Abstract:
:There have been three periods of significant discovery in the exploration of fern and lycophyte genetics. First, during the 1930s, Andersson-Kottö conducted crossing studies on ferns. The publication of Manton's magnum opus on fern chromosomes in 1950 stimulated the second. The third emerged from Klekowski's 1973 American Journal of Botany publication that posed hypotheses linking breeding system dynamics and polyploid genetic architecture. Although Klekowski's assertions (predominant inbreeding and active polyploid genomes) were not supported, his hypotheses served as the impetus for improving our knowledge of the evolutionary mechanisms of ferns and lycophytes. It is now understood that (1) homosporous vascular plants are genetically diploid at high chromosome numbers and (2) both heterosporous and homosporous plants store and release genetic variation through a similar range of breeding systems. However, the seeming paradox of diploid genetic expression in homosporous vascular plants with high chromosome numbers remains unresolved. Ongoing and future research should include (1) more studies of gametophyte biology to elucidate the range and frequency of different breeding systems; (2) genomic analyses and new research on the mechanisms controlling bivalent formation to help discover how and why homosporous plant chromosomes appear so structurally stable; (3) considering whether the frequency of allopolyploidy in lineages can help explain why some are highly polyploid; and (4) chromosome painting studies to identify the dynamics of chromosome behavior in homosporous vascular plants. These open questions and continuing investigations demonstrate the longstanding impact of Klekowski's stimulating contribution.
journal_name
Am J Botjournal_title
American journal of botanyauthors
Haufler CHdoi
10.3732/ajb.1400317subject
Has Abstractpub_date
2014-12-01 00:00:00pages
2036-42issue
12eissn
0002-9122issn
1537-2197pii
ajb.1400317journal_volume
101pub_type
杂志文章,评审abstract:PREMISE OF THE STUDY:Fossilized seeds similar to Cissus (Vitaceae) have been recognized from the Miocene of Kenya, though some were previously assigned to the Menispermaceae. We undertook a comparative survey of extant African Cissus seeds to identify the fossils and consider their implications for the evolution and bi...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1600177
更新日期:2016-09-01 00:00:00
abstract::Seed size and germination requirements of eight (of nine) Sarracenia species, and 13 populations of S. purpurea were studied. All species except for S. purpurea are restricted to the southeastern United States, whereas S. purpurea ranges across Canada, southward along the eastern United States into Maryland and Virgin...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:2001-03-01 00:00:00
abstract:PREMISE OF THE STUDY:Herbivory affects pollination success and reproductive output in plants. However, the different stages in the process from pollination to seed maturation have hardly been investigated within the context of herbivory. Herbivory might affect these stages via its effect on geitonogamous pollination an...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500291
更新日期:2015-12-01 00:00:00
abstract:PREMISE OF THE STUDY:Microsatellite loci were developed in the endangered Pericopsis elata using a combination of low-cost procedures. METHODS AND RESULTS:Microsatellite isolation was performed simultaneously on three distinct species through a newly available procedure that associates multiplex microsatellite enrichm...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100070
更新日期:2011-10-01 00:00:00
abstract::Phloem, as a major tissue mediating long-distance communication, has been an object of extensive research ever since its structure was first reported in 1837. Functional phloem consists of sieve elements (SEs) and companion cells (CCs). While SEs are enucleated conducting cells in the phloem, CCs are cells with intact...
