Population cycles: generalities, exceptions and remaining mysteries

Myers, Judith H.

doi:10.1098/rspb.2017.2841

Cited by 80 publications

(82 citation statements)

References 96 publications

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“…Similar cycles are seen with other species in other parts of the world e.g., the snowshoe hare ( Lepus americanus ) in the boreal ecosystems of North America [11]. Although the mechanisms are still contested, predator-prey interactions are generally regarded as the most parsimonious explanation underlying the cyclic dynamics of rodents [12, 13], especially due to specialist predators, such as mustelids [14].…”

Section: Introductionmentioning

confidence: 73%

Impacts of predator-mediated interactions along a climatic gradient on the population dynamics of an alpine bird

Bowler

Kvasnes

Pedersen

et al. 2020

Preprint

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15According to classic theory, species interactions are less important than climatic variation for species ' 16 population dynamics and distributions in climatically harsh regions compared with more climatically 17 benign regions. In boreal ecosystems, the cyclic dynamics of rodents strongly affect many other 18 species, including ground-nesting birds. According to the 'alternative prey hypothesis' (APH), high 19 rodent densities positively affect the abundance of ground-nesting birds due to predator-mediated 20 interactions. We analysed a spatiotemporal dataset of willow ptarmigan (Lagopus lagopus) and 21 rodents to examine how the role of predator-mediated interactions changes along a climatic 22 harshness gradient in comparison with climatic variation. Ptarmigan and rodent data were collected 23 during a national program of line-transect sampling across Norway during 2007-2017. We build a 24 hierarchical Bayesian model to estimate the sensitivity of ptarmigan populations to interannual 25 variation in climate and rodent occurrence. Ptarmigan abundance was positively linked with rodent 26 occurrence, consistent with the APH. Moreover, we found that both rodent dynamics and temporal 27 climatic variation had stronger effects on ptarmigan in colder regions. Our study highlights how 28 species interactions play an important role for the population dynamics of species at higher latitudes 29 and suggest that they become even more important in the most climatically harsh regions. 30 31

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Section: Introductionmentioning

confidence: 73%

Impacts of predator-mediated interactions along a climatic gradient on the population dynamics of an alpine bird

Bowler

Kvasnes

Pedersen

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Through a combination of parameters of statistically rigorous capture–recapture modeling framework and 40 yr of field data on the same population, our study fills the aforementioned knowledge gaps by (1) providing the first rigorous, empirically based demographic characterization of the rates of population change that must be explained; (2) providing evidence that the demography of snowshoe hare cycles showed a repeatable pattern over five population cycles; (3) discerning demographic mechanisms underlying the increase, peak, and decline phases; and (4) explaining the variation in peak densities achieved by the same population across different cycles. Cyclic mammals inhabit variety of habitats across northern hemisphere and exhibit diverse life histories, but they all show similar dynamical patterns (Krebs , Myers , Oli ). Similar analyses of other cyclic mammal populations would help us understand whether or to what extent cyclic mammalian populations are demographically similar.…”

Section: Discussionmentioning

confidence: 99%

Demography of snowshoe hare population cycles

Oli

Kenney

Boonstra

et al. 2020

Ecology

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Cyclic fluctuations in abundance exhibited by some mammalian populations in northern habitats (“population cycles”) are key processes in the functioning of many boreal and tundra ecosystems. Understanding population cycles, essentially demographic processes, necessitates discerning the demographic mechanisms that underlie numerical changes. Using mark–recapture data spanning five population cycles (1977–2017), we examined demographic mechanisms underlying the 9–10‐yr cycles exhibited by snowshoe hares (Lepus americanus Erxleben) in southwestern Yukon, Canada. Snowshoe hare populations always decreased during winter and increased during summer; the balance between winter declines and summer increases characterized the four, multiyear cyclic phases: increase, peak, decline, and low. Little or no recruitment occurred during winter, but summer recruitment varied markedly across the four phases with the highest and lowest recruitment observed during the increase and decline phase, respectively. Population crashes during the decline were triggered by a substantial decline in winter survival and by a lack of subsequent summer recruitment. In contrast, initiation of the increase phase was triggered by a twofold increase in summer recruitment abetted secondarily by improvements in subsequent winter survival. We show that differences in peak density across cycles are explained by differences in overall population growth rate, amount of time available for population growth to occur, and starting population density. Demographic mechanisms underlying snowshoe hare population cycles were consistent across cycles in our study site but we do not yet know if similar demographic processes underlie population cycles in other northern snowshoe hare populations.

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“…Ecological factors can exert strong pressures on wildlife populations, often resulting in substantial seasonal or multi-annual density fluctuations (Krebs, 2013;Stenseth et al, 2002;Myers, 2018). These fluctuations can influence the transmission dynamics of many parasites and have been linked to disease outbreaks in both wildlife and humans (Altizer et al, 2006;Davis et al, 2004;Hartley et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Density dependence and persistence of Morogoro arenavirus transmission in a fluctuating population of its reservoir host

Mariën

Borremans

Verhaeren

et al. 2019

Journal of Animal Ecology

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A key aim in wildlife disease ecology is to understand how host and parasite characteristics influence parasite transmission and persistence. Variation in host population density can have strong impacts on transmission and outbreaks, and theory predicts particular transmission–density patterns depending on how parasites are transmitted between individuals. Here, we present the results of a study on the dynamics of Morogoro arenavirus in a population of multimammate mice (Mastomys natalensis). This widespread African rodent, which is also the reservoir host of Lassa arenavirus in West Africa, is known for its strong seasonal density fluctuations driven by food availability. We investigated to what degree virus transmission changes with host population density and how the virus might be able to persist during periods of low host density. A seven‐year capture–mark–recapture study was conducted in Tanzania where rodents were trapped monthly and screened for the presence of antibodies against Morogoro virus. Observed seasonal seroprevalence patterns were compared with those generated by mathematical transmission models to test different hypotheses regarding the degree of density dependence and the role of chronically infected individuals. We observed that Morogoro virus seroprevalence correlates positively with host density with a lag of 1–4 months. Model results suggest that the observed seasonal seroprevalence dynamics can be best explained by a combination of vertical and horizontal transmission and that a small number of animals need to be infected chronically to ensure viral persistence. Transmission dynamics and viral persistence were best explained by the existence of both acutely and chronically infected individuals and by seasonally changing transmission rates. Due to the presence of chronically infected rodents, rodent control is unlikely to be a feasible approach for eliminating arenaviruses such as Lassa virus from Mastomys populations.

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Population cycles: generalities, exceptions and remaining mysteries

Cited by 80 publications

References 96 publications

Impacts of predator-mediated interactions along a climatic gradient on the population dynamics of an alpine bird

Impacts of predator-mediated interactions along a climatic gradient on the population dynamics of an alpine bird

Demography of snowshoe hare population cycles

Density dependence and persistence of Morogoro arenavirus transmission in a fluctuating population of its reservoir host

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