Distribution and ecological consequences of ploidy variation in Artemisia sieberi in Iran

Genetic fingerprinting revealed the existence of two genetically differentiated subgroups independent of ploidy but with some geographic and ecological pattern. We conclude that diploids and tetraploids have a different ecological distribution and that the absence of mixed diploid-tetraploid populations is a reflection of differing fitness in different habitats. We suspect that a key ecological difference between diploids and tetraploids is the increased stomatal size of tetraploids, possibly resulting from the increased genome and hence cell size following polyploidisation. Polyploid-formation may be constrained in arid habitats by problems of water-use efficiency associated with the larger stomata originally produced.