Nuclear DNA amounts have been estimated for more than 200 angiosperm species since the last collected list of such values for about 750 species was published by Bennett & Smith in 1976 (Phil. Trans. R. Soc. Lond. B 274, 227-274). These new estimates are either scattered in a wide range of scientific journals or, in many cases, unpublished; so they are not readily accessible. A publication, collecting these data in a single list is required. This paper contains a supplementary list of absolute DNA values, including estimates for 240 angiosperm species not listed by Bennett & Smith in 1976, as well as additional estimates for 41 species already listed by them. These data are assembled primarily for reference purposes. Consequently, the species are listed in alphabetical order, as this was felt to be more helpful to cyto- and biochemists, who it is anticipated will be among the major users.

Nuclear DNA Amounts in Angiosperms

Preface. Part I: Molecules and genomes in plant systematics. Chloroplast DNA and the study of plant phylogeny: present status and future prospects - M T Clegg and G Zurawski Use of chloroplast DNA rearrangements in reconstructing plant phylogeny - S R Downie and J D Palmer Mitochondrial DNA in plant systematics: applications and limitations - J D Palmer Ribosomal RNA as a phylogenetic tool in plant systematics - R K Hamby and E A Zimmer Evolution of the NOR and 5S DNA loci in the Triticeae - R Appels and B Baum Part II: Molecular approaches to plant evolution Intraspecific chloroplast DNA variation: systematic and phylogenetic implications - D E Soltis, P S Soltis and B G Milligan Molecular data and polyploid evolution in plants - P S Soltis, J J Doyle and D E Soltis Molecular systematics and crop evolution - J Deobley Part III: Model studies of phylogenetic relationships Contributions of molecular data to polyploid evolution in plants - P S Soltis, J J Doyle and D E Soltis Molecular systematics and crop evolution - J Deobley Contributions of molecular data to papilionoid legume systematics - J J Doyle, M Levin and A Bruneau Chloroplast DNA variation in the asteraceae: phylogenetic and evolutionary implications - R K Jansen, H J Michaels, R S Wallace, K-J Kim, S C Keeley, L E Watson and J D Palmer Chloroplast DNA restriction site variation and the evolution of the annual habit in North American Coreopsis (Asteraceae) - D J Crawford, J D Palmer and M Kobayashi Molecular systematics of onagraceae: examples from Clarkia and Fuschia - K J Systema and J E Smith Floral morphology and chromosome number in the subtribe oncidiinae (Orchidaceae): evolutionary insights from a phylogenetic analysis of the chloroplast DNA restriction site variation - M W Chase and J D Palmer Part IV: Theoretical perspectives The suitability of molecular and morphological evidence in reconstructing plant phylogeny -M J Donaghue and M J Sanderson Character-site weighting for restriction site data in phylogenetic reconstruction, with an example from chloroplast DNA - V A Albert, B D Mishler and M W Chase Polymorphism, hybridization and variable evolutionary rate in molecular phylogenies - K Ritland and J E Eckenwalder Index.

