scholarly journals Broad variation in rates of polyploidy and dysploidy across flowering plants is correlated with lineage diversification

2021 ◽  
Author(s):  
Shing Hei Zhan ◽  
Sarah P Otto ◽  
Michael S Barker
Keyword(s):  
Chromosome Number ◽  
Genome Duplication ◽  
Chromosomal Evolution ◽  
Future Research ◽  
Relative Importance ◽  
Single Chromosome ◽  
Diversification Rates ◽  
Broad Variation ◽  
Complex Relationships ◽  
Lineage Diversification

Changes in chromosome number are considered an important driver of diversification in angiosperms. Single chromosome number changes caused by dysploidy may produce strong reproductive barriers leading to speciation. Polyploidy, or whole genome duplication, yields new species that are often reproductively isolated from progenitors and may exhibit novel morphology or ecology that may further facilitate diversification. Here, we examined the rates of polyploidy, dysploidy, and diversification across the angiosperms. Our analyses of nearly 30,000 taxa representing 46 orders and 147 families found that rates of polyploidy and dysploidy differed by two to three orders of magnitude. The rates of polyploidy and dysploidy were positively correlated with diversification rates, but relative importance analyses indicated that variation in polyploidy was better correlated with diversification rates than dysploidy. Our results provide an overview of angiosperm chromosomal evolution and a roadmap for future research on the complex relationships among polyploidy, dysploidy, and diversification.

scholarly journals Interaction Between Ploidy, Breeding System, and Lineage Diversification

2019 ◽  
Author(s):  
Rosana Zenil-Ferguson ◽  
J. Gordon Burleigh ◽  
William A. Freyman ◽  
Boris Igić ◽  
Itay Mayrose ◽  
...  
Keyword(s):  
Breeding System ◽  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Whole Genome ◽  
Self Incompatibility ◽  
Evolutionary Pathway ◽  
Diversification Rates ◽  
Extinction Rates ◽  
Biological Hierarchy ◽  
Lineage Diversification

AbstractIf particular traits consistently affect rates of speciation and extinction, broad macroevolutionary patterns can be understood as consequences of selection at high levels of the biological hierarchy. Identifying traits associated with diversification rate differences is complicated by the wide variety of characters under consideration and the statistical challenges of testing for associations from comparative phylogenetic data. Ploidy (diploid vs. polyploid states) and breeding system (self-incompatible vs. self-compatible states) have been repeatedly suggested as possible drivers of differential diversification. We investigate the connections of these traits, including their interaction, to speciation and extinction rates in Solanaceae. We show that the effect of ploidy on diversification can be largely explained by its correlation with breeding system and that additional unknown factors, alongside breeding system, influence diversification rates. These results are largely robust to allowing for diploidization. Finally, we find that the most common evolutionary pathway to polyploidy in Solanaceae occurs via direct breakdown of self-incompatibility by whole genome duplication, rather than indirectly via breakdown followed by polyploidization.

scholarly journals Teacher enthusiasm and students’ social-behavioral learning engagement: The mediating role of student enjoyment and boredom in Chinese EFL classes

2021 ◽  
pp. 136216882110145
Author(s):  
Jean-Marc Dewaele ◽  
Chengchen Li
Keyword(s):  
Second Language Acquisition ◽  
Qualitative Interviews ◽  
Future Research ◽  
Learning Engagement ◽  
Behavioral Learning ◽  
Mediating Role ◽  
English Classes ◽  
Teacher Enthusiasm ◽  
Instructed Second Language Acquisition ◽  
Complex Relationships

