Global Commitments to Conserving and Monitoring Genetic Diversity Are Now Necessary and Feasible.

Global conservation policy and action have largely neglected protecting and monitoring genetic diversity-one of the three main pillars of biodiversity. Genetic diversity (diversity within species) underlies species' adaptation and survival, ecosystem resilience, and societal innovation. The low priority given to genetic diversity has largely been due to knowledge gaps in key areas, including the importance of genetic diversity and the trends in genetic diversity change; the perceived high expense and low availability and the scattered nature of genetic data; and complicated concepts and information that are inaccessible to policymakers. However, numerous recent advances in knowledge, technology, databases, practice, and capacity have now set the stage for better integration of genetic diversity in policy instruments and conservation efforts. We review these developments and explore how they can support improved consideration of genetic diversity in global conservation policy commitments and enable countries to monitor, report on, and take action to maintain or restore genetic diversity.

Taxonomic similarity does not predict necessary sample size for ex situ conservation: a comparison among five genera.

Effectively conserving biodiversity with limited resources requires scientifically informed and efficient strategies. Guidance is particularly needed on how many living plants are necessary to conserve a threshold level of genetic diversity in ex situ collections. We investigated this question for 11 taxa across five genera. In this first study analysing and optimizing ex situ genetic diversity across multiple genera, we found that the percentage of extant genetic diversity currently conserved varies among taxa from 40% to 95%. Most taxa are well below genetic conservation targets. Resampling datasets showed that ideal collection sizes vary widely even within a genus: one taxon typically required at least 50% more individuals than another (though Quercus was an exception). Still, across taxa, the minimum collection size to achieve genetic conservation goals is within one order of magnitude. Current collections are also suboptimal: they could remain the same size yet capture twice the genetic diversity with an improved sampling design. We term this deficiency the 'genetic conservation gap'. Lastly, we show that minimum collection sizes are influenced by collection priorities regarding the genetic diversity target. In summary, current collections are insufficient (not reaching targets) and suboptimal (not efficiently designed), and we show how improvements can be made.

Applying the zoo model to conservation of threatened exceptional plant species.

Maintaining a living plant collection is the most common method of ex situ conservation for plant species that cannot be seed banked (i.e., exceptional species). Viability of living collections, and their value for future conservation efforts, can be limited without coordinated efforts to track and manage individuals across institutions. Using a pedigree-focused approach, the zoological community has established an inter-institutional infrastructure to support long-term viability of captive animal populations. We assessed the ability of this coordinated metacollection infrastructure to support the conservation of 4 plant species curated in living collections at multiple botanic gardens around the world. Limitations in current practices include the inability to compile, share, and analyze plant collections data at the individual level, as well as difficulty in tracking original provenance of ex situ material. The coordinated metacollection framework used by zoos can be adopted by the botanical community to improve conservation outcomes by minimizing the loss of genetic diversity in collections. We suggest actions to improve ex situ conservation of exceptional plant species, including developing a central database to aggregate data and track unique individuals of priority threatened species among institutions and adapting a pedigree-based population management tool that incorporates life-history aspects unique to plants. If approached collaboratively across regional, national, and global scales, these actions could transform ex situ conservation of threatened plant species.