journal_title:American journal of botany
pub_type: 杂志文章,评审
doi:10.3732/ajb.1400197
更新日期:2014-09-01 00:00:00
abstract::Pinus rzedowskii is an endangered pine species from Michoacán (central México), which has been previously reported from only three localities. Classified within the subgenus Strobus, it exhibits intermediate morphological characters between subgenera Strobus and Pinus. We analyzed genetic aspects that could shed light...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1999-05-01 00:00:00
abstract:PREMISE OF THE STUDY:The ability of insect visitors to learn to manipulate complex flowers has important consequences for foraging efficiency and plant fitness. We investigated learning by two butterfly species, Danaus erippus and Heliconius erato, as they foraged on the complex flowers of Asclepias curassavica, as wel...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1700040
更新日期:2017-08-01 00:00:00
abstract:PREMISE OF THE STUDY:The presence or absence of a functional copy of a plastid gene may reflect relaxed selection, and may be phylogenetically significant, reflecting shared ancestry. In some liverworts, the plastid gene cysA is a pseudogene (inferred to be nonfunctional). We surveyed 63 liverworts from all major clade...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1100010
更新日期:2011-08-01 00:00:00
abstract::Detailed investigations on Lower Cretaceous Ephedra L. fossils (Gnetopsida) reveal morphological characters similar to those of extant Ephedra rhytidosperma Pachomova, including articulate branches with many fine longitudinal striations, a dichasial branching pattern, uni- or bi-ovulate cones with paired bracts, cones...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.92.2.231
更新日期:2005-02-01 00:00:00
abstract::The degree to which plants self-fertilize may impact their potential for genetic adaptation. Given that the mating system influences genetic processes within and among populations, the mating system could limit or promote local adaptation. I conducted a literature survey of published reciprocal transplant experiments ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.0900224
更新日期:2010-02-01 00:00:00
abstract::Nuclear and chloroplast DNA variation was assayed for two populations of Louisiana irises (Bayou Teche and Young's Coulee) that demonstrated extreme morphological variation and for a sample of the putative hybrid species, Iris nelsonii. The genetic markers examined in this analysis were diagnostic for either Iris fulv...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/j.1537-2197.1993.tb13843.x
更新日期:1993-05-01 00:00:00
abstract:PREMISE OF THE STUDY:Identifying recently diverged taxa can be useful for studying the process of speciation. Ipomoea lacunosa and I. cordatotriloba, along with a putative homoploid hybrid, I. ×leucantha, are closely related taxa, which are promising for investigating the early stages of speciation. The objectives of t...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1200467
更新日期:2013-11-01 00:00:00
abstract::Many plant species are characterized by a life cycle with a long-lived, subterranean phase that is completely dependent on mycorrhizal fungal symbionts for fixed carbon. This type of life cycle is both phylogenetically and ecologically widespread and is found in diverse vascular plant lineages from the tropics to suba...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.94.7.1248
更新日期:2007-07-01 00:00:00
abstract:PREMISE OF THE STUDY:Documented fossil floras in the neotropics are sparse, yet their records provide evidence on the spatial and temporal occurrence of taxa, allowing for testing of biogeographical and diversification scenarios on individual lineages. A new fossil Piper from the Late Cretaceous of Colombia is describe...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1400427
更新日期:2015-02-01 00:00:00
abstract::Chrysothamnus nauseosus (Asteraceae) is a complex polymorphic shrub species widely distributed in western North America. In a study of 86 populations belonging to 15 subspecies, achene mass varied among populations over a sevenfold range. Achene mass was closely correlated with capitulum size at the subspecies level, ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1997-04-01 00:00:00
abstract:PREMISE OF THE STUDY:The apical meristem generates indeterminate apical growth of the stem and root of vascular plants. Our previous examination showed that shoot apical meristems (SAMs) can be classified into two types based on plasmodesmatal networks (PNs), which are important elements in symplasmic signaling pathway...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.1002/ajb2.1153
更新日期:2018-09-01 00:00:00
abstract:UNLABELLED: PREMISE OF THE STUDY:Taxonomic groups have often been recognized on the basis of geographic distinctions rather than accurately representing evolutionary relationships. This has been particularly true for temperate and tropical members from the same family. Polygonaceae exemplifies this problem, wherein th...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1000022
更新日期:2010-08-01 00:00:00
abstract:UNLABELLED:• PREMISE OF THE STUDY:Contact zones between diploids and their autopolyploid descendants represent a unique evolutionary venue for studying polyploid establishment, cytotype coexistence, and interactions. Here, we examine cytotype coexistence in a diploid-tetraploid contact zone of a perennial herb, Cardam...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500052
更新日期:2015-08-01 00:00:00
abstract:PREMISE OF THE STUDY:Subtribe Hakeinae (526 spp.) represents a large Australian plant radiation central to our understanding of that flora's evolution and ecology. It contains Grevillea-the third largest plant genus in Australia and a group inferred to have among the highest diversification rates in the angiosperms. Ho...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500195
更新日期:2015-10-01 00:00:00
abstract::Reproductive traits of tropical tree species vary predictably in relation to successional stage, but this variation may be due to the species' phylogenetic histories rather than selective pressures imposed by regeneration requirements. Reproductive phenology, tree size at the onset of reproduction, and fecundity of 11...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:1999-12-01 00:00:00
abstract:UNLABELLED: PREMISE OF THE STUDY:Sphagnum dominates vast expanses of wetland habitats throughout the northern hemisphere and species delimitation within the genus is important because floristic changes associated with a warming global climate may have measureable impacts on large-scale ecological processes. Most north...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1200630
更新日期:2013-06-01 00:00:00
abstract::Several alpine species have outlying populations in the lowlands and lower mountains north of the Alps. These small, isolated populations are usually described as either (1) glacial relics, (2) descendants from populations living on forelands and moraines during the ice ages, or (3) populations founded by long-distanc...
