Charles Heiser Special Contributed Paper Session
Kephart, Susan , Patzer, Jaime , Archibald, Jenny , Sultany, Molly .
Demystifying species divergence in Camassia (Agavaceae): Integrating phenology, pollination, and floral trait manipulation.
Deciphering variability lies at the core of both classic and novel approaches that inform species delimitation, phylogenetic inference, and evolutionary divergence in natural populations. Mosaic genomes and complex morphological patterns pose challenges for classification, particularly in dynamic, yet distinct lineages influenced by hybridization and introgression. Species complexes in the North American genus, Camassia (Agavaceae) provide a unique opportunity to study populations in varying stages of divergence and reproductive isolation. Camassia is an important spring-flowering perennial in wet prairies and oak savannas. The six species and 10 subspecies include rare and common taxa that exhibit ecological differentiation and span a broad geographic range, with the highest diversity centered in Oregon. We extend prior molecular, phenological, and morphometric analyses by investigating variation in flowering time and floral trait divergence for sister and non-sister species pairs of C. angusta, C. quamash, C. howellii, C.leichtlinii, and C.scilloides. For two species, we further test the response of pollinators in natural populations to artificial flowers manipulated for key diagnostic traits, including floral symmetry. Previous research suggests that these species comprise distinct phylogenetic lineages, yet specific and subspecific delimitation have been problematic historically due to mosaic patterns of trait differentiation that vary geographically. Thus, we compare sympatric populations with a long history of divergence, and variable intergradation, with putatively more recent progenitor-derivative pairs. Habitat isolation is evident between several taxa and phenological divergence is strong in all species pairs, with significant differences in sympatry versus allopatry for western C. quamash and C. leichtlinii. Asymmetric post-mating barriers to hybridization in these species imply that morphological complexity is greatest in sympatric sites where crossability and ecological overlap are high. Our ultimate goal includes a comprehensive classification that will improve taxonomic keys for these ecologically and culturally important monocots. The paired analyses of in-situ populations framed in a phylogenetic context will also lend insight into the processes underlying the diverse origins of complex phenotypic patterns and reproductive isolation in plants.
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1 - WILLAMETTE UNIVERSITY, Department Of Biology, SALEM, OR, 97301, USA
2 - University Of Kansas, RL McGregor Herbarium & Bridwell Botanical Research Lab, 2045 Constant Ave, Lawrence, KS, 66047-3729, USA
3 - Lewis & Clark College, Graduate School of Education, 0615 S.W. Palatine Hill Road , Salem, OR, 97219
Presentation Type: Oral Paper:Papers for Topics
Location: Lindell D/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 9:15 AM