The Relationship of Clarkias from Two Continents

Publisher Website
Google Scholar
Abstract
First and second generation hybrids that have been obtained between the tetraploid speciesClarkia tenella andC. davyi suggest a very close relationship between the two.C. tenella is a species of south-western South America, whereasC. davyi is restricted to the sea-coast of central and northern California. The two are morphologically similar and chromosome pairing in their hybrid indicates a high degree of homology. The hybrids are nevertheless highly sterile. In view of the cytological and morphological similarity ofC. tenella andC. davyi, and taking into account their relation to other species of the sectionGodetia, their origin from a common segmental allotetraploid ancestor in North America is postulated. The conditions permitting rapid evolution ofClarkia into various xeric habitats which became available as a result of climatic changes in late Cenozoic time probably also permitted the successful introduction of the tetraploid ancestor ofC. tenella and of various other herbaceous species into South America by long-distance dispersal in late Pliocene or more recent time.

This publication has 0 references indexed in Scilit: