The origin of parthenogenesis in the genus Campeloma was investigated by analyzing the karyotypes and oogenesis of numerous populations in Florida and Georgia. The species studied were Campeloma geniculum, C. fluoridense, C. limum, C. parthenum and 4 populations of unnamed parthenogens. Campeloma geniculum and C. floridense are diploid (2n = 28) and reproduction is exclusively sexual. Campeloma limum is also diploid and may reproduce either sexually or parthenogenetically, the latter being predominant. Campeloma parthenum and three other populations of unnamed parthenogens are triploid and parthenogenetic. Parthenogenesis was determined to be apomictic with a single maturation division in both the diploids and triploids. / Diploid parthenogenetic Campeloma in Georgia and Florida are considered to have been derived from diploid sexual ancestors by selection. In contrast, the triploid parthenogens are probably the result of the hybridization of a diploid parthenogen and C. geniculum. The karyotypes of the triploids show evidence of multiple chromosomal rearrangements probably involving C. geniculum chromosomes exclusively. Observed misdivisions could lead to altered karyotypes, as well as loss of genetic material and reduced fecundity for some parthenogenetic females. The karyotypes of parthenogenetic and sexual C. limum are indistinguishable, therefore, there are two different reproductive modes within this species. At least some individuals of C. limum can reproduce either apomictically or meiotically. The karyotype of C. floridense is indistinguishable from that of C. limum, therefore, C. floridense and C. limum may be conspecific. / Source: Dissertation Abstracts International, Volume: 50-08, Section: B, page: 3292. / Major Professor: William H. Heard. / Thesis (Ph.D.)--The Florida State University, 1989.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_78063 |
| Contributors | Dougherty, Brian Joseph., Florida State University |
| Source Sets | Florida State University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | 189 p. |
| Rights | On campus use only. |
| Relation | Dissertation Abstracts International |
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