Abstract：
:Multicellularity has evolved at least once in every major eukaryotic clade (in all ploidy levels) and numerous times among the prokaryotes. According to a standard multilevel selection (MLS) model, in each case, the evolution of multicellularity required the acquisition of cell-cell adhesion, communication, cooperation, and specialization attended by a compulsory alignment-of-fitness phase and an export-of-fitness phase to eliminate cell-cell conflict and to establish a reproductively integrated phenotype. These achievements are reviewed in terms of generalized evolutionary developmental motifs (or "modules") whose overall logic constructs were mobilized and executed differently in bacteria, plants, fungi, and animals. When mapped onto a matrix of theoretically possible body plan morphologies (i.e., a morphospace), these motifs and the MLS model identify a "unicellular ⇒ colonial ⇒ multicellular" transformation series of body plans that mirrors trends observed in the majority of algae (i.e., a polyphyletic collection of photoautotrophic eukaryotes) and in the land plants, fungi, and animals. However, an alternative, more direct route to multicellularity theoretically exists, which may account for some aspects of fungal and algal evolution, i.e., a "siphonous ⇒ multicellular" transformation series. This review of multicellularity attempts to show that natural selection typically acts on functional traits rather than on the mechanisms that generate them ("Many roads lead to Rome.") and that genome sequence homologies do not invariably translate into morphological homologies ("Rome isn't what it used to be.").
journal_name
Am J Botjournal_title
American journal of botanyauthors
Niklas KJdoi
10.3732/ajb.1300314subject
Has Abstractpub_date
2014-01-01 00:00:00pages
6-25issue
1eissn
0002-9122issn
1537-2197pii
ajb.1300314journal_volume
101pub_type
杂志文章,评审abstract：:The evolutionary history of maize (Zea mays subsp. mays) is of general interest because of its economic and scientific importance. Here we show that many cellular traits described previously in developing caryopses of maize are also seen in its wild progenitor teosinte (Zea mays subsp. parviglumis). These features, ea...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0900059
更新日期：2009-10-01 00:00:00
abstract：:Maximum parsimony analysis of DNA sequence data from the internal and external transcribed spacer (ITS and ETS) regions of 18S-26S nuclear ribosomal DNA and the 3' trnK intron of chloroplast DNA from over 60 populations of Lasthenia sect. Amphiachaenia yielded a well-supported tree showing that the most common species...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.89.7.1103
更新日期：2002-07-01 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：:This study shows that structural data, when carefully examined, can provide valuable characters for delimiting monophyletic groups and can complement DNA with observable features to recognize and circumscribe taxa. In the angiosperm order Apiales, traditional classification has relied heavily (often exclusively) on fr...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.93.9.1357
更新日期：2006-09-01 00:00:00
abstract：:Deciphering species relationships and hybrid origins in polyploid agamic species complexes is notoriously difficult. In this study of cheilanthoid ferns, we demonstrate increased resolving power for clarifying the origins of polyploid lineages by integrating evidence from a diverse selection of biosystematic methods. ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0900019
更新日期：2009-09-01 00:00:00
abstract：UNLABELLED: PREMISE OF THE STUDY:Despite the ecological, economic, and cultural importance of the palm Mauritia flexuosa in Amazonia, knowledge of its reproductive biology is scarce. Previous observations of this species suggested beetles as the probable pollinator, but experimental work to confirm this hypothesis was...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200446
更新日期：2013-03-01 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：:The American chestnut (Castanea dentata; Fagaceae) was a dominant canopy tree in the Appalachian Mountains of North America. Since the introduction of the chestnut blight fungus (Cryphonectria parasitica; Valsaceae) in America, the American chestnut has been reduced to a predominantly clonal, understory species. Our o...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.90.2.207
更新日期：2003-02-01 00:00:00
abstract：:In spite of the ecological and economic importance of temperate bamboos, relatively little is known about their population biology or evolutionary history. Recently, hybridization has emerged as a potential source of diversity in this group, as well as an underlying cause of taxonomic problems. As part of a broader ph...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0900244
更新日期：2010-03-01 00:00:00
abstract：:In turnip mitochondria the cox2 gene is partially contained within a 2-kb (kilobase) direct repeat that is the site of homologous recombination events that generate subgenomic molecules. Because of its partial presence within the direct repeat, the turnip cox2 gene exists in four genomic contexts, two on the master ch...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1998-02-01 00:00:00
abstract：:In a detailed analysis of how limited seed dispersal can create spatial structuring of genetic variation, several nuclear microsatellites were assayed in seedlings from two forests of Pinus strobus, one old growth (OG) and the other (second site, SS) logged in ca. 1900. By using loci with a large number of alleles and...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.91.4.549
更新日期：2004-04-01 00:00:00
abstract：UNLABELLED:• PREMISE OF THE STUDY:Adansonia digitata L. is one of the most important indigenous fruit trees of mainland Africa. Despite its significance for subsistence and income generation of local communities, little is known about the genetic and morphological variability of East African populations of A. digitata...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1400198
更新日期：2014-09-01 00:00:00
abstract：PREMISE:The ecological implications of hyperaccumulation have been investigated at the organismal level, but are poorly understood at the plant community level. Questions addressed here were: Does the presence of selenium (Se) hyperaccumulators affect Se distribution and concentration in their native soil, and do hyper...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/ajb2.1500
