Everywhere but Antarctica: Using a Super Tree to Understand the Diversity and Distribution of the Compositae

BS 55 343 Everywhere but Antarctica: Using a super tree to understand the diversity and distribution of the Compositae VICKI A. FUNK, RANDALL J. BAYER, STERLING KEELEY, RAYMUND CHAN, LINDA WATSON, BIRGIT GEMEINHOLZER, EDWARD SCHILLING, JOSE L. PANERO, BRUCE G. BALDWIN, NURIA GARCIA-JACAS, ALFONSO SUSANNA AND ROBERT K. JANSEN FUNK, VA., BAYER, R.J., KEELEY, S., CHAN, R., WATSON, L, GEMEINHOLZER, B., SCHILLING, E., PANERO, J.L., BALDWIN, B.G., GARCIA-JACAS, N., SUSANNA, A. &JANSEN, R.K 2005. Everywhere but Antarctica: Using a supertree to understand the diversity and distribution of the Compositae. Biol. Skr. 55: 343-374. ISSN 0366-3612. ISBN 87-7304-304-4. One of every 10 flowering plant species is in the family Compositae. With ca. 24,000-30,000 species in 1600-1700 genera and a distribution that is global except for Antarctica, it is the most diverse of all plant families. Although clearly mouophyletic, there is a great deal of diversity among the members: habit varies from annual and perennial herbs to shrubs, vines, or trees, and species grow in nearly every type of habitat from lowland forests to the high alpine fell fields, though they are most common in open areas. Some are well-known weeds, but most species have restricted distributions, and members of this family are often important components of 'at risk' habitats as in the Cape Floral Kingdom or the Hawaiian Islands. The sub-familial classification and ideas about major patterns of evolution and diversification within the family remained largely unchanged from Beutham through Cronquist. Recently obtained data, both morphological and molecular, have allowed us to examine the distribution and evolution of the family in a way that was never before possible. It is now known that the tribe formerly thought to be ancestral (Heliantheae s. I.) is actually nested high in the phylogeny while one previously thought to be in a derived position (Mutisieae s. I.) is basal. Likewise, tribes previously thought to be closely related, Eupatorieae and Vernonieae, are now widely separated, and the Cardueae (thistles) are embedded in the African Mutisieae clade. The results of recent broad-scale molecular studies of the tribes, both published and unpublished, were used to produce a supertree formed by linking the respective trees together. By examining the distribution of the terminal taxa on the phylogeny using parsimony analysis with optimization and ancestral areas analysis, a biogeographic pattern emerges. Basal lineages of the family as well as the sister group Calyceraceae, are all South American and mostly southern South American, and it appears incontrovertible that the origin of extant members of the Compositae was in southern South America. Although numer- ous, these basal clades represent only a small percentage of the diversity in the family. A subse- quent radiation in Africa gave rise to most of the tribes we know today. The African radiation was followed by the movement of individual clades into Asia and Eurasia as well as Australia. Finally, there was a North American origin and diversification of the Heliantheae s. I. that involved repeated incursions into Mexico and South America. The South American radiation followed by the African explosion might suggest a Gondwauan origin for the family, but the few data that exist from pollen records and geology seem to indicate a more recent origin for the family. The existence of the mouotypic genus Hecastocleis, endemic to the mountains of Nevada and Death Valley, inserts a North American taxou in between the South American and African radiations which might indicate long distance dispersal, or a North American or even an Asian presence in 344 BS 55 between South America and Africa. Also of interest is the geographic origin of the ancestor of the Heliantheae s. I. clade. The sister-group to the western hemisphere clade Heliantheae s. I. is the small tribe Athroismeae, a group of three genera from eastern tropical Africa, leaving a unknown area, possibly Asia, between Africa and western North America. This global picture of the Com- positae provides a framework for studies in morphology and clearly indicates the need for future molecular and morphological studies. Vicki A. Funk, US National Herbarium, Smithsonian Institution MRC 166, P.O. Box 37012, Washington D.C. 20013-7012, USA. E-mail:[email protected]. RandallJ. Bayer, Australian National Herbarium, P.O. Box 4008, CSIRO, Canberra, ACT 2600, Aus- tralia. Sterling Keeley, Department of Botany, 3109 Maile Way, #101, University of Hawaii, Manoa, Oahu, f&zwa:: 96822-227% USA. Raymund Chan, 43 Siglap Plain, Singapore 456032, Republic of Singapore. Linda Watson, Department of Botany, Miami University, Oxford, OH, 45056, USA. Gemeinholzer, Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, D-06466, Gatersleben, Germany. Edward