Species distributions are limited by the availability of suitable habits. Species ranges can shift either when range margin populations adapt to new conditions, or when previously unsuitable habitats become suitable, e.g. as a result of climate change. Range shifts can lead to strong natural selection on life history traits.

I study the wall brown butterfly (Lasiommata megera), which has recently expanded northwards in Sweden. I am interested in how the butterflies adapt to the new conditions they face in their new range. An important part of the life cycle of most temperate insects is winter diapause, a resting stage that allows correct timing of growth and reproduction to the summer. To time the start of diapause, most insects use day length as a cue: shortening days indicate that winter is near, while long days mean that there is still time to grow and reproduce. When expanding northwards, insects will face a different photoperiodic system from what they have adapted to further south.

I want to find out if and how southern and northern Swedish populations of the wall brown have adapted locally. My work includes laboratory experiments to assess differences in diapause induction and fitness during and after diapause, as well as field transplant experiments to study these differences and their fitness consequences in more natural conditions. I will also sample genomic differences among populations and look for genomic signs of evolution.

A selection from Stockholm University publication database

• Limited dispersal and an unexpected aggression pattern in a native supercolonial ant

  2020. Sanja M. Hakala (et al.). Ecology and Evolution 10 (8), 3671-3685

  Article

  Understanding how social groups function requires studies on how individuals move across the landscape and interact with each other. Ant supercolonies are extreme cooperative units that may consist of thousands of interconnected nests, and their individuals cooperate over large spatial scales. However, the inner structure of suggested supercolonial (or unicolonial) societies has rarely been extensively studied using both genetic and behavioral analyses. We describe a dense supercolony‐like aggregation of more than 1,300 nests of the ant Formica (Coptoformica ) pressilabris . We performed aggression assays and found that, while aggression levels were generally low, there was some aggression within the assumed supercolony. The occurrence of aggression increased with distance from the focal nest, in accordance with the genetically viscous population structure we observe by using 10 DNA microsatellite markers. However, the aggressive interactions do not follow any clear pattern that would allow specifying colony borders within the area. The genetic data indicate limited gene flow within and away from the supercolony. Our results show that a Formica supercolony is not necessarily a single unit but can be a more fluid mosaic of aggressive and amicable interactions instead, highlighting the need to study internest interactions in detail when describing supercolonies.

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Show all publications by Mats Ittonen at Stockholm University