Red foxes colonizing the tundra: genetic analysis as a tool for population management

Abstract

Climate change accelerates biodiversity alterations in northern ecosystems. A prevalent example is that tundra regions are invaded by boreal species. This impacts negatively on native species through competition, predation and transmission of zoonoses. Scandinavian red foxes (Vulpes vulpes) have emerged into the tundra and have altered the structure and function of the tundra community. For instance, they threaten persistence of the endangered Swedish Arctic fox (Vulpes lagopus). County board administrations implement control of the tundra red foxes, but little is known about the underlying expansion dynamics. A broad-scale study revealed high connectivity where northern areas were supplemented with red foxes from surrounding population. However, red fox expansion is most prevalent in tundra regions and the fine-scaled expansion dynamics in these areas have not yet been disseminated. With the aim of identifying the invasive pathways of tundra red foxes, we present microsatellite data for 205 Swedish red foxes and mitochondrial sequence variation in 102 foxes sampled across the historical boreonemoral distribution and recently colonized tundra regions. Genetic structuring was low with high levels of ongoing, asymmetric dispersal from surrounding boreal zones into tundra habitats causing high genetic admixture. In both tundra and boreo-nemoral regions, inter-individual relatedness decreased with increasing geographic distance and data suggests male-biased dispersal patterns. Overall, finescaled expansion patterns were affected by multiple factors and we discuss its implications for future red fox management.

Homage to Hersteinsson and Macdonald: climate warming and resource subsidies cause red fox range expansion and Arctic fox decline

“…The Fennoscandian red fox population is connected by high and asymmetric dispersal, but no major genetic temporal shift has been detected, which indicates that the ongoing northern population increase is a combined effect of in situ demographic growth and immigration (Norén et al 2015). Surrounding boreal areas thus function as sources that augment the alpine tundra population with colonizers from multiple directions (Norén et al 2017).…”

Microsatellite evidence of dispersal mechanism of red swamp crayfish (Procambarus clarkii) in the Pearl River basin and implications for its management

“…A genetic approach to the management of invasive species is gathering momentum. The information gleaned from this analysis of gene flow and population structure has broad implications for quarantine, trade and management of Bactrocera correcta 7 , Bemisia tabaci biotype B 8 , and Vulpes vulpes 9 . Coupled with ecological information on dispersal and/or colonization mechanisms and life-history characteristics, population genetics analyses provide a strong basis to formulate management strategies 10 .…”

Multiple recolonization routes towards the north: population history of the Fennoscandian red fox (Vulpes vulpes)

“…Previous studies (Norén et al 2015, Norén et al 2017 revealed low levels of red fox population structure. We therefore estimated basic population genetic parameters within each country.…”

“…We assembled 259 red foxes, of which 79 originated from Sweden, 66 from Finland, 94 from Norway, 16 from Denmark, and 4 from the Kola Peninsula. These samples have previously been included in (Norén et al 2015, Norén et al 2017 or range-wide phylogeography (Statham et al 2014). Among these 259 samples, 72 sequences were collected by Statham et al (2014) and references therein.…”

“…In Fennoscandia, the red fox emerged northwards and established in tundra areas during warmer periods of the 19 th century (Hersteinsson & Macdonald 1992). The present northern red fox population increase in northern areas is most likely a consequence of both range expansion from boreal zones (boreal invasion) as well as demographic increases of the local northern populations (Norén et al 2015, Norén et al 2017. Through a combination of ancient and modern genetic data collected throughout Europe, low levels of phylogeographic structuring was recorded which was suggested to be a consequence of high dispersal and capacity to inhabit a wide variety of habitat types .…”