Abstract Detail

Systematics

Majure, Lucas Charles [1].

On the origin of the two putative allopolyploids, Opuntia curvispina and O. martiniana, a case of cryptic speciation in prickly pear cacti.

The putative allotetraploid taxon, Opuntia curvispina, is distributed from northeastern Arizona and southern Nevada to southeastern California, where it often grows in close proximity to, or sympatric with, O. chlorotica (2n=22), O. engelmannii (2n=66) and O. phaeacantha (2n=66). Another putative allotetraploid, O. martiniana, grows sympatrically with O. curvispina in only one area north of the Hualapai Mts., in northwestern Arizona. My objective was to determine the origins of both O. curvispina and O. martiniana to test previous hypotheses of hybrid origin, with O. curvispina putatively derived from O. chlorotica and O. phaeacantha and O. martiniana putatively derived from O. chlorotica and O. engelmannii. Plastid and nrDNA data indicate that O. curvispina may likely be an autopolyploid derived strictly from O. chlorotica, while O. martiniana appears to be most likely derived from O. curvispina and O. macrorhiza (2n=44), two taxa not before implicated in the origin of that taxon. Careful morphological characterization of O. martiniana clearly separates that species from O. curvispina, although it may be considered only cryptically different, a likely result of its partial putative origin from O. curvispina. This work demonstrates the care that must be taken with prickly pears, and plants in general, when making broad assumptions about the origin of polyploids using morphology alone and without incorporating DNA data. However, it also emphasizes the necessity for incorporating ploidal and morphological data to fully understand species complexes. Thus, a total evidence approach is necessary for disentangling confusing species complexes, especially where those taxa are derived from reticulate evolution.

1 - Desert Botanical Garden, Research, Conservation, and Collections, 1201 N. Galvin Parkway, Phoenix, AZ, 85008, USA

Keywords:
Cactaceae
Hybridization
Mojave Desert
Opuntia
Polyploidy.

Presentation Type: Poster
Session: P, Systematics
Location: Exhibit Hall/Omni Hotel
Date: Monday, June 26th, 2017
Time: 5:30 PM This poster will be presented at 6:15 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PSY006
Abstract ID:215
Candidate for Awards:None