scholarly journals Ecological and evolutionary constraints on regional avifauna of passerines in China

2020 ◽  
Author(s):  
Tianlong Cai ◽  
Qing Quan ◽  
Gang Song ◽  
Yongjie Wu ◽  
Zhixin Wen ◽  
...  
Keyword(s):  
Species Richness ◽  
Southwest China ◽  
Climatic Factors ◽  
Diversification Rate ◽  
Pearl River ◽  
Passerine Birds ◽  
Strong Correlations ◽  
Eastern Himalayas ◽  
Path Analyses ◽  
Path Models

Abstract Strong correlations between species diversity and climate have been widely observed, but the mechanism underlying this relationship is unclear. Here, we explored the causes of the richness–climate relationships among passerine birds in China by integrating tropical conservatism and diversification rate hypotheses using path models. We found that assemblages with higher species richness southwest of the Salween–Mekong–Pearl River Divide are phylogenetically overdispersed and have shorter mean root distances (MRDs), while species-rich regions northeast of this divide (e.g., north Hengduan Mountains–south Qinling Mountains) are phylogenetically clustered and have longer MRDs. The results of the path analyses showed that the direct effect of climatic factors on species richness was stronger than their indirect effects on species richness via phylogenetic relatedness, indicating that neither tropical conservatism nor diversification rate hypotheses can well explain the richness–climate relationship among passerines in China. However, when path analyses were conducted within subregions separately, we found that the tropical conservatism hypothesis was well supported in the southwestern Salween–Mekong–Pearl River Divide, while the diversification rate hypothesis could explain the richness–climate relationship well in the northeastern divide. We conclude that the diversity patterns of passerines in different subregions of the Eastern Himalayas-Mountains of Southwest China may be shaped by different evolutionary processes related to geological and climatic histories, which explains why the tropical conservatism or diversification rate hypothesis alone cannot fully explain the richness–climate relationships.

Advantages of Nonlinear over Segmentation Analyses in Path Models

2016 ◽  
Vol 12 (4) ◽  
pp. 1-6 ◽  
Author(s):  
Ned Kock
Keyword(s):  
Latent Variables ◽  
Software Tools ◽  
Finite Mixture ◽  
Nonlinear Analyses ◽  
Nonlinear Relationships ◽  
Data Segmentation ◽  
Path Analyses ◽  
Path Models ◽  
Linear Algorithms

The recent availability of software tools for nonlinear path analyses, such as WarpPLS, enables e-collaboration researchers to take nonlinearity into consideration when estimating coefficients of association among linked variables. Nonlinear path analyses can be applied to models with or without latent variables, and provide advantages over data segmentation analyses, including those employing finite mixture segmentation techniques (a.k.a. FIMIX). The latter assume that data can be successfully segmented into subsamples, which are then analyzed with linear algorithms. Nonlinear analyses employing WarpPLS also allow for the identification of linear segments mirroring underlying nonlinear relationships, but without the need to generate subsamples. The author demonstrates the advantages of nonlinear over data segmentation analyses.

scholarly journals Annual Runoff is Highly Linked to Precipitation Extremes in Karst Catchments of Southwest China

2017 ◽  
Vol 18 (10) ◽  
pp. 2745-2759 ◽  
Author(s):  
Zhenwei Li ◽  
Xianli Xu ◽  
Chaohao Xu ◽  
Meixian Liu ◽  
Kelin Wang ◽  
...  
Keyword(s):  
Water Resources ◽  
Southwest China ◽  
Climatic Factors ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Annual Runoff ◽  
Climatic Variables ◽  
Precipitation Extremes ◽  
Karst Area ◽  
Least Squares Regression

Abstract Karst landforms cover 7%–12% of the Earth’s continental area and provide water resources for 25% of the global population. Climate, particularly frequent climate extremes, may greatly affect the annual runoff, especially in climate-sensitive regions such as a karst area of southwest China. Knowledge of the linkage between climate and runoff is urgently needed for smart water resources management. This study therefore selected five catchments that have different carbonized rock coverage (from 11% to 64%) to detect the dominant climatic variables driving changes in annual runoff for the period of 1957–2011 in southwest China. Because climatic variables are highly codependent, a partial least squares regression (PLSR) was used to elucidate the linkages between runoff and 17 climatic variables. Results indicated that the dominant climatic factors driving annual runoff are annual total precipitation, rainy days, heavy precipitation amount, heavy precipitation days, rainstorm amount, and rainstorm days. These six factors are generally used to represent extreme climatic events, and hence it may demonstrate that annual runoff is highly linked to precipitation extremes in this region. The PLSR approach presented in this study is beneficial and novel, as it enables the elimination of codependency among the variables and facilitates a more unbiased view of the contribution of the changes in climatic variables to the changes in runoff. As a practical and simple tool, the PLSR approach is thus recommended for application to a variety of other catchments.

scholarly journals Diversification rates and species richness across the Tree of Life

2016 ◽  
Vol 283 (1838) ◽  
pp. 20161334 ◽  
Author(s):  
Joshua P. Scholl ◽  
John J. Wiens
Keyword(s):  
Species Richness ◽  
Positive Relationship ◽  
Tree Of Life ◽  
Diversification Rate ◽  
Substantial Variation ◽  
Diversification Rates ◽  
Higher Taxa ◽  
Over Time

