Freshwater habitats in Arctic landscapes provide essential food resources to predaceous terrestrial fauna. However, climate change threatens the continuation of aquatic resources as increased temperatures prompt widespread drying. We investigated how declines in surface waters in the Arctic may have implications for the diets of the wolf spider Pardosa glacialis (Araneae: Lycosidae), an abundant top predator in western Greenland known to consume both aquatic and terrestrial prey. We estimated the abundance of ground-dwelling prey taxa near and far from shallow ponds to compare resource availability for P. glacialis. We also measured the stable isotopes ratios of carbon and nitrogen of potential prey taxa and used linear mixing models to estimate the relative proportions of aquatic and terrestrial prey in the diets of P. glacialis collected near ponds versus drier, upland locations. Overall, near ponds there was a 3.7 times greater abundance of ground-dwelling organisms compared to locations far from ponds. Near ponds, depleted δ13C values of P. glacialis compared to the upland locations were explained by the consumption of aquatic insects, which were relatively depleted in 13C compared to terrestrial ground-dwelling and canopy taxa. Our linear mixing model indicated that the mean relative contribution of aquatic taxa to the diets of P. glacialis at pond locations was ~ 23% versus ~ 0% at upland locations, though these results were accompanied by significant uncertainty. Our results emphasize the importance of Arctic ponds in providing habitat to potential prey of terrestrial predators. We highlight how climate change, and the continued disappearance of aquatic habitats, could disrupt critical linkages between aquatic insects and terrestrial predators.

Changing abiotic conditions can affect the phenology of animals and plants with implications for their reproductive output, especially in rapidly changing regions like the Arctic. For instance in arthropods, it was recently shown that females of the spider species Pardosa glacialis (Thorell 1872) (Lycosidae) are able to produce two clutches within one growing season in years when snowmelt occurs particularly early. This phenomenon could be widespread in northern latitudes, and here we investigated the voltinism of two other very abundant species of wolf spiders in the Low-Arctic, Pardosa hyperborea (Thorell 1872) and Pardosa furcifera (Thorell 1875), over the period 2015–2017. Whilst a bimodal pattern in the clutch size frequency distribution was only revealed for P. hyperborea, we were able to show that both species can produce a second clutch over the active season by using information on the embryonic stages. We also observed significantly larger first than second clutches. We argue that information about the embryonic stage can be critical for evaluating evidence of wolf spider populations producing more than one clutch in a season. Our study provides evidence that bivoltinism could be a more widespread pattern than expected in Arctic wolf spiders. It remains to be investigated what the trophic consequences of such patterns are in a global warming context. We thus highlight the need for a coordinated framework for such further studies, integrating and relating various functional traits.

Aquatic insects are often consumed by terrestrial predators in Arctic tundra. However, this aquatic-terrestrial linkage may be disrupted by rapid warming that is causing a decrease in freshwater habitats across large areas of the Arctic. In this study, we investigated emerging mosquitoes (Diptera: Culicidae) as a resource subsidy for wolf spiders (Araneae: Lycosidae) in western Greenland, an area where significant pond drying has occurred in recent decades. We used pitfall trapping to compare the abundance, size, and fecundity of wolf spiders collected near (< 1 m) versus far (75–100 m) from the margins of three tundra ponds before, during, and after mosquito emergence. Nearly 90% of the wolf spiders collected in our study were Pardosa glacialis, the species that subsequently became the focus of our analyses. P. glacialis abundances, sizes, and the proportion of females with an egg sac were similar throughout the season both near and far from ponds. However, females near ponds produced about 20% more eggs per egg sac. Stable isotope analyses and a laboratory experiment confirmed mosquito consumption by P. glacialis and demonstrated that individuals collected near tundra ponds were significantly depleted in 13C relative to those in upland habitats, indicating differences in food resources among habitats. Our evidence indicates that mosquitoes do indeed serve as a subsidy to wolf spiders in western Greenland, but the demographic effects on spiders appear to be modest. Thus, P. glacialis abundance in the landscape may be relatively robust to pond drying and associated biotic and abiotic changes. Further studies will be needed to assess the broader effects for tundra ecosystems of disruptions to this and other aquatic-terrestrial linkages via the drying of ponds.

Temperature affects both the Grinnellian and Eltonian dimensions of ecological niches – A tale of two Arctic wolf spiders

Spiders as biomonitors of metal pollution at Arctic mine sites: The case of the Black Angel Pb-Zn-mine, Maarmorilik, West Greenland

Analysing the structure and dynamics of biotic interaction networks and the processes shaping them is currently one of the key fields in ecology. In this paper, we develop a novel approach to gut content analysis, thereby deriving a new perspective on community interactions and their responses to environment. For this, we use an elevational gradient in the High Arctic, asking how the environment and species traits interact in shaping predator-prey interactions involving the wolf spider Pardosa glacialis. To characterize the community of potential prey available to this predator, we used pitfall trapping and vacuum sampling. To characterize the prey actually consumed, we applied molecular gut content analysis. Using joint species distribution models, we found elevation and vegetation mass to explain the most variance in the composition of the prey community locally available. However, such environmental variables had only a small effect on the prey community found in the spider's gut. These observations indicate that Pardosa exerts selective feeding on particular taxa irrespective of environmental constraints. By directly modelling the probability of predation based on gut content data, we found that neither trait matching in terms of predator and prey body size nor phylogenetic or environmental constraints modified interaction probability. Our results indicate that taxonomic identity may be more important for predator-prey interactions than environmental constraints or prey traits. The impact of environmental change on predator-prey interactions thus appears to be indirect and mediated by its imprint on the community of available prey.

