Variation and the evolution in the genus Cryptocoryne (Araceae) or Are species – of Cryptocoryne – natural evolutionary units?
Niels Jacobsen*, Conny Asmussen Lange, Jan Bastmeijer, Hendra Budianto, Takashige Idei, Isa B. Ipor, Ahmad Sofiman Bin Othman, Duangchai Sookchaloem, Suwidji Wongso, and Marian Ørgaard.
* dept. Agriculture & Ecology, Copenhagen University
The southeast Asian genus Cryptocoryne is unique in its pollination syndrome as well as in the aquatic to amphibious habitats.
Cryptocoryne reproduces by seeds, but the extension of the populations are to a considerable extent dependant upon vegetative reproduction by far creeping stolons thereby producing large clonal growths.
A number of accessions made in recent years have extended our view of the occurrence of natural hybrids: of the accepted taxa at the “species level”, and including unnamed accessions, more than 20% are recognised as being hybrids. This shows that hybridization is a commoner phenomenon than generally believed: the pollinators being small flies seeking carrion remains (?) and they will transport pollen to any Cryptocoryne spathe that smells disgusting. As Cryptocoryne hybridize easily, and because of their vegetative reproduction, the hybrids produced in nature over time, are accumulated to a degree not usual in flowering plants.
It would be appropriate to view the genus Cryptocoryne as consisting of numerous populations in different river systems, and that “hybridization” would be a driving evolutionary force. The Cryptocoryne “species” cannot be considered as natural evolutionary units, but what we see are populations that are the results of stochastic parameters brought about by “historical” events etc. As an element in this scenario the dramatic changes in the water level over the last 10.000 – 20. 000 years in SE Asia will facilitate this understanding.
