An Experimental Study of Interference Competition Among Terrestrial Salamanders
1980
Wrobell, David J. | Gergits, William F. | Jaeger, Robert G.
Previous studies showed that the terrestrial salamander Plethodon cinereus competitively excludes a sibling species, P. shenandoah, from optimal habitats in Virginia. However, the mode of competition (interference or exploitation) was not well understood. In the present study, pairs of congeners and pairs of conspecifics were maintained in experimental enclosures in the laboratory food—limited conditions. Mass changes and behavioral interactions during feeding periods were monitored over 20 mo. Behavioral data were compared both between species and between "winners" and "losers." (The winning salamander gained more or lost less mass than the cohabiting loser.) Winners exhibited more aggressive activity than losers among interspecific pairs, suggesting that aggressive superiority and foraging superiority are associated. However, P. cinereus did not win more often than P. shenandoah, although it was on the average more aggressive. Males of both species were more aggressive than conspecific females. The data suggested that interference competition occurs both within and between the two species. We suggest that interference may be involved in competition for space, rather than for food items per se.
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