In years with earlier snowmelt, first clutches occurred earlier and the proportion of second clutches produced was larger.
We found that assigned second clutches appeared significantly later in the season than first clutches. We tested whether the median capture date differed among first and second clutches, whether clutch size was correlated to female size, and whether the proportion of second clutches produced within a season was related to climate. Upon the discovery of a bimodal frequency distribution of clutch sizes, as is typical for wolf spiders at lower latitudes producing a second clutch, we assigned egg sacs to being a first or second clutch depending on clutch size. We dissected individual egg sacs and counted the number of eggs and partially developed juveniles, and measured carapace width of the mothers. To determine if this is already happening, we used specimens of the wolf spider Pardosa glacialis caught by pitfall traps from the long-term (1996–2014) monitoring programme at Zackenberg, NE Greenland. Yet the timing of snowmelt is advancing in the Arctic, which may allow some species to produce an additional clutch. Høye says.Spiders at southern latitudes commonly produce multiple clutches, but this has not been observed at high latitudes where activity seasons are much shorter. "We can only speculate about how the ecosystems change, but we can now ascertain that changes in the reproduction of species are an important factor to include when we try to understand how Arctic ecosystems react to the rising temperatures on the planet," Toke T. If there are more spiders - or insects - in the future Arctic, it can have an influence on the food chains on land. Wolf spiders feed on small organisms such as springtails in the soil. The researchers see the spiders' response to climate change as an ability to adapt to the new conditions. "These changes in the life history have not been seen earlier and evidence suggests that the phenomenon plays an important role for Arctic insects and spiders," Toke T.
Arctic wolf spider series#
The long time series tells the researchers that the earlier the snow disappears from the ground, the greater the proportion of spiders that can produce a second clutch of offspring. The large amount of data allows us to show how small animals in the Arctic change their life history in response to climate change," says Toke T. "We now have the longest time series of spiders collected the Arctic. By looking at the distribution of the number of eggs in the egg sacs throughout the season, it became clear that in some summers the spiders produced two egg sacs - a phenomenon that is known from warmer latitudes, but which has not previously been observed in the Arctic. The researchers counted the number of eggs in the individual spider's egg sacs and compared this information with the time of the season that the animal was caught. Wolf spiders carry their eggs in a so-called egg sac. The spiders were caught in small pitfall traps set up in different vegetation types. Høye from the Arctic Research Centre and Department of Bioscience at Aarhus University has now shown that changes are also occurring in the reproduction of invertebrates.įor almost 20 years, researchers at the Zackenberg Research Station in north-eastern Greenland have caught wolf spiders as part of the monitoring programme Greenland Ecosystem Monitoring. There are also signs that species move farther north and up into the mountains.Ī team of researchers led by senior researcher Toke T. Researchers have previously reported how plants bloom earlier and earlier in the season. The average temperature is increasing significantly and this affects the ecosystems. A lot, actually.Ĭlimate change is more dramatic here than in no other place on Earth. īut something is happening in the high north in these years. They typically take several years to become adults, and only produce offspring. Arctic spiders are at the top of the food chain among invertebrates and are numerous on the Arctic tundra.
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