Revista Chilena de Historia Natural 80 (4): 455-468, 2007
RESEARCH ARTICLE
Consequences of microclimate variation on insect pollinator visitation in two species of
Chaetanthera (Asteraceae) in the central Chilean Andes
CRISTIAN TORRES-DÍAZ, LOHENGRIN A. CAVIERES, CARLOS MUÑOZ RAMÍREZ & MARY T. K.
Insect pollinator activity can be influenced by biotic (e.g., patch floral density and floral
display) or by abiotic factors (e.g., temperature, wind velocity, cloudiness). In spite of microsite, seasonal and interannual variation in
temperature in the alpine zone, the consequences of local microclimatic variation on pollinator activity has been rarely studied in high
mountain ecosystems. In this study we compared flower visitation rates on a north-facing slope and a west-facing slope in
Chaetanthera apiculata (3,100 m of altitude) and on an east-facing slope and a west-facing slope in Chaetanthera
lycopodioides (3,300 m of altitude). We studied the breeding system in each species in order to determine level of dependence
on external pollinators. While the northfacing slope inhabited by C. apiculata was warmer (1.8 °C) and visited (7.8-fold)
more frequently than the west-facing slope, in C. lycopodioides the east-facing slope was warmer (3 °C) and
visited more frequently (4-fold) than the west-facing slope. In C. apiculata only Faunula leucoglene
(Lepidóptera: Satyridae) showed higher activity in the warmer population. In C. lycopodioides, F. leucoglene
and Liphantus sp. (Himenóptera: Andrenidae) showed higher activity rates in the warmer population. Flower
visitation rate in Faunula leucoglene was correlated with temperature in C. apiculata and C.
lycopodioides. Both C. apiculata and C. lycopodioides are partially self-compatible, and
thus require exogenous pollen for maximum seed set. Our results show that in high elevation environments flower visitation rates can
be highly variable and that microclimatic conditions can be more important for pollinator variation among populations than head density.
Our results offer valuable insights on the potential consequences of global warming on plant pollination at high
elevation.
microclimate, floral
density, flower visitation rates, Chaetanthera, high mountains, Andes, breeding systems, global climate
change
