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Browsing by Subject "reproductive success"

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  • Liu, Che (2016)
    Snowmelt timing has been proven critical to the phenology in subarctic and alpine ecosystems. Nevertheless, its impacts on the phenology of dwarf-shrub-dominated vegetation on high-latitudinal Fennoscandian fells are not yet sufficiently studied. This project focusses on the divergences in phenological timings and reproductive success caused by naturally different snowmelt timings in this area. The study site was on fell Saana in northwest Finland. The data was collected from a site covering three snowmelt timings located in two aspects (fully factorial, 4 replicates) from 20th of May to 4th of September, 2015, totalling 108 days. The phenological events (e.g. leaf unfolding, anthesis, and leaf colouring) of 12 species of three growth forms (dwarf shrub, forb, and graminoid) were recorded. The statistical analyses show that different snowmelt timings result in significant differences in the time points (expressed in day of year, DOY) of peak flowering and shoot elongation, as well as the green-leaved durations (days); however, flowering duration is rather constant across snowmelt timings. Significant differences are also found in the reproductive success of several species. The results suggest that in subarctic-alpine vegetation, an earlier snowmelt timing 1) elongates the duration of vegetative growth, 2) advances the timing of peak flowering while the flowering duration remains unchanged, and 3) potentially impedes reproductive success in some species, but generally the pattern is heterogeneous. Thus, snowmelt timing is causing divergences among the phenological traits and potentially within the reproductive success of dwarf shrub species in this area. In the long term, these phenomena may impact the local biodiversity and biochemical cycles, which may be a long-term effect of the shifting snowmelt timing due to global change.
  • Maamela, Katja (2021)
    In teleost fish, various egg traits play a crucial role in the development, growth, and survival of the offspring and thus affect maternal reproductive success. Atlantic salmon (Salmo salar) is a species where age at maturity, an important life-history trait influencing reproductive success, is under environmental and genetic control. In this study, I assessed how genetics of the vgll3 genotype and the dietary energy content affect egg traits and female maturation rate. The fish used in this study were lab-bred, three-year- old female Atlantic salmon with different vgll3 genotypes fed on one of two diets differing in energy content. The eggs traits included in the study were egg size, lipid, and protein content. Female maturation rate was not affected by the energy level of the diet or the vgll3 genotype. Egg size expressed as egg dry weight differed between females in the two feed treatments. These differences may be attributed to the increased lipid content of the eggs due to the higher fat content of the maternal diet. Females receiving high energy feed had a significantly higher egg lipid content compared to the low energy feed treatment. Females homozygous for the vgll3 allele associated with early maturity had a significantly lower egg lipid content in comparison to the females homozygous for the vgll3 late maturity allele indicating a potential reproductive fitness cost associated with early maturity. No effect of diet or vgll3 was found in egg protein content. This study provides the first evidence of vgll3 not only affecting Atlantic salmon age at maturity, as found in previous studies, but also egg lipids through maternal provisioning of nutrients.