diversification pattern
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Author(s):  
Poonam Rani ◽  
Ajeet Kumar Sahoo

This study examines the structure of agriculture productivity and crop diversification across different zones in Punjab, India during 1966–1967 to 2017–2018. The composite entropy index shows that almost all zones are specialised in few crops but some of them are relatively less or some are more. Hence, we found zones are experiencing a lateral movement toward crop specialisation and crop diversification is not happening. Further, results reveals that accessibility of market and roadhave a positive influenced the level of crop diversification are accessibility of market, roads have found a positive influenced on crop diversification. Whereas more use of fertiliser, intensity of irrigation and rainfall have leads to concentration rather than crop diversification. Similarly, study also analysed the factors that are responsible of variation in productivity by regional factors such as better road, fertiliser, urbanisation, literacy and cropping intensity. As the analysis indicates that there is need to emphasise on agro-climatic regional preparation by clearly identifying the existing resource endowments and constraints of the agro-climatically homogeneous regions. JEL: C23,Q10, Q19


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Kay Lucek ◽  
Selim Bouaouina ◽  
Amanda Jospin ◽  
Andrea Grill ◽  
Jurriaan M. de Vos

Abstract Background Wolbachia is an endosymbiont common to most invertebrates, which can have significant evolutionary implications for its host species by acting as a barrier to gene flow. Despite the importance of Wolbachia, still little is known about its prevalence and diversification pattern among closely related host species. Wolbachia strains may phylogenetically coevolve with their hosts, unless horizontal host-switches are particularly common. We address  these issues in the genus Erebia, one of the most diverse Palearctic butterfly genera. Results We sequenced the Wolbachia genome from a strain infecting Erebia cassioides and showed that it belongs to the Wolbachia supergroup B, capable of infecting arthropods from different taxonomic orders. The prevalence of Wolbachia across 13 closely related Erebia host species based on extensive population-level genetic data revealed that multiple Wolbachia strains jointly infect all investigated taxa, but with varying prevalence. Finally, the phylogenetic relationships of Wolbachia strains are in some cases significantly associated to that of their hosts, especially among the most closely related Erebia species, demonstrating mixed evidence for phylogenetic coevolution. Conclusions Closely related host species can be infected by closely related Wolbachia strains, evidencing some phylogenetic coevolution, but the actual pattern of infection more often reflects historical or contemporary geographic proximity among host species. Multiple processes, including survival in distinct glacial refugia, recent host shifts in sympatry, and a loss of Wolbachia during postglacial range expansion seem to have jointly shaped the complex interactions between Wolbachia evolution and the diversification of its host among our studied Erebia species.


2021 ◽  
Author(s):  
Nicolas Chazot ◽  
Patrick Blandin ◽  
Vincent Debat ◽  
Marianne Elias ◽  
Fabien L. Condamine

AbstractAssessing the relative importance of geographical and ecological drivers of evolution is paramount to understand the diversification of species and traits at the macroevolutionary scale. Here, we use an integrative approach, combining phylogenetics, biogeography, ecology, and quantified phenotypes to investigate the drivers of both species and phenotypic diversification of the iconic Neotropical butterfly genus Morpho. We generated a time-calibrated phylogeny for all known species and inferred historical biogeography. We fitted models of time-dependent (accounting for rate heterogeneity across the phylogeny) and paleoenvironment-dependent diversification (accounting for global effect on the phylogeny). We used geometric morphometrics to assess variation of wing size and shape across the tree, and investigated their dynamics of evolution. We found that the diversification of Morpho is best explained when considering multiple independent diversification dynamics across the tree, possibly associated with lineages occupying different microhabitat conditions. First, a shift from understory to canopy was characterized by an increased speciation rate partially coupled with an increasing rate of wing shape evolution. Second, the occupation of dense bamboo thickets accompanying a major host-plant shift from dicotyledons towards monocotyledons was associated with a simultaneous diversification rate shift and an evolutionary “jump” of wing size. Our study points to a diversification pattern driven by punctual ecological changes instead of a global driver or biogeographic history.


