Premium
Dioecy and the evolution of pollination systems in Schiedea and Alsinidendron (Caryophyllaceae: Alsinoideae) in the Hawaiian Islands
Author(s) -
Weller Stephen G.,
Sakai Ann K.,
Rankin Anne E.,
Golonka Annette,
Kutcher Brenda,
Ashby Karen E.
Publication year - 1998
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.2307/2446396
Subject(s) - biology , pollination , anemophily , pollen , nectar , inflorescence , zoophily , dioecy , ovule , caryophyllaceae , hummingbird , botany , pollen source , alpine plant , ecology , pollinator
The transition from biotic to wind pollination and the consequences of this transition for the evolution of dioecious breeding systems were investigated in Schiedea and Alsinidendron (Caryophyllaceae: Alsinoideae), genera endemic to the Hawaiian Islands. The potential for wind pollination was studied for five species of Schiedea using a wind tunnel. Morphological correlates of wind pollination for these species were then used to infer the presence or absence of wind pollination in the remaining Schiedea species. Hermaphroditic Alsinidendron and Schiedea species, which occur in mesic to wet forests, or less commonly in dry habitats, show little or no indication of wind pollination. These species had low pollen:ovule ratios, large relative pollen size, diffuse inflorescences, substantial nectar production in several cases, and appear to be biotically pollinated or autogamous. Sexually dimorphic species, which all occur in dry habitats, are wind pollinated, based on wind tunnel results or morphological adaptations indicating the potential for wind pollination. These adaptations include high pollen:ovule ratios, small pollen size, moderately to highly condensed inflorescences, and reduced nectaries and nectar production. Shifts to wind pollination and dimorphism are strongly correlated in Schiedea , suggesting the close functional relationship of the two phenomena.