European Wolves

[Ngala]

1 - SCANDINAVIAN POPULATION 

"This population consists of about 460 individuals (90% in Sweden, the rest in Norway or in the border area between these countries; Svensson et al., 2015). Exterminated in the 1960s and naturally recolonized since the 1980s by immigrant wolves from Finland (Karelia) (Wabakken et al., 2001; Vil`a et al., 2003a), the Scandinavian population is growing and is currently distributed in the central part of Sweden and southeastern Norway. The population has been continuously monitored with genetic methods (Ellegren, Savolainen & Rosen, 1996; Ellegren, 1999; Flagstad et al., 2003; Vilà et al., 2003a,b; Seddon et al., 2005, 2006; Hagenblad et al., 2009). Particular attention has been paid to ongoing immigration from the neighbouring Finnish/Russian (Karelian) wolf population (Flagstad et al., 2003; Vilà et al., 2003a; Seddon et al., 2006), which was shown to coincide with episodes of marked population increase in Russian Karelia (Flagstad et al., 2003), and the identification of four immigrant wolves in northern Sweden in 2002–2005 from Finland (Seddon et al., 2006). The Scandinavian population has been investigated through a period of severe inbreeding depression [inbreeding coefficient (FIS) varied from 0 to 0.42 for wolves born in 1983–2002 in Liberg et al., 2005]; followed by a remarkable genetic recovery thanks to a single immigrant from an eastern (Karelian?) wolf population that brought new genetic material into the population (Vilà et al., 2003a); and through a further period of increasing inbreeding; until the recent immigration of four Finnish/Russian wolves between 2008 and 2013 that rescued the population once again (Akesson et al., 2016). FIS (hereafter referred to as the inbreeding coefficient) is often misleadingly used synonymously with inbreeding. Inbreeding (and resulting inbreeding depression) is a major conservation concern in several wolf populations. However, the parameter that frequently is reported as ‘inbreeding coefficient’, and often discussed with strong statements about inbreeding in a population (or lack of it), is Wright’s FIS (Wright, 1965).
This parameter is easily calculated using genetic data (which probably explains why it is so often reported), but will in most cases carry little information about inbreeding in a natural population. FIS measures departures from Hardy Weinberg expectations (HWE) in a population, and while it is positive in the case of assortative mating (which does lead to an increase of F), it will be zero in a single generation of random mating. When a population is small, even random mating can lead to matings between relatives, meaning that inbreeding in the population (i.e. F) can be high, but FIS will still be zero or even negative (Waples, 2015). On the other hand, there are common causes for departures from HWE (population substructure, gene flow, genotyping errors) which can increase FIS and cause serious misinterpretations of a population’s inbreeding if the biological meaning of FIS is not understood correctly. Herein we report inbreeding coefficients estimated in the referenced studies as well as their values, but attempt to avoid some of the biological (mis)interpretations."

The main threats 
"By 1966 wolves were functionally extinct on the Scandinavian Peninsula (Wabakken et al., 2001). Since their re-establishment in 1983, wolves in Scandinavia have been subject to long-term monitoring. Due to the very limited number of founders, major conservation issues in this population have been genetic-related: inbreeding depression, low genetic variability and low-level gene flow with other populations (Vilà et al., 2003a; Liberg et al., 2005; Bensch et al., 2006; Raikkonen et al., 2006).. Inbreeding has caused strong reductions in two fitness components: winter litter size (Liberg et al., 2005) and recruitment of individuals to breeding (Bensch et al., 2006). It has also led to a high proportion of congenital malformations in the backbone (Raikkonen et al., 2006). Poaching (Table 4; Fig. 8) has been another major threat, accounting for approximately half of the total mortality in Sweden with more than two-thirds of total poaching remaining undetected by conventional methods (Liberg et al., 2012). Norway culled some wolves in 2001, claiming the population had already spread too far. In 2010, Sweden licensed the hunting of wolves to keep the population down to 210 individuals, a temporary goal set by the country’s parliamentary decree which assumed continuous gene flow from neighbouring populations (although genetic data shows this to be an exceptional rather than a frequent event). The wolf hunt and its effect on conservation and management issues has been highly questioned in popular media and scientific journals (Laikre et al., 2013).The Swedish Society for Nature Conservation has been critical, claiming that culling is against EU legislation as the Swedish wolf population had not reached a healthy status. The issue eventually reached the European Commission (EC): the Union biodiversity legislation requires all member states to follow ‘favourable conservation status’. As a result of the complaints, EC sent a reasoned opinion (in June 2015) requesting Sweden to amend its policy to protect the endangered wolf population in the country. This included the request for Sweden to bring wolf hunting into line with EU legislation, thus guaranteeing that the species reach favourable conservation status. A recent report suggests that a long-term goal for the Scandinavian wolf population should be 500 wolves (Kaczensky et al., 2013). Based on another report by commissioned expert statements, the Swedish Environmental Protection Agency decided (in October 2015) that, given that the Scandinavian wolves are a part of a larger northeastern European population by gene flow (including a minimum of one effective immigrant per generation into the Scandinavian population), the Swedish population needs to consist of at least 300 wolves to be considered to have favourable conservation status."

Source: 
Hindrikson, M., Remm, J., Pilot, M., Godinho, R., Stronen, A. V., Baltrūnaité, L., Czarnomska, S. D., Leonard, J. A., Randi, E., Nowak, C., Åkesson, M., López-Bao, J. V., Álvares, F., Llaneza, L., Echegaray, J., Vilà, C., Ozolins, J., Rungis, D., Aspi, J., Paule, L., Skrbinšek, T. and Saarma, U. (2016), Wolf population genetics in Europe: a systematic review, meta-analysis and suggestions for conservation and management. Biol Rev. doi:10.1111/brv.12298

Wolf from Sweden. Credits to NaturResor Annelie Utter.

*This image is copyright of its original author

Reply