Abstract Detail

Macroevolution

Suissa, Jacob [1], Friedman, William [2].

Rapid diversification of vascular architecture underlies the Carboniferous fern radiation.

Vascular plants account for 93% of Earth’s terrestrial flora. Xylem and phloem, vital for transporting water and nutrients through the plant, unite this diverse clade. Three-dimensional arrangements of these tissues (vascular architecture) are manifold across living and extinct species. However, the evolutionary processes underlying this variation remain elusive. Using ferns, a diverse clade with multiple radiations over their c. 400-million-year history, we synthesized data across 3,339 species to explore the tempo and mode of vascular evolution and to contextualize dynamics of phenotypic innovation during major fern diversification events. Our results reveal three paradigm shifts in our understanding of fern vascular evolution. 1. The canonical theory on the stepwise and unidirectional evolution of vascular architecture does not capture the complexities of character evolution among ferns. Rather, a new model permitting additional transitions, rate heterogeneity, and multiple reversions is more likely. 2. Major shifts in vascular architecture correspond to developmental changes in body size, not regional water availability 3. The early Carboniferous radiation of crown group ferns was characterized by an explosion of phenotypic innovation. In contrast, during the Cretaceous and Cenozoic rise of eupolypods, rates of vascular evolution were dramatically low and seemingly decoupled from lineage diversification.

1 - Harvard University, 26 Oxford St., 1300 Centre St, Cambridge, MA, 02138, United States
2 - Harvard University, Arnold Arboretum, 1300 Centre St., Boston, MA, 02131, United States

Keywords:
macroevolution
 morphology
Anatomy
vascular tissues
Ferns
stelar morphology.

Presentation Type: Oral Paper
Number: MACRO I002
Abstract ID:165
Candidate for Awards:None