Comparative Genetic Diversity and Structure of the Rhus Gall Aphid Schlechtendalia Chinensis and Its Host-Plant Rhus Chinensis

Author(s):  
Zhu Ren ◽  
Hong He ◽  
Yang Zhang ◽  
Xu Su

Abstract Studying the population genetic structure of both parasites and their host-plants is expected to yield new valuable insights into their coevolution. In this study, we examined and compared the population genetic diversity and structure of 12 populations of the Rhus gall aphid, Schlechtendalia chinensis, and its host-plant, Rhus chinensis, using amplified fragment length polymorphism (AFLP) markers. AMOVA analysis showed that the genetic variance of the aphid and its host-plant were both higher within populations compared to that among them, suggesting that a co-evolutionary history has yielded similar patterns of population genetic structure. We did not detect significant correlation between genetic and geographic distance for either the aphid or host-plant populations, therefore rejecting an isolation by distance model for the demographic histories of the two species. However, our results appeared to suggest that genetically diverse host -plant Rhus populations correlated to similarly genetically diverse populations of gall aphid parasites.

2020 ◽  
Vol 13 ◽  
pp. 194008292094917
Author(s):  
Misael D. Mancilla-Morales ◽  
Santiago Romero-Fernández ◽  
Araceli Contreras-Rodríguez ◽  
José J. Flores-Martínez ◽  
Víctor Sánchez-Cordero ◽  
...  

Estimations on the influence of evolutionary and ecological forces as drivers of population gene diversity and genetic structure have been performed on a growing number of colonial seabirds, but many remain poorly studied. In particular, the population genetic structure of storm-petrels (Hydrobatidae) has been evaluated in only a few of the 24 recognized species. We assessed the genetic diversity and population structure of the Black Storm-Petrel ( Hydrobates melania) and the Least Storm-Petrel ( Hydrobates microsoma) in the Gulf of California. The two species were selected because they are pelagic seabirds with comparable ecological traits and breeding grounds. Recent threats such as introduced species of predators and human disturbance have resulted in a decline of many insular vertebrate populations in this region and affected many different aspects of their life histories (ranging from reproductive success to mate selection), with a concomitant loss of genetic diversity. To elucidate to what extent the population genetic structure occurs in H. melania and H. microsoma, we used 719 base pairs from the mitochondrial cytochrome oxidase c subunit I gene. The evaluation of their molecular diversity, genetic structure, and gene flow were performed through diversity indices, analyses of molecular and spatial variance, and isolation by distance (IBD) across sampling sites, respectively. The population genetic structure (via AMOVA and SAMOVA) and isolation by distance (pairwise p-distances and FST/1– FST (using ΦST) were inferred for H. microsoma. However, for H. melania evidence was inconclusive. We discuss explanations leading to divergent population genetic structure signatures in these species, and the consequences for their conservation.


Insects ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 117
Author(s):  
Da Wang ◽  
Xiaoqin Shi ◽  
Deguang Liu ◽  
Yujing Yang ◽  
Zheming Shang

Host plant affinity and geographic distance can play critical roles in the genetic divergence of insect herbivores and evolution of insect biotypes, but their relative importance in the divergence of insect populations is still poorly understood. We used microsatellite markers to test the effects of host plant species and geographic distance on divergence of two biotypes of the English grain aphid, Sitobion avenae (Fabricius). We found that clones of S. avenae from western provinces (i.e., Xinjiang, Gansu, Qinghai and Shaanxi) had significantly higher genetic diversity than those from eastern provinces (i.e., Anhui, Henan, Hubei, Zhejiang and Jiangsu), suggesting their differentiation between both areas. Based on genetic diversity and distance estimates, biotype 1 clones of eastern provinces showed high genetic divergence from those of western provinces in many cases. Western clones of S. avenae also showed higher genetic divergence among themselves than eastern clones. The Mantel test identified a significant isolation-by-distance (IBD) effect among different geographic populations of S. avenae, providing additional evidence for a critical role of geography in the genetic structure of both S. avenae biotypes. Genetic differentiation (i.e., FST) between the two biotypes was low in all provinces except Shaanxi. Surprisingly, in our analyses of molecular variance, non-significant genetic differentiation between both biotypes or between barley and wheat clones of S. avenae was identified, showing little contribution of host-plant associated differentiation to the divergence of both biotypes in this aphid. Thus, it is highly likely that the divergence of the two S. avenae biotypes involved more geographic isolation and selection of some form than host plant affinity. Our study can provide insights into understanding of genetic structure of insect populations and the divergence of insect biotypes.


