Spatiotemporal palaeodiversity patterns of modern crocodiles (Crocodyliformes: Eusuchia)

2019 ◽  
Vol 189 (2) ◽  
pp. 635-656 ◽  
Author(s):  
Ane De Celis ◽  
Iván Narváez ◽  
Francisco Ortega
Keyword(s):  
South America ◽  
Least Squares ◽  
Late Miocene ◽  
North American ◽  
Fossil Record ◽  
Generalized Least Squares ◽  
Global Scale ◽  
Biotic Factors ◽  
Species Dynamics ◽  
Over Time

Abstract Eusuchia is a crocodyliform clade with a rich and diverse fossil record dating back to the Mesozoic. There are several recent studies that analyse crocodyliform palaeodiversity over time, but none of them focuses exclusively on eusuchians. Thus, we estimated subsampled eusuchian palaeodiversity species dynamics over time not only at a global scale, but also by continents and main crocodylian lineages (Alligatoroidea, Crocodyloidea and Gavialoidea). These estimates reveal complex spatiotemporal palaeodiversity patterns, in which two maxima can be detected: the first during the Palaeocene and the second, which is also the biggest, in the middle-late Miocene. The Palaeocene shift is related to a North American alligatoroid diversification, whereas the middle–late Miocene maximum is related to a diversification of the three main Crocodylia lineages in Gondwanan land masses, but especially in South America. Additionally, a model-based study using generalized least squares was carried out to analyse the relationships between different abiotic and sampling proxies and eusuchian palaeodiversity. The results show that palaeotemperature is the most important factor amongst the analysed proxies, in accordance with previous studies. However, the results suggest that, along with palaeotemperature, other abiotic and/or biotic factors might also be driving eusuchian palaeodiversity dynamics.

Estimating an Autoregressive Current Effects Model of Sales Response when Observations are Aggregated over Time: Least Squares versus Maximum Likelihood

1988 ◽  
Vol 25 (3) ◽  
pp. 301-307
Author(s):  
Wilfried R. Vanhonacker
Keyword(s):  
Maximum Likelihood ◽  
Least Squares ◽  
Serial Correlation ◽  
Mean Squared Error ◽  
Generalized Least Squares ◽  
Parameter Estimates ◽  
Squared Error ◽  
Positive Serial Correlation ◽  
Serial Correlation Coefficient ◽  
Over Time

Estimating autoregressive current effects models is not straightforward when observations are aggregated over time. The author evaluates a familiar iterative generalized least squares (IGLS) approach and contrasts it to a maximum likelihood (ML) approach. Analytic and numerical results suggest that (1) IGLS and ML provide good estimates for the response parameters in instances of positive serial correlation, (2) ML provides superior (in mean squared error) estimates for the serial correlation coefficient, and (3) IGLS might have difficulty in deriving parameter estimates in instances of negative serial correlation.

scholarly journals MODELAGEM NÃO LINEAR DO CRESCIMENTO EM ALTURA DO CAFEEIRO IRRIGADO E NÃO IRRIGADO EM DIFERENTES DENSIDADES

Irriga ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 140
Author(s):  
Adriele Aparecida Pereira ◽  
Tales Jesus Fernandes ◽  
Myriane Stella Scalco ◽  
Augusto Ramalho De Morais
Keyword(s):  
Least Squares ◽  
Least Squares Method ◽  
Gompertz Model ◽  
Generalized Least Squares ◽  
Residual Variance ◽  
Growth Data ◽  
Nonlinear Growth ◽  
Heterogeneity Of Variance ◽  
E Mail ◽  
Over Time

MODELAGEM NÃO LINEAR DO CRESCIMENTO EM ALTURA DO CAFEEIRO IRRIGADO E NÃO IRRIGADO EM DIFERENTES DENSIDADES  ADRIELE APARECIDA PEREIRA1; TALES JESUS FERNANDES2; MYRIANE STELLA SCALCO3 E AUGUSTO RAMALHO DE MORAIS4 1Licenciada em Matemática, Mestre, DEX/UFLA, Lavras-MG, e-mail: [email protected] em Matemática, Doutor, Prof. DEX/UFLA, Lavras-MG, e-mail: [email protected] Agrônoma, Doutora, DAG/UFLA, Lavras-MG, e-mail: [email protected] Agrônomo, Doutor, Prof. DEX/UFLA, Lavras-MG, e-mail: [email protected]  1 RESUMO Heterogeneidade de variâncias e autocorrelação residual são características inerentes à dados de crescimento ao longo do tempo que se não considerados nas análises podem conduzir a resultados imprecisos. Este estudo teve por objetivo comparar os ajustes dos modelos Logístico e Gompertz, considerando os métodos de mínimos quadrados: ordinários e generalizados. Os dados utilizados referem-se à altura de plantas do cafeeiro, submetidas aos regimes de irrigação Si (testemunha), 60 kPa e 140 kPa, nas densidades de plantio 2500 e 5000 plantas ha-1. Segundo o desvio padrão residual e a análise de resíduos, o ajuste do modelo Gompertz pelo método de mínimos quadrados generalizados, que incorpora a heterogeneidade de variâncias e autocorrelação residual na modelagem, apresentou os melhores resultados para todos os dados analisados, sendo indicado para modelar o crescimento em altura do cafeeiro ao longo do tempo. Os ajustes referentes às plantas irrigadas apresentaram as maiores estimativas para a altura assintótica, confirmando que a irrigação da lavoura proporciona maior crescimento das plantas. Palavras-Chave: Autocorrelação residual, Gompertz, Heterocedasticidade.  PEREIRA, A. A.; FERNANDES, T. J.; SCALCO, M. S.; MORAIS, A. R. de MODELING NONLINEAR GROWTH IN HEIGHT COFFEE WITH AND WITHOUT IRRIGATION IN DIFFERENT DENSITIES  2 ABSTRACT Heterogeneity of variance and residual autocorrelation characteristics are inherent in the growth data over time that is not considered in the analysis may lead to inaccurate results. This study aimed to compare the settings of the Logistic and Gompertz models, considering the methods of least squares: ordinary and generalized. The data used refer to the height of the coffee plants, subjected to irrigation systems Si (non irrigated), 60 kPa and 140 kPa, the planting densities in 2500 and 5000 plants ha-1. According to the residual standard deviation and the residual analysis, the fit of the Gompertz model by generalized least squares method, which incorporates the heterogeneity of residual variance and autocorrelation in modeling, showed the best results for all data analyzed, suitable for modeling the growth in height of the coffee over time. The adjustments related to the irrigated plants had the highest estimates for the asymptotic height, confirming that the crop irrigation provides greater plant growth. Keywords: Residual autocorrelation, Gompertz, Heteroscedasticity.

