Systematics of three North American polyploid arctic alkali grasses (Puccinellia, Poaceae): morphology, ploidy, and AFLP markers

摘要

We used flow cytometry. amplified fragment length polymorphisms (AFLP). and macromorphology front field and common garden specimens to delimit and identify parental taxa of three polyploid species of Puccinellia from the North American Arctic, Tetraploid Puccinellia bruggemannii T.J. Sorensen. hexaploid Puccinellia augustata (R. Br.) E.L. Rand & Redfield, and octoploid Puccinellia andersonii Swallen were generally separable based oil ploidy and AFLP pattern, and showed allopolyploid origin. All three shared AFLP hands with at least two diploids and with Puccinellia phryganodes (Trin.) Scribn. & Merr., shown here to have both triploid and tetraploid populations in Canada. Approximately 10% of hexaploid individuals had AFLP patterns that were intermediate between P. angustata and P. bruggemannii, or P. angustata and P. andersonii. and occupied corresponding intermediate positions in morphological ordinations. Geographic distributions provide better support for introgression than for multiple polyploid events to account for these intermediate patterns. In common garden experiments, half of the characters had significantly different values between field and common garden specimens. but these plastic characters varied depending oil the species pair analyzed and between experiments. Moreover. several characters were significantly different among species, but these characters were also different in each of the two experiments. Given this variation. we pooled the field and common garden data to determine important key characters by discriminant analysis of species pairs.