Vanessa SchreiberPhD student
My current research aims to understand the relationship between the evolution of life history strategies and variable resource conditions in the Arctic fox (Vulpes lagopus) by analysing and comparing long-term data on demography, reproductive investment and genetics of two different Arctic fox ecotypes. Investigating life history strategies in long-lived wild animals exposed to contrasting environmental conditions and resource availability in both time and space can advance our insight about the life history trade-off and the evolution of different strategies within the same species. While populations in a stable environment advance towards optima in a life history trait, populations of the same species in a fluctuating environment maintain either average optima or phenotypic plasticity to react to unpredictable resource availability.
The collection of individual data on wild carnivores can be complicated as they are mostly nocturnal and non-habituated to humans. The Scandinavian Arctic fox population has been under yearly monitoring as individuals become more tolerant to observers and, in combination with bright summer nights, allow a 24-hour-surveillance during the summer. To facilitate lifelong individual following arctic foxes are trapped, individually ear tagged with unique colour combinations and a tissue sample is taken to allow genetic analyses and thus enabling the collection of a long-term data series since 1985 with more than 1000 individuals. Additionally, we have access to a corresponding data series from the Icelandic arctic fox population collected from carcasses since 1980 and onwards. While the Scandinavian population is depending on a relationship with the cyclic rodent population in the tundra, the Icelandic population can rely on a temporally stable resource access to marine food resulting in a contrasting reproductive output of each population.
Beside resource availability I am also interested in sex- and age-specific effects on variations in life history strategies and what impact does the relationship between individuals have on life history traits. Furthermore I will investigate the impact of variable resource conditions during different phases of the rodent cycle as well as between the two ecotypes and parental effects on offspring phenotype and fitness during early-life and the consequences on life history trade-offs in late-life.