On the evolution of reproductive rates in populations with equilibrium and cyclic densities

Ugland, Karl I.; Stenseth, Nils Chr.

doi:10.1016/0025-5564(85)90025-2

Cited by 6 publications

(3 citation statements)

References 79 publications

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“…There is a good correlation between CV and the commonly used S-index for rodent cycles (e.g. Ugland & Stenseth 1985, and our results). The expression of the expected productivity (on which both juvenile and floater abundances depend) becomes p e ¼ pð NÞ þ 1 2 p 00 ð NÞ N 2 CV 2 .…”

Section: Floaters Buffer Lemming Lowssupporting

confidence: 85%

Demographic responses of a site‐faithful and territorial predator to its fluctuating prey: long‐tailed skuas and arctic lemmings

Barraquand

Høye

Henden

et al. 2013

Journal of Animal Ecology

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Summary1. Environmental variability, through interannual variation in food availability or climatic variables, is usually detrimental to population growth. It can even select for constancy in key life-history traits, though some exceptions are known. Changes in the level of environmental variability are therefore important to predict population growth or life-history evolution. Recently, several cyclic vole and lemming populations have shown large dynamical changes that might affect the demography or life-histories of rodent predators. 2. Skuas constitute an important case study among rodent predators, because of their strongly saturating breeding productivity (they lay only two eggs) and high degree of site fidelity, in which they differ from nomadic predators raising large broods in good rodent years. This suggests that they cannot capitalize on lemming peaks to the same extent as nomadic predators and might be more vulnerable to collapses of rodent cycles. 3. We develop a model for the population dynamics of long-tailed skuas feeding on lemmings to assess the demographic consequences of such variable and non-stationary prey dynamics, based on data collected in NE Greenland. The model shows that populations of long-tailed skua sustain well changes in lemming dynamics, including temporary collapses (e.g. 10 years). A high floater-to-breeder ratio emerges from rigid territorial behaviour and a long-life expectancy, which buffers the impact of adult abundance's decrease on the population reproductive output. 4. The size of the floater compartment is affected by changes in both mean and coefficient of variation of lemming densities (but not cycle amplitude and periodicity per se). In Greenland, the average lemming density is below the threshold density required for successful breeding (including during normally cyclic periods). Due to Jensen's inequality, skuas therefore benefit from lemming variability; a positive effect of environmental variation. 5. Long-tailed skua populations are strongly adapted to fluctuating lemming populations, an instance of demographic lability in the reproduction rate. They are also little affected by poor lemming periods, if there are enough floaters, or juveniles disperse to neighbouring populations. The status of Greenland skua populations therefore strongly depends upon floater numbers and juvenile movements, which are not known. This reveals a need to intensify colour-ringing efforts on the long-tailed skua at a circumpolar scale.

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Section: Floaters Buffer Lemming Lowssupporting

confidence: 85%

Demographic responses of a site‐faithful and territorial predator to its fluctuating prey: long‐tailed skuas and arctic lemmings

Barraquand

Høye

Henden

et al. 2013

Journal of Animal Ecology

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“…In a population exposed to more or less regular density crashes, those strategies minimizing the time needed to build up the population to crash density will be favored by natural selection. This is equivalent to maximizing the Malthusian parameter, r, defined by Fisher (1930) (see Ugland and Stenseth 1985). The frequency Q) N "iii ... Two density-dependent functions defining the population dynamics completely in an environmentally favorable habitat: (A) the density-dependent specific birth rate, b(X); (B) the density-dependent survival rate, s(X).…”

