Demographic processes shaping genetic variation of the solitarious phase of the desert locust

Chapuis, Marie Pierre; Plantamp, Christophe; Blondin, Laurence; Pagès, Christine; Vassal, Jean-Michel; Lecoq, Michel

doi:10.1111/mec.12687

Cited by 27 publications

(36 citation statements)

References 68 publications

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“…They probably cover hundreds of kilometres between complementary areas for breeding (Waloff, ; Roffey & Magor, ). These solitarious populations are probably much more abundant than previously believed (Chapuis et al., , ). Their role in the invasions’ genesis is crucial (Lecoq, , ; Magor et al., ), as it was also demonstrated in other locust and grasshopper species (Lecoq, , ).…”

Section: Introductionmentioning

confidence: 74%

Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Lazar

Piou

Doumandji-Mitiche

et al. 2016

Entomologia Exp Applicata

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The desert locust, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), is a major pest and well known in its gregarious phase. However, it is not well understood during recession periods, when the solitarious phase populations are discrete. Nonetheless, these populations are at the origin of the invasions when ecological conditions become favourable. This lack of knowledge of the solitarious phase individuals impedes effective preventive management of this pest. Archive data collected in Algeria from 1980 to 2011 were used to analyse solitarious population dynamics across the Algerian Sahara where some outbreak areas are located that play a major role in the invasion process. The results confirm previous empirical observations on solitarious population dynamics. First, a clear difference could be documented between the northern and southern Saharan regions of Algeria concerning the locust dynamics and the impact of environmental conditions. The importance of runoff was clear to create suitable habitats over a long period and to very distant places from rainy areas. Second, a link, on an annual basis, between green vegetation and presence of solitarious locusts was found. Third, statistical relationships between various locations demonstrated a clear regional dynamics. Our study confirmed the importance of migrations of solitarious populations among Algerian regions and more generally within the recession area of this species. The operational implications of these findings are multiple. First, they confirm the need of a flexible and scalable preventive system during the year, from 1 year to another and with a clear distinction between the northern and southern Saharan areas of Algeria. Second, they also confirm the necessity for the inclusion of wadis and soil moisture estimations from remote sensing in geographic information systems for preventive management. And third, they clearly illustrate the importance to target solitarious locusts for more efficient preventive survey operations.

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Section: Introductionmentioning

confidence: 74%

Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Lazar

Piou

Doumandji-Mitiche

et al. 2016

Entomologia Exp Applicata

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“…In conclusion, the independent information on the priors for mutational parameters reinforces the conclusions of Chapuis et al . (): the plague declines do not lead to crashes in effective population sizes of desert locust populations, but instead to persistent populations that are much larger than previously thought.…”

Section: Resultsmentioning

confidence: 87%

“…For all other model settings, we used standard values and parameter estimation was carried out as in Chapuis et al . (). Accuracies in parameter estimations were compared for the informed and noninformed settings by computing the relative median absolute deviation (RMedAD) from a set of 10 000 test data sets (i.e.…”

Section: Methodsmentioning

confidence: 97%

“…In Chapuis et al . (), prior values for μ were drawn from a large uniform distribution bounded between 10 −5 and 10 −3 , P values were standardly drawn in a uniform distribution bounded between 0.1 and 0.3, and allele size constraint was not considered. Herein, we fixed these priors at our new empirical values of mean mutation rate and proportion of multistep mutations, and the maximum ranges of contiguous allelic sizes estimated following Pollock et al .…”

Section: Methodsmentioning

confidence: 99%

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Microsatellite evolutionary rate and pattern in Schistocerca gregaria inferred from direct observation of germline mutations

et al. 2015

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Unravelling variation among taxonomic orders regarding the rate of evolution in microsatellites is crucial for evolutionary biology and population genetics research. The mean mutation rate of microsatellites tends to be lower in arthropods than in vertebrates, but data are scarce and mostly concern accumulation of mutations in model species. Based on parent-offspring segregations and a hierarchical Bayesian model, the mean rate of mutation in the orthopteran insect Schistocerca gregaria was estimated at 2.1e(-4) per generation per untranscribed dinucleotide locus. This is close to vertebrate estimates and one order of magnitude higher than estimates from species of other arthropod orders, such as Drosophila melanogaster and Daphnia pulex. We also found evidence of a directional bias towards expansions even for long alleles and exceptionally large ranges of allele sizes. Finally, at transcribed microsatellites, the mean rate of mutation was half the rate found at untranscribed loci and the mutational model deviated from that usually considered, with most mutations involving multistep changes that avoid disrupting the reading frame. Our direct estimates of mutation rate were discussed in the light of peculiar biological and genomic features of S. gregaria, including specificities in mismatch repair and the dependence of its activity to allele length. Shedding new light on the mutational dynamics of grasshopper microsatellites is of critical importance for a number of research fields. As an illustration, we showed how our findings improve microsatellite application in population genetics, by obtaining a more precise estimation of S. gregaria effective population size from a published data set based on the same microsatellites.

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“…This suggests that rates of tychoparthenogenesis may be very low in nature. This is corroborated by indirect molecular approaches that did not reveal any tychoparthenogenetic offspring (i.e., fully homozygous, see Booth et al., 2012) within large numbers of wild desert locusts genotyped so far (Chapuis et al., 2014, 2017). Altogether, our results, with their methodological restrictions, did not bring evidence for an important adaptive role of tychoparthenogenesis in newly solitarized populations of the locust.…”

Section: Discussionmentioning

confidence: 99%

Exploring the relationship between tychoparthenogenesis and inbreeding depression in the Desert Locust, Schistocerca gregaria

Little

Chapuis

Blondin

et al. 2017

Ecology and Evolution

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Tychoparthenogenesis, a form of asexual reproduction in which a small proportion of unfertilized eggs can hatch spontaneously, could be an intermediate evolutionary link in the transition from sexual to parthenogenetic reproduction. The lower fitness of tychoparthenogenetic offspring could be due to either developmental constraints or to inbreeding depression in more homozygous individuals. We tested the hypothesis that in populations where inbreeding depression has been purged, tychoparthenogenesis may be less costly. To assess this hypothesis, we compared the impact of inbreeding and parthenogenetic treatments on eight life‐history traits (five measuring inbreeding depression and three measuring inbreeding avoidance) in four laboratory populations of the desert locust, Schistocerca gregaria, with contrasted demographic histories. Overall, we found no clear relationship between the population history (illustrated by the levels of genetic diversity or inbreeding) and inbreeding depression, or between inbreeding depression and parthenogenetic capacity. First, there was a general lack of inbreeding depression in every population, except in two populations for two traits. This pattern could not be explained by the purging of inbreeding load in the studied populations. Second, we observed large differences between populations in their capacity to reproduce through tychoparthenogenesis. Only the oldest laboratory population successfully produced parthenogenetic offspring. However, the level of inbreeding depression did not explain the differences in parthenogenetic success between all studied populations. Differences in development constraints may arise driven by random and selective processes between populations.

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Demographic processes shaping genetic variation of the solitarious phase of the desert locust

Cited by 27 publications

References 68 publications

Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Importance of solitarious desert locust population dynamics: lessons from historical survey data in Algeria

Microsatellite evolutionary rate and pattern in Schistocerca gregaria inferred from direct observation of germline mutations

Exploring the relationship between tychoparthenogenesis and inbreeding depression in the Desert Locust, Schistocerca gregaria

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