Schilling, Department of Botany, University of Tennessee, Knoxville, Tennessee 37996, USA. Jose L. Panero, Section of Integrative Biology, University of Texas, Austin, Texas 78712, USA. Bruce G. Baldwin, Jepson Herbarium and Department of Integrative Biology, University of California, Berke- 6% Ca&/brma 94720, USA. Nuria Garcia-Jacas, Laboratory of Biosystematics and Molecular Systematics, Botanic Institute of Barcelona (CSIC-Ajuntament de Barcelona), Pg. del Migdia, s.n., E-08038, Barcelona, Spain. Alfonso Susanna, Laboratory of Biosystematics and Molecular Systematics, Botanic Institute of Barcelona (CSIC-Ajuntament de Barcelona), Pg. del Migdia, s.n., E-08038, Barcelona, Spain. Robert K. Jansen, Section of Integrative Biology, University of Texas, Austin, Texas 78712 USA. Introduction ^ pkwts, then one out of every 8-12 species of flowering plants is in the Compositae (about The Compositae (Asteraceae) contains the 10%). The family is monophyletic, character- largest number of described species of any ized by florets arranged on a receptacle in cen- plant family, 24,000-30,000, distributed in tripetal heads and surrounded by bracts, by 1600-1700 genera occurring on all continents anthers fused in a ring with the pollen pushed except Antarctica. Estimates vary, but assuming or brushed out by the style and by the presence that there are 200,000-300,000 species of flow- of achenes (cypselas) often with a pappus (Fig. BS55 345 1). Although the family is well-defined, there is tion seem to be more frequent near the base of a great deal of variation among the members: the tree and these clades do have a lot of the habit varies from annual and perennial brightly colored flowers (Fig. 2-7, 2-8, 2-13 herbs to shrubs, vines, or trees, although few to 16). Throughout the family pollination is are true epiphytes; the heads can have one to also facilitated by all types of insects, however more than 1000 florets; chromosome numbers in the more highly nested portions of the fam- range from n=2 to high level polyploidy with ily there is less bird and Lepidoptera pollina- n=114; and species grow in just about every tion and more bee, fly, etc. pollination and type of habitat from forests to high elevation most flowers are yellow or white (with a few grasslands, however they are less common in notable exceptions; Fig. 2-3, 2-5, 2-10, 2-11). tropical wet forests and more common in open When wind pollination occurs the heads can areas. Most groups in the family contain some have a quite different appearance from most useful and some noxious species as well as com- groups in the family (Fig. 2-12). mon and rare taxa. They can be fragrant or That the family is monophyletic has never foul, breath takingly beautiful or nondescript. been in question. Every early worker in plant However, the general perception of this family classification recognized the Compositae as a as "weedy" is not correct. Certainly there are group at some level. The distinctive inflores- members that benefit from disturbance such as cence (centripetal head) often found in the a few species of dandelions, goldenrods, and striking ray/disk arrangement (Fig. 1, 2-2, 5, 10 thistles, but most species have a restricted dis- & 11, 13 & 14) along with the fruit type (ach- tribution, and just about every 'at risk' habitat ene) and the development of the calyx into a in the world contains members of this family pappus enabled everyone to accurately delimit that are an important part of the flora. Fig. 2 is this group (Bentham 1873a, b; Cassini 1818). a grouping of photographs that show the diver- In every type of analysis the results show that sity within the Compositae and also illustrate a the family is monophyletic (i. e., Bremer 1992; number of the characters. Of particular inter- Hansen 1991a; Jansen & Palmer 1987; Small est are the bilabiate corollas of Leucheria (Fig. 1919). However, within the family things are 2-16) characteristic of many taxa in the less clear. From the beginning those who stud- Mutisieae and the rolled actinomorphic corol- ied this family thought the ray and disk floret las of Stifftia (Fig. 2-7; probably in the Mutisieae pattern (Fig. 1) represented the basic head as well). The deeply divided corollas of many of structure in the family. In the classic illustra- the non-Asteroideae taxa are illustrated in Fig. tion by Cassini (Fig. 3) the Heliantheae is at 2-15. Corollas that are not deeply divided, and the center; the Vernonieae and Eupatorieae are often characteristic of the Asteroideae taxa, are at one end and the Mutisieae and are shown in several photos (Fig. 2-9 to 11). Cichorieae (Lactuceae) at the other. This view Acmella is a good example of a paleaceous persisted with some modification until the receptacle (Fig. 2-6). Many species in the fam- 1980's. The treatment by Bentham (1873a) ily are woody, e.g., the species in Montanoa (Fig.

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