An island biogeography model for beta diversity and endemism: The roles of speciation, extinction and dispersal

2015 ◽  
Vol 08 (01) ◽  
pp. 1550011 ◽  
Author(s):  
Youhua Chen
Keyword(s):  
Numerical Simulation ◽  
Community Composition ◽  
Beta Diversity ◽  
Island Biogeography ◽  
Positive Relationship ◽  
Community Patterns ◽  
Speciation Rate ◽  
Immigration Rate ◽  
Extinction Rates

A community composition island biogeography model was developed to explain and predict two community patterns (beta diversity and endemism) with the consideration of speciation, extinction and dispersal processes. Results showed that rate of speciation is positively and linearly associated with beta diversity and endemism, that is, increasing species rates typically could increase the percentage of both endemism and beta diversity. The influences of immigration and extinction rates on beta diversity and endemism are nonlinear, but with numerical simulation, I could observe that increasing extinction rates would lead to decreasing percentage of endemism and beta diversity. The role of immigration rate is very similar to that of speciation rate, having a positive relationship with beta diversity and endemism. Finally, I found that beta diversity is closely related to the percentage of endemism. The slope of this positive relationship is determined jointly by different combinations of speciation, extinction and immigration rates.

scholarly journals Beta diversity patterns derived from island biogeography theory

2018 ◽  
Author(s):  
Muyang Lu ◽  
David Vasseur ◽  
Walter Jetz
Keyword(s):  
Community Composition ◽  
Beta Diversity ◽  
Island Biogeography ◽  
Species Abundance ◽  
Alpha Diversity ◽  
Species Level ◽  
Neutral Model ◽  
Diversity Patterns ◽  
Species Abundance Distributions ◽  
Species Area

AbstractThe Theory of Island Biogeography (TIB) has been successful in predicting alpha diversity patterns such as species-area relationships and species-abundance distributions. Although beta diversity (i.e. the dissimilarity of community composition) has long been recognized as an important element of the TIB and is crucial for understanding community assembly processes, it has never been formally incorporated into the theory. Here we derive theoretical predictions for the expected pairwise beta diversity values under a species-level neutral scenario where all species have equal colonization and extinction rates. We test these predictions for the avian community composition of 42 islands (and 93 species) in the Thousand Island Lake, China. We find that alpha diversity patterns alone do not distinguish a species-level neutral model from a non-neutral model. In contrast, beta diversity patterns clearly reject a species-level neutral model. We suggest that the presented theoretical integration beta diversity offers a powerful path for testing the presence of neutral processes in ecology and biogeography.

An experimental approach to communal coping

2021 ◽  
pp. 026540752199246
Author(s):  
Melissa Zajdel ◽  
Vicki S. Helgeson
Keyword(s):  
Health Outcomes ◽  
Positive Relationship ◽  
Experimental Approach ◽  
Positive Mood ◽  
Self Report ◽  
Communal Coping ◽  
Observational Measures ◽  
Relationship Outcomes ◽  
The Individual

Communal coping has been linked to better psychological and physical health across a variety of stressful contexts. However, there has been no experimental work causally linking communal coping to relationship and health outcomes. In addition, research has emphasized the collaboration over the shared appraisal component of communal coping. The present study sought to isolate the role of appraisal by manipulating whether dyads viewed a stressor as shared or individual. Friend dyads (n = 64 dyads; 128 participants) were randomly assigned to view a stressor as either a shared or an individual problem, but both groups were allowed to work together. Across self-report and observational measures dyads reported more collaboration and support, better relationship outcomes, and more positive mood after the stressor in the shared than the individual appraisal group. This is the first laboratory evidence to establish causal links of communal coping—specifically shared appraisal—to positive relationship and health outcomes.

scholarly journals The lung microbiota in Korean patients with non-tuberculous mycobacterial pulmonary disease

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Sung-Yoon Kang ◽  
Hyojung Kim ◽  
Sungwon Jung ◽  
Sang Min Lee ◽  
Sang Pyo Lee
Keyword(s):  
Principal Component Analysis ◽  
Respiratory Tract ◽  
Pulmonary Disease ◽  
Beta Diversity ◽  
Lower Respiratory Tract ◽  
Principal Component ◽  
Control Group ◽  
Flexible Bronchoscope ◽  
Bronchial Washing

Abstract Background The microbiota of the lower respiratory tract in patients with non-tuberculous mycobacterial pulmonary disease (NTM-PD) has not been fully evaluated. We explored the role of the lung microbiota in NTM-PD by analyzing protected specimen brushing (PSB) and bronchial washing samples from patients with NTM-PD obtained using a flexible bronchoscope. Results Bronchial washing and PSB samples from the NTM-PD group tended to have fewer OTUs and lower Chao1 richness values compared with those from the control group. In both bronchial washing and PSB samples, beta diversity was significantly lower in the NTM-PD group than in the control group (P = 2.25E-6 and P = 4.13E-4, respectively). Principal component analysis showed that the PSBs and bronchial washings exhibited similar patterns within each group but differed between the two groups. The volcano plots indicated differences in several phyla and genera between the two groups. Conclusions The lower respiratory tract of patients with NTM-PD has a unique microbiota distribution that is low in richness/diversity.