Environmental gradients can help us comprehend the range of adaptations or plasticity that a given species can exhibit in response to climatic change. In this study, we assessed the response in female body size, clutch size and egg volume to elevational gradients in closely related wolf spiders. We measured these traits in Pardosa glacialis, P. hyperborea, P. furcifera and P. palustris, collected along elevational gradients across six sites in Arctic and sub-Arctic regions (four sites in Greenland, one in Iceland and one in the Faroe Islands), although not all species were found at all sites. Body size and reproductive traits did not vary with elevation in a consistent manner among species although smaller species were more sensitive to the gradients. The positive relationship between body size and clutch size was most pronounced in the larger species, indicating that larger species are better able to translate favourable environmental conditions into a larger reproductive output. Our study illustrates that elevational gradients may not fully capture spatial variation in environmental conditions experienced by high-latitude wolf spider species.

No detectable trophic cascade in a high-Arctic arthropod food web

Extensive niche overlap among the dominant arthropod predators of the High Arctic

Abstract Parasitoids can have significant impacts on the life history of their hosts, as well as on local population and community dynamics. These effects could be particularly pronounced in the Arctic where the breeding season is short. We studied the incidence and loads of egg sac parasitoids, and whether these varied with body size or among species in three Arctic wolf spider species: Pardosa sodalis Holm 1970, Pardosa lapponica (Thorell 1872) and Pardosa moesta Banks 1892 from the Yukon Territory in northwestern Canada. We found a high incidence of egg sac parasitism (by Gelis sp.) and that the incidence of parasitism increased significantly with body size in two of the spider species; however, it did not change in the largest species. Among the three species investigated, parasitism was highest in the largest species (P. sodalis). Parasitism loads ranged from one to fourteen individuals per egg sac, and incidence reached 29.6% overall in P. sodalis. Parasitism may have significant impacts on the life...

Life changes as polar regions thaw

We studied populations of three tundra-dwelling wolf spider (Lycosidae) species to determine reproductive trait relationships and developmental timing in the Arctic. We collected 451 Pardosa lapponica (Thorell, 1872), 176 Pardosa sodalis Holm, 1970, and 117 Pardosa moesta Banks, 1892 during summer 2008. We used log-likelihood ratio tests and multiple linear regressions to determine the best predictors of fecundity and relative reproductive effort. Female body size best explained the variation in fecundity and body condition was the best predictor for relative reproductive effort. We tested for a trade-off between the allocation of resources to individual eggs and the number of eggs produced (fecundity) within each species using linear regression. There was variation in detectable egg size and number trade-offs among sites and these may be related to local variation in resource allocation linked to density-related biotic or abiotic factors. These findings contribute to knowledge about the fitness of arctic wolf spiders in the region of study and are particularly relevant in light of the effects that climate changes are predicted to have on the arctic fauna.

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 41:259-265 (2010) - DOI: https://doi.org/10.3354/cr00855 Climate change and altitudinal variation in sexual size dimorphism of arctic wolf spiders Toke Thomas Høye1,*, Jörg U. Hammel2 1Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, Aarhus University, Grenåvej 14, 8410 Rønde, Denmark 2Institute of Systematic Zoology and Evolutionary Biology with Phyletic Museum, Friedrich-Schiller-University Jena, Erbertstr. 1, 07743 Jena, Germany *Email: toh@dmu.dk ABSTRACT: Climate change is advancing the onset of the growing season, and this is happening at a particularly fast rate in the Arctic. Although this has recently been shown to affect the sexual size dimorphism (SSD) of a wolf spider species through time, it remains to be shown whether spatial variation in the physical environment is similarly affecting SSD. We studied altitudinal variation in adult body size of male and female wolf spiders on Disko Island, West Greenland. Two species exhibited female-biased SSD (measured by carapace width) at sea level but not at higher altitudes. Males and females of a third species were of equal size at both altitudes, and the 2 remaining species found on Disko Island were only present at 1 low altitude site each. Altitudinal variation in SSD is probably a result of sex differences in body size response to shorter growing seasons with altitude. Our results suggest that climate change may result in increased SSD. Constraints on body size may increase with altitude, and expanding growing seasons due to climate change may predominantly affect SSD at higher altitudes. Such intra-specific effects of climate may be widespread and suggest that further research in this topic is needed. KEY WORDS: Body size · Carapace width · Climate impacts · Intra-specific variation · Lycosidae Full text in pdf format Supplementary material PreviousCite this article as: Høye TT, Hammel JU (2010) Climate change and altitudinal variation in sexual size dimorphism of arctic wolf spiders. Clim Res 41:259-265. https://doi.org/10.3354/cr00855Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 41, No. 3. Online publication date: May 04, 2010 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2010 Inter-Research.

I investigated the relationship between clutch size, female size and mass, and clutch mass in two species of arctic spiders, Alopecosa hirtipes and Pardosa glacialis (Araneae: Lycosidae). Female mass and number of young were significantly correlated with female size in both years of the study. Cocoon mass was significantly correlated with female size in 1991 only. These results are discussed within the context of reproductive trade-offs and models of reproductive effort based on size.

Eleven spider species were collected from the Mestersvig district ... of which eight were trapped on the dune sands of Noret .... Pardosa glacialis Thor. was encountered most often in the general collection and was also common on the dunes. ...