2021 ◽  
Vol 101 (2) ◽  
pp. 217-232
Author(s):  
Ved Prakash Kumar ◽  
Bheem Dutt Joshi ◽  
Reeta Sharma ◽  
Ankita Rajpoot ◽  
Animesh Talukdar ◽  
...  

2020 ◽  
Vol 12 (4) ◽  
pp. 713-727
Author(s):  
S. Roy ◽  
S. I. Maiti ◽  
S. K. Saikia ◽  
S. Ray

The present study investigated ecomorphological patterns of fish assemblage from freshwater ponds on two functional categories, i.e., foraging behavior and habitat preference. Nine ecomorphological indices were derived from eight morphometric variables and examined on 566 adult individuals belonging to 9 species, 7 families and 4 orders. Samples were collected during April 2016 to September 2017 from freshwater ponds in Birbhum, West Bengal. Mantel test was performed to investigate correlation between morphological, taxonomic, trophic and habitat guild matrices. The partial Mantel test was done to investigate the direct correlation between trophic and habitat guilds with morphology discounting the effect of taxonomic relatedness on species assemblage. The interspecific ecomorphological diversification pattern was analysed by HCPC method. At least three ecomorphological assemblages among these fish species with two significant principal axes of variations were observed. Ecomorphological attributes associated with mouth aspect ratio, compression index and relative body height were on PC1 axis, and relative length and height of head, relative area of eye were on PC 2 axis. Mantel and partial Mantel test showed significant correlation between morphology and trophic guild structure. Outcomes show that morphology is a good predictor of trophic structure of fish assemblage in studying convergent assemblage pattern irrespective of taxonomy.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Marie Drábková ◽  
Nikola Jachníková ◽  
Tomáš Tyml ◽  
Hana Sehadová ◽  
Oleg Ditrich ◽  
...  

Abstract Population structure and biogeography of marine organisms are formed by different drivers than in terrestrial organisms. Yet, very little information is available even for common marine organisms and even less for their associated parasites. Here we report the first analysis of population structure of both a cephalopod host (Sepia officinalis) and its dicyemid parasite, based on a homologous molecular marker (cytochrome oxidase I). We show that the population of common cuttlefish in the Mediterranean area is fragmented into subpopulations, with some areas featuring restricted level of gene flow. Amongst the studied areas, Sardinia was genetically the most diverse and Cyprus the most isolated. At a larger scale, across the Mediterranean, the population structure of the parasite shows co-diversification pattern with its host, but a slower rate of diversification. Differences between the two counterparts are more obvious at a finer scale, where parasite populations show increased level of fragmentation and lower local diversities. This discrepancy can be caused by local extinctions and replacements taking place more frequently in the dicyemid populations, due to their parasitic lifestyle.


VirusDisease ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 74-83 ◽  
Author(s):  
Debayan Mondal ◽  
Somnath Mandal ◽  
Sandip Shil ◽  
Nandita Sahana ◽  
Goutam Kumar Pandit ◽  
...  

2019 ◽  
Author(s):  
Melisa Olave ◽  
Luciano J. Avila ◽  
Jack W. Sites ◽  
Mariana Morando

AbstractMacroevolutionary studies commonly apply multiple models to test state-dependent diversification. These models track the association between states of interest along a phylogeny, but they do not consider whether independent shifts in character states are associated with shifts in diversification rates. This potentially problematic issue has received little theoretical attention, while macroevolutionary studies implementing such models in increasing larger scale studies continue growing. A recent macroevolutionary study has found that Andean orogeny has acted as a species pump driving diversification of the family Liolaemidae, a highly species-rich lizard family native to temperate southern South America.This study approaches a distribution-dependent hypothesis using the Geographic State Speciation and Extinction model (GeoSSE). However, more recent analyses have shown that there is a clear heterogeneous diversification pattern in the Liolaemidae, which likely biased the GeoSSE analysis. Specifically, we show here that there are two shifts to accelered speciation rates involving species groups that were classified as “Andean” in their distributions. We demonstrate that this GeoSSE result is meaningless when heterogeneous diversification rates are included. We use the lizard family Liolaemidae to demonstrate potential risks of ignoring clade-specific differences in diversification rates in macroevolutionary studies.


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