Teacher enthusiasm is attracting growing attention in educational and learner psychology research. There is evidence that teacher enthusiasm is contagious in class and positively affects student emotions. Their fundamental role in shaping student engagement has also been well documented. However, the links – between teacher enthusiasm and student emotions, and between student emotions and engagement – remain underexplored in instructed second language acquisition. The present study adopted a mixed-method approach to examine the complex relationships between perceived teacher enthusiasm, emotions (enjoyment and boredom), and social-behavioral learning engagement among 2,002 learners of English as a foreign language (EFL) from 11 universities in China. Quantitative analyses showed small to large correlations between perceived teacher enthusiasm, enjoyment, boredom, and social-behavioral learning engagement. In addition, student enjoyment and boredom were found to co-mediate the relationship between perceptions of teacher enthusiasm and student social-behavioral engagement in English classes. Qualitative interviews with nine students provided insights into the potential causes of the statistical patterns. Theoretical and pedagogical implications are discussed, followed by directions for future research.

Effectiveness of a Modified Version of Airflow Therapy

1982 ◽  
Vol 47 (2) ◽  
pp. 160-164
Author(s):  
Glenn L. Falkowski ◽  
Arthur M. Guilford ◽  
Jack Sandler
Keyword(s):  
Success Rate ◽  
Scientific Literature ◽  
Future Research ◽  
Relative Importance ◽  
Differential Effectiveness ◽  
History Of ◽  
One Year ◽  
Main Components

Utilizing airflow therapy, Schwartz (1976) has claimed an 89% success rate with stutterers following treatment and an 83% success rate at one year follow-up. Such claims have yet to be documented in the scientific literature. The purposes of this study were: (a) to investigate the effectiveness of a modified version of airflow therapy; (b) to examine the relative importance of its two main components—passive airflow and elongation of the first vowel spoken. The speech of two adult male stutterers with a lengthy history of stuttering, was assessed with spontaneous speaking and reading tasks. Results indicated marked improvement in both subjects' speech on the reading task was maintained at follow-up 10 weeks later. For spontaneous speech, results were generally weaker and less durable. Effects of the two treatment components were cumulative and did not allow determination of any differential effectiveness between components. Implications of these findings were considered and directions for future research discussed.

Competition theory — science and application in mixed forest stands: review of experimental and modelling methods and suggestions for future research

2013 ◽  
Vol 21 (2) ◽  
pp. 71-84 ◽  
Author(s):  
Guy R. Larocque ◽  
Nancy Luckai ◽  
Shailendra N. Adhikary ◽  
Arthur Groot ◽  
F. Wayne Bell ◽  
...  
Keyword(s):  
Mixed Forest ◽  
Single Species ◽  
Experimental Designs ◽  
Competitive Interactions ◽  
Future Research ◽  
Relative Importance ◽  
Forest Stands ◽  
Management Scenarios ◽  
Mixed Stands ◽  
Individual Tree

Competition in forest stands has long been of interest to researchers. However, much of the knowledge originates from empirical studies that examined the effects of competition. For instance, many studies were focused on the effects of the presence of herbaceous species on the development of tree seedlings or the decrease in individual tree growth with increases in stand density. Several models that incorporate competitive effects have been developed to predict tree and stand growth, but with simplified representations of competitive interactions. While these studies provided guidance useful for forest management, they contributed only partially to furthering our understanding of competitive mechanisms. Also, most competition studies were conducted in single-species stands. As competitive interactions occurring in mixed stands are characterized by a higher degree of complexity than those in single-species stands, a better understanding of these mechanisms can contribute to developing optimal management scenarios. The dynamics of forest stands with at least two species may be affected not only by competition, but also by facilitation or complementarity mechanisms. Thus, knowledge of the mechanisms may provide insight into the relative importance of intra- versus inter-specific competition and whether competition is symmetric or asymmetric. Special attention to the implementation of field experimental designs is warranted for mixed stands. While traditional spacing trials are appropriate for single-species stands, the examination of competitive interactions in mixed stands requires more complex experimental designs to examine the relative importance of species combinations. Forest productivity models allow resource managers to test different management scenarios, but again most of these models were developed for single-species stands. As competitive interactions are more complex in mixed stands, models developed to predict their dynamics will need to include more mechanistic representations of competition.

