Origins of old lineages in New Caledonia: A geologically informed test of the island‐hopping hypothesis

• Published in: Journal of Biogeography
• Main Authors: Malem, Julien, Robillard, Tony, Cluzel, Dominique, Bellier, Loïc, Nattier, Romain, Grandcolas, Philippe, Legendre, Frédéric
• Other Authors: Institut de Systématique, Evolution, Biodiversité (ISYEB ), Muséum national d'Histoire naturelle (MNHN)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Université de la Nouvelle-Calédonie (UNC)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: relicts; paleoendemics; New Caledonia; paleogeography; historical biogeography; phylogenetic dating; insects; stepping stones; BioGeoBEARS; competing hypotheses; vanished islands; [SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry; Molecular Biology/Molecular biology; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; New Zealand; Pacific; Stepping Stones; Antarc*; Antarctica
• Online Access: https://cnrs.hal.science/hal-04362969; https://cnrs.hal.science/hal-04362969/document; https://cnrs.hal.science/hal-04362969/file/Malem-et-al_island-hopping_JoB_2023.pdf; https://doi.org/10.1111/jbi.14673

International audience Although New Caledonia (NC) is now considered an oceanic island that emerged ca. 60 Ma, a few terrestrial clades are significantly older, raising the question of the origin of these groups. Classically, old lineages on more recent islands are hypothesized to originate through a process of hopping on now‐vanished islands (i.e., island‐hopping hypothesis) or other territories. We aim to test this hypothesis by studying a group of cockroaches with several lineages found in NC. Location New Caledonia, New Zealand, Australia. Taxon Insects: Blattodea. Methods We generated a dated phylogeny for blattid cockroaches (Blattidae and Tryonicidae) using Bayesian inference along with fossil calibrations. We reviewed studies on the palaeogeography of the Southwest Pacific region, including hypotheses about the existence of yet‐to‐be‐discovered past islands, and constructed biogeographical tests accordingly. We computed ancestral area estimation under different models in BioGeoBEARS (DEC, BAYAREALIKE, DIVALIKE, with or without +J) to test the role of an island‐hopping hypothesis in the establishment of NC blattid fauna. Results We find divergence times older than 60 Ma for two NC clades. We show that these ‘old’ endemic lineages can partially be explained by indirect dispersal from Australia or New Zealand through now disappeared islands. Alternative hypotheses suggest multiple independent colonizations of NC from Antarctica or Australia. Main Conclusions Our results indicate that island‐hopping may explain the presence of old groups in NC. The island‐hopping hypothesis is nonetheless only supported for a period‐area from which geological evidence is ambiguous. Our work highlights both the fruitful interactions between geology and biogeography and the underlying difficulties. The multiple colonization events inferred for NC provide additional insights into the composite nature of NC biota.