Species richness varies dramatically among clades across the Tree of Life, by over a million-fold in some cases (e.g. placozoans versus arthropods). Two major explanations for differences in richness among clades are the clade-age hypothesis (i.e. species-rich clades are older) and the diversification-rate hypothesis (i.e. species-rich clades diversify more rapidly, where diversification rate is the net balance of speciation and extinction over time). Here, we examine patterns of variation in diversification rates across the Tree of Life. We address how rates vary across higher taxa, whether rates within higher taxa are related to the subclades within them, and how diversification rates of clades are related to their species richness. We find substantial variation in diversification rates, with rates in plants nearly twice as high as in animals, and rates in some eukaryotes approximately 10-fold faster than prokaryotes. Rates for each kingdom-level clade are then significantly related to the subclades within them. Although caution is needed when interpreting relationships between diversification rates and richness, a positive relationship between the two is not inevitable. We find that variation in diversification rates seems to explain most variation in richness among clades across the Tree of Life, in contrast to the conclusions of previous studies.

PATTERNS OF DIVERSITY IN THE CANADIAN INSECT FAUNA

1993 ◽  
Vol 125 (S165) ◽  
pp. 51-74 ◽  
Author(s):  
H.V. Danks
Keyword(s):  
Species Richness ◽  
Climatic Factors ◽  
Interspecific Interactions ◽  
The Arctic ◽  
Large Area ◽  
The West ◽  
Insect Fauna ◽  
Climatic Trend ◽  
The North ◽  
Historical Factors

AbstractThe diversity of the Canadian insect fauna decreases and its composition (at all taxonomic levels) changes as climates become progressively more harsh toward the north. This climatic trend dominates patterns of diversity, but many other factors interact to produce the observed patterns. In the arctic, species richness is greatest in the west. Farther south, overall species richness is greatest in the west (especially British Columbia), associated with coastal and cordilleran habitats, and to a somewhat smaller degree in the southeast (especially Ontario), associated with deciduous forests and particularly with transitional forests which occupy a large area of southeastern Canada. However, certain taxa are better represented in the west or in the east, depending on present-day habitats and on historical factors. These conclusions, based chiefly on a sample of taxa of different types, are possible only because basic systematic work has been carried out to distinguish and map the species. Preliminary data on numerical patterns, such as the numbers of species relative to different potential resources such as host plants in different zones, tend to suggest that the occurrence of species in the north may depend so heavily on climatic factors that potential resources are not fully exploited and the effects of interspecific interactions on diversity are reduced.

Species richness and vertical stratification of epiphytic lichens in subtropical primary and secondary forests in southwest China

2015 ◽  
Vol 17 ◽  
pp. 30-40 ◽  
Author(s):  
Su Li ◽  
Wen-Yao Liu ◽  
Da-Wen Li ◽  
Liang Song ◽  
Xian-Meng Shi ◽  
...  
Keyword(s):  
Species Richness ◽  
Southwest China ◽  
Vertical Stratification ◽  
Secondary Forests ◽  
Epiphytic Lichens

scholarly journals Continuum beliefs in the stigma process regarding persons with schizophrenia and depression: results of path analyses

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2360 ◽  
Author(s):  
Anna C. Makowski ◽  
Eva E. Mnich ◽  
Matthias C. Angermeyer ◽  
Olaf von dem Knesebeck
Keyword(s):  
Mental Illness ◽  
Social Distance ◽  
Emotional Responses ◽  
Emotional Reactions ◽  
Path Analyses ◽  
Stigmatizing Attitudes ◽  
Path Models ◽  
Persons With Schizophrenia ◽  
The Relationship ◽  
The Continuum

BackgroundIndividuals with mental illness often experience stigmatization and encounter stereotypes such as being dangerous or unpredictable. To further improve measures against psychiatric stigma, it is of importance to understand its components. In this study, we attend to the step of separation between “us” and “them” in the stigma process as conceptualized by Link and Phelan. In using the belief in continuity of mental illness symptoms as a proxy for separation, we explore its associations with stereotypes, emotional responses and desire for social distance in the stigma process.MethodsAnalyses are based on a representative survey in Germany. Vignettes with symptoms suggestive of schizophrenia (n = 1,338) or depression (n = 1,316) were presented to the respondents, followed by questions on continuum belief, stereotypes, emotional reactions and desire for social distance. To examine the relationship between these items, path models were computed.ResultsRespondents who endorsed the continuum belief tended to show greater prosocial reactions (schizophrenia: 0.07; p < 0.001, depression: 0.09; p < 0.001) and less desire for social distance (schizophrenia: −0.13; p < 0.001, depression: −0.14; p < 0.001) toward a person with mental illness. In both cases, agreement with the stereotypes of unpredictability and dangerousness was positively associated with feelings of anger and fear as well as desire for social distance. There were no statistically significant relations between stereotypes and continuum beliefs.DiscussionAssumptions regarding continuum beliefs in the stigma process were only partially confirmed. However, there were associations of continuum beliefs with less stigmatizing attitudes toward persons affected by either schizophrenia or depression. Including information on continuity of symptoms, and thus oppose perceived separation, could prove helpful in future anti-stigma campaigns.

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