Transposable element islands facilitate adaptation to novel environments in an invasive species

Peer reviewe

Recombination and its impact on the genome of the haplodiploid parasitoid wasp Nasonia

Homologous meiotic recombination occurs in most sexually reproducing organisms, yet its evolutionary advantages are elusive. Previous research explored recombination in the honeybee, a eusocial hymenopteran with an exceptionally high genome-wide recombination rate. A comparable study in a non-social member of the Hymenoptera that would disentangle the impact of sociality from Hymenoptera-specific features such as haplodiploidy on the evolution of the high genome-wide recombination rate in social Hymenoptera is missing. Utilizing single-nucleotide polymorphisms (SNPs) between two Nasonia parasitoid wasp genomes, we developed a SNP genotyping microarray to infer a high-density linkage map for Nasonia. The map comprises 1,255 markers with an average distance of 0.3 cM. The mapped markers enabled us to arrange 265 scaffolds of