A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
Changes in population structure and reproduction during a 3-yr population cycle of voles
Tekijät: Norrdahl K, Korpimaki E
Kustantaja: WILEY-BLACKWELL
Julkaisuvuosi: 2002
Journal: Oikos
Tietokannassa oleva lehden nimi: OIKOS
Lehden akronyymi: OIKOS
Vuosikerta: 96
Numero: 2
Aloitussivu: 331
Lopetussivu: 345
Sivujen määrä: 15
ISSN: 0030-1299
DOI: https://doi.org/10.1034/j.1600-0706.2002.960215.x
Tiivistelmä
Cyclic changes in population growth rate are caused by changes in survival and,or reproductive rate. To find out whether cyclic changes in reproduction are an important part of the mechanism causing cyclic fluctuations in small mammal population,;, e studied changes in the population structure and reproduction of field voles (Microtus agrestis), sibling voles (M. rossianemeridionalis), bank votes (Clethrionomys glareolus), and common shrews (Sorex araneus) in western Finland during 1984-1992. in an area with 3-yr vole cycles, We also modelled the population growth of voles using parameter values from this studs, The animals studied ere collected by snap trapping in April. May, June, August. September, and, during 1986 1990, also in October. We found several phase-related differences in the population structure (age structure, sex ratio, proportion of mature individuals) and reproduction (litter size. length of the breeding season) of voles, In non-cyclic common shrews. the only significant phase-related difference was a lower proportion of overwintered individuals in the increase phase, According to the analyses and the vole model, phase-related changes in titter size had only a minor impact on population growth rate. The same was true for winter breeding in the increase phase, The length and intensity of the summer breeding season had an effect on yearly I population growth but this impact was relatively weak compared to the effect of cyclic changes in survival. The population increase rates of Microtus were delayed dependent on density (8-12-month time tag). Our results indicate that cyclic changes in reproduction are not an important part of the mechanism driving cyclic fluctuations in vole populations, Low survival of young individuals appeared to play an important role in the shift from the peak to the decline phase in late summer and early autumn.
Cyclic changes in population growth rate are caused by changes in survival and,or reproductive rate. To find out whether cyclic changes in reproduction are an important part of the mechanism causing cyclic fluctuations in small mammal population,;, e studied changes in the population structure and reproduction of field voles (Microtus agrestis), sibling voles (M. rossianemeridionalis), bank votes (Clethrionomys glareolus), and common shrews (Sorex araneus) in western Finland during 1984-1992. in an area with 3-yr vole cycles, We also modelled the population growth of voles using parameter values from this studs, The animals studied ere collected by snap trapping in April. May, June, August. September, and, during 1986 1990, also in October. We found several phase-related differences in the population structure (age structure, sex ratio, proportion of mature individuals) and reproduction (litter size. length of the breeding season) of voles, In non-cyclic common shrews. the only significant phase-related difference was a lower proportion of overwintered individuals in the increase phase, According to the analyses and the vole model, phase-related changes in titter size had only a minor impact on population growth rate. The same was true for winter breeding in the increase phase, The length and intensity of the summer breeding season had an effect on yearly I population growth but this impact was relatively weak compared to the effect of cyclic changes in survival. The population increase rates of Microtus were delayed dependent on density (8-12-month time tag). Our results indicate that cyclic changes in reproduction are not an important part of the mechanism driving cyclic fluctuations in vole populations, Low survival of young individuals appeared to play an important role in the shift from the peak to the decline phase in late summer and early autumn.