Phylogeography of Solomon Islands blossom bats reflects oceanic divides and Pleistocene connections

Abstract

Aim Periodic lowering of sea levels and formation of land bridges can reshape phylogeographic patterns of insular biotas. Using archipelago‐wide sampling, we aimed to test if phylogeography of an old‐endemic bat lineage reflected Pleistocene land bridges. Location Solomon Islands and Papua New Guinea. Taxon Melonycteris and Nesonycteris bats (Pteropodidae). Methods We sequenced genome‐wide RADseq data for 49 specimens from 15 islands. We assessed phylogenetic relationships using maximum likelihood in RAxML and quartet‐based methods in SVDquartets, population structure using Structure, and admixture using maximum likelihood methods in TreeMix. We tested for genetic and geographic distance correlations using distance‐based redundancy analyses (dbRDA), identifying best‐fit models using stepwise model selection. Results Phylogenetic analyses identified five Nesonycteris clades corresponding to Greater Bukida, Guadalcanal, Makira, Malaita and New Georgia group. Makira samples were sister to remaining Nesonycteris. Structure identified four populations: New Ireland Melonycteris melanops; and Nesonycteris from Greater Bukida (including Guadalcanal); Malaita and Makira; and New Georgia group. Genetic backgrounds of Mono, Ngella and Guadalcanal separated from remaining Greater Bukida islands. Makira and Malaita separated into two populations. New Georgia group lacked structure, and genetic and geographic distances were not correlated. The best‐fit geographic distance models for Nesonycteris and a Greater Bukida subset were least shore‐to‐shore distance; and Euclidean and least‐cost distances respectively. Main Conclusions Influences of modern and Pleistocene island isolation and connectivity were evident in the overall Phylogeography of Nesonycteris. The lack of structure or geographic distance correlations within the New Georgia group indicated all islands were interconnected during the Last Glacial Maximum or contemporary oceanic divides are ineffective barriers. Conversely, genetic divergence across Greater Bukida islands reflected land‐bridge constrained dispersal. A Makira clade sister to all Nesonycteris possibly indicates an origin on Makira. Alternately it reflects Makira's long‐isolated geographic status, as similar results exist for a range of taxa.

Parallel evolution in an island archipelago revealed by genomic sequencing of Hipposideros leaf-nosed bats

“…The evidence for gene flow found between H. diadema individuals from Rendova and Gatokae is highly plausible, considering these two islands lie in close proximity within the New Georgia group and may have been physically interconnected during lowered sea levels of the Last Glacial Maximum ( Lavery et al, 2023 ). Supported gene flow events between H. dinops on Guadalcanal and Rendova and H. diadema on Gatokae and Ngella were more difficult to interpret because these lineages are not in close geographic proximity.…”

“…A growing body of Solomon Islands-focused research has elucidated the value of this archipelago for understanding how island configurations and ontogenies, oceanic barriers, and intermittent land bridge formations can shape genetic and taxonomic diversities ( Brown et al, 2015 ; Hagen et al, 2012 ; Lavery et al, 2023 ; Manthey et al, 2020 ; Moyle et al, 2009 ; Pulvers & Colgan, 2007 ; Smith & Filardi, 2007 ; Toussaint et al, 2016 ). Here, we have further enriched this body of work with evidence for extensive paraphyly among Solomon Islands’ Hipposideros bats.…”

“…(1) What is the broader pattern of evolutionary history in Solomon Islands Hipposideros when wider sampling is incorporated, and how many independent shifts in body size are apparent in the group? To address this question, additional sampling of sympatric (or preferably syntopic) pairs of H. diadema and H. dinops are needed from major biogeographic units (i.e., Malaita, Bougainville–Choiseul–Isabel, Vella La Vella–Ranongga, Kolombangara–New Georgia–Vangunu–Gatokae, and Rendova–Tetepare) (see Lavery et al, 2023 ; Lavery & Flannery, 2023 ). (2) Are ecological factors driving such a rapid, repeated, and clear divergence of large ecomorphs from H. diadema ancestors?…”

Phylogenetic, morphological and niche differentiation unveil new species limits for the big brown bat ( Eptesicus fuscus )

“…Phylogeographic accounts of mammals across insular fragmented landscapes support high levels of genetic variation and/or population structure of species-like lineages [24][25][26][27][28]. Compared to non-volant mammals, bats are an exemplary model for studying patterns of diversification and structure.…”