Secondary Sympatry Caused by Range Expansion Informs on the Dynamics of Microendemism in a Biodiversity Hotspot

Abstract

Islands are bounded areas where high endemism is explained either by allopatric speciation through the fragmentation of the limited amount of space available, or by sympatric speciation and accumulation of daughter species. Most empirical evidence point out the dominant action of allopatric speciation. We evaluate this general view by looking at a case study where sympatric speciation is suspected. We analyse the mode, tempo and geography of speciation in Agnotecous, a cricket genus endemic to New Caledonia showing a generalized pattern of sympatry between species making sympatric speciation plausible. We obtained five mitochondrial and five nuclear markers (6.8 kb) from 37 taxa corresponding to 17 of the 21 known extant species of Agnotecous, and including several localities per species, and we conducted phylogenetic and dating analyses. Our results suggest that the diversification of Agnotecous occurred mostly through allopatric speciation in the last 10 Myr. Highly microendemic species are the most recent ones (<2 Myr) and current sympatry is due to secondary range expansion after allopatric speciation. Species distribution should then be viewed as a highly dynamic process and extreme microendemism only as a temporary situation. We discuss these results considering the influence of climatic changes combined with intricate soil diversity and mountain topography. A complex interplay between these factors could have permitted repeated speciation events and range expansion.

Recent species in old Islands: the origin of introduced populations of Litoria aurea (Anura: Hylidae) in New Caledonia and Wallis

“…Hundreds of introduced species recently arose in New Caledonia, particularly the last 50-60 years, and provoked serious damages to native biota and ecosystems (Pellens and Grandcolas, 2010). Given the recent colonisation of the island it is not surprising that no tendency for microendemism was recorded in this species, contrary to what was observed in many other taxonomic groups (e.g., Bartish et al, 2005;Balke et al, 2007;Murienne et al, 2008;Murienne, Guilbert and Grandcolas, 2009;Bauer et al, 2012;Nattier et al, 2012). The whole picture for L. aurea drawn from the present study reinforces the scenario for primitive natural absence of Amphibia in the old island New Caledonia, and is consistent with the new biogeographical paradigm that this island was totally re-colonized after emergence in Eocene.…”

Cricket calling communities as an indicator of the invasive ant Wasmannia auropunctata in an insular biodiversity hotspot

“…1.5*IQR, IQR being the interquartile range between Q1 and Q3. Forest, preforest and shrubland free from invasive species are in blank plots, while invaded habitats by Wasmannia auropunctata are in gray plots, for daytime and nighttime periods been rapidly identified as one of the main putative model groups, with studies devoted to acoustic evolution (Robillard et al 2007;Anso et al 2016a), speciation (Nattier et al 2012), and more recently, the succession of cricket communities in different habitats . The results presented here are considered in the context of complementary taxonomic, ecological and acoustic knowledge acquisition of this group in New Caledonia Anso et al 2016b;Desutter-Grandcolas et al 2016).…”

New lineages of Lebinthini from Australia (Orthoptera: Gryllidae: Eneopterinae)

“…We used a tree-based approach with a maximum likelihood tree reconstructed with the IQ-TREE web service (Nguyen et al 2015). We used a fragment of the small mitochondrial ribosomal subunit (12S rRNA, ~ 400 bp), easy to amplify and which proved to be variable between closely related species in crickets (e.g., Robillard & Desutter-Grandcolas 2006;Nattier et al 2012). Molecular works were performed at the "Service de Systématique Moléculaire" of the MNHN.…”

“…DNA extractions were made from median legs of crickets using the Epmotion 5075 robot (Eppendorf). All sequences were generated using the amplification and sequencing protocols described in Nattier et al (2012), with similar primers and annealing temperatures. Newly generated sequences were edited in Sequencher v.4.9 (Gene Codes Co.) and BioEdit v.7.0.5.3 (Hall 1999), blasted with NCBI blast tools and compared; the data will be published as part of a phylogenetic study of the Lebinthini in preparation.…”