Molecular Systematics of Plants

For nearly a century, biologists, and botanists in particular, have been interested in the determination and documentation of chromosome numbers for extant taxa (reviewed in Goldblatt & Lowry, 2011) as well as extinct ones (Laane & Hoiland, 1986; Masterson, 1994). These data have beenwidely used to evaluate the evolutionary pattern of chromosome number change and to estimate the base chromosome number of clades of interest. Chromosome numbers have also been extensively utilized as an important phylogenetic character in the context of cytotaxonomy (Chatterjee & Kumar Sharma, 1969; Schlarbaum & Tsuchiya, 1984; Guerra, 2012). Perhaps the most influential use of chromosome number data has been in the inference of major genomic events such aswhole genomeduplications (polyploidy), as well as changes in single chromosome numbers (e.g. dysploidy). Early researchers analyzed the distribution of chromosome numbers within a group of interest and employed various threshold techniques to estimate ploidy levels for the analyzed taxa (Stebbins, 1938; Grant, 1963; Goldblatt, 1980).More recently, phylogenetic information was incorporated into the analyses, allowing researchers to infer transitions in chromosome numbers along branches of the tree using either the maximum parsimony principle (Schultheis, 2001; Hansen et al., 2006; Ohi-Toma et al., 2006; Wood et al., 2009) or by using a probabilistic evolutionary model within the likelihood paradigm (Mayrose et al., 2010; Cusimano et al., 2012; Glick & Mayrose, 2014). Due to their significance and the relative ease by which chromosome numbers can be obtained, it is not surprising that chromosome number is the most extensively and consistently recorded cytological property in most plant families and genera (Guerra, 2008). These data have been documented along the years in an array of journal manuscripts, printed books (L€ove & L€ove, 1948; Darlington & Wylie, 1955; Fedorov, 1969) and, more recently, in the form of online databases (Goldblatt & Johnson, 1979; Watanabe, 2002; Bennett & Leitch, 2011). To date, the most comprehensive data source is the Index to PlantChromosome Numbers (IPCN; Goldblatt & Johnson, 1979), which provides reference point to original chromosome counts reported in the literature. IPCN was initially established at the University of California Berkeley in the 1950s and was later maintained by Canada Department of Agriculture, Missouri Botanical Garden, and currently by the International Association for Plant Taxonomy (IAPT). A large portion of the counts referenced during 1979– 2006, the years that IPCN has been housed in the Missouri Botanical Garden, can be accessed and searched online. Counts reported in more recent years are currently published under IAPT/ IOPBChromosomeData series (Marhold, 2006) but are not stored within a central, easily searched, database. In addition to IPCN, several other online data sources are available, most of which are dedicated to either a specific geographical region (Slovakia – Marhold et al., 2007; Poland –G oralski et al., 2009 onwards) or to a certain taxonomic group (e.g. Hieracium – Schuhwerk, 1996; Asteraceae –Watanabe, 2002). The amount of chromosome counts that exist to date is extensive, and searching the large number of resources that contain such information is a daunting task, particularly when a large number of taxa is examined. Consequently, many researchers search for chromosome number information only through the largest online database(s), while smaller but nonetheless valuable sources are ignored.This usually results inmissing data for someof the species in question, which may lead to erroneous conclusions drawn from the analysis. Obviously, a large accessible database that unifies all currently known databases, including both printed and online sources, would be of great value to the botanical community and wouldmake the task of data collectionmuch easier. In addition, such a central resource would enable researchers to add new counts as soon as they are being reported, facilitating the task of data sharing. Here, we present the Chromosome Counts Database (CCDB), as a community resource of plant chromosome numbers. The database incorporates data from dozens of sources, more than doubling the amount of data available within any single resource. The online database additionally enables researchers to add new counts or to comment on existing data entries, thereby facilitating data sharing. The extensive amount of data currently available in CCDB further allowed us to analyze the patterns of chromosome number distribution among major plant groups. We estimate the percentage of plant species exhibiting intraspecific variation in chromosome numbers as well as in their ploidy levels.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/nph.13191

The Chromosome Counts Database (CCDB) – a community resource of plant chromosome numbers

Phenotypic plasticity is ubiquitous and generally regarded as a key mechanism for enabling organisms to survive in the face of environmental change Because no organism is infinitely or ideally plastic, theory suggests that there must be limits (for example, the lack of ability to produce an optimal trait) to the evolution of phenotypic plasticity, or that plasticity may have inherent significant costs Yet numerous experimental studies have not detected widespread costs Explicitly differentiating plasticity costs from phenotype costs, we re-evaluate fundamental questions of the limits to the evolution of plasticity and of generalists vs specialists We advocate for the view that relaxed selection and variable selection intensities are likely more important constraints to the evolution of plasticity than the costs of plasticity Some forms of plasticity, such as learning, may be inherently costly In addition, we examine opportunities to offset costs of phenotypes through ontogeny, amelioration of phenotypic costs across environments, and the condition-dependent hypothesis We propose avenues of further inquiry in the limits of plasticity using new and classic methods of ecological parameterization, phylogenetics and omics in the context of answering questions on the constraints of plasticity Given plasticity's key role in coping with environmental change, approaches spanning the spectrum from applied to basic will greatly enrich our understanding of the evolution of plasticity and resolve our understanding of limits

https://digitalcommons.wcupa.edu/cgi/viewcontent.cgi?article=1032&context=bio_facpub

Constraints on the evolution of phenotypic plasticity: limits and costs of phenotype and plasticity

