]

Methods

Results

Conclusion