Search bioRxiv⌕ Search

Biology subjects

Carlile, N.

Publications and source records attributed to Carlile, N..

4 recordsLinked to original sources

The BEAC, an epigenetic clock for birds

Epigenetic clocks are powerful tools for estimating both chronological and biological age, enabling the integration of age information into population monitoring, demographic modelling, and research on the ecophysiology and evolution of ageing. Most epigenetic clocks so far have been developed for mammals: here, we present the Bird Epigenetic Ageing Clock (BEAC) for estimating chronological age in avian species. BEAC was established based on genome-wide enzymatic methylation sequencing data of known-age king penguins (Aptenodytes patagonicus), and validated in nine other bird species. The BEAC collects age-informative signals into a bisulfite amplicon sequencing panel of 24 primer pairs, providing a highly accurate and cost-effective alternative to sequencing-intensive approaches. It achieved strong predictive performance in independent king penguin training (R{superscript 2}=0.88; MAE=1.7 years, n=78) and testing data (R{superscript 2}=0.79; MAE=2.3 years, n=41), with negligible batch effects, high longitudinal consistency, and resilience to reduced sample size or missing loci. Importantly, cross-species validation across 180 samples showed that BEAC reliably captures age-associated methylation signals in nine additional bird species across seven clades, demonstrating that a single set of loci can be predictive of ageing across multiple different bird species. BEAC offers a flexible, empirically validated tool and a transferable framework for developing epigenetic clocks in avian species, providing a highly valuable resource for eco-evolutionary studies of ageing in wild species.

molecular biology↗

Increases in invertebrate abundance and shifts in assemblage composition following Rodent Eradication on Lord Howe Island

Invasive species are one of the major threatening processes impacting biodiversity on islands. In particular, introduced rodents represent one of the most serious threats to island ecosystems, affecting a wide range of native plants, vertebrates and invertebrates. While nearly ubiquitous on human-modified islands, the last four decades have seen the advent of targeted rodent eradications, which have generally resulted in positive impacts for biodiversity. Invertebrates, which are crucial to the functioning of island ecosystems, are known to be negatively impacted by rodents, but their response to rodent removal is less well understood. The largest rodent eradication on an inhabited island was undertaken in 2019 on Australias Lord Howe Island, which successfully extirpated black rats (Rattus rattus) and house mice (Mus musculus) more than a century after their introduction. To examine the impacts of rodents on invertebrates on Lord Howe Island, we collected arboreal and terrestrial species both pre- and post-eradication and identified them to Order. Total invertebrate abundance increased after the eradication of rodents, alongside substantial shifts in assemblage composition, however Ordinal diversity did not change significantly. Orders with large increases in abundance included Isopoda and Blattodea, while the abundance of Coleoptera and Polydesmida did not change. In addition, the abundance of large invertebrates, which are presumably subject to stronger rat predation, rose dramatically following rodent eradication. Our results suggest an ecological rearrangement following the relaxation of predation pressure and augment documented evidence of improved biodiversity outcomes for forest tree species, seabirds and land birds.

ecology↗

Pleistocene sea-level fluctuation shapes archipelago-wide population structure in the Endangered Lord Howe Island cockroach Panesthia lata

Studies of biogeographic processes have often centred islands as model systems, yet questions remain about the role of Pleistocene sea-level fluctuations in shaping islands biodiversity. One novel, potentially informative model system is the Lord Howe Island Group of Australia. Despite the World Heritage status of this archipelago, almost nothing is known of the biogeographic origins, evolutionary distinctiveness or genetic diversity of the ecological communities across its 28 islands. In this study, we focused on the cockroach Panesthia lata, an ecologically specialized invertebrate with one of the broadest recorded distributions of any LHIG species. To investigate the influence of Pleistocene sea-level fluctuations on LHIG fauna, we explored the phylogeography of P. lata using single-nucleotide polymorphisms and complete mitochondrial genomes. Our analyses reveal that the lineage on the permanently isolated islet Balls Pyramid is highly divergent from the remaining populations, while those on the episodically connected Lord Howe, Roach and Blackburn Islands experienced gene flow during the last glacial period. These results offer the first evidence that Pleistocene land bridges allowed for overland migration across the archipelago. Further, although P. lata was believed to have been locally extirpated by rodents on Lord Howe Island, we discovered two surviving, relict populations. We also detected high levels of inbreeding in all populations, emphasizing the need for ongoing conservation management. Finally, the combination of shallow genetic structure and low diversity suggests that genetic rescue from another island may be a viable strategy to conserve the Lord Howe Island population of P. lata, as well as other species that have been similarly impacted by rodents.

evolutionary biology↗

Plio-Pleistocene decline of mesic forest underpins diversification in a clade of Australian Panesthia cockroaches

The progressive aridification of the Australian continent, and coincident decline of mesic forest, has been a powerful driver of allopatric and environmental speciation in native species. The relictual mesic forests of the eastern seaboard now harbor a diverse group of endemic fauna, including the wood-feeding cockroaches of the genus Panesthia, which reached the continent via two separate invasions from Melanesia. The more recent of these colonization events gave rise to a group of five recognized species, occurring in mainland woodlands, sclerophylls and rainforests, as well as the forests and grasslands of the Lord Howe Island Group. Due to limited sampling in molecular studies and doubt regarding the standing taxonomy, there is little certainty about relationships among the species and poor understanding of the effects of ancient climatic changes upon their evolution. We undertook a comprehensive phylogenetic analysis of the clade, using complete mitogenomes and nuclear ribosomal markers from nearly all known morphospecies and populations. Our time-calibrated phylogenetic analyses reveal six unrecognized, highly divergent lineages, and suggest that these have arisen primarily through vicariance as rainforests fragmented during Plio-Pleistocene glacial cycles (2-5 million years ago). Ancestral niche reconstructions also evidence a tropical rainforest origin for the group, followed by at least three niche transitions into drier forest, including one associated with the singular colonization of the Lord Howe Island Group. Finally, we find evidence of frequent, parallel wing reduction, in potential association with the contraction of forest habitats into small refugia. Our results reiterate the far-reaching role of ancient aridification in driving speciation, niche expansion and morphological evolution in Australian fauna.

evolutionary biology↗