Despite a recent new classification, a stable phylogeny for the cycads has been elusive, particularly regarding resolution of Bowenia, Stangeria and Dioon. In this study, five single-copy nuclear genes (SCNGs) are applied to the phylogeny of the order Cycadales. The specific aim is to evaluate several gene tree–species tree reconciliation approaches for developing an accurate phylogeny of the order, to contrast them with concatenated parsimony analysis and to resolve the erstwhile problematic phylogenetic position of these three genera. DNA sequences of five SCNGs were obtained for 20 cycad species representing all ten genera of Cycadales. These were analysed with parsimony, maximum likelihood (ML) and three Bayesian methods of gene tree–species tree reconciliation, using Cycas as the outgroup. A calibrated date estimation was developed with Bayesian methods, and biogeographic analysis was also conducted. Concatenated parsimony, ML and three species tree inference methods resolve exactly the same tree topology with high support at most nodes. Dioon and Bowenia are the first and second branches of Cycadales after Cycas, respectively, followed by an encephalartoid clade (Macrozamia–Lepidozamia–Encephalartos), which is sister to a zamioid clade, of which Ceratozamia is the first branch, and in which Stangeria is sister to Microcycas and Zamia. A single, well-supported phylogenetic hypothesis of the generic relationships of the Cycadales is presented. However, massive extinction events inferred from the fossil record that eliminated broader ancestral distributions within Zamiaceae compromise accurate optimization of ancestral biogeographical areas for that hypothesis. While major lineages of Cycadales are ancient, crown ages of all modern genera are no older than 12 million years, supporting a recent hypothesis of mostly Miocene radiations. This phylogeny can contribute to an accurate infrafamilial classification of Zamiaceae.

Premise of research. The genus Zamia L. (Zamiaceae), consisting of 79 species, is the most species-rich and widely distributed cycad genus in the New World and arguably the most morphologically and ecologically diverse genus in the Cycadales. However, a strong phylogenetic framework for this genus is still lacking.Methodology. We used a multilocus sequence data set of 10 independent loci (nine single-copy nuclear genes [SCNGs] and one plastid) and extensive taxon sampling (ca. 90% of species) to infer phylogenetic relationships within Zamia. We implemented a concatenated matrix analysis with maximum parsimony, a partitioned maximum likelihood (ML) analysis, and a time-calibrated Bayesian species tree-estimation approach. Diversification, historical biogeography, and ancestral character state reconstruction analyses were conducted using the species tree topology that was the most morphologically and geographically congruent.Pivotal results. We inferred a robust phylogenetic tree for the genus with a strong...

Conservation of imperiled plant species often requires ex situ (offsite) living collections. Protocols for developing these collections most often emphasize sampling depth, but little is known about the genetics of such collections. This study compares how well a single collecting protocol can capture the diversity in wild populations of two closely related species. We selected two exemplar species, bay rush (Zamia lucayana) and sinkhole cycad (Zamia decumbens), based on similarities and differences that allow for rigorous comparison, including geographic isolation and reproductive factors. For each species, we compared in situ plants to ex situ plants via the same panel of 10 microsatellite markers. Genetic distance analysis shows high fidelity of the ex situ collections to their in situ source populations and sub-populations. Structured resampling of allele capture from the in situ populations by the ex situ collections shows that allele capture increases as number of ex situ plants maintained increases, but with a diminishing rate of increase. Difference in the rate of allele capture between the two species was significant at the α = 0.1 level, (p = 0.097) but not at the α = 0.05 level. At larger collection sizes, the difference in rate of allele capture showed a high practical significance (d = 5.41). These data illustrate that a unified collecting protocol can achieve similar allele capture among related species, but also that geographic and reproductive factors can influence the rate of allele capture.

Two major lineages of beetles inhabit cycad cones in the New World: weevils (Curculionoidea) in the subtribe Allocorynina, including the genera Notorhopalotria Tang and O’Brien, Parallocorynus Voss, Protocorynus O’Brien and Tang and Rhopalotria Chevrolat, and beetles in the family Erotylidae, including the genus Pharaxonotha Reitter. Analysis of the 16S ribosomal RNA (rRNA) mitochondrial gene as well as cladistic analysis of morphological characters of the weevils indicate four major radiations, with a probable origin on the cycad genus Dioon Lindl. and comparatively recent host shifts onto Zamia L. Analysis of the 16S rRNA gene for erotylid beetles indicates that an undescribed genus restricted to New World Ceratozamia Brongn. is the most early-diverging clade, and this lineage is sister to a large radiation of the genus Pharaxonotha onto Zamia, with apparent host shifts onto Dioon and Ceratozamia. Analysis of beetles are in accord with current models of continental drift in the Caribbean basin, support some proposed species groupings of cycads, but not others, and suggest that pollinator type may impact population genetic structure in their host cycads.

A conservation assessment for the three cycad species native to the Bahamas Islands is presented. Results are based on field surveys on all islands where these species occur.Zamia angustifoliais native to Eleuthera,Zamia integrifoliais native to Abaco, Andros, Eleuthera, Grand Bahama and New Providence, andZamia lucayanais endemic to Long Island.Z. angustifoliais of the highest conservation concern because of the small number of adult plants, its restricted distribution and the extensive development occurring within its habitat.Z. integrifoliaalso has a restricted distribution on Eleuthera and Grand Bahama and, although threatened by urban development in New Providence, it is relatively common on Abaco and Andros.Z. lucayanacomprises three populations within a narrow strip of land of c. 1 km²; we propose a reassignment of its current conservation status from Endangered to Critically Endangered. We assessed the genetic structure ofZ. lucayanabased 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.