Who hasn’t picked up a fluffy dandelion, blew a deep breath, and smiled as the seeds fly along on the wind? But did you know that those seeds are possibly clones of the parent plant?
Dandelions (Taraxacum sp.) can produce seeds asexually, a process called apomixis that involves no fusion of egg and sperm. The ability to make seeds without fertilization has helped these charismatic yellow herbs reach worldwide distributions. Sexually reproducing dandelions do occur in Europe, and at times coexist with apomictic dandelions. In fact, sometimes a sexually reproducing dandelion gets fertilized by an apomictic dandelion (that provides a diploid pollen grain) resulting in a triploid apomictic! How cool is that?! These genetically diverse apomictic plants then spread to new environments where they reproduce via clonal seeds. Apomixis is the only reproduction mode in North American dandelions.
Lisa Mazumder and colleagues (University of Massachusetts; Kesseli Lab) study dandelion populations in the Boston area of Massachusetts. They examined the genetic diversity, population structure, and flowering time at three sites to determine if populations are locally adapted to their urban surroundings. Genetic analysis showed three main haplotypes all of which occurred at each site. However, when further analyzed using discriminant analysis, the individual plants clustered not only by site but also by flowering time. Spring and fall flowering time are distinct genotypes. The observed population structure and phenological differences suggest that local adaptation may be occurring in urban populations. And surprisingly, despite relying on an apomictic mode of reproduction, these populations are genetically diverse. They found around 100 different clonal genotypes at each site!
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