Systematics Section / ASPT
Crawford, Daniel J. , Archibald, Jenny K. , Santos-Guerra, Arnoldo , Mort, Mark E. .
Allozyme diversity within and divergence among species of Tolpis (Asteraceae- Cichorieae) in the Canary Islands: systematic, evolutionary, and biogeographical implications.
ENZYME electrophoresis was used to examine allozyme diversity within and divergence among species of Tolpis in the Canary Islands. All recognized endemic taxa, two segregate species, several variants possibly worthy of taxonomic recognition, and one nonendemic species were studied. Tolpis is similar to many other island groups in having generally high allozyme similarities among species, but lowered identities were found among four groups of endemics: T. coronopifolia, T. crassiuscula, T. glabrescens, and the T. laciniata-T. lagopoda complex. The latter is defined as T. laciniata, the two species (T. calderae and T. proustii) that are sometimes segregated from T. laciniata, several undescribed morphological variants, T. lagopoda, and T. webbii. Allozyme data suggest that certain of the segregate taxa and unnamed variants represent distinct genetic entities. Tolpis laciniata and T. lagopoda as now recognized do not appear to be distinct entities based on allozymes and preliminary field observations of morphological variation. The tetraploid T. glabrescens is divergent from the endemic diploid species, and allozymes do not implicate any extant diploids in the origin of the tetraploid. The lowest species diversity occurs in the two self-compatible species T. barbata and T. coronopifolia, both of which also harbor a much higher proportion of their total diversity among populations compared to the highly self-incompatible species. The nonendemic Tolpis barbata shows no greater allozymic divergence from the endemics than some endemics exhibit among themselves. Both changes in allele frequencies and unique alleles (presumably generated by mutation) are responsible for lowered genetic identities among species of Tolpis in the Canary Islands.
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1 - University of Kansas, Department of Ecology & Evolutionary Biology, Natural History Museum and Biodiversity Research Center, 1200 Sunnyside Avenue, Lawrence, Kansas, 66045-7534, USA
2 - Indiana University of Pennsylvania, Department of Biology, Indiana, Pennsylvania, 15705, USA
3 - Jardín de Aclimatación de La Orotava, Puerto de la Cruz, Canary Islands, Tenerife, , Spain
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 2:45 PM