Abstract Detail

Paleobotany

Jud, Nathan [1], De Benedetti, Facundo [2], Hermsen, Elizabeth J. [3], Gandolfo, Maria [4].

Estimating the phylogeny of Azolla: a comparison between analysis of morphology and molecular data with and without tip-dating.

Azolla is a small genus within Salviniales, an order of heterosporous aquatic and semi-aquatic ferns. Previous attempts to estimate phylogenetic relationships and divergence times in the genus Azolla using only DNA sequence data are missing much of the diversity of the genus, which is largely comprised of fossil species. While there are only 5-7 extant species of Azolla, more than 60 species have been described from fossils, including some for which both spores and sporophytes are known. Here, we compare the results of two phylogenetic analyses incorporating fossil species and morphological data in an attempt to test long-standing hypotheses about relationships and character evolution in extant Azolla. We developed a matrix of 33 morphological characters, five extant species, and seven fossil species. We included only those fossil species for which megaspore apparatuses, microspore massulae, and sporophytes are known and 1) are either found in attachment or 2) are associated with one another with a high degree of confidence. We ran two bayesian analyses, one with unconstrained branch lengths and another using tip-dating with fixed ages for the fossils. We used fixed ages because the uncertainty associated with the fossil ages from individual localities is negligible compared to the age of the clade. Both analyses were implemented in MrBayes 3.2.7. Our results show that including fossils influences our understanding of character evolution in the genus, and including age information directly also influences the topology of the resulting tree.

1 - William Jewell College, Biology, 300 College Hill, Liberty, MO, 64068, United States
2 - Museo Paleontol�gico Egidio Feruglio, Avenida Fontana 140, Trelew, U, 9100, Argentina
3 - Paleontological Research Institution, 1259 Trumansburg Road, Ithaca, NY, 14850, United States
4 - Cornell University, L.H. Bailey Hortorium, Section Of Plant Biology, 410 Mann Library Building, Ithaca, NY, 14853.0, United States

Keywords:
Fossils
Bayesian
phylogeny
Ferns.

Presentation Type: Poster
Session: P, Paleobotany Posters
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 5:00 PM Time and date to be determined
Number: PPB005
Abstract ID:583
Candidate for Awards:None