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 These new estimates are either scattered in a wide range of scientific journals or, in many cases, unpublished; so they are not readily accessible.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

Reduction of the nuclear DNA amount in a constant number of n = 9 chromosomes characterizes the evolutionary genetics of the genus Microseris Correlated with this reduction are physiological, ecological and morphological changes The morphological changes are of two kinds: (1) nucleotypic, ie changes in the dimensions correlated with DNA amount changes; (2) qualitative, specifically concerning an increase in the degree of developmental canalization with a decrease in genome size The latter changes are amenable to formal genetic analysis, and two polygenic systems are described in some detail As far as preliminary estimates indicate, the complexity of these polygenic systems is independent of genome size They are probabely influenced by genome size via nucleotypic limitations on gene expression

Genome Size and Phenotypic Evolution in Microseris ( Asteraceae, Cichorieae )

We measured DNA content of 210 plants of Microseris douglasii collected between 1980 and 1982 representing 10 populations. One major site, Parkfield-Coalinga, had a mixture of plants with a low to high DNA content in 1977, the last year of a major California drought. Collections in 1980-1982 showed an increase in mean DNA content and a reduction in variation. No differences in DNA content were detected among plants growing in different microsite habitats. Since 1978-1982 were years of generally abundant rainfall, these results are compatible with the hypothesis that increased moisture availability may be conducive to selection for higher DNA amounts. At a second site, Jolon, temporal shifts were observed from low DNA amount in the drought year of 1962 to high DNA values in 1973, and back to low DNA content in 1977. All plants of the general collections of 1980-1982 had low DNA amounts. Some high-DNA plants were detected by selectively sampling for extremely robust growth forms. The population, therefore, ...

Patterns of Mean Nuclear DNA Content in Microseris douglasii (Asteraceae) Populations

In the flora of temperate South America are two species of Compositae, tribe Cichorieae, subtribe Microseridinae, that are disjunct from the North American centers of distribution of their respective genera. Microseris pygmaea, an autogamous annual of central Chile, is morphologically similar to several species of like habit, found in the climatically comparable Californian region. A hybrid obtained between M. pygmaea and the closely related North American species, M. bigelovii, showed normal meiotic behavior and was almost fully fertile. In an F, generation of 55 plants, phenotypic segregation was more in the direction of M. bigelovii, and two individuals resembled that species with only minor differences. There was a complex pattern of inheritance for the number of pappus scales on the fruit, a characteristic of major taxonomic importance in distinguishing the parent species. A reduction in seed fertility of certain hybrid plants was ascribed to segregation of a small, nonreciprocal chromosome translocation. It was concluded that the two species are adequately distinct taxonomically but are genetically closely related and interfertile. Microseris probably reached South America by long-distance dispersal, the most likely time for migration being the middle or late Pliocene Epoch. In the second example, Agoseris coronopifolia is a variable species, distributed over the southern tip of the continent, which can be differentiated from the North American Agoseris heterophylla only with difficulty. Both species are composed primarily of annual or perennial plants with autogamous reproduction. Adaptations for out-crossing are present in some races of A. heterophylla but not in A. coronopifolia. Preliminary crossing experiments suggest that genetic barriers exist between the species. The general pattern of phytogeographical and evolutionary relationships in Agoseris and Microseris is like that in certain other families of simxilar distribution.

Amphitropical species pairs in microseris and agoseris (compositae: cichorieae)

The fossil flower Tropidogyne pikei Chambers, Poinar & R. T. Buckley, previously described from Burmese amber has five spreading, epigynous sepals with five major veins and branched, anastomosing veinlets. On top of the inferior ovary is a broad, flat nectar gland from which project three short, arched styles (Chambers et al. 2010). The present paper describes the flowers of another species of this genus, T. pentaptera sp. nov., based on seven separate specimens from the same amber bed. The new species has spreading, veiny sepals, a nectar disc, and a ribbed inferior ovary like T. pikei, but differs in being bicarpellate, with two elongate, slender styles, and in the ribs of its inferior ovary lacking darkly pigmented terminal glands. A relationship of these fossils to the family Cunoniaceae is proposed, in particular to Ceratopetalum D. Don, an extant Southern Hemisphere genus known from fossils of the Tertiary Period.

https://bioone.org/journals/Palaeodiversity/volume-10/issue-1/pale.v10.a10/Tropidogyne-pentaptera-sp-nov-a-new-mid-Cretaceous-fossil-angiosperm/10.18476/pale.v10.a10.pdf

Tropidogyne pentaptera, sp. nov., a new mid-Cretaceous fossil angiosperm flower in Burmese amber

All North American annual species of the genusMicroseris have a five-part pappus, the one South American annual,M. pygmaea, has ten pappus parts. The pappus develops over a constant number of ten provascular bundles with or without inhibition between alternate sites of pappus development. Each natural population contains a predictable proportion of achenes with aberrant pappus part numbers. Hybridization betweenM. bigelovii (5 parts) andM. pygmaea results in F 1 and F 2 plants with many aberrant achenes. In each plant either five or ten can be shown to be the basic number with aberrant numbers following a Poisson distribution for numbers added to 5 or deleted from 10. Occasional plants show no basic number but have a random distribution of numbers about an intermediate mean. The evolutionary genetics of this character is discussed.

Kenton L. Chambers

Papers

Genome Size and Phenotypic Evolution in Microseris ( Asteraceae, Cichorieae )

Patterns of Mean Nuclear DNA Content in Microseris douglasii (Asteraceae) Populations

Amphitropical species pairs in microseris and agoseris (compositae: cichorieae)

Tropidogyne pentaptera, sp. nov., a new mid-Cretaceous fossil angiosperm flower in Burmese amber

Pappus part number in annual species ofMicroseris (Compositae, Cichoriaceae)