The paradox of invasion: Reeves' muntjac deer invade the British Isles from a limited number of founding females

Abstract

High levels of genetic diversity and high propagule pressure are favoured by conservation biologists as the basis for successful reintroductions and ensuring the persistence of populations. However, invasion ecologists recognize the ‘paradox of invasion’, as successful species introductions may often be characterized by limited numbers of individuals and associated genetic bottlenecks. In the present study, we used a combination of high‐resolution nuclear and mitochondrial genetic markers to investigate the invasion history of Reeves' muntjac deer in the British Isles. This invasion has caused severe economic and ecological damage, with secondary spread currently a concern throughout Europe and potentially globally. Microsatellite analysis based on eight loci grouped all 176 introduced individuals studied from across the species' range in the UK into one genetic cluster, and seven mitochondrial D‐loop haplotypes were recovered, two of which were present at very low frequency and were related to more common haplotypes. Our results indicate that the entire invasion can be traced to a single founding event involving a low number of females. These findings highlight the fact that even small releases of species may, if ignored, result in irreversible and costly invasion, regardless of initial genetic diversity or continual genetic influx.

A centenary tale: population genetic insights into the introduction history of the oriental fire-bellied toad (Bombina orientalis) in Beijing

“…That is thus associated with significantly reduced genetic variability, increased inbreeding depression, and fixed deleterious mutations caused by demographic bottlenecks and genetic drift [ 39 ]. However, there are many examples of introduced species establishing stable populations while showing no apparent signs of inbreeding depression, despite low genetic diversity [ 13 , 26 , 40 – 42 ]. An infamous example of that is when 101 cane toads ( Rhinella marina ), a species native to South and Central America, were brought to Queensland in 1935 and, despite its low genetic diversity, their progeny spread along the Australian coasts, becoming a major invasive species in that country [ 43 , 44 ].…”

“…However, some species have successfully, although rarely, established populations from a single introduction of a few founders, and those populations have persisted in isolation from other populations [ 11 – 13 ]. Such introduced populations are expected to have very low genetic diversity levels because initial founder bottlenecks allow only limited gene pools to propagate, and subsequently the strong genetic drift causes random allele loss in small populations [ 14 – 17 ].…”

Een genetische studie van Chinese muntjak in Vlaanderen

“…Muntjak werd inderdaad reeds in verschillende Europese landen in het wild waargenomen (Baiwey et al 2013, Carden et al 2011, Dick et al 2010, European Union 2017, Freeman et al 2016, Tsiamis et al 2017, Figuur 3). Het is hierbij niet steeds duidelijk of er sprake is van vestiging, en wat de omvang is.…”

“…Williams et al (1995) suggereren dat de huidige muntjakpopulatie het resultaat is van meerdere onafhankelijke introducties. Freeman et al (2016) daarentegen concluderen dat de huidige populatie ontstaan is uit één enkele introductie bestaande uit slechts een handvol exemplaren.…”

Detection of a novel gammaherpesvirus (genus Rhadinovirus) in wild muntjac deer in Northern Ireland

“…Analyses were conducted using MEGA6 So while the risks associated with viruses in invasive muntjac deer in Ireland are not fully understood, if the muntjac population becomes established, it could potentially interact with livestock in terms of the evolution, spread and maintenance of viral infections. Camera trap and anecdotal evidence strongly suggest that muntjac are becoming established in Ireland and it is known that muntjac can form successful populations from a limited number of founding females [18]. As such, there is significant value in monitoring the virological status of these invasive animals.…”