The advent of fast, relatively inexpensive (thus, widely available) microcomputers is transforming the way we analyze data in ecological and evolutionary research. Even more profound, however, are the associated changes in questions asked, empirical methods used, studies conducted, and interpretations offered. Now that an array of computation-intensive statistical methods is newly available for general use, it seems particularly important to assess their advantages and limitations, to note how they are currently being used, and then to consider implications for the future. I focus in this review on four related techniques known in the statistical and biological literature as randomization (or permutation) tests, Monte Carlo methods, bootstrapping, and the jackknife. I refer to them collectively as resampling methods, because each involves taking several-to-many samples from the original data set (randomization, bootstrap, jackknife) or from a stochastic process like the one believed to have generated the data set (Monte Carlo). Each of these methods is actually an extensive family of techniques and specific applications that cannot be thoroughly examined here; instead, I briefly characterize the focal methods and then survey the recent literature in ecology and evolution to identify the issues most frequently associated with these techniques. It emerges that resampling methods are well represented in

Resampling methods for computation-intensive data analysis in ecology and evolution

Two flowers embedded in a single block of amber from Myanmar are here proposed as a second species of the previously described fossil genus Lachnociona. The mid-Cretaceous age of the fossils was earlier established through paleontological and U-Pb isotope dating methods. Because they lie within millimeters of each other in the amber, the flowers are assumed to have come from the same parent plant. One flower is hermaphrodite while the other is functionally pistillate. They differ by the number of styles—4 in the perfect flower and 5 in the unisexual one—and most notably by the presence, in the perfect flower, of 10 conspicuous nectar glands forming a disc above the whorl of stamens. The pistillate flower has no such glands. In the new species, the arched styles are widely divergent and the ovary is fully inferior, while in the earlier-described Lachnociona terriae, the flower is functionally pistillate, with styles that are erect and connivent or connate. It could not be determined whether the ovary is superior or half-inferior. The best-preserved anther in the perfect flower of L. camptostylus resembles, in its dorsal filament attachment and hooked filament tip, a vestigial anther present in the flower of L. terriae. Pollen of the new species is tri- or tetracolpate. As proposed in the previous paper, the genus may have participated in the early diversification of the rosid clade of eudicots.

Fossil flowers of Lachnociona camptostylus sp. nov., a second record for the genus in mid-Cretaceous Myanmar Amber

The proportion of the outer, “hairy” achenes in capitula of hybrid D 14 (Microseris pygmaea × M. bigelovii) is determined by the same major gene as in its sister hybrid, B 87, as shown by marker segregation. Crossover between major gene and markers shows their genetic independence. Two modifiers segregating 9:7 influence the proportion of hairies in plants homozygous for the major gene. These same modifiers (or two genes linked with them) also determine the segregation of the number of achenes per head. Most likely, the modifiers act indirectly via a residual dependence of heterocarpy on capitulum size within strict quantitative limits set by the major gene. The identification of modifiers in a polygenic system as major genes for another character acting pleiotropically supports our contention that relatively few genes interact in plant development to determine key morphological characteristics at the organismic level.

Modifiers of heterocarpy determine capitulum size inMicroseris hybrid D 14 (Asteraceae — Lactuceae)

Strombothelya, a new genus of fossil angiosperms from Myanmar amber deposits, is represented by 2 flowers that are here described as separate species. Flowers of Strombothelya have 5 spreading, more or less distinctly veined sepals. Petals are absent. There are 10 inwardly arching stamens and a half-inferior ovary, whose broadly conic superior portion terminates in 1 or 3 stout, columnar, apically truncate styles. The superior portion has a papillate surface that was probably nectarifer-ous. The inferior portion of the ovary in both species is obconic and 5- or 10-ribbed. The fossils are comparable in certain respects to the genus Tropidogyne, described earlier from the same amber deposits. The 3 species of Tropidogyne have flowers with 5 or 10 stamens and 2 or 3 slender, curved, acutely-tipped styles. The inferior portion of the ovary is strongly 10-ribbed, while the superior portion is flat or cushion-shaped and bears a lobed nectar-disc. Strombothelya and Tropidogyne inhabited a Cretaceous araucarian rainforest, which may have been located in the Southern Hemisphere continent of Gondwana.

Kenton L. Chambers

Papers

Fossil flowers of Lachnociona camptostylus sp. nov., a second record for the genus in mid-Cretaceous Myanmar Amber

Modifiers of heterocarpy determine capitulum size inMicroseris hybrid D 14 (Asteraceae — Lactuceae)

Strombothelya gen. nov., a fossil angiosperm with two species in mid-Cretaceous Myanmar amber

Infrageneric classification and nomenclatural notes for pycnanthemum (lamiaceae)

Chromosome Numbers and Relationships of Claytonia saxosa and C. arenicola (Portulacaceae)