Aplicación del Modelo Zoológico a la Conservación de Especies Excepcionales de Plantas Amenazadas Resumen El mantenimiento de una colección de plantas vivas es el método más común para de conservación ex situ para especies de plantas que no pueden almacenarse en bancos de semillas (i. e., especies excepcionales). La viabilidad de las colecciones vivientes, junto con el valor que representan para los futuros esfuerzo de conservación, puede estar limitada si no existen esfuerzos coordinados para rastrear y manejar a los individuos entre las instituciones. Mediante una estrategia enfocada en el linaje, la comunidad de zoológicos ha establecido una infraestructura interinstitucional que respalda la viabilidad a largo plazo de las poblaciones de animales en cautiverio. Evaluamos la habilidad de esta infraestructura coordinada de metacolecciones para apoyar en la conservación de cuatro especies de plantas curadas en colecciones vivientes en varios jardines botánicos de todo el mundo. Las limitaciones de las prácticas contemporáneas incluyen la incapacidad de recopilar, compartir y analizar los datos de las colecciones de plantas a nivel individual, así como la dificultad de rastrear la procedencia original del material ex situ. El marco de trabajo de metacolecciones coordinadas que utilizan los zoológicos puede ser adoptado por la comunidad botánica para mejorar los resultados de conservación al minimizar la pérdida de la diversidad genética que ocurre en las colecciones. Sugerimos acciones que aumenten la conservación ex situ de las especies excepcionales de plantas. Estas acciones incluyen el desarrollo de una base de datos central para acumular datos y rastrear entre las instituciones a los individuos únicos de las especies amenazadas prioritarias y la adaptación de una herramienta de manejo poblacional basada en el linaje que incorpore los aspectos únicos de la historia de vida de las plantas. Si estas acciones se plantean colaborativamente a escala regional, nacional y global, podrían transformar la conservación ex situ de las especies amenazadas de plantas.

First cycad seedling foliage from the fossil record and inferences for the Cenozoic evolution of cycads.

The morphology of the early ontogenetic stages of cycad foliage may help resolve the relationships between extinct to extant cycad lineages. However, prior to this study, fossil evidence of cycad seedlings was not known. We describe a compression fossil of cycad eophylls with co-occurring fully developed leaves of adult specimens from the early Palaeocene ( ca 63.8 Ma) Castle Rock flora from the Denver Basin, CO, USA and assign it to the fossil genus Dioonopsis (Cycadales) based on leaf morphology and anatomy. The new fossil seedling foliage is particularly important because fully differentiated pinnate leaves of adult plants and the eophylls belong to the same species based on shared epidermal micromorphology, therefore, increasing the number of morphological characteristics that can be used to place Dioonopsis phylogenetically. Significantly, the seedling fossil has a basic foliage structure that is very similar to seedlings of extant cycads, which is consistent with a cycadalean affinity of Dioonopsis. Nevertheless, the set of morphological characters in the seedling and adult specimens of Dioonopsis suggests a distant relationship between Dioonopsis and extant Dioon. This indicates that extinct lineages of cycads were present and widespread during the early Cenozoic (Palaeogene) coupled with the subordinate role of extant genera in the Palaeogene fossil record of cycads.

Shifting Quaternary migration patterns in the Bahamian archipelago: Evidence from the Zamia pumila complex at the northern limits of the Caribbean island biodiversity hotspot.

PREMISE OF THE STUDY: The Bahamas archipelago is formed by young, tectonically stable carbonate banks that harbor direct geological evidence of global ice-volume changes. We sought to detect signatures of major changes on gene flow patterns and reconstruct the phylogeographic history of the monophyletic Zamia pumila complex across the Bahamas. METHODS: Nuclear molecular markers with both high and low mutation rates were used to capture two different time scale signatures and test several gene flow and demographic hypotheses. KEY RESULTS: Single-copy nuclear genes unveiled apparent ancestral admixture on Andros, suggesting a significant role of this island as main hub of diversity of the archipelago. We detected demographic and spatial expansion of the Zamia pumila complex on both paleo-provinces around the Piacenzian (Pliocene)/Gelasian (Pleistocene). Populations evidenced signatures of different migration models that have occurred at two different times. Populations on Long Island (Z. lucayana) may either represent a secondary colonization of the Bahamas by Zamia or a rapid and early-divergence event of at least one population on the Bahamas. CONCLUSIONS: Despite changes in migration patterns with global climate, expected heterozygosity with both marker systems remains within the range reported for cycads, but with significant levels of increased inbreeding detected by the microsatellites. This finding is likely associated with reduced gene flow between and within paleo-provinces, accompanied by genetic drift, as rising seas enforced isolation. Our study highlights the importance of the maintenance of the predominant direction of genetic exchange and the role of overseas dispersion among the islands during climate oscillations.

The U.S. Culture Collection Network Lays the Foundation for Progress in Preservation of Valuable Microbial Resources.

