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Population cycles can be caused by consumer-resource interactions. Confirming the role of consumer-resource interactions, however, can be challenging due to an absence of data for the resource candidate. For example, interactions between midge larvae and benthic algae likely govern the high-amplitude population fluctuations of Tanytarsus gracilentus in Lake Mývatn, Iceland, but there are no records of benthic resources concurrent with adult midge population counts. Here, we investigate consumer population dynamics using the carbon stable isotope signatures of archived T. gracilentus specimens collected from 1977 to 2015, under the assumption that midge δ

Ecosystem engineers have large impacts on the communities in which they live, and these impacts may feed back to populations of engineers themselves. In this study, we assessed the effect of ecosystem engineering on density-dependent feedbacks for midges in Lake Mývatn, Iceland. The midge larvae reside in the sediment and build silk tubes that provide a substrate for algal growth, thereby elevating benthic primary production. Benthic algae are in turn the primary food source for the midge larvae, setting the stage for the effects of engineering to feed back to the midges themselves. Using a field mesocosm experiment manipulating larval midge densities, we found a generally positive but nonlinear relationship between density and benthic production. Furthermore, adult emergence increased with the primary production per midge larva. By combining these two relationships in a simple model, we found that the positive effect of midges on benthic production weakened negative density dependence at low to intermediate larval densities. However, this benefit disappeared at high densities when midge consumption of primary producers exceeded their positive effects on primary production through ecosystem engineering. Our results illustrate how ecosystem engineering can alter density-dependent feedbacks for engineer populations.

Phenological shifts are the most widely reported ecological responses to climate change, but the requirements to distinguish their causes (i.e. phenotypic plasticity vs. microevolution) are rarely met. To do so, we analysed almost two decades of parturition data from a wild population of North American red squirrels (Tamiasciurus hudsonicus). Although an observed advance in parturition date during the first decade provided putative support for climate change-driven microevolution, a closer look revealed a more complex pattern. Parturition date was heritable [h2 = 0.14 (0.07-0.21 (HPD interval)] and under phenotypic selection [β = -0.14 ± 0.06 (SE)] across the full study duration. However, the early advance reversed in the second decade. Further, selection did not act on the genetic contribution to variation in parturition date, and observed changes in predicted breeding values did not exceed those expected due to genetic drift. Instead, individuals responded plastically to environmental variation, and high food [white spruce (Picea glauca) seed] production in the first decade appears to have produced a plastic advance. In addition, there was little evidence of climate change affecting the advance, as there was neither a significant influence of spring temperature on parturition date or evidence of a change in spring temperatures across the study duration. Heritable traits not responding to selection in accordance with quantitative genetic predictions have long presented a puzzle to evolutionary ecologists. Our results on red squirrels provide empirical support for one potential solution: phenotypic selection arising from an environmental, as opposed to genetic, covariance between the phenotypic trait and annual fitness.

Assessments of population genetic structure have become an increasing focus as they can provide valuable insight into patterns of migration and gene flow. structure, the most highly cited of several clustering-based methods, was developed to provide robust estimates without the need for populations to be determined a priori. structure introduces the problem of selecting the optimal number of clusters, and as a result, the ΔK method was proposed to assist in the identification of the "true" number of clusters. In our review of 1,264 studies using structure to explore population subdivision, studies that used ΔK were more likely to identify K = 2 (54%, 443/822) than studies that did not use ΔK (21%, 82/386). A troubling finding was that very few studies performed the hierarchical analysis recommended by the authors of both ΔK and structure to fully explore population subdivision. Furthermore, extensions of earlier simulations indicate that, with a representative number of markers, ΔK frequently identifies K = 2 as the top level of hierarchical structure, even when more subpopulations are present. This review suggests that many studies may have been over- or underestimating population genetic structure; both scenarios have serious consequences, particularly with respect to conservation and management. We recommend publication standards for population structure results so that readers can assess the implications of the results given their own understanding of the species biology.

In the early years of near-surface geophysical applications, measurements obtained using electromagnetic induction (Slingram or dipole–dipole) instruments were first interpreted in terms of electrical conductivity. Afterwards, studies began considering the importance of magnetic susceptibility. Until now, however, no attention has been paid to possible responses in dielectric permittivity. After reviewing the current state of knowledge regarding the expected theoretical responses in the very low frequency to low frequency (VLF-LF) range (3–300 kHz) and the value range of this property for soils, we propose the use of multi-frequency instruments to define a process allowing for the determination of the apparent conductivity and permittivity in the higher part of the frequency range above 20 kHz. We test this process through a series of experiments at archaeological sites in Greece using the GEM-2 (Geophex Ltd) instrument. In our experiments, the soil permittivity values fall between several hundredths and several thousandths. The results indicate lateral variations different from the other properties with a significant influence of the stone content and of the ionic strength, while a decrease with frequency may also provide further information on soil dielectric behaviours.

