Abstract Detail

Systematics

Hinojosa-Espinosa, Oscar [1], Potter, Daniel [2].

Are the Fetid Marigolds (Dyssodia, Tageteae: Asteraceae) a clade?

Dyssodia is a New World genus of the tribe Tageteae (Asteraceae). As in most members of this tribe, the leaves and bracts of Dyssodia have aromatic oil glands, which are responsible for their odor. Dyssodia was revised by Strother (1969), who recognized 32 species in three subgenera. However, in a systematic review of the Tageteae, Strother (1977) later acknowledged that each of the subgenera seemed more closely related to another genus of the tribe than to the other subgenera. Subsequently Strother (1986) published a renovated concept of Dyssodia, in which it was narrowed to four species of annual and perennial herbs. The type, D. papposa, occurs from Canada to South America, while D. pinnata and D. tagetiflora are endemic to Mexico, and D. decipiens is confined to southern Mexico and Guatemala. They are all favored by disturbance and are common on roadsides, open sites, and other weedy habitats. The renovation of Dyssodia required the restoration of several old genera as well as the segregation of new ones, which was supported by the molecular phylogenetic analyses of the Tageteae by Loockerman et al. (2002). However, thier study did not sample all species of Dyssodia. We previously showed that phylogenetic analyses based on denser sampling did not support the monophyly of some restored genera (e.g., Adenophyllum). We wondered whether the genus Dyssodia sensu lato would be supported as monophyletic if all species were subjected to phylogenetic analyses. Our hypothesis is that the genus is monophyletic only sensu stricto, as in this narrow circumscription it is extremely homogenous in morphology. We conducted phylogenetic analyses using nuclear and plastid DNA sequences and Bayesian inference. All 32 species of Dyssodia sensu lato were sampled. Our results corroborate that Dyssodia sensu lato is paraphyletic, but sensu stricto it is a clade with significant support. Moreover, some of the restored genera by Strother (1986) are not monophyletic. Robust phylogenies are important for maximizing the informativeness of classifications as well as for providing evolutionary frameworks to investigate other topics, such as divergence times, ancestral biogeography, and character evolution. These phylogenetic studies can also have economic importance, such as guiding the search for new medicines. For example, D. papposa has been used in traditional medicine and some antimicrobial compounds have been found in D. pinnata. Other species in the genus and in its closest relatives may also have therapeutic properties.

1 - 417 Iris Place, Davis, CA, 95616, United States
2 - University Of California, Plant Sciences Mail Stop 2, 1 Shields Avenue, Davis, CA, 95616.0, United States

Keywords:
Compositae
Heliantheae Alliance
Marigold tribe
phylogenetic analysis.

Presentation Type: Oral Paper
Session: SYSTV, Systematics V: Euasterids cont.
Location: Virtual/Virtual
Date: Thursday, July 22nd, 2021
Time: 2:00 PM(EDT)
Number: SYSTV007
Abstract ID:541
Candidate for Awards:None