Phylogeny of Agavaceae Based on ndhF, rbcL, and its Sequences

Abstract

Great advances have been made in our understanding of the phylogeny and classification of Agavaceae in the last 20 years. In older systems Agavaceae were paraphyletic due to overemphasis of ovary position or habit. Discovery of a unique bimodal karyotype in Agave and Yucca eventually led to a reexamination of concepts and relationships in all the lilioid monocots, which continues to the present day. Developments in cytogenetics, microscopy, phylogenetic systematics, and most recently DNA technology have led to remarkable new insights. Large-scale rbcL sequence studies placed Agavaceae with the core Asparagales and identified closely related taxa. Analysis of cpDNA restriction sites, rbcL, and ITS nrDNA sequences all supported removal of Dracaenaceae, Nolinaceae, and clarified relationships. Agavaceae s.s. presently consists of Agave, Beschorneria, Furcraea, Hesperaloe, Hesperoyucca, Manfreda, Polianthes, Prochnyanthes, and Yucca. In this paper we analyze recently obtained ndhF sequence data from Agavaceae and Asparagales and discuss the implications for classification. Parsimony analysis of ndhF data alone resolves most genera of Agavaceae and supports the inclusion of Camassia, Chlorogalum, Hesperocallis, and Hosta within Agavaceae s.l. Analysis of combined ndhF and rbcL data sets of selected Asparagales results in better resolution and stronger bootstrap support for many relationships. Combination of all available ndhF, rbcL, and ITS data in a single analysis results in the best resolution currently available for Agavaceae s.l. Implications for classification schemes past and present are discussed.

Phylogeny, Genome Size, and Chromosome Evolution of Asparagales

“…(APG II 2003). The exact relationship of Hesperocallis to other genera of Agavaceae is discussed in detail elsewhere (Pires et al 2004;Bogler et al 2006).…”

“…For example, within Asparagaceae s.l., the bimodal karyotype is found in several genera of Hyacinthaceae s.s. and Agavaceae. Given that Agave and Yucca are related, Darlington's scenario was problematic because we now infer that Hosta is related to Agave and Yucca (Agavaceae s.s., now including Hesperocallis, see Pires et al 2004;and Bogler et al 2006). Darlington's other hypotheses are also off the mark because Aloe and Phormium (Xanthorrhoeaceae s.l.)…”

“…1). Specifically, we now have a clearer idea about the relationships between Agave, Aloe, Hosta, and the "New World hyacinths" such as Camassia and Chlorogalum (Bogler andSimpson 1995, 1996;Chase et al 1995Chase et al , 2000bPfosser and Speta 1999;Fay et al 2000). One ambiguity was the phylogenetic placement of the enigmatic Hesperocallis (monotypic Hesperocallidaceae ), which was unplaced in APG (1998) and mentioned by Fay et al (2000) as a critical taxon to sample in future studies.…”

“…With respect to Darlington's scenario for the evolution of the bimodal karyotype, a number of studies has given us new hypotheses about the relationship of Agavaceae to Hosta and "New World Hyacinthaceae" such as Camassia Lindl., Chlorogalum Kunth, and other genera (Bogler andSimpson 1995, 1996;Chase et al 1995;Pfosser and Speta 1999;Pires et al 2004;Bogler et al 2006). Currently, Asparagales are recognized as a large and diverse monophyletic order of monocots that includes ca.…”

Manfreda parva (Agavaceae), especie nueva del estado de Guerrero, México

“…recientemente, algunos autores incluyen a Hesperoyucca (engelm.) Baker en la misma familia (Bogler et al, 2006;good-Avila et al, 2006).…”