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Ramsey J, Robertson A, Husband BC. Rapid adaptive divergence in New World Achillea, an autopolyploid complex of ecological races. Evolution 62: 639-653

Department of Integrated Biology, University of Guelph, 488 Gordon St, Guelph, ON N1G 2W1, Canada.
Evolution (Impact Factor: 4.61). 04/2008; 62(3):639-53. DOI: 10.1111/j.1558-5646.2007.00264.x
Source: PubMed

ABSTRACT

Adaptive evolution is often associated with speciation. In plants, however, ecotypic differentiation is common within widespread species, suggesting that climatic and edaphic specialization can outpace cladogenesis and the evolution of postzygotic reproductive isolation. We used cpDNA sequence (5 noncoding regions, 3.5 kb) and amplified fragment length polymorphisms (AFLPs: 4 primer pairs, 1,013 loci) to evaluate the history of ecological differentiation in the North American Achillea millefolium, an autopolyploid complex of "ecological races" exhibiting morphological, physiological, and life-history adaptations to diverse environments. Phylogenetic analyses reveal North American A. millefolium to be a monophyletic group distinct from its European and Asian relatives. Based on patterns of sequence divergence, as well as fossil and paleoecological data, colonization of North America appears to have occurred via the Bering Land Bridge during the Pleistocene (1.8 MYA to 11,500 years ago). Population genetic analyses indicate negligible structure within North American A. millefolium associated with varietal identity, geographic distribution, or ploidy level. North American populations, moreover, exhibit the signature of demographic expansion. These results affirm the "ecotype" concept of the North American Achillea advocated by classical research and demonstrate the rapid rate of ecological differentiation that sometimes occurs in plants.

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    • "In California, Achillea millefolium L. (Asteraceae) is one of the few native species that is able to coexist with the widespread invasive perennial grass Holcus lanatus (Poaceae), and also one of the few native species that is able to apply a competitive effect on H. lanatus (Muir 2009). Achillea millefolium is palearctic, and a phylogeographic analysis places BMR populations in a clade that colonized North America via the Bering Land Bridge during the Pleistocene (Ramsey et al. 2008). Over the last century, H. lanatus, a Eurasian native, has successfully established on several continents and is now found throughout the United States (Watt 1978; USDA NRCS 2010). "
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    Full-text · Article · Nov 2012 · Heredity
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    • "assessed using fi ve microsatellite loci developed in our laboratory: PHL28, PHL33, PHL68, PHL98, and PHL113 ( Fehlberg et al., 2008 ). Primer sequences for PHL28 are as follows: forward (5 ′ -GTTGCCACCTCACAGATTCC-3 ′ ) and reverse (5 ′ -AATTGGGCGGTAAAAATGAA-3 ′ ). Primer sequences for PHL33, PHL68, PHL98, and PHL113 are described by Fehlberg et al. (2008) . Amplifi cation products from each locus for several individuals were cloned and sequenced to confi rm that the intended microsatellite locus was being amplifi ed. General amplifi cation and genotyping procedures followed that described by Fehlberg et al. (2008) . When microsatellite loci are genotyped in polyploid individuals that are"
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