Abstracts (first author)

Talk 

Pollinator-mediated selection on floral size and color in two Iris species

Author(s): Sapir Y, Lavi R

Summary:

Pollinator-mediated selection is considered the major drive of floral evolu-tion and the evolution of floral diversity among angiosperms. Yet, causes of selection on traits contributing to attract pollinators have rarely been tested experimentally in natural populations. We quantified phenotypic selection on floral size and color in two species of the Oncocyclus irises in two years, and experimentally assessed the contribution of pollinators for this selection. Flowers of the Oncocyclus irises are among the largest in the East Mediter-ranean flora, and are usually dark-colored, from purple to black. Floral color is utilized to absorb the morning sun rays and to increase temperature within the flower. This morning floral heat rewards the pollinators of the irises: male solitary bees that shelter overnight in the flowers. To determine whether selection on floral size and color can be attributed to interactions with pollinators, selection was quantified for both open-pollinated controls and for plants receiving supplemental hand-pollination. The latter treatment is expected to remove pollinator limitation and hence to relax pollinator-mediated selection. Supplemental hand-pollination changed the extent and direction of selec-tion, suggesting pollinator-mediated selection on these traits. Pollinator-mediated directional selection on floral size and color was detected in Iris atropurpurea, and non-linear pollinator-mediated selection was detected in Iris haynei. This study provides evidence that pollinators of these irises are the selec-tion agent on floral traits, and support the contention that pollinators can drive the evolution of floral display size and color.



Abstracts (coauthor)

Summary:

Models of future climate change predict a rapid decrease in precipitation and lower water availability in the East Mediterranean region. One consequence of this change will be a northward desertification process into the Mediterranean climate region, threatening the Mediterranean ecosystems. To survive this climate change, plants may adapt by a plastic response, or by an evolutionary-genetic response, which can be either genetic or epigenetic mechanisms. Understanding the rate and direction of evolutionary change of wild plants under climate change will enable better ecosystem management. Natural geo-climatic gradients provide a natural lab for studying the outcome of climate changes. Thus, the arid areas in Israel can serve as the predicted climate in the Mediterranean region following climate change. This study provides evidence for a rapid evolution of phenotypic traits following experimental rapid climate change. We tested different traits of the annual grass Brachypodium distachyon (Poaceae), related to the cereal crops, from Mediterranean and semi-arid sites in Israel. Seeds were collected from both sites after five and ten generations of experimental rain decrease (drought), and morphological and physiological traits were compared in common-garden conditions. We found differences in life-history and morphological traits after five generations only. We also found that while Mediterranean plants can undergo rapid evolution, semi-arid ones are pre-adapted. We argue that plants can adapt to future climate change and undergo a rapid evolution under strong environmental selection. These results are important not only in a conservation perspective but also in an agricultural perspective.

Contacts

Chairman: Octávio S. Paulo
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Address

XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon
Portugal

Website

Computational Biology & Population Genomics Group 
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