What does Solitude Mean to the Aged?

1988 ◽  
Vol 7 (4) ◽  
pp. 358-371 ◽  
Author(s):  
Marc-André Delisle
Keyword(s):  
Social Isolation ◽  
The Elderly ◽  
Complex Problem ◽  
Future Research ◽  
Relative Importance ◽  
Affective Needs ◽  
Quebec Literature ◽  
Comprehensive Study

AbstractThis article examines the extent and the meaning of solitude among the aged. A comprehensive study of the foreign, Canadian and Quebec literature was undertaken to prepare this document, but priority was given to the somewhat lesser known investigations originating from Quebec. First, the concepts most often utilized in discussing the phenomena under scrutiny were defined: solitude, social isolation and the feeling of loneliness. Then, the relative importance of each phenomenon was assessed, based on the available data. In order to fully understand the meaning of the facts observed, their causes were also examined. Finally, avenues for future research were proposed. This study suggests that solitude among the elderly is a more complex problem than believed. Even if the isolated and (or) lonely aged are in the minority, this does not mean that all their socio-affective needs are being met. These people spend long periods of time alone and this affects their lives. The problem as such is largely caused by the position the elderly occupy in the society and, in turn, this position probably influences their behaviour. However, gerontologists have scarcely studied this hypothesis. This article then highlights certain aspects of the solitude phenomenon which have so far been overlooked by gerontologists.

The Market Structure and Characteristics of Electronic Games

2011 ◽  
pp. 257-285 ◽  
Author(s):  
Kerri-Ann L. Kuhn
Keyword(s):  
Market Structure ◽  
Rapid Growth ◽  
Academic Research ◽  
Sports Participation ◽  
Future Research ◽  
Game Play ◽  
The World ◽  
Complex Relationships ◽  
Electronic Games

A multi-billion dollar industry, electronic games have been experiencing strong and rapid growth in recent times. The world of games is not only exciting due to the magnificent growth of the industry however, but due to a host of other factors. This chapter explores electronic games, providing an analysis of the industry, key motivators for game play, the game medium and academic research concerning the effects of play. It also reviews the emerging relationship games share with sport, recognizing that they can replicate sports, facilitate sports participation and be played as a sport. These are complex relationships that have not yet been comprehensively studied. The current chapter serves to draw academic attention to the area and presents ideas for future research.

Ecological Interactions and Macroevolution: A New Field with Old Roots

2020 ◽  
Vol 51 (1) ◽  
pp. 215-243 ◽  
Author(s):  
David H. Hembry ◽  
Marjorie G. Weber
Keyword(s):  
Species Interactions ◽  
Interspecific Interactions ◽  
Biotic Interactions ◽  
Evolutionary Change ◽  
Future Research ◽  
Ecological Interactions ◽  
Open Questions ◽  
Work Done ◽  
Lineage Diversification

Linking interspecific interactions (e.g., mutualism, competition, predation, parasitism) to macroevolution (evolutionary change on deep timescales) is a key goal in biology. The role of species interactions in shaping macroevolutionary trajectories has been studied for centuries and remains a cutting-edge topic of current research. However, despite its deep historical roots, classic and current approaches to this topic are highly diverse. Here, we combine historical and contemporary perspectives on the study of ecological interactions in macroevolution, synthesizing ideas across eras to build a zoomed-out picture of the big questions at the nexus of ecology and macroevolution. We discuss the trajectory of this important and challenging field, dividing research into work done before the 1970s, research between 1970 and 2005, and work done since 2005. We argue that in response to long-standing questions in paleobiology, evidence accumulated to date has demonstrated that biotic interactions (including mutualism) can influence lineage diversification and trait evolution over macroevolutionary timescales, and we outline major open questions for future research in the field.

