Global weather and local butterflies: variable responses to a large-scale climate pattern along an elevational...

Area of Science:

• Ecology
• Climate Science
• Population Biology

Background:

• Understanding environmental variation's impact on populations is crucial, especially with climate change.
• Large-scale climate phenomena like the El Niño Southern Oscillation (ENSO) affect terrestrial taxa, but studies are often limited in scope.
• Investigating climate-driven biotic-abiotic interactions requires extensive spatial and temporal data.

Purpose of the Study:

• To explore associations between butterfly population abundance and ENSO-derived sea surface temperature anomalies (SSTA).
• To analyze how these associations vary across an elevational gradient and among different butterfly species.
• To assess the utility of large-scale climate indices for understanding species' responses to environmental change.

Main Methods:

• Utilized 23 years (1988-2010) of long-term butterfly monitoring data.
• Analyzed population abundance data for 28 butterfly species across 10 sites in California's Sierra Nevada.
• Correlated butterfly abundance with ENSO-derived sea surface temperature anomalies (SSTA) across a 2750 m elevational range.

Main Results:

• Detected a positive, regional effect of increased SSTA on overall butterfly abundance (wetter, warmer years correlated with more observations).
• Found significant variation in SSTA's influence on butterfly abundance along the elevational gradient and among species.
• Identified stronger relationships between ENSO-derived SSTA and migratory butterfly species.

Conclusions:

• The ecological effects of large-scale climatic factors are context-dependent, varying by site and species.
• Long-term data sets are powerful for revealing subtle climatic effects on populations.
• Extrapolating findings from single locations or species to broader ecological patterns should be done cautiously.