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Life Histories of Alpine Tundra Arachnida in Colorado
The American Midland Naturalist
Vol. 83, No. 1 (Jan., 1970), pp. 119-133
Published by: The University of Notre Dame
Stable URL: http://www.jstor.org/stable/2424011
Page Count: 15
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Pitfall jars were used to collect 16,342 specimens of spiders, phalangids, erythraeid mites, and ground beetles at 3500-4270 m (11,500-14,000 ft) elevation. Most alpine tundra arachnid species have biennial life cycles, but some are annuals. This biennial pattern also predominates near sea level at high latitudes (50⚬N+). Annual cycles are more typical of mid-latitude (40⚬N), low-elevation regions. Various species of alpine tundra Pardosa wolf spiders have either two-or one-year cycles; the length of life appears to be directly proportional to the net primary productivity of the various species habitats. Mating and egg-laying in Pardosa tend to occur later in the year in the alpine tundra than at low elevations. No significant differences in the number of eggs per cocoon in Pardosa were noted when tundra and low-altitude data were compared. The overwintering stages of alpine tundra spiders (young and penultimate juveniles) are the same as for sea level, except that no tundra species overwinter as adults, whereas many low-elevation species do. Pardosa concinna spends its first winter within the cocoon, a novel behavior for a wolf spider. Dramatic temporal changes in the abundance or activity of some carabid ground beetles were recorded from incidental data obtained on this group.
The American Midland Naturalist © 1970 The University of Notre Dame