The U.S. Culture Collection Network was formed in 2012 by a group of culture collection scientists and stakeholders in order to continue the progress established previously through efforts of an ad hoc group. The network is supported by a Research Coordination Network grant from the U.S. National Science Foundation (NSF) and has the goals of promoting interaction among collections, encouraging the adoption of best practices, and protecting endangered or orphaned collections. After prior meetings to discuss best practices, shared data, and synergy with genome programs, the network held a meeting at the U.S. Department of Agriculture (USDA)-Agricultural Research Service (ARS) National Center for Genetic Resources Preservation (NCGRP) in Fort Collins, Colorado in October 2015 specifically to discuss collections that are vulnerable because of changes in funding programs, or are at risk of loss because of retirement or lack of funding. The meeting allowed collection curators who had already backed up their resources at the USDA NCGRP to visit the site, and brought collection owners, managers, and stakeholders together. Eight formal collections have established off-site backups with the USDA-ARS, ensuring that key material will be preserved for future research. All of the collections with backup at the NCGRP are public distributing collections including U.S. NSF-supported genetic stock centers, USDA-ARS collections, and university-supported collections. Facing the retirement of several pioneering researchers, the community discussed the value of preserving personal research collections and agreed that a mechanism to preserve these valuable collections was essential to any future national culture collection system. Additional input from curators of plant and animal collections emphasized that collections of every kind face similar challenges in developing long-range plans for sustainability.

Distribution of gelatinous fibers in seedling roots of living cycads.

UNLABELLED: • PREMISE OF THE STUDY: The presence of gelatinous (tension) fibers (GFs) in the roots of two extant cycadales (Cycas and Zamia) in a recent publication raises interesting issues of GF distribution in seed plants. An immediate question that arises from this discovery is whether GFs occur consistently in the radicle of all extant cycad genera and therefore might have a similar role in root contraction. We present results of a survey of nursery-grown material of all 10 genera.• METHODS: We sequentially sectioned seedling root material and used simple staining and histochemical methods to follow anatomical changes along the radicle of all 10 genera.• KEY RESULTS: We found GFs in nine genera; Stangeria appears to be the only genus without them. In all genera, there is a wide variation in the number of GFs and also variation in the development of thickened, fleshy roots. "Tertiary expansion" is a useful term to describe late cell division and enlargement of both primary and secondary parenchyma, the latter produced by the vascular cambium. Certain other histological features can be diagnostically useful at the generic level.• CONCLUSIONS: The functional interpretation of GFs as being wholly responsible for apparent tissue contraction is now somewhat compromised, especially as distortion of tracheary elements by changes in dimensions of parenchyma cells can falsely suggest root contraction when it may not occur. These preliminary results point the way to a more precise investigation of study material grown in more uniform environments using advanced technological methods.

Root contraction in Cycas and Zamia (Cycadales) determined by gelatinous fibers.

UNLABELLED: • PREMISE OF THE STUDY: Reaction wood (RW) in seed plants can induce late and usually secondary changes in organ orientation. Conifers produce compression wood (CW), generated by compression tracheids, which generate a push force. Angiosperms produce tension wood (TW), generated by tension wood fibers (TWF) often described as "gelatinous fibers," which exert a pull force. Usually RW is produced eccentrically, but it can occur concentrically, as in aerial roots of Ficus. However, gymnosperms can produce gelatinous fibers (tension fibers, TF), as in cortical and secondary phloem tissues (Gnetum). TFs are therefore limited neither to wood, xylem, nor angiosperms. Here we demonstrate that TFs in secondary phloem are involved in contraction of roots of cycads and compare them with TFs of Ficus.• METHODS: We sectioned root material of cycads at various stages of seedling development using simple staining and histochemical procedures to follow the course of secondary phloem development. Aerial roots of Ficus were compared with the cycad root material.• KEY RESULTS: Tension fibers (gelatinous fibers) occur extensively and continuously in the secondary phloem in roots that undergo contraction. Older tissues, but notably the xylem, become distorted by contraction. TFs in cycads correspond in cell wall features to TFs that occur in Ficus, but do not occur in secondary xylem. The individual fibers visibly contract.• CONCLUSIONS: Tissue contraction in Cycas and Zamia corresponds to that found in angiosperms and Gnetum and further broadens the scope of the activity of tension tissues. This finding possibly indicates that gelatinous fibers originated at a very early period of seed plant evolution.

