Décembre 2023 : publication European Journal of Wildlife Research
Landscape structure does not hinder the dispersal of an invasive herbivorous mammal in the New Caledonian biodiversity hotspot
Biological invasions are a major threat to biodiversity and have particularly devastating impacts on island ecosystems. The New Caledonia archipelago is considered a biodiversity hotspot due to its diverse native flora. Javan rusa deer (Rusa timorensis) were introduced to New Caledonia in 1870 and the population consists of several hundred thousand individuals today. They directly threaten rare endemic species and affect the composition and structure of the vegetation. While a rusa deer management plan has identified ten priority areas for deer control operations, removing deer could be offset by the dispersal of animals back into the control areas. Here, we genotyped 628 rusa deer using 16 microsatellite markers to analyse the genetic structure of the animals in New Caledonia. We aimed to assess fine-scale genetic structure, to identify natural barriers to deer movement and to assess functional connectivity by optimising individual-based landscape resistance models. Our results suggested that rusa deer formed a single genetic population on the main New Caledonian island. The isolation-by-distance pattern suggested that female dispersal was limited, whereas males had larger dispersal distances. We assessed functional connectivity using different genetic distance metrics and all models performed poorly (mR2 ≤ 0.0043). Landscape features thus hardly affected deer movement. The characteristics of our results suggested that they were not an artefact of the colonisation history of the species. Achieving an effective reduction of deer population sizes in specific management areas will be difficult because of the deer’s high dispersal capabilities and impossible without very substantial financial investment.
Figure : Le cerf rusa, espèce invasive en Nouvelle Calédonie. En détruisant les sous-bois et en écorçant les arbres, le cerf rusa est l’un des principaux facteurs de destruction des paysages néo-calédoniens, impactant la faune et la flore, notamment endémique. Pour cette étude, l’ADN de 628 cerfs rusa répartis sur l’ensemble de la Grande Terre a été analysé. Crédits illustration : Lionnel Brinon, Emilie Berlioz, Sabine Riffaut.
Références
Frantz A. C., Luttringer A., Colyn M., Kazilas C., Berlioz B. 2023 – « Landscape structure does not hinder the dispersal of an invasive herbivorous mammal in the New Caledonian biodiversity hotspot » – Eur J Wildl Res 70, 6 – doi.org/10.1007/s10344-023-01757-0