Phylogeny, leaf morphology and biogeography of Chuquiraga (Asteraceae-Barnadesioideae)

EZCURRA, C.

St. Louis

Congreso; XVI International Botanical Congress; 1999

IAPT

Phylogenetic relationships among Chuquiraga species were resolved by parsimonycladistic analysis using morphological characters. The resulting cladogram was usedto interpret morphological, ecological, and biogeographical patterns in a historical context.Biotic and abiotic environmental factors hypothesized to have exerted selective pressure onmorphological traits of its species were optimized onto the phylogeny to suggest how andwhen these factors may have affected the evolution and diversification of the genus. Results suggest an origin of the genus in southern South America, with two major evolutionaryradiations, one more northern in the Central and Northern Andes, and the other in theSouthern Andes and the North Chilean, Patagonia and Monte Deserts. Pollination by hummingbirds seems to have been an important factor in the origin of the northern clade, affectingfloral morphology. Herbivory by vertebrates and increased aridity seem to have been importantselective forces in the evolution and diversification of the southern clade, especially affectingleaf morphology. These changes were probably associated with the major elevation ofthe Andes in late Tertiary and with the hyperaridization and climatic fluctuations of Pleistoceneand Holocene times <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-TRAD;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} /* List Definitions */ @list l0 {mso-list-id:1821924793; mso-list-type:simple; mso-list-template-ids:201981967;} @list l0:level1 {mso-level-tab-stop:18.0pt; mso-level-number-position:left; margin-left:18.0pt; text-indent:-18.0pt;} ol {margin-bottom:0cm;} ul {margin-bottom:0cm;} -->