Trade-offs prevent selection from driving all fitness-enhancing traits towards values that would maximize fitness. Life-history trade-offs, such as the one between survival and reproduction are well-studied, yet trade-offs can also involve behavioural or cognitive traits. Because males and females have different routes to successful reproduction, the optimal resolution of life-history trade-offs can differ between the sexes. However, shared genome can constrain the evolution of sex-specific adaptations. In this thesis, I explore the links between sex-specific life histories, cognition and behaviour. I start by linking sex differences in life histories to sex differences in learning performance in the outcrossing nematode Caenorhabditis remanei (Paper I). I report that age-related learning differs between the sexes and that it corresponds to sexual dimorphism in life history. Then, I use experimental evolution to select for learning performance to study the patterns of genetic correlations between learning and life-history traits in both sexes (Paper II). The results demonstrate the correlated evolution of sexual dimorphism in life history indicating sex-specific fitness costs and benefits of learning. In Paper III I use the fruit fly Drosophila melanogaster to ask about the extent to which cognitive and demographic aging are independent. The results reveal that selection for late-life reproduction alone bears no effect on late-life learning and that joint selection on late-life learning and reproduction does not yield lifespan benefits. The selection might have affected, however, female age-specific reproductive effort. Motivated by the questions on aging I proceed to ask why a potent lifespan extending drug – rapamycin affects sexes differently (Paper IV). I take a closer look at the trade-off between growth, lifespan and reproduction and propose that the sex experiencing a stronger relationship between size and fitness pays a higher cost of lifespan extension. Finally, I focus on another sex-specific trait – dispersal (Paper V). I conduct experimental evolution to uncover a negative genetic correlation between dispersal and reproduction and show sex-specific genetic variation for dispersal. In summary, my thesis unravels the complex pattern of interdependence between life-history, behavioural and cognitive traits, where sex emerges as an important factor that can maintain genetic variation for trade-offs.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-329035 |
| Date | January 2017 |
| Creators | Zwoinska, Martyna K. |
| Publisher | Uppsala universitet, Zooekologi, Uppsala |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, info:eu-repo/semantics/doctoralThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 1555 |
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