Nematology ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 165-177 ◽  
Author(s):  
Rasha Haj Nuaima ◽  
Johannes Roeb ◽  
Johannes Hallmann ◽  
Matthias Daub ◽  
Holger Heuer

Summary Characterising the non-neutral genetic variation within and among populations of plant-parasitic nematodes is essential to determine factors shaping the population genetic structure. This study describes the genetic variation of the parasitism gene vap1 within and among geographic populations of the beet cyst nematode Heterodera schachtii. Forty populations of H. schachtii were sampled at four spatial scales: 695 km, 49 km, 3.1 km and 0.24 km. DGGE fingerprinting showed significant differences in vap1 patterns among populations. High similarity of vap1 patterns appeared between geographically close populations, and occasionally among distant populations. Analysis of spatially sampled populations within fields revealed an effect of tillage direction on the vap1 similarity for two of four studied fields. Overall, geographic distance and similarity of vap1 patterns of H. schachtii populations were negatively correlated. In conclusion, the population genetic structure was shaped by the interplay between the genetic adaptation and the passive transport of this nematode.


Author(s):  
Assel Akhmetova ◽  
Jimena Guerrero ◽  
Paul McAdam ◽  
Liliana C.M. Salvador ◽  
Joseph Crispell ◽  
...  

AbstractBackgroundBovine tuberculosis (bTB) is a costly epidemiologically complex, multi-host, endemic disease. Lack of understanding of transmission dynamics may undermine eradication efforts. Pathogen whole genome sequencing improves epidemiological inferences, providing a means to determine the relative importance of inter- and intra- species host transmission for disease persistence. We sequenced an exceptional data set of 619Mycobacterium bovisisolates from badgers and cattle in a 100km2bTB ‘hotspot’ in Northern Ireland. Historical molecular subtyping data permitted the targeting of an endemic pathogen lineage, whose long-term persistence provided a unique opportunity to study disease transmission dynamics in unparalleled detail. Additionally, to assess whether badger population genetic structure was associated with the spatial distribution of pathogen genetic diversity, we microsatellite genotyped hair samples from 769 badgers trapped in this area.ResultsGraph transmission tree methods and structured coalescent analyses indicated the majority of bacterial diversity was found in the local cattle population. Results pointed to transmission from cattle to badger being more common than badger to cattle. Furthermore, the presence of significant badger population genetic structure in the landscape was not associated with the spatial distribution ofM. bovisgenetic diversity, suggesting that badger-to-badger transmission may not be a key determinant of disease persistence.SignificanceOur data were consistent with badgers playing a smaller role in the maintenance ofM. bovisinfection in this study site, compared to cattle. Comparison to other areas suggests thatM. bovistransmission dynamics are likely to be context dependent, and the role of wildlife difficult to generalise.


Heredity ◽  
2020 ◽  
Vol 126 (1) ◽  
pp. 63-76
Author(s):  
Sarah M. Griffiths ◽  
Mark J. Butler ◽  
Donald C. Behringer ◽  
Thierry Pérez ◽  
Richard F. Preziosi

AbstractUnderstanding population genetic structure can help us to infer dispersal patterns, predict population resilience and design effective management strategies. For sessile species with limited dispersal, this is especially pertinent because genetic diversity and connectivity are key aspects of their resilience to environmental stressors. Here, we describe the population structure of Ircinia campana, a common Caribbean sponge subject to mass mortalities and disease. Microsatellites were used to genotype 440 individuals from 19 sites throughout the Greater Caribbean. We found strong genetic structure across the region, and significant isolation by distance across the Lesser Antilles, highlighting the influence of limited larval dispersal. We also observed spatial genetic structure patterns congruent with oceanography. This includes evidence of connectivity between sponges in the Florida Keys and the southeast coast of the United States (>700 km away) where the oceanographic environment is dominated by the strong Florida Current. Conversely, the population in southern Belize was strongly differentiated from all other sites, consistent with the presence of dispersal-limiting oceanographic features, including the Gulf of Honduras gyre. At smaller spatial scales (<100 km), sites showed heterogeneous patterns of low-level but significant genetic differentiation (chaotic genetic patchiness), indicative of temporal variability in recruitment or local selective pressures. Genetic diversity was similar across sites, but there was evidence of a genetic bottleneck at one site in Florida where past mass mortalities have occurred. These findings underscore the relationship between regional oceanography and weak larval dispersal in explaining population genetic patterns, and could inform conservation management of the species.


2020 ◽  
Vol 187 ◽  
pp. 106106
Author(s):  
M. Martínez-Trancón ◽  
J.C. Parejo ◽  
A. Rabasco ◽  
P. Padilla ◽  
J.A. Padilla

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