The fossil record and macroevolutionary history of North American ungulate mammals: standardizing variation in intensity and geography of sampling

Paleobiology ◽  
10.1666/13052 ◽  
2014 ◽  
Vol 40 (2) ◽  
pp. 238-255 ◽  
Author(s):  
Jonathan D. Marcot
Keyword(s):  
Convex Hull ◽  
Environmental Change ◽  
Geographic Variation ◽  
North American ◽  
Fossil Record ◽  
Geographic Distance ◽  
Geographic Location ◽  
Pairwise Distance ◽  
Evolutionary Response ◽  
Over Time

The record of the taxonomic evolution of North American ungulates is critical to our understanding of mammalian evolution and environmental change throughout the Cenozoic. The distribution of sampling in the ungulate fossil record over time and geographic space and the degree to which this biases the observed patterns of taxonomic evolution is poorly understood. To address these issues, I placed fossil collections and occurrences drawn from the Paleobiology Database into 2-Myr time intervals between 55 and 1 Ma. I determined the variation in numbers of fossil collections and occurrences, using three metrics to measure geographic variation: first, the area of the convex hull containing all collections in an interval, to determine the areal coverage of sampling; second, the mean pairwise geographic distance among collections as a measurement of the dispersion of collections within that area; and third, the interval-to-interval migration of the geographic centroid of all collections, to calculate changes in the geographic location of sampling. Each of these showed considerable variation over the Cenozoic, and both the area of the convex hull (ACH) encompassing all collections in an interval, and mean pairwise distance (MPWD) among them showed increasing trends over time.To minimize the effect of variation in numbers of fossil samples over time, I used standard sample-standardization procedures. To minimize the effect of geographic variation in sampling over time, I standardized the area of sampling among intervals. I also employed both standardizations sequentially. Each standardization procedure had surprisingly little effect on observed patterns of taxonomic richness and rates. This indicates that, for North American ungulates, neither variation in number nor geographic distribution of fossil samples exerts an overwhelming influence on perceived macroevolutionary patterns. These results confirm the ungulate fossil record as a critical and faithful record for our understanding of Cenozoic environmental change and the mammalian evolutionary response.

scholarly journals Effects of Dysbiosis and Dietary Manipulation on the Digestive Microbiota of a Detritivorous Arthropod

2021 ◽  
Vol 9 (1) ◽  
pp. 148
Author(s):  
Marius Bredon ◽  
Elisabeth Depuydt ◽  
Lucas Brisson ◽  
Laurent Moulin ◽  
Ciriac Charles ◽  
...  
Keyword(s):  
Crucial Role ◽  
Structure And Function ◽  
Ecological Interactions ◽  
Dietary Manipulation ◽  
Biotic Factors ◽  
Abiotic And Biotic Factors ◽  
And Function ◽  
Multicellular Organisms ◽  
Over Time

The crucial role of microbes in the evolution, development, health, and ecological interactions of multicellular organisms is now widely recognized in the holobiont concept. However, the structure and stability of microbiota are highly dependent on abiotic and biotic factors, especially in the gut, which can be colonized by transient bacteria depending on the host’s diet. We studied these impacts by manipulating the digestive microbiota of the detritivore Armadillidium vulgare and analyzing the consequences on its structure and function. Hosts were exposed to initial starvation and then were fed diets that varied the different components of lignocellulose. A total of 72 digestive microbiota were analyzed according to the type of the diet (standard or enriched in cellulose, lignin, or hemicellulose) and the period following dysbiosis. The results showed that microbiota from the hepatopancreas were very stable and resilient, while the most diverse and labile over time were found in the hindgut. Dysbiosis and selective diets may have affected the host fitness by altering the structure of the microbiota and its predicted functions. Overall, these modifications can therefore have effects not only on the holobiont, but also on the “eco-holobiont” conceptualization of macroorganisms.

scholarly journals A comparison between generalized least squares regression and top-kriging for homogeneous cross-correlated flood regions

2021 ◽  
Author(s):  
Simone Persiano ◽  
Jose Luis Salinas ◽  
Jery Russell Stedinger ◽  
William H. Farmer ◽  
David Lun ◽  
...  
Keyword(s):  
Least Squares ◽  
Generalized Least Squares ◽  
Least Squares Regression
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