Phylogeography and niche modelling of the relict plant Amborella trichopoda (Amborellaceae) reveal multiple Pleistocene refugia in New Caledonia

• Published in: Molecular ecology Vol. 22; no. 24; pp. 6163 - 6178
• Main Authors: Poncet, Valérie, Munoz, François, Munzinger, Jérôme, Pillon, Yohan, Gomez, Céline, Couderc, Marie, Tranchant‐Dubreuil, Christine, Hamon, Serge, Kochko, Alexandre
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.12.2013; Blackwell
• Subjects: Amborella trichopoda; Amborellaceae; Animal, plant and microbial ecology; Bayes Theorem; Biological and medical sciences; Biological evolution; Cluster Analysis; Ecology - methods; Ecosystem; environmental factors; Fundamental and applied biological sciences. Psychology; Gene Flow; General aspects. Techniques; Genetic Variation; Genetics of eukaryotes. Biological and molecular evolution; Genetics, Population - methods; Genotype; habitat suitability; last glacial maximum; Magnoliopsida - genetics; Methods and techniques (sampling, tagging, trapping, modelling...); Microsatellite Repeats; Models, Genetic; New Caledonia; niche modelling; Phylogeography; population genetics; Population genetics, reproduction patterns; rain forests; refuge habitats; refugia; Sequence Analysis, DNA; New Caledonia; Melanesia; Oceania; last glacial maximum; Genetic variability; Tropical zone; Biological evolution; Phylogeography; genetic variation; Habitat suitability; Modeling; refugia; Amborella trichopoda; Amborellaceae; niche modelling; Dicotyledones; Angiospermae; Ecological niche; Spermatophyta; Pleistocene; habitat suitability
• ISSN: 0962-1083; 1365-294X
• DOI: 10.1111/mec.12554

Amborella trichopoda Baill. (Amborellaceae, Amborellales), the sole living member of the sister group to all other extant angiosperms, is endemic to New Caledonia. We addressed the intraspecific phylogeography of Amborella by investigating whether its present population genetic structure could be related to its current and past habitats. We found moderate range‐wide genetic diversity based on nuclear microsatellite data and detected four well‐differentiated, geographically distinct genetic groups using Bayesian clustering analyses. We modelled the ecological niche of Amborella based on the current climatic and environmental conditions. The predictive ability of the model was very good throughout the Central East mainland zone, but Amborella was predicted in the northern part of the island where this plant has not been reported. Furthermore, no significant barrier was detected based on habitat suitability that could explain the genetic differentiation across the area. Conversely, we found that the main genetic clusters could be related to the distribution of the suitable habitat at the last glacial maximum (LGM, c. 21 000 years BP), when Amborella experienced a dramatic 96.5% reduction in suitable area. At least two lineages survived in distinct putative refugia located in the Massif des Lèvres and in the vicinity of Mount Aoupinié. Our findings finally confirmed the importance of LGM rainforest refugia in shaping the current intra‐ and interspecific diversity in New Caledonian plants and revealed the possibility of an as yet unreported refugium. The combination of niche modelling and population genetics thereby offered novel insight into the biogeographical history of an emblematic taxon.