Section: The Theorymentioning

confidence: 99%

On the Evolution of Reproductive Rates in Microtine Rodents

Stenseth¹,

Gustafsson²,

Hansson³

et al. 1985

Ecology

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The purpose of this study was to evaluate the effects of various patterns of population dynamics on the evolution of reproductive rates of voles. Population sizes of both field voles (Microtus agrestis) and bank voles (Clethrionomys glareolus) show different degrees of fluctuation in different regions; the degree of cyclicity increases northwards. Animals caught in both optimal and suboptimal habitats in three regions of Sweden were examined regarding litter size and length of reproductive season. The litter size was greater in optimal than in suboptimal habitats during the increase phase of cyclic populations. The breeding season was shorter during the peak than during the increase phase. In both species, during low—density phase, the reproductive rate of overwintered females increased northwards. Young—of—the—year females of the field vole, but not of the bank vole, showed a decrease in the reproductive rate with distance northwards. These results were compared with predictions based on three hypotheses on the evolution of reproductive rates, emphasizing, respectively, (1) food supply, (2) the pattern of density fluctuations, and (3) a combination of both food supply and the pattern of fluctuation. Observed between—habitat differences in reproductive patterns could be explained by hypothesis. 1. However, hypothesis 2 could explain part of the remaining variation among regions. In addition, when data from optimal habitats in the present study were combined with similar data from the literature, a high correlation was found between litter size and degree of cyclicity, confirming the predictions of hypothesis 2.

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“…On the other hand, this has been the subject of much theoretical work (see, for example, Schaffer & Tamarin 1973; Stenseth 1978; Stenseth & Framstad 1980; Stenseth & Ugland 1985; Stenseth et al . 1985; Ugland & Stenseth 1985; Gyllenberg, Hanski & Lindström 1996; Kokko & Ranta 1996). Among life history studies on periodically fluctuating rodents, some attention has been given to the study of the variation in the proportion of females reproducing and their age at first reproduction, as well as to how these traits are influenced by density and food supply (see, for example, Kalela 1957; Kalela 1962; Hansson & Henttonen 1985; Desy, Batzli & Liu 1990).…”

Section: Introductionmentioning

confidence: 99%

Delayed maturation in female bank voles: optimal decision or social constraint?

Prévot‐Julliard

Henttonen

Yoccoz

et al. 1999

Journal of Animal Ecology

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120

124

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Summary 0[ Density\ maturation and survival of female bank vole "Clethrionomys glareolus# in the northern taiga of Finnish Lapland were studied using long!term captureÐmarkÐ recapture data from two large grids\ one food!addition grid and one control grid\ in 0871Ð83[ 1[ The density on the food grid was consistently higher than the density on the control grid[ 2[ Females born early in the breeding season usually matured\ except at very high densities[ Those born later in the summer season commonly delayed maturation to the following spring[ 3[ Winter survival of sub!adult "having delayed maturation# females was signi_cantly higher than survival of adult "breeding# females[ However\ empirical values of sub! adult and adult survival\ as well as di}erence between them\ were not consistent with survival values assumed in theoretical models on optimal deferred breeding[ 4[ There was a density!dependent relationship between the maturation rate of young voles and the density of already established breeding females "both bank voles and all Clethrionomys together^C[ rutilus and C[ rufocanus occasionally occurred on the study grids#[ This density dependence was di}erent for the two grids "weaker on the food!addition grid#[ 5[ These _ndings are discussed within an evolutionary context] we have\ on the basis of these _ndings\ no evidence suggesting that the observed delayed maturation represents an evolutionary optimal strategy[ Rather\ there is evidence suggesting that the delay is due to social constraints[ Key!words] captureÐmarkÐrecapture "CMR# statistical modelling\ Clethrionomys\ food addition experiment\ population cycles\ survival[ Journal of Animal Ecology "0887# 57\ 573Ð586

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On the evolution of reproductive rates in populations with equilibrium and cyclic densities

Cited by 6 publications

References 79 publications

Demographic responses of a site‐faithful and territorial predator to its fluctuating prey: long‐tailed skuas and arctic lemmings

Demographic responses of a site‐faithful and territorial predator to its fluctuating prey: long‐tailed skuas and arctic lemmings

On the Evolution of Reproductive Rates in Microtine Rodents

Delayed maturation in female bank voles: optimal decision or social constraint?

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