Effects of hunting on genetic diversity, inbreeding and dispersal in Finnish black grouse (Lyrurus tetrix).

Intensive hunting activities such as commercial fishing and trophy hunting can have profound influences on natural populations. However, less intensive recreational hunting can also have subtle effects on animal behaviour, habitat use and movement, with implications for population persistence. Lekking species such as the black grouse (Lyrurus tetrix) may be especially prone to hunting as leks are temporally and spatially predictable, making them easy targets. Furthermore, inbreeding in black grouse is mainly avoided through female-biased dispersal, so any disruptions to dispersal caused by hunting could lead to changes in gene flow, increasing the risk of inbreeding. We therefore investigated the impact of hunting on genetic diversity, inbreeding and dispersal on a metapopulation of black grouse in Central Finland. We genotyped 1065 adult males and 813 adult females from twelve lekking sites (six hunted, six unhunted) and 200 unrelated chicks from seven sites (two hunted, five unhunted) at up to thirteen microsatellite loci. Our initial confirmatory analysis of sex-specific fine-scale population structure revealed little genetic structure in the metapopulation. Levels of inbreeding did not differ significantly between hunted and unhunted sites in neither adults nor chicks. However, immigration rates into hunted sites were significantly higher among adults compared to immigration into unhunted sites. We conclude that the influx of migrants into hunted sites may compensate for the loss of harvested individuals, thereby increasing gene flow and mitigating inbreeding. Given the absence of any obvious barriers to gene flow in Central Finland, a spatially heterogeneous matrix of hunted and unhunted regions may be crucial to ensure sustainable harvests into the future.

Ecosystem restoration with teeth: what role for predators?

Recent advances highlight the potential for predators to restore ecosystems and confer resilience against globally threatening processes, including climate change and biological invasions. However, releasing the ecological benefits of predators entails significant challenges. Here, we discuss the economic, environmental and social considerations affecting predator-driven ecological restoration programmes, and suggest approaches for reducing the undesirable impacts of predators. Because the roles of predators are context dependent, we argue for increased emphasis on predator functionality in ecosystems and less on the identities and origins of species and genotypes. We emphasise that insufficient attention is currently given to the importance of variation in the social structures and behaviours of predators in influencing the dynamics of trophic interactions. Lastly, we outline experiments specifically designed to clarify the ecological roles of predators and their potential utility in ecosystem restoration.

Short- and long-term population dynamical consequences of asymmetric climate change in black grouse.

Temporal asymmetry in patterns of regional climate change may jeopardize the match between the proximate and ultimate cues of the timing of breeding. The consequences on short- and long-term population dynamics and trends as well as the underlying mechanisms are, however, often unknown. Using long-term data from Finland, we demonstrate that black grouse (Tetrao tetrix) have responded to spring warming by advancing both egg-laying and hatching. However, early summer (the time of hatching) has not advanced, and chicks have to face colder post-hatching conditions. Demonstrating that these conditions are critical to post-hatching survival, we show that chicks are increasingly suffering higher mortality because they hatch too early. Consequently, breeding success and population size has severely declined over the past four decades. Finally, we modelled the impact of this particular climate change scenario on population dynamics and show that the mismatch can further explain the observed collapse of cyclic fluctuations. Because the evolutionary response of grouse is lagging behind the novel selective pressures, seasonally asymmetric climate change is likely to constitute an important determinant of future short- and long-term changes in the dynamics of black grouse populations.