Niche Relationships between Two Sympatric Liolaemus Lizards in a Fluctuating Environment: The "Lean" versus "Feast" Scenario

Abstract

Liolaemus fuscus and L. lemniscatus are two similarly-sized, completely sympatric species of central Chile. In some localities they are also syntopic, sharing the same microhabitat (rocks). We studied the microhabitat, time, and food use of these two species throughout one year, computing standard niche metrics. Between-species similarities on these three niche dimensions were very high at all times of the year (mean = 82% for all three microhabitat, time, and food overlaps), slightly decreasing during winter. The feast seasons of plentiful food, when dietary overlaps reached 90 and 99% (spring and summer, respectively) were associated with the two species overlapping broadly in microhabitat (77 and 81%, for spring and summer, respectively) and activity time (92 and 91%, respectively). Lean times were associated with decreased overlap in both diet (59 and 81% for fall and winter, respectively) and activity time (87 and 58%, respectively), but not in microhabitat (71 and 97%, respectively). Our data provide limited support for the view that interspecific niche relationships in fluctuating environments may be understood within the lean versus feast times scenario.