Phylogeny of the cycads based on multiple single-copy nuclear genes: congruence of concatenated parsimony, likelihood and species tree inference methods.

BACKGROUND AND AIMS: 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. METHODS: 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. KEY RESULTS: 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. CONCLUSIONS: 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.

Reproductive phases coincide with changes in morphology and photosynthetic physiology in an endangered cycad species.

Cycadales is highly endangered and one of the oldest dioecious gymnosperm lineages, making their reproductive biology highly relevant to conservation efforts and our understanding of the impact of dioecy, yet cycad reproductive ecophysiology is poorly understood. We examined how the costs associated with reproduction may impact basic physiological variation in cycad species. Specifically, we measured traits related to functional morphology and photosynthetic physiology in sterile and fertile staminate plants ('males') of Zamia portoricensis. Light response curves showed that sterile plants had greater light-use efficiency and maximum photosynthetic capacity per area compared with fertile plants. However, fertile and sterile plants exhibited similar respiration rates. We found significantly more nitrogen in leaves of fertile individuals, but similar nitrogen isotope composition and no differences in carbon content between sterile and fertile individuals. Despite having lower leaf-level photosynthetic rates, fertile plants had greater canopy-level photosynthesis than sterile plants, which was achieved by increasing leaf number and total leaf area. Our data suggest that sterile individuals may have greater light demands relative to fertile individuals, and fertile individuals may have greater nitrogen demands, which may be critical for successful reproductive events in staminate plants of the endangered cycad, Z. portoricensis.

Zamia (Cycadales: Zamiaceae) on Puerto Rico: asymmetric genetic differentiation and the hypothesis of multiple introductions.

PREMISE OF THE STUDY: This study of Zamia in Puerto Rico is the most intensive population genetics investigation of a cycad to date in terms of number of markers, and one of few microsatellite DNA studies of plants from the highly critical Caribbean biodiversity hotspot. Three distinctive Zamia taxa occur on the island: Z. erosa on the north coast, and Z. portoricensis and Z. pumila, both in the south. Their relationships are largely unknown. We tested three hypotheses about their genetic diversity, including the possibility of multiple introductions. METHODS: We used 31 microsatellite loci across 10 populations and analyzed the data with AMOVA, Bayesian clustering, and ABC coalescent modeling. KEY RESULTS: Puerto Rican zamias exhibit an amalgam of patterns of genetic differentiation that have been reported for cycads. Overall, the taxa are slightly inbred, with high infra-populational variation and little evidence of recent bottlenecks. Zamia erosa exhibits a more than threefold greater degree of population differentiation than the other two taxa. Admixture is evident only between Z. portoricensis and Z. pumila. Zamia portoricensis is inferred to be the youngest taxon on the island, on the basis of estimates of coalescence time and effective population size. A selective sweep may be underway in a small population of Z. erosa in a saline environment. CONCLUSIONS: Zamia erosa may represent an independent introduction into Puerto Rico; Z. portoricensis and Z. pumila fit a scenario of allopatric speciation. This will be explored further in the context of genetic analysis across the entire Caribbean region.

Phylogeny of Opuntia s.s. (Cactaceae): clade delineation, geographic origins, and reticulate evolution.

