Abstract Detail

Anatomy and Morphology

Glos, Rosemary [1], Salzman, Shayla [1], Calonje, Michael [2], Vovides, Andrew [3], Specht, Chelsea [1].

A Phylogenetic and Geographic Analysis of Leaflet Anatomy in Zamia (Cycadales: Zamiaceae).

Cycads (Cycadales) are among the most ancient lineages of extant seed-bearing plants and are the most threatened plant order on Earth, with circa 75% of the 355 accepted species threatened with extinction. Zamia L. is the most species-rich (81 spp.) and widely distributed cycad genus in the Americas, notable for its morphological and ecological diversity. Across the genus, there is a high degree of convergence among macromorphological characters rendering them unsuitable for use in elucidating species relationships. As such, species-level relationships have only recently been resolved through phylogenetic analyses of DNA-based character data. However, it remains unknown whether fine-scale variation in leaflet structure corresponds with evolutionary (phylogenetic) or ecological (geographic/habitat) patterns, as has been investigated in Dioon Lindl. and Cycas L. This project presents the first broad comparative survey of leaflet anatomy across Zamia species with the goals of defining diagnostic characters and understanding character evolution. Leaflets were examined from 20 Zamia species and one outgroup, Microcycas calocoma [Miq.] A.DC., representing all five major clades and spanning the geographic distribution of the genus. Leaflets were sampled from the living collections at Montgomery Botanical Center and fixed in formalin-acetic-acid-alcohol (FAA). Transverse, longitudinal, and epidermal preparations were stained with toluidine blue to elucidate structures, observed under light microscopy, and scored for a range of anatomical characters. Selected characters were analyzed in the context of published phylogenetic relationships and geographic distributions. Character state reconstructions were used to identify potential homoplasy and evaluate phylogenetic signal using Mesquite. Characters showing informative variation as well as phylogenetic convergence are discussed. The knowledge obtained through this project improves our understanding of micromorphological character evolution, anatomical diversity, and phylogenetic relationships within Zamia. With this knowledge, we may better understand phenotypic evolution and facilitate the identification, classification, and conservation of these highly threatened plants.

1 - Cornell University, School of Integrative Plant Science and L.H. Bailey Hortorium, 502 Mann Library, Ithaca, NY, 14850, USA
2 - Montgomery Botanical Center, 11901 Old Cutler Road, Miami, FL, 33156, USA
3 - Instituto De Ecologia Ac, Apdo Postal 63, Xalapa, VER, 91000, Mexico

Keywords:
Cycadales
cycads
epidermis
Gymnosperms
Leaf anatomy
Biogeography
convergence.

Presentation Type: Poster
Session: P, Anatomy and Morphology Posters
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 5:00 PM Time and date to be determined
Number: PAM008
Abstract ID:108
Candidate for Awards:None