Numerical Simulation on the Effect of Compound Roof Separation Position on Bolting Performance

2014 ◽  
Vol 953-954 ◽  
pp. 1638-1642
Author(s):  
Ai Qing Liu ◽  
Jian Zhang ◽  
Peng Cheng ◽  
Yu Hai Zhang
Keyword(s):  
Numerical Simulation ◽  
Simulation Analysis ◽  
Surrounding Rock ◽  
Cohesive Force ◽  
Roof Strata ◽  
Poor Stability ◽  
Key Parameter

Prestress is a key parameter in bolting, while the cohesive force of layers in the compound roof strata is low and prone to separation, causing the prestress proliferation very poor. With the method of numerical simulation analysis,the location of separation in compound roof to affect the performance of bolting support was researched. It is concluded the roof separation in the edge of anchorage zone, the prestress field superpose, but is away from the deep surrounding rock and shows poor stability,however the role of cable can make up for the defect of rockbolts support. It has been found the highly prestressed strength bolting system adapts to the compound roof.

Accounting Conservatism and Firm Growth Financed by External Debt

2016 ◽  
Vol 32 (2) ◽  
pp. 182-208 ◽  
Author(s):  
Tony Kang ◽  
Gerald J. Lobo ◽  
Michael C. Wolfe
Keyword(s):  
Firm Growth ◽  
Positive Relationship ◽  
External Debt ◽  
Debt Maturity ◽  
Accounting Conservatism ◽  
Debt Contracting ◽  
Conservative Accounting ◽  
Agency Risk

Previous research shows that accounting conservatism facilitates debt contracting. Extending this line of literature, we examine whether the role of accounting conservatism in accessing external debt to attain firm growth varies with its maturity. We find evidence of a positive relationship between conservatism and debt maturity. We also observe a positive relationship between conservative accounting and future growth funded by all classes of debt, but this relation is due to long-term rather than short-term debt, which is less prone to agency risk. Furthermore, the associations between conservatism and debt maturity and conservatism and growth financed by long-term debt are mostly observed for firms with fewer anti-takeover provisions in place. These findings suggest that the demand for accounting conservatism is not uniform across different debt maturity horizons.

Career Plateau and Turnover Intention in Chinese Employees: Career Anchor as Moderator

2015 ◽  
Vol 43 (5) ◽  
pp. 757-766 ◽  
Author(s):  
Yueran Wen ◽  
Liu Liu
Keyword(s):  
Turnover Intention ◽  
Positive Relationship ◽  
Management Practices ◽  
Career Anchor ◽  
Career Plateau ◽  
Strong Positive Relationship ◽  
High Level ◽  
The Relationship ◽  
Moderating Role

Based on a survey of 147 Chinese employees, we examined the relationship between perceived career plateau and turnover intention, and the moderating role of career anchor in challenge in this process. We hypothesized that perceived career plateau would be positively related to turnover intention, and that this relationship would be stronger in employees with a higher level of career anchor in challenge than in those with a lower level. The results showed that perceived career plateau had a strong positive relationship with turnover intention, especially in employees with a high level of career anchor in challenge. These findings have implications for research in career development and turnover intention, as well as in management practices.

How does renqing influence purchase intentions in the Chinese business-to-business context?

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xun Zhang ◽  
Biao Xu ◽  
Jun Wu
Keyword(s):  
Positive Relationship ◽  
Purchase Intentions ◽  
Moderating Effect ◽  
Content Type ◽  
Mediating Role ◽  
Chinese Business ◽  
The Relationship ◽  
Business To Business ◽  
Positive Effect

Purpose This study aims to examine the relationship between renqing and purchase intentions and the mechanism of its impact in the Chinese business-to-business (B2B) context. Design/methodology/approach Renqing in China has played an important role in business relationships and has been receiving increased attention in both practice and theory. However, little is known about whether it can influence purchase intentions in a rational B2B condition. This research aims to examine the relationship between renqing and purchase intentions and the mechanism of its impact in the Chinese B2B context. Based on a survey of 1,010 industry buyers from 468 Chinese downstream buyer companies, the empirical findings indicate a positive relationship between renqing and purchase intentions and the mediating role of long-term orientation (LTO) for increasing purchase intentions. In addition, this study also finds that product involvement (PI) has a negative moderating effect on the relationship between renqing and purchase intentions, which means that renqing has a big positive effect on purchase intentions in low PI conditions. The results highlight several implications for B2B companies that sell products to Chinese enterprises. Findings The empirical findings indicate a positive relationship between renqing and purchase intentions and the mediating role of LTO for increasing purchase intentions. In addition, this study also finds that PI has a negative moderating effect on the relationship between renqing and purchase intentions, which means that renqing has a big positive effect on purchase intentions in low PI conditions. Originality/value First of all, by answering the research question, this study shows that renqing has a positive effect on purchase intentions in Chinese B2B context. Second, this study elucidates the influence mechanism of renqing on purchase intention and identifies the mediating effect of LTO and the moderating effect of PI.

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