Molecular Ecology and Evolution
Kephart, Susan , Adler, Constance , Clark-Snustad, Kindra , Gross, Briana .
Habitat differentiation and reproductive barriers between sympatric species of Camassia (Agavaceae).
The genus Camassia Lindl. (Agavaceae) reaches its greatest phenotypic diversity in western North America, where plants grow in habitats ranging from low elevation riparian forests to montane wet prairies. Despite apparent differences in habitat and flowering onset, hybrid zones occur where the two most prevalent species, great camas (Camassia leichtlinii) and common camas (C. quamash) overlap in the Pacific Northwest. We used “smart habitat sensors,” pollination and glasshouse experiments, fluorescence microscopy, and multivariate analyses to investigate species boundaries and putative hybrid zones at multiple sites. The habitats most closely associated with these species varied significantly in light levels. Interspecific crosses differed in outcome with population and maternal parent, but yielded reduced seed set relative to intraspecific pollinations. Camassia quamash and C. leichtlinii also vary significantly in many traits including bulb size, plant height, leaf size, flower number, and tepal symmetry, size and withering. Putative hybrids may show intermediacy, parental characteristics, or transgressive traits. Less than 10 % of hybrid seeds germinated in sympatric populations, significantly fewer than for open-pollinated controls. Principal Component Analysis (PCA) of morphological traits, habitat differences, and asymmetric reproductive barriers all suggest genetic differentiation between C. quamash and C. leichtlinii. However, among population variability in the extent of crossing barriers, pollinator sharing, and the prevalence of putative hybrids further imply that barriers to gene flow are semi-permeable. Experimental plantings of Camassia are now in place for community-linked habitat restoration and in situ studies of hybrid zone dynamics.
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1 - Willamette University, Biology, 900 State Street, Salem, OR, 97301, USA
2 - Indiana University, Biology, 1001 East Third Street, Bloomington, Indiana, 47405, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Boulevard B/Hilton
Date: Wednesday, July 11th, 2007
Time: 10:30 AM