INVESTIGADORES
AIZEN Marcelo Adrian
artículos
Título:
Erosion of a pollination mutualism along an environmental gradient in a south Andean treelet, Embothrium coccineum (Proteaceae)
Autor/es:
CHALCOFF, V.R., M.A. AIZEN Y C. EZCURRA
Revista:
OIKOS
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2012 vol. 121 p. 471 - 480
ISSN:
0030-1299
Resumen:
The limit of a species distribution can be determined biotically if an environmental gradient causes the loss of critical
mutualists such as pollinators. We assessed this hypothesis for Embothrium coccineum , a self-incompatible red-flowered
treelet growing along a strong west-east precipitation gradient from rainforest to forest-steppe ecotone in the rain shadow
of the southern Andes in northwestern Patagonia. For 16 populations along this gradient, we quantified composition of
the pollinator assemblage, pollination effi ciency and limitation, and reproductive output. Th e treelet has a generalized pollination
system, but the hummingbird Sephanoides sephaniodes was the most effective pollinator. The relative importance
of this hummingbird as a fl ower visitor within populations influenced pollen transfer and fruit set more strongly than
local precipitation. As hummingbirds and other pollinators, including passerine birds and nemestrinid fl ies, were replaced
by bees towards the dry eastern range limit, pollen limitation increased and reproduction eventually failed. These results
support the hypothesis that pollinators can act as important biotic filters infl uencing plant distribution, and warn against
predictions of geographical range shifts based solely on climatic variables.