Patterns of recurrent evolution and geographic parthenogenesis within apomictic polyploid Easter daises (Townsendia hookeri).
Mol Ecol
; 15(11): 3389-400, 2006 Oct.
Article
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| MEDLINE
| ID: mdl-16968277
ABSTRACT
Geographic patterns of parthenogenesis and the number of transitions from sexual diploidy to asexual (apomictic) autopolyploidy were examined for 40 populations of the Easter daisy, Townsendia hookeri. Analyses of pollen diameter and stainability characterized 15 sexual diploid and 25 apomictic polyploid populations from throughout the plant's western North American range. Sexual diploids were restricted to two Wisconsin refugia Colorado/Wyoming, south of the ice sheets, and northern Yukon/Beringia. Chloroplast DNA sequencing uncovered 17 polymorphisms within the ndhF gene and trnK intron, yielding 10 haplotypes. Phylogenetic analyses indicated that five exclusively polyploid haplotypes were derived from four haplotypes that are shared among ploidies, conservatively inferring a minimum of four origins of apomictic polyploidy. Three of these apomictic polyploid origins were derived from southern sexual diploids, while the fourth origin was derived from northern sexual diploids. Analyses of regional diversity were suggestive of a formerly broad distribution for sexual diploids that has become subsequently fragmented, possibly due to the last round of glaciation. As sexual diploids were exclusively found north and south of the glacial maximum, while formerly glaciated areas were exclusively inhabited by asexual polyploids derived from both northern and southern sexual lineages, it is more likely that patterns of glaciation, as opposed to a particular latitudinal trend, played a causal role in the establishment of the observed pattern of geographic parthenogenesis in Easter daisies.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Partenogénesis
/
Filogenia
/
Poliploidía
/
Ecosistema
/
Evolución Molecular
/
Asteraceae
País/Región como asunto:
America do norte
Idioma:
En
Revista:
Mol Ecol
Asunto de la revista:
BIOLOGIA MOLECULAR
/
SAUDE AMBIENTAL
Año:
2006
Tipo del documento:
Article