更新日期：2020-07-01 00:00:00
abstract：:We provide an overview of research on climbing plants from Charles Darwin to the present day. Following Darwin's interests, this review will focus on functional perspectives including attachment mechanisms and stem structure and function. We draw attention to a number of unsolved problems inviting future research. The...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.0900045
更新日期：2009-07-01 00:00:00
abstract：PREMISE OF THE STUDY:Factors shaping spatiotemporal patterns of associations in mutualistic systems are poorly understood. We used the lichen-forming fungi Peltigera and their cyanobacterial partners Nostoc to investigate the spatial structure of this symbiosis at an intrabiome scale and to identify potential factors s...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.1002/ajb2.1119
更新日期：2018-07-01 00:00:00
abstract：PREMISE OF THE STUDY:Seed cone scales assigned to the genus Schizolepidopsis are widespread in Late Triassic to Cretaceous Eurasian deposits. They have been linked to the conifer family Pinaceae based on associated vegetative remains, but their exact affinities are uncertain. Recently discovered material from the Early...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1300173
更新日期：2013-12-01 00:00:00
abstract：UNLABELLED: PREMISE OF THE STUDY:Microsatellite loci were developed to characterize genetic variation and population subdivision in Khaya senegalensis (Desr.) A. Juss. (Meliaceae). • METHODS AND RESULTS:Microsatellite loci were identified from genomic DNA sequences generated using the 454 GS-FLX titanium platform. Pr...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000300
更新日期：2010-11-01 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:Phylogenetic incongruence between "gene trees" and "species trees" has been widely acknowledged in phylogenetic research. Conflicts may emerge from several processes including paralogy, hybridization, and incomplete lineage sorting. Although phylogenetic incongruence appears common, its impact on m...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1400527
更新日期：2015-04-01 00:00:00
abstract：PREMISE OF THE STUDY:Endophytic fungi are common inhabitants of cool-season grasses that can affect host growth and reproduction. One prerequisite for the expected coevolution between symbionts is that there exist variable effects of the endosymbiont on its host in different environments. Here, the impact of endophytes...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1000226
更新日期：2011-05-01 00:00:00
abstract：:Pedilanthus coalcomanensis was described from specimens collected by George B. Hinton in 1941 but was not collected again until 1999, when we found it in a tropical deciduous forest near Tehuantepec, in Chinicuila, Michoacán, Mexico. After analyzing Hinton's original collection notes, we concluded that this is the typ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.89.9.1485
更新日期：2002-09-01 00:00:00
abstract：:We assessed the effects of local environment on survival, growth, and development in six clones (genotypes) of Vallisneria americana grown at five sites in the Huron-Erie Corridor. Detrimental effects of local environment on plant performance (rate of clonal growth, leaf and root production, surface area of leaves and...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1997-12-01 00:00:00
abstract：:A well-integrated plant shows extensive carbohydrate translocation through the plant body. Even in highly integrated plants, however, translocation patterns will be sectorial if vascular tissue restricts carbon movement to sectors along stems. Both integration and sectorial translocation patterns are sensitive to plan...
journal_title：American journal of botany
pub_type： 杂志文章
doi：
更新日期：1998-12-01 00:00:00
abstract：:Because leaf pubescence of the desert shrub Encelia farinosa increases in response to drought and influences photosynthesis and transpiration, we hypothesized that differences in water availability across the range of this species may result in genetic differentiation for pubescence and associated productivity traits....
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.90.10.1481
更新日期：2003-10-01 00:00:00
abstract：UNLABELLED:• PREMISE OF THE STUDY:Two ovulate conifer cones, one of which is attached terminally to a short leafy shoot, reveal the presence of a new species of Hughmillerites in the Early Cretaceous Apple Bay flora of Vancouver Island, British Columbia, Canada. This ancient conifer expands the diversity of Cupressace...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1400369
更新日期：2014-12-01 00:00:00
abstract：:We examined the effects of size and spatial isolation of fens on the isozyme variability of 17 populations of Swertia perennis. This long-lived perennial is a locally abundant fen specialist in Switzerland, where wetlands have been strongly fragmented. Isozyme variability was comparable to other outcrossing plants (A ...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.89.5.801
更新日期：2002-05-01 00:00:00
abstract：:A long-term survey (1990-2000) of pollination modes of 86 tree species was carried out at Kakachi, a mid-elevation wet forest site in southern Western Ghats, India. Observations were made on 86 tree species. This comprises 80% of the total arborescent species present in the site. Approximately 75% of these species wer...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.90.4.650
更新日期：2003-04-01 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:Koelreuteria (Sapindaceae) has four extant deciduous tree species, disjunctly distributed in eastern Asia and the Fiji Islands. While K. paniculata is widely cultivated, the biogeographic origin and evolutionary history of Koelreuteria remain unclear. METHODS:Fruits, pollen, wood, and leaves of cl...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.1200415
更新日期：2013-02-01 00:00:00
abstract：:The origin of polyploid Bromus species of section Genea was investigated using molecular data. This group of annual species native from the Old-World is composed of three diploids, two tetraploids, one hexaploid, and one octoploid. Molecular cloning, sequencing, and phylogenetic analyses were performed on several acce...
journal_title：American journal of botany
pub_type： 杂志文章
doi：10.3732/ajb.95.4.454
更新日期：2008-04-01 00:00:00
