Use this URL to cite or link to this record in EThOS:
Title: Evolution in the Asplenium majoricum complex
Author: Hunt, H. V.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
Availability of Full Text:
Full text unavailable from EThOS.
Please contact the current institution’s library for further details.
Asplenium majoricum is an allotetraploid rock fern known only from the Balearic island of Majorca and from a very few sites in the province of Valencia on the Spanish mainland. In the latter of these areas, A. majoricum grows sympatrically with its diploid parents. A. fontanum and A. petrarchae subsp. bivalens, and with the hybrid between these taxa, A. x protomajoricum, that constitutes its diploid precursor. One of the two parental diploid taxa, A. petrarchae subsp. bivalens, has also given rise to an autotetraploid (A. petrarchae subsp. petrarchae). This autotetraploid, in contrast to A. majoricum, has attained a wide geographical distribution, with populations scattered throughout the Mediterranean region. Polyploidy is an important evolutionary phenomenon in the plant kingdom. The current study explores the dynamics of polyploid species formation and establishment through the use of nuclear and chloroplast genetic markers. The diversity present in A. x. protomajoricum, A. majoricum and A. petrarchae subsp. petrarchae is explained with reference to the alleles and haplotypes found in A. fontanum and A. petrarchae subsp. bivalens. Sampling of these two diploid parental taxa from across their geographic ranges therefore forms an essential foundation for the investigation of polyploid speciation dynamics. The patterns of genetic variation enable the elucidation of these species’ histories and breeding systems. The levels, and distribution, of genetic diversity in the polyploid taxa are used to test hypotheses regarding their number of origins, and the geographic location of these. Polyploid species establishment emerges as a rare event, which appears to be mediated by ecological niche separation and/or creation of vacant habitat by disturbance. A switch in breeding system may also play an important role, particularly in allowing polyploids to colonise new areas by long-distance dispersal. The availability of opportunities to escape parental competition and found new populations elsewhere is, therefore, a key determinant of the demographic success of polyploid species.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available