journal_title:American journal of botany
pub_type: 杂志文章
doi:
更新日期:2000-04-01 00:00:00
abstract:PREMISE OF THE STUDY:Bignoniaceae is an important component of neotropical forests and a model for evolutionary and biogeographical studies. A previous combination of molecular markers and morphological traits improved the phylogeny of the group. Here we demonstrate the value of next-generation sequencing (NGS) to asse...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1700302
更新日期:2017-10-01 00:00:00
abstract::Based on positive results for 11 of 17 species included in an anatomical survey of tree roots, we concluded that the origin of adventitious branch roots (ABR) on established, undisturbed woody parental root axes is a widespread occurrence. ABR were morphologically indistinguishable from branch roots formed in primary ...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.92.5.802
更新日期:2005-05-01 00:00:00
abstract:PREMISE OF THE STUDY:Phylogenetic and morphological studies have helped clarify the systematics of large and complex groups such as the tribe Crotoneae (Euphorbiaceae). However, very little is known about the diversity, structure, and function of anatomical features in this tribe. Crotoneae comprises the species-rich p...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1500017
更新日期:2015-06-01 00:00:00
abstract::For more than a century, the common ancestor of flowering plants was thought to have had a seven-celled, eight-nucleate Polygonum-type female gametophyte. It is now evident that not one, but in fact three, patterns of female gametophyte development and mature structure characterize the common ancestors of the four mos...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.0800311
更新日期:2009-01-01 00:00:00
abstract::To investigate the relationship between the altitudinal distribution of Quercus laceyi and Q. sideroxyla and their physiological responses to drought, we measured relative water content (RWC), water potentials (Ψ(predawn) and Ψ(midday)), photosynthesis (A(max)), stomatal conductance (g), chlorophyll fluorescence (F(v)...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.94.5.809
更新日期:2007-05-01 00:00:00
abstract:PREMISE OF THE STUDY:Plant-herbivore networks are highly specialized in their interactions, yet they are highly variable with regard to the relative importance of specific host species for herbivores. How host species traits determine specialization and species strength in this antagonistic network is still an unanswer...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1600045
更新日期:2016-08-01 00:00:00
abstract:PREMISE OF THE STUDY:High intraspecific cytogenetic variation in the sedge genus Carex (Cyperaceae) is hypothesized to be due to the "diffuse" or non-localized centromeres, which facilitate chromosome fission and fusion. If chromosome number changes are dominated by fission and fusion, then chromosome evolution will re...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1000046
更新日期:2011-01-01 00:00:00
abstract:PREMISE OF THE STUDY:Microsatellite primers were developed in the native legume tree Anadenanthera colubrina var. cebil to study the genetic diversity and genetic structure in natural populations in Argentina. METHODS AND RESULTS:Nine microsatellite markers were identified using a genomic library enriched for tandemly...
journal_title:American journal of botany
pub_type: 杂志文章
doi:10.3732/ajb.1200078
更新日期:2012-09-01 00:00:00