Karyotypes of Leptarrhena and Tanakaea (Saxifragaceae)

1984 ◽  
Vol 62 (4) ◽  
pp. 671-673 ◽  
Author(s):  
Douglas E. Soltis
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Chromosomal Evolution ◽  
Conservative Nature ◽  
Chromosomal Data ◽  
Base Chromosome Number ◽  
Flavonoid Chemistry

In an attempt to clarify subtribal relationships in tribe Saxifrageae, chromosome numbers and karyotypes were determined for the two species comprising subtribe Leptarrheninae: Leptarrhena pyrolifolia and Tanakaea radicans. In both species 2n = 14, a common chromosome number throughout Saxifrageae. The two species have distinctive karyotypes that appear to differ in the centromeric positions of three pairs of chromosomes. These findings, in conjunction with earlier studies, demonstrate that genera of Saxifrageae often differ karyotypically. Leptarrhena exhibits considerable karyotypic similarity to genera of subtribe Saxifraginae characterized by a base chromosome number of x = 7. Chromosomal data, therefore, do not clearly differentiate subtribes Saxifraginae and Leptarrheninae. This observation is in agreement with evidence from paly-nology and flavonoid chemistry. Karyotypic studies continue to demonstrate the conservative nature of chromosomal evolution in tribe Saxifrageae.

scholarly journals Explaining the ocean's richest biodiversity hotspot and global patterns of fish diversity

2018 ◽  
Vol 285 (1888) ◽  
pp. 20181314 ◽  
Author(s):  
Elizabeth Christina Miller ◽  
Kenji T. Hayashi ◽  
Dongyuan Song ◽  
John J. Wiens
Keyword(s):  
Large Scale ◽  
Fish Diversity ◽  
Relative Importance ◽  
Diversification Rates ◽  
Marine Habitats ◽  
History Of ◽  
Richness Patterns ◽  
Colonization Time ◽  
Almost All

For most marine organisms, species richness peaks in the Central Indo-Pacific region and declines longitudinally, a striking pattern that remains poorly understood. Here, we used phylogenetic approaches to address the causes of richness patterns among global marine regions, comparing the relative importance of colonization time, number of colonization events, and diversification rates (speciation minus extinction). We estimated regional richness using distributional data for almost all percomorph fishes (17 435 species total, including approximately 72% of all marine fishes and approximately 33% of all freshwater fishes). The high diversity of the Central Indo-Pacific was explained by its colonization by many lineages 5.3–34 million years ago. These relatively old colonizations allowed more time for richness to build up through in situ diversification compared to other warm-marine regions. Surprisingly, diversification rates were decoupled from marine richness patterns, with clades in low-richness cold-marine habitats having the highest rates. Unlike marine richness, freshwater diversity was largely derived from a few ancient colonizations, coupled with high diversification rates. Our results are congruent with the geological history of the marine tropics, and thus may apply to many other organisms. Beyond marine biogeography, we add to the growing number of cases where colonization and time-for-speciation explain large-scale richness patterns instead of diversification rates.

scholarly journals Chromosomal Evolution in the Lizard Genus Varanus (Reptilia)

1975 ◽  
Vol 28 (1) ◽  
pp. 89 ◽  
Author(s):  
Max Kinga ◽  
Dennis King
Keyword(s):  
Chromosome Number ◽  
Pericentric Inversion ◽  
Sex Chromosome ◽  
Chromosomal Rearrangements ◽  
Chromosomal Evolution ◽  
Size Groups ◽  
Sex Chromosome System

The karyotypes have been determined of 16 of the 32 species of the genus Varanus, including animals from Africa, Israel, Malaya and Australia. A constant chromosome number of 2n = 40 was observed. The karyotype is divided into eight pairs of large chromosomes and 12 pairs of microchromosomes. A series of chromosomal rearrangements have become established in both size groups of the karyotype and are restricted to centromere shifts, probably caused by pericentric inversion. Species could be placed in one of six distinct karyotype groups which are differentiated by these rearrangements and whose grouping does not always correspond with the current taxonomy. An unusual sex chromosome system of the ZZjZW type was present in a number of the species examined.

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