Population fluctuations of chironomid and simuliid Diptera at Myvatn in 1977–1996

Gardarsson, Arnthór; Einarsson, Árni; Gíslason, Gísli Már; Hrafnsdottir, T.; Ingvason, Haraldur R.; Jonsson, E.; Ólafsson, Jón S.

doi:10.1023/b:aeco.0000032051.14118.e1

Cited by 39 publications

(38 citation statements)

References 17 publications

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“…Genetic, behavioural and demographic data (Corbet 1999; Purse & Thompson 2003; Rouquette & Thompson 2006) indicate that the latter has little or no effect in lowering the N e of C. mercuriale, and accordingly, we estimated N e from the expected effect of VRS only. However, over many generations the sizes of C. mercuriale populations are likely to vary, like those of other insects (Hanski 2003; Gardarsson et al . 2004).…”

Section: Discussionmentioning

confidence: 99%

Compatible genetic and ecological estimates of dispersal rates in insect (Coenagrion mercuriale: Odonata: Zygoptera) populations: analysis of ‘neighbourhood size’ using a more precise estimator

Watts¹,

Rousset²,

Saccheri³

et al. 2007

Molecular Ecology

122

151

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Genetic and demographic estimates of dispersal are often thought to be inconsistent. In this study, we use the damselfly Coenagrion mercuriale (Odonata: Zygoptera) as a model to evaluate directly the relationship between estimates of dispersal rate measured during capture-mark-recapture fieldwork with those made from the spatial pattern of genetic markers in linear and two-dimensional habitats. We estimate the 'neighbourhood size' (Nb) - the product of the mean axial dispersal rate between parent and offspring and the population density - by a previously described technique, here called the regression method. Because C. mercuriale is less philopatric than species investigated previously by the regression method we evaluate a refined estimator that may be more applicable for relatively mobile species. Results from simulations and empirical data sets reveal that the new estimator performs better under most situations, except when dispersal is very localized relative to population density. Analysis of the C. mercuriale data extends previous results which demonstrated that demographic and genetic estimates of Nb by the regression method are equivalent to within a factor of two at local scales where genetic estimates are less affected by habitat heterogeneity, stochastic processes and/or differential selective regimes. The corollary is that with a little insight into a species' ecology the pattern of spatial genetic structure provides quantitative information on dispersal rates and/or population densities that has real value for conservation management.

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Section: Discussionmentioning

confidence: 99%

Compatible genetic and ecological estimates of dispersal rates in insect (Coenagrion mercuriale: Odonata: Zygoptera) populations: analysis of ‘neighbourhood size’ using a more precise estimator

Watts¹,

Rousset²,

Saccheri³

et al. 2007

Molecular Ecology

122

151

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“…, Gardarsson et al. ). Because positive autocorrelation causes a variable of interest to fluctuate slowly over the possible range of values it can take, autocorrelation can increase type I errors (false positives) in statistical tests of correlation between two variables.…”

Section: Methodsmentioning

confidence: 98%

“…, Einarsson and Gulati , Gardarsson et al. ). Because midges make up more than 90% of the secondary production of the lake benthos (1972–1974; Lindegaard and Jónasson ), the fluctuations generate huge changes to the trophic structure of the lake and drive fluctuations throughout the lake food web (Einarsson and Gulati ).…”

Section: Introductionmentioning

confidence: 99%

“…The midge fluctuations are cyclic, in the sense that they show clear, multigenerational peaks and troughs, yet they are not strictly periodic, because the time between consecutive peaks ranges from 4 to 7 years (Gardarsson et al. ).…”

Section: Introductionmentioning

confidence: 99%

“…While almost all of the 20 species of midges in the lake show synchronous population fluctuations, the fluctuations of T. gracilentus are the most extreme (five orders of magnitude) and, at peak abundances, this species makes up roughly 80% of the midge population by numbers (Gardarsson et al. ). In the 23‐year (46‐generation) time series from 1977 to 1999, the adult body size of T. gracilentus decreased during the generations before population collapse, suggesting resource limitation leading up to troughs in the cycles (Einarsson et al.…”

