William Sowersby

William Sowersby


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Works at Department of Zoology
Telephone 08-16 40 58
Visiting address Svante Arrheniusväg 18 B
Room D 525
Postal address Zoologiska institutionen: Etologi 106 91 Stockholm

About me

I have broad interests in behavioural and evolutionary ecology. I finished my PhD (Monash University, Australia) on behavioural and morphological variation in Neotropical cichlids at the start of 2016. I moved to Stockholm University shortly after to commence my first post-doc position, working with Dr Björn Rogell and Dr Alejandro Gonzalez-Voyer, on large-scale comparative studies of life-history evolution, behaviour, physiology and secondary sexual traits. As a model system, we use freshwater killifishes (25+ species), which display extreme divergences in life-history strategies (annual vs non-annual).


Twitter : @willsowersby


A selection from Stockholm University publication database
  • 2017. Will Sowersby, Topi K. Lehtonen, Bob B. M. Wong. Hydrobiologia 791 (1), 237-245

    In biparental species, the costs and benefits of parental investment can vary between the sexes and shift over time. However, such sex-specific and temporal changes in territory defense are not well understood. Here, we experimentally investigated parental investment in breeding territory defense in a feral population of the color-polymorphic, biparental cichlid fish, the red devil (Amphilophus labiatus). We presented either gold- or dark-colored conspecific intruder models (i.e., dummy models) to A. labiatus pairs at three key stages during the breeding cycle (i.e., after pair formation, after eggs have been laid, and when fry were free-swimming). We found that males were more aggressive when the pair first formed, whereas females significantly increased their territory defense with time, and were most aggressive when fry were free-swimming. These results show that parental roles in territory defense can markedly shift over key stages of the breeding cycle. Our results demonstrate that parental behaviors may not only vary between the sexes, but can also shift dramatically over the course of the brood cycle.

  • 2017. Simon Eckerström-Liedholm (et al.). Evolution 71 (7), 1900-1910

    Initial offspring size is a fundamental component of absolute growth rate, where large offspring will reach a given adult body size faster than smaller offspring. Yet, our knowledge regarding the coevolution between offspring and adult size is limited. In time-constrained environments, organisms need to reproduce at a high rate and reach a reproductive size quickly. To rapidly attain a large adult body size, we hypothesize that, in seasonal habitats, large species are bound to having a large initial size, and consequently, the evolution of egg size will be tightly matched to that of body size, compared to less time-limited systems. We tested this hypothesis in killifishes, and found a significantly steeper allometric relationship between egg and body sizes in annual, compared to nonannual species. We also found higher rates of evolution of egg and body size in annual compared to nonannual species. Our results suggest that time-constrained environments impose strong selection on rapidly reaching a species-specific body size, and reproduce at a high rate, which in turn imposes constraints on the evolution of egg sizes. In combination, these distinct selection pressures result in different relationships between egg and body size among species in time-constrained versus permanent habitats.

Show all publications by William Sowersby at Stockholm University

Last updated: June 12, 2018

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