Evolutionary Genetics of the Genus Zamia (Zamiaceae, Cycadales)
Abstract
The genus Zamia L. (Zamiaceae), consisting of 77 species, is the most species-rich and widely distributed cycad genus in the New World and is arguably the most morphologically and ecologically diverse genus in the Cycadales. We utilized a multilocus sequence dataset of 10 independent loci (9 single copy nuclear genes + 1 plastid) and extensive taxon sampling (over 90% of species) to infer phylogenetic relationships within Zamia. We infer a robust phylogenetic tree for the genus with a strong geographic delimitation of clades and find that four morphological characters typically used for diagnostic purposes in the genus exhibit a high degree of homoplasy. We genotyped four populations of the Belizean endemic cycad Zamia decumbens using ten microsatellite loci and analyzed the data using a variety of population genetic analyses methods. The populations occurred in two different habitat types: inside dolines (one at a cave entrance and two at the bottom of sinkholes) and one on steep karstic terrain on a hilltop. We found the genetic variation was not structured geographically or by habitat type, but rather seemed to reflect the demographic history of the populations and their genetic connectivity. Contemporary geneflow between populations is generally low, with the Cave population being the most important population in facilitating genetic connectivity in the region, mostly as a source of migrants to other populations. A conservation assessment for the three cycad species native to the Bahamas Islands is presented based on field surveys on all islands where these species occur. Zamia angustifolia is native to Eleuthera, Zamia integrifolia is native to Abaco, Andros, Eleuthera, Grand Bahama and New Providence, and Zamia lucayana is endemic to Long Island. We assessed the genetic structure of Z. lucayana based on 15 polymorphic microsatellite DNA loci; this indicated that the three known populations should be considered a single management unit. However, the high number of private alleles suggests that genetic drift, indicative of recent fragmentation, is progressing. We propose in situ conservation strategies, and we also collected germplasm from a total of 24 populations of these three cycad species, for ex situ conservation.
Subject Area
Botany|Genetics|Plant sciences
Recommended Citation
Bazar, Michael Calonje, "Evolutionary Genetics of the Genus Zamia (Zamiaceae, Cycadales)" (2019). ProQuest ETD Collection for FIU. AAI28966483.
https://digitalcommons.fiu.edu/dissertations/AAI28966483