Section: Introductionmentioning

confidence: 99%

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Identifying consumer–resource population dynamics using paleoecological data

Einarsson

Hauptfleisch

Leavitt

et al. 2016

Ecology

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Ecologists have long been fascinated by cyclic population fluctuations, because they suggest strong interactions between exploiter and victim species. Nonetheless, even for populations showing high-amplitude fluctuations, it is often hard to identify which species are the key drivers of the dynamics, because data are generally only available for a single species. Here, we use a paleoecological approach to investigate fluctuations in the midge population in Lake Mývatn, Iceland, which ranges over several orders of magnitude in irregular, multigeneration cycles. Previous circumstantial evidence points to consumer-resource interactions between midges and their primary food, diatoms, as the cause of these high-amplitude fluctuations. Using a pair of sediment cores from the lake, we reconstructed 26 years of dynamics of midges using egg remains and of algal groups using diagnostic pigments. We analyzed these data using statistical methods that account for both the autocorrelated nature of paleoecological data and measurement error caused by the mixing of sediment layers. The analyses revealed a signature of consumer-resource interactions in the fluctuations of midges and diatoms: diatom abundance (as inferred from biomarker pigment diatoxanthin) increased when midge abundance was low, and midge abundance (inferred from egg capsules) decreased when diatom abundance was low. Similar patterns were not found for pigments characterizing the other dominant primary producer group in the lake (cyanobacteria), subdominant algae (cryptophytes), or ubiquitous but chemically unstable biomarkers of total algal abundance (chlorophyll a); however, a significant but weaker pattern was found for the chemically stable indicator of total algal populations (β-carotene) to which diatoms are the dominant contributor. These analyses provide the first paleoecological evaluation of specific trophic interactions underlying high amplitude population fluctuations in lakes.

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Invertebrate diversity in groundwater‐filled lava caves is influenced by both neutral‐ and niche‐based processes

Kristjánsson,

Combot,

Reilent

et al. 2024

Ecology and Evolution

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Understanding which factors shape and maintain biodiversity is essential to understand how ecosystems respond to crises. Biodiversity observed in ecological communities is a result of the interaction of various factors which can be classified as either neutral‐ or niche‐based. The importance of these processes has been debated, but many scientists believe that both processes are important. Here, we use unique ecosystems in groundwater‐filled lava caves near Lake Mývatn, to examine the importance of neutral‐ versus niche‐based factors for shaping invertebrate communities. We studied diversity in benthic and epibenthic invertebrate communities and related them to ecological variables. We hypothesized that if neutral processes are the main drivers of community structure we would not see any clear relationship between the structure of community within caves and ecological factors. If niche‐based processes are important we should see clear relationships between community structure and variation in ecological variables across caves. Both communities were species poor, with low densities of invertebrates, showing the resource limited and oligotrophic nature of these systems. Unusually for Icelandic freshwater ecosystems, the benthic communities were not dominated by Chironomidae (Diptera) larvae, but rather by crustaceans, mainly Cladocera. The epibenthic communities were not shaped by environmental variables, suggesting that they may have been structured primarily by neutral processes. The benthic communities were shaped by the availability of energy, and to some extent pH, suggesting that niche‐based processes were important drivers of community structure, although neutral processes may still be relevant. The results suggest that both processes are important for invertebrate communities in freshwater, and research should focus on understanding both of these processes. The ponds we studied are representative of a number of freshwater ecosystems that are extremely vulnerable for human disturbance, making it even more important to understand how their biodiversity is shaped and maintained.

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Population fluctuations of chironomid and simuliid Diptera at Myvatn in 1977–1996

Cited by 39 publications

References 17 publications

Compatible genetic and ecological estimates of dispersal rates in insect (Coenagrion mercuriale: Odonata: Zygoptera) populations: analysis of ‘neighbourhood size’ using a more precise estimator

Compatible genetic and ecological estimates of dispersal rates in insect (Coenagrion mercuriale: Odonata: Zygoptera) populations: analysis of ‘neighbourhood size’ using a more precise estimator

Identifying consumer–resource population dynamics using paleoecological data

Invertebrate diversity in groundwater‐filled lava caves is influenced by both neutral‐ and niche‐based processes

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