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Reproductive isolation among three sympatric Achimenes species: pre‐ and post‐pollination components
Author(s) -
RamírezAguirre Erandi,
MarténRodríguez Silvana,
QuesadaAvila Gabriela,
Quesada Mauricio,
MartínezDíaz Yesenia,
Oyama Ken,
EspinosaGarcía Francisco J.
Publication year - 2019
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 - 10.1002/ajb2.1324
Subject(s) - biology , pollination , pollinator , interspecific competition , sympatry , sympatric speciation , intraspecific competition , hand pollination , reproductive isolation , pollen , phenology , zoophily , ecology , botany , population , demography , sociology
Premise Closely related species occurring in sympatry may experience the negative consequences of interspecific pollen transfer if reproductive isolation ( RI ) barriers are not in place. We evaluated the importance of pre‐ and post‐pollination RI barriers in three sympatric species of Achimenes (Gesneriaceae), including ecogeographic, phenological, floral isolation, self‐pollination, and hybrid viability (fruit and seed set). Methods We recorded geographic distribution throughout species ranges and assessed flowering phenology and pollinator visitation at one site in central Mexico. In the greenhouse, we measured floral traits involved in RI and quantified fruit and seed set for from self, intraspecific, and interspecific crosses. Results Ecogeographic barriers were important in RI , but under sympatry, phenological and floral barriers contributed more to total RI . Phenological RI varied between species and years, while floral RI was 100% effective at preventing interspecific visitation. Species showed differences in floral morphology, color, and scents associated with specialized pollination systems ( A. antirrhina –hummingbirds , A. flava –bees, A. patens –butterflies); heterospecific visitation events were restricted to rare secondary pollinators. Hybrid crosses consistently yielded progeny in lower numbers than intraspecific crosses. Conclusions This study indicated that neither autogamy nor early post‐pollination barriers prevent interspecific pollen flow between Achimenes species. However, floral isolation, acting through a combination of attraction and reward traits, consistently ensures specificity of the pollination system. These results suggest that selection on floral traits to reduce the costs of hybrid progeny production may have played a role in evolution or maintenance of specialized pollination systems in Achimenes .