PREMISE OF THE STUDY: The opuntias (nopales, prickly pears) are not only culturally, ecologically, economically, and medicinally important, but are renowned for their taxonomic difficulty due to interspecific hybridization, polyploidy, and morphological variability. Evolutionary relationships in these stem succulents have been insufficiently studied; thus, delimitation of Opuntia s.s. and major subclades, as well as the biogeographic history of this enigmatic group, remain unresolved. METHODS: We sequenced the plastid intergenic spacers atpB-rbcL, ndhF-rpl32, psbJ-petA, and trnL-trnF, the plastid genes matK and ycf1, the nuclear gene ppc, and ITS to reconstruct the phylogeny of tribe Opuntieae, including Opuntia s.s. We used phylogenetic hypotheses to infer the biogeographic history, divergence times, and potential reticulate evolution of Opuntieae. KEY RESULTS: Within Opuntieae, a clade of Tacinga, Opuntia lilae, Brasiliopuntia, and O. schickendantzii is sister to a well-supported Opuntia s.s., which includes Nopalea. Opuntia s.s. originated in southwestern South America (SA) and then expanded to the Central Andean Valleys and the desert region of western North America (NA). Two major clades evolved in NA, which subsequently diversified into eight subclades. These expanded north to Canada and south to Central America and the Caribbean, eventually returning back to SA primarily via allopolyploid taxa. Dating approaches suggest that most of the major subclades in Opuntia s.s. originated during the Pliocene. CONCLUSIONS: Opuntia s.s. is a well-supported clade that includes Nopalea. The clade originated in southwestern SA, but the NA radiation was the most extensive, resulting in broad morphological diversity and frequent species formation through reticulate evolution and polyploidy.

Sweet drinks are made of this: conservation genetics of an endemic palm species from the Dominican Republic.

Pseudophoenix ekmanii is a threatened palm species endemic to the Dominican Republic. Sap from trees is extracted to make a local drink; once they are tapped the individual usually dies. Plants are also illegally harvested for the nursery trade and destroyed by poachers hunting the endemic and threatened Hispaniolan parrot. We used 7 DNA microsatellite markers to assist land managers in developing conservation strategies for this palm. We sampled 4 populations along the known distribution range of this species (3 populations from the mainland and 1 from the small island of Isla Beata), for a total sample of n = 104. We found strong evidence for genetic drift, inbreeding, and moderate gene flow (i.e., all populations had at least 4 loci that were not in Hardy-Weinberg equilibrium, at least 9 loci pairs were in linkage disequilibrium, the pairwise F(ST) values ranged from 0.069 to 0.266, and had positive F(IS) values). Data supported an isolation-by-distance model, and cluster analyses based on genetic distances resolved 2 groups that match a north-south split. The population from Isla Beata had the lowest levels of genetic diversity and was the only one in which we found pairs of individuals with identical shared multilocus genotypes.

A noteworthy case of rewilding Chinese yew from a garden population in eastern China.

Chinese yew (Taxus wallichiana var. mairei) is ranked as a rare and endangered plant of first-grade protection of China. It has been widely cultivated in 17 provinces of China over the past few decades. However, little is known about the dispersion, rewilding, and ecological influence of Chinese yew's offspring during cultivation. Here, we report a noteworthy case of this species, via ex situ conservation, which has successfully spread into different secondary forests, thus forming a stable regenerating population in eastern China. The establishment of this yew population, which has > 900 individuals and 7 ha area, can be ascribed to two key ecological factors: (1) secondary forest near the parent yews that provided suitable microhabitats in which progeny yews could germinate and grow, and (2) seed-foraging and transportation by native birds. Thus, this case may offer a pathway for conserving endangered Chinese Taxus species, which can attract frugivorous birds to disperse their seeds. In addition, it is necessary to monitor the growth performance of progeny population in the field.

Height increment of Cycas micronesica informs conservation decisions.

Growth dynamics of pachycaulous stems of arborescent cycad plants are not well understood, and most observations have been made in cultivated garden plants. We studied Cycas micronesica plants in Guam, Tinian, and Yap to understand the influences of geography, plant size, sex, and herbivory on stem growth. We also determined the changes in demography of Guam's population after 15 years of damage by non-native insect herbivores. The height increment (HI) was similar for plants within the height range from 100 cm to more than 600 cm, so the relative growth rate declined with height. Female tree HI was 68% of male tree HI, and Yap tree HI was 87% of Guam tree HI. Chronic herbivory by non-native insect herbivores caused a mean 44% decline in HI. Plants in managed gardens grew more rapidly than plants in a wild habitat. The HI was used to estimate that Guam has experienced a complete loss of ≈70 y of demographic depth resulting from the selective mortality of small plants since 2005. When future conservation interventions successfully mitigate the ubiquitous biological threats, our HI may be useful for empirically quantifying recovery of plant health.

