Microsatellite DNA analysis of population structure in Cornops aquaticum (Orthoptera: Acrididae), over a cline for three Robertsonian translocations

COLOMBO, PABLO CÉSAR; COLOMBO, PABLO CÉSAR; REMIS, MARÍA ISABEL; REMIS, MARÍA ISABEL; ROMERO, MARÍA LUCIANA; ROMERO, MARÍA LUCIANA

EVOLUTIONARY ECOLOGY

SPRINGER

Año: 2017 vol. 31 p. 937 - 953

0269-7653

The grasshopper Cornops aquaticum occurs between Mexico (23N) and Uruguayand Central Argentina (35S). It was recently introduced as a pest control agent of theneotropical water-hyacinth Eichhornia crassipes in South Africa. The information aboutthe amount and distribution of genetic variability of the native populations may optimisethe results of biological control programmes. Here we analyse microsatellite variability atthe south of C. aquaticum?s distribution, coinciding with a cline for three polymorphicRobertsonian translocations along the Parana´ River in order to: (1) estimate the amount ofintrapopulation variation and its correlation with geographic/climatic variables, (2) inferinterpopulation genetic variation and assess connectivity between local populations and (3)compare chromosome, morphometric and molecular variation patterns to analyse theprobable causes involved in the maintenance of intraspecific variation. Our sample of 170individuals of C. aquaticum from seven Argentine populations between latitudes 27S to34S showed 211 alleles across seven microsatellite loci. Genetic diversity was estimatedthrough average number of alleles, allelic richness, expected heterozygosity and observedheterozygosity. The analysis of molecular variance showed significant genetic differentiationamong populations. Pairwise comparisons of FST/RST and Bayesian populationassignment method and the discriminant analysis of principal components revealed that thetwo southernmost populations are more differentiated. Genetic diversity is negativelycorrelated with Southern latitude and with Robertsonian translocation frequencies. Our results showed that the Parana´ River?s middle course populations are genetically undifferentiatedand more genetically diverse than the highly chromosomally polymorphicdownstream ones. The chromosomal polymorphisms are associated with increased bodysize in the direction in which larger size is adaptive. This may be relevant for C. aquaticum?srole as a pest control agent, since chromosome variability would enhance theability of the species for a successful settlement in its new habitats, especially in temperate regions of the world.