Synchronous diversification of Sulawesi's iconic artiodactyls driven by recent geological events.

Dagmar Obbles,Sharron Ogle,Hally Day,Peter Galbusera,Laurent Frantz ,Robert Hall,Jeroen Van Den Hurk,Mia J Hillyer ,Alastair A Macdonald,Ben Evans ,Rodrigo Vega,Stefan Meker,Thomas Von Rintelen,Evan K Irving-Pease,Ita Djuwita Wiryadi,Simon Y W Ho,Chandramaya Siska Damayanti,Abdul Haris Mustari,Jeremy B Searle,Darren Shaw ,Greger Larson,Ardern Hulme-Beaman,Friederike Johansson,Stefano Mona ,Andrew C Kitchener,Muhammad Yazrin Yasin ,James Burton,Anna Rudzinski,Richard Allen,Mark G Thomas,Allowen Evin,Sarah Gillemot,Kusdiantoro Mohamad,Kristin Leus,Cristina Atofanei,Jimmy A Mcguire,James Haile,Jill M Shephard ,Abang Mansyursyah Surya Nugraha,J L Williams ,Ross Barnett,Anna Linderholm

doi:10.1098/rspb.2017.2566

Abstract

The high degree of endemism on Sulawesi has previously been suggested to have vicariant origins, dating back to 40 Ma. Recent studies, however, suggest that much of Sulawesi's fauna assembled over the last 15 Myr. Here, we test the hypothesis that more recent uplift of previously submerged portions of land on Sulawesi promoted diversification and that much of its faunal assemblage is much younger than the island itself. To do so, we combined palaeogeographical reconstructions with genetic and morphometric datasets derived from Sulawesi's three largest mammals: the babirusa, anoa and Sulawesi warty pig. Our results indicate that although these species most likely colonized the area that is now Sulawesi at different times (14 Ma to 2–3 Ma), they experienced an almost synchronous expansion from the central part of the island. Geological reconstructions indicate that this area was above sea level for most of the last 4 Myr, unlike most parts of the island. We conclude that emergence of land on Sulawesi (approx. 1–2 Myr) may have allowed species to expand synchronously. Altogether, our results indicate that the establishment of the highly endemic faunal assemblage on Sulawesi was driven by geological events over the last few million years.

Highlights

Alfred Russel Wallace was the first to document the ‘anomalous’ biogeographic region in Island Southeast Asia (ISEA) known as Wallacea [1,2]
Using an analysis of molecular variance (AMOVA), we found that these areas of endemism explained approximately 17%, 27% and 5% of the variance in allele frequencies in anoa, babirusa and SWP, respectively
While the different geological components of Sulawesi were assembled at about 23 Ma, the island only acquired its distinctive modern form in the last few million years

Summary

Introduction

Alfred Russel Wallace was the first to document the ‘anomalous’ biogeographic region in Island Southeast Asia (ISEA) known as Wallacea [1,2]. To determine the timings of diversification of the three largest endemic mammals on the island, we generated and analysed genetic and/or morphometric data from a total of 1289 samples of the SWP, anoa and babirusa obtained from museums, zoos and wild populations (456, 520 and 313 samples, respectively; electronic supplementary material, table S1). Our data corroborate previous studies in indicating that both SWP and babirusa are monophyletic with respect to their most closely related taxa on neighbouring islands (e.g. Borneo), which is consistent with only one colonization of Sulawesi (electronic supplementary material, figure S4–S6) [30]. Increasing land area may have promoted a simultaneous diversification and range expansion in babirusa, SWPs and anoas To test this hypothesis, we used a new reconstruction that depicts land area in the Sulawesi region through time using information from the geological record. To further assess whether these Plio-Pleistocene uplifts were responsible for a synchronous expansion, we inferred the most likely geographical origin of expansion using microsatellite (a) (i)

B2 B3 B4 B5 B6

Findings

Conclusion