Unlocking a high bacterial diversity in the coralloid root microbiome from the cycad genus Dioon.

Cycads are among the few plants that have developed specialized roots to host nitrogen-fixing bacteria. We describe the bacterial diversity of the coralloid roots from seven Dioon species and their surrounding rhizosphere and soil. Using 16S rRNA gene amplicon sequencing, we found that all coralloid roots are inhabited by a broad diversity of bacterial groups, including cyanobacteria and Rhizobiales among the most abundant groups. The diversity and composition of the endophytes are similar in the six Mexican species of Dioon that we evaluated, suggesting a recent divergence of Dioon populations and/or similar plant-driven restrictions in maintaining the coralloid root microbiome. Botanical garden samples and natural populations have a similar taxonomic composition, although the beta diversity differed between these populations. The rhizosphere surrounding the coralloid root serves as a reservoir and source of mostly diazotroph and plant growth-promoting groups that colonize the coralloid endosphere. In the case of cyanobacteria, the endosphere is enriched with Nostoc spp and Calothrix spp that are closely related to previously reported symbiont genera in cycads and other early divergent plants. The data reported here provide an in-depth taxonomic characterization of the bacterial community associated with coralloid root microbiome. The functional aspects of the endophytes, their biological interactions, and their evolutionary history are the next research step in this recently discovered diversity within the cycad coralloid root microbiome.

Cyclone tolerance in new world arecaceae: biogeographic variation and abiotic natural selection.

BACKGROUND AND AIMS: Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection. METHODS: New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts. KEY RESULTS: Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0.001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality. CONCLUSIONS: Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas.

Conserved genetic regions across angiosperms as tools to develop single-copy nuclear markers in gymnosperms: an example using cycads.

Several individuals of the Caribbean Zamia clade and other cycad genera were used to identify single-copy nuclear genes for phylogeographic and phylogenetic studies in Cycadales. Two strategies were employed to select target loci: (i) a tblastX search of Arabidopsis conserved ortholog sequence (COS) set and (ii) a tblastX search of Arabidopsis-Populus-Vitis-Oryza Shared Single-Copy genes (APVO SSC) against the EST Zamia databases in GenBank. From the first strategy, 30 loci were selected, and from the second, 16 loci. In both cases, the matching GenBank accessions of Zamia were used as a query for retrieving highly similar sequences from Cycas, Picea, Pinus species or Ginkgo biloba. After retrieving and aligning all the sequences in each locus, intron predictions were completed to assist in primer design. PCR was carried out in three rounds to detect paralogous loci. A total of 29 loci were successfully amplified as a single band of which 20 were likely single-copy loci. These loci showed different diversity and divergence levels. A preliminary screening allowed us to select 8 promising loci (40S, ATG2, BG, GroES, GTP, LiSH, PEX4 and TR) for the Zamia pumila complex and 4 loci (COS26, GroES, GTP and HTS) for all other cycad genera.

The origins of an important cactus crop, Opuntia ficus-indica (Cactaceae): new molecular evidence.

Opuntia ficus-indica is a long-domesticated cactus crop that is important in agricultural economies throughout arid and semiarid parts of the world. The biogeographic and evolutionary origins of this species have been obscured through ancient and widespread cultivation and naturalization. The origin of O. ficus-indica is investigated through the use of Bayesian phylogenetic analyses of nrITS DNA sequences. These analyses support the following hypotheses: that O. ficus-indica is a close relative of a group of arborescent, fleshy-fruited prickly pears from central and southern Mexico; that the center of domestication for this species is in central Mexico; and that the taxonomic concept of O. ficus-indica may include clones derived from multiple lineages and therefore be polyphyletic.