Kristin Löwenborg


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Works at Department of Zoology
Visiting address Svante Arrheniusväg 18 B
Room D 546
Postal address Zoologiska institutionen: Ekologi 106 91 Stockholm

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A selection from Stockholm University publication database
  • 2017. Kristin Löwenborg, Mattias Hagman. Biological Journal of the Linnean Society 120 (1), 189-194

    Thermally-induced scale asymmetries in reptiles are often considered to be indicative of underlying osteological deformities that incur fitness costs. However, this typically rests on subjective plausibility arguments and anecdotal reports about links between deformities and fitness, as well as between superficial asymmetries and deeper deformities rather than on empirical data. To shed light on these issues, we used a combination of Xrays of museum specimens and locomotor performance trials of hatchlings grass snakes (Natrix natrix) incubated in the laboratory at either 25 degrees C or 31 degrees C. We found that 30% of the museum specimens with asymmetrical ventral scales also had a rib duplication on one side of the underlying vertebrae associated with a scale asymmetry. In some cases, there was also a second extra rib on the opposite side of the vertebrae. However, although there was a statistically significant association between asymmetric ventral scales and rib duplication, a relatively weak correlation coefficient (r(s) = 0.35) indicated that scale asymmetries are not a very strong predictor of rib duplication. In the performance trials, scale asymmetries had a significant effect on terrestrial but not aquatic locomotor ability of the hatchlings, and the magnitude of this effect depended on the temperature regimes that they experienced as embryos during incubation. Although both asymmetrical and normal snakes incubated at the higher temperature had more stamina than their respective counterparts incubated at the lower temperature, asymmetrical hatchlings overall became exhausted much sooner than normal snakes across the two treatments.

  • 2016. Kristin Löwenborg Di Marino (et al.).

    The onset of agriculture about 12,000 years ago has had a major influence on the biodiversity of plants and animals. Unfortunately, the rapid changes in agricultural practices that has occurred in recent times has negatively affected many farmland species. One such species is the grass snake (Natrix natrix), which has been reported to decline in many parts of Europe, including Sweden. The grass snake is unique, not only in that it is the most northerly distributed oviparous reptile in the world, but also because of its habit of using anthropogenic heat sources such as manure heaps and composts as nesting-sites. Unfortunately changes in manure management and abandonment of farmlands have resulted in a decline and fragmentation of these environments. This may pose a threat for the northernmost populations of the grass snake, because natural nests in these areas may not provide sufficient heat for the eggs to hatch. The eggs and embryos of reptiles are highly sensitive to incubation temperatures, which can influence not only hatching success but also many phenotypic traits in the hatchlings. In this thesis I used a series of laboratory and field experiments to investigate the importance of anthropogenic heat sources for the reproductive ecology of cold-climate populations of grass snakes.  More specifically, I aimed to investigate thermal regimes of nests and how they influence embryonic development and offspring traits associated with survival and fitness. The results showed that manure heaps and composts are significantly warmer than potential natural nests and that natural nests do not provide sufficient heat to sustain embryonic development. Further, manure heaps were warmer and more constant in temperature than composts, resulting in higher hatching success and earlier hatching in manure heaps. The higher thermal variability in composts increased the frequency of abnormalities that are likely to negatively affect survival and fitness. In conclusion, this thesis shows that the use of anthropogenic heat sources has enabled grass snakes to expand their range farther north than any other oviparous reptile and that the thermal dichotomy in the primary nesting environments used by grass snakes contribute to important life-history variation in this species. These findings have important implications for conservation of reptile populations in general and grass snakes in particular.  

  • 2015. Mattias Hagman, Kristin Löwenborg, Richard Shine. Behavioural Processes 113, 60-65

    Many organisms exhibit diverse anti-predator tactics, influenced by genetics and prior experience. In ectothermic taxa, offspring phenotypes are often sensitive to developmental temperatures. If the effectiveness of alternative anti-predator responses depends on thermally sensitive traits, then the temperatures experienced during embryonic life should also affect how offspring respond to an approaching predator. We incubated 16 clutches of Swedish grass snakes (Natrix natrix) at a range of developmental temperatures, and scored body size, colour pattern, locomotor performance and anti-predator responses of 213 hatchlings from those clutches. A hatchling snake’s size and locomotor abilities were affected by its clutch of origin, its developmental temperature, and by an interaction between these two factors. Anti-predator tactics were strongly linked to locomotor ability, such that slower snakes tended to rely upon aggressive displays rather than flight. Incubation temperatures that generated slow (and thus aggressive) snakes also modified the colour of the snake’s nuchal spot. Temperatures in the low to medium range generated mostly cream, white and orange spots, whereas medium to high temperatures generated more yellow spots. Incubation effects, and gene X environment interactions, thus may generate complex correlations between morphology, locomotor ability, and anti-predator tactics.

Show all publications by Kristin Löwenborg at Stockholm University

Last updated: November 19, 2018

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