Genetic diversity in three colonizing orchids with contrasting mating systems

Area of Science:

• Plant genetics
• Ecology
• Evolutionary biology

Background:

• Comparative studies on genetic attributes of colonizing orchids with diverse mating systems are scarce.
• Colonizing orchids Eulophia sinensis, Spiranthes hongkongensis, and Zeuxine strateumatica are common in new Hong Kong habitats.
• Mating systems vary: E. sinensis (self-compatible outcrossing), S. hongkongensis (self-pollinating), and Z. strateumatica (apomictic).

Purpose of the Study:

• To investigate the population genetic attributes of three colonizing orchid species with contrasting mating systems.
• To compare their genetic profiles with other colonizing plant species.

Main Methods:

• Electrophoretic surveys were used to analyze allozyme variation.
• Genetic attributes were assessed within and among populations.
• Gene duplications and fixed heterozygosity were examined.

Main Results:

• All three species exhibited a striking lack of allozyme variation, irrespective of their mating systems.
• Gene duplications were evident, suggesting polyploid origins.
• Fixed heterozygosity percentages were 10% (E. sinensis), 21.4% (S. hongkongensis), and 20% (Z. strateumatica).

Conclusions:

• Colonizing orchids display low genetic variation despite diverse mating strategies.
• Polyploidy likely contributes to the genetic makeup of these species.
• Genetic attributes are comparable to other successful colonizing plants.