Summary Energy expenditure is a trait of central importance in ecological and evolutionary theory. We examined the correlates of, the strength of selection on, and the heritability of, daily energy expenditure (DEE; kJ day−1) during lactation in free-ranging North American red squirrels (Tamiasciurus hudsonicus). Over 7 years, lactating squirrels with greater DEE had higher annual reproductive success (ARS; standardized selection gradient: β′ = 0·47; top 12% of published estimates). Surprisingly, positive fecundity selection on lactation DEE for increased ARS did not result because lactation DEE was correlated with typical measures of reproductive performance and/or investment. We found no evidence of costs of elevated lactation DEE acting through female survival, subsequent year lactation DEE or subsequent year reproduction. Lactation DEE was not significantly repeatable, and heritability was not significantly different from zero. Elevated lactation DEE enhances ARS through a link between DEE and an unidentified measure of maternal or environmental quality, but there is limited evolutionary potential for lactation DEE to respond to our documented selection.

A trait must genetically correlate with fitness in order to evolve in response to natural selection, but theory suggests that strong directional selection should erode additive genetic variance in fitness and limit future evolutionary potential. Balancing selection has been proposed as a mechanism that could maintain genetic variance if fitness components trade off with one another and has been invoked to account for empirical observations of higher levels of additive genetic variance in fitness components than would be expected from mutation– selection balance. Here, we used a long-term study of an individually marked population of North American red squirrels (Tamiasciurus hudsonicus) to look for evidence of (1) additive genetic variance in lifetime reproductive success and (2) fitness trade-offs between fitness components, such as male and female fitness or fitness in high- and low-resource environments. “Animal model” analyses of a multigenerational pedigree revealed modest maternal effects on fitness, but very low levels of additive genetic variance in lifetime reproductive success overall as well as fitness measures within each sex and environment. It therefore appears that there are very low levels of direct genetic variance in fitness and fitness components in red squirrels to facilitate contemporary adaptation in this population. This is an electronic version of an article that was originally published as: McFarlane, S.E., Gorrell, J.C., Coltman, D.W., Humphries, M.M., Boutin, S., & McAdam, A.G. (2014). Very low levels of direct additive genetic variance in fitness and fitness components in a red squirrel population. Ecology and Evolution, 4(10), 1729-1738. DOI: 10.1002/ece3.982. Ecology and Evolution is an open access journal published by Wiley-Blackwell. More information about the journal can be found at: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2045-7758. This article can be accessed at: http://onlinelibrary.wiley.com/doi/10.1002/ece3.982/full. Ecology and Evolution Journal Cover Image (Volume 4, Issue 10) : A grizzly bear (Ursus arctos) of the Greater Yellowstone Ecosystem, which encompasses portions of Wyoming, Montana, and Idaho, USA. Photo by Ray Paunovick, Wild Planet Films, Bozeman, Montana, USA. https://viuspace.viu.ca/bitstream/handle/10613/3208/Gorrell.EE.pdf?sequence=4

This paper draws on a project ‘Banner Tales of Glasgow’, which is the result of an ongoing collaboration between geographers, museum staff and trade unionists. The paper draws on testimonies from workers involved in two labour disputes in the mid 1980s. We use these testimonies to think about the use of banners in the construction of working-class solidarities. This discussion is used to illuminate the relations between the formation of a working-class presence and the role of discourses of a moral economy in shaping particular community-making practices. Through doing so, we use a focus on banners to illuminate different aspects of the spatial practices of labour organising and argue that the construction of a working-class presence and articulations of a moral economy can be mutually reinforcing.

Consistent individual differences in behaviour, and behavioural correlations within and across contexts, are referred to as animal personalities. These patterns of variation have been identified in many animal taxa and are likely to have important ecological and evolutionary consequences. Despite their importance, genetic and environmental sources of variation in personalities have rarely been characterized in wild populations. We used a Bayesian animal model approach to estimate genetic parameters for aggression, activity and docility in North American red squirrels (Tamiasciurus hudsonicus). We found support for low heritabilities (0.08-0.12), and cohort effects (0.07- 0.09), as well as low to moderate maternal effects (0.07-0.15) and permanent environmental effects (0.08-0.16). Finally, we found evidence of a substantial positive genetic correlation (0.68) and maternal effects correlation (0.58) between activity and aggression providing evidence of genetically based behavioural correlations in red squirrels. These results provide evidence for the presence of heritable variation in red squirrel behaviour, but also emphasize the role of other sources of variation, including maternal effects, in shaping patterns of variation and covariation in behavioural traits.