Showing items related by title, author, creator and subject.

• 
  
  
  International Single Species Action Plan for the Conservation of the Common Eider : Baltic, North & Celtic Seas Population, Norway & Russia Population, Svalbard & Franz Josef Land Population. Somateria m. mollissima and S. m. borealis 

  Lehikoinen, Petteri; Alhainen, Mikko; Frederiksen, Morten; Jaatinen, Kim; Juslin, Robin; Kilpi, Mikael; Mikander, Nina; Nagy, Szabolcs (UNEP, AEWA, 2022)

  AEWA Technical Series
• 
  
  
  
  From individuals to populations : the distribution of Eurasian lynx individuals in space and time and consequences for the local population structure and dynamics 

  Herrero, Annika (Helsingin yliopisto, 2021)

  Large terrestrial carnivores are capable of long dispersal distances and thus have a potentially high rate of gene flow between populations. Even with such high mobility, discontinuous habitat and human-caused mortality may constrain dispersal and gene flow. Therefore, isolation of populations because of habitat fragmentation may cause genetic structuring in them because of genetic drift. In a continuous population, geographic barriers should not significantly affect dispersal and gene flow, so the effects of social, ecological and evolutionary forces are easier to detect. In large carnivores, males generally disperse more often and earlier than females and their dispersal distances are longer than those of females. The direction of sex-bias in dispersal is commonly explained by inbreeding avoidance, polygynous mating system and male-male competition. Remaining in, or near, the natal home range is explained by kin selection and inclusive fitness. Molecular evidence reveals the spatial genetic structure and clustering of relatives and family lines that may underlie these traits. We studied the spatial genetic relatedness, family structure, movement patterns and sex- bias of dispersal in the Eurasian lynx (Lynx lynx) in an unfragmented population in southern Finland. We used GIS and resource selection functions to analyse telemetry data of dispersing lynx and genetic methods to analyse data obtained from hunted lynx. Dispersal onset age, duration, distance, route or route linearity did not differ statistically between males and females that dispersed. However, the small number of females and the high variation in all dispersal parameters likely affected the outcome of analysis. Linear distance between the start and the end comprised only 20 % of the total dispersal route. Lynx selected their habitat non-randomly. During daylight hours lynx were more discerning in their habitat selection, while most of the traveling took place at night, reflecting the crepuscular and nocturnal activity of the lynx. According to the results of genetic analyses, the majority of females stayed close to their natal home range after reaching independence. Males dispersed and settled randomly in space. This led to genetic differentiation and spatial clustering of related females but not of males. Females form the backbone of the local populations, and genetic evidence is in line with the idea that females facilitate the settling of related females. In contrast to females, for males, relatedness is inversely important to avoid inbreeding. Hunting of adult lynx may disturb the forming of matrilineages and decrease genetic variation. Hunting should aim at mimicking a natural mortality pattern, which means hunting mostly young lynx, as the natural adult survival in Eurasian lynx is high.
• 
  
  
  
  Population growth correlates with increased fecundity in three-spined stickleback populations in a human-disturbed environment 

  Candolin, Ulrika; Voigt, Heinz-Rudolf (2020)

  Human activity is altering the dynamics of populations through effects on fecundity, mortality and migration. An increased abundance of three-spined stickleback (Gasterosteus aculeatus) in the Baltic Sea has been attributed to a human-caused decline of top predators. However, recent research indicates that a top-down effect cannot fully explain the population growth, but the contribution of a bottom-up effect has not been investigated. Yet, anthropogenic eutrophication has increased algae biomass at the spawning sites of the stickleback and, thus, the abundance of benthic prey. We investigated if increased fecundity could have contributed to the population growth of the stickleback by analysing a two decade time series of stickleback abundance, fecundity, and body size at three spawning sites. The results show an increase in the proportion of gravid females in the populations, which correlates with the population growth. In particular, the proportion of gravid females late in the spawning season has increased, which indicates enhanced food intake at the sites during the spawning season. Thus, a bottom-up effect could have contributed to the growth of the populations by increasing the number of egg clutches females produce. These results stress the importance of considering both bottom-up and top-down processes when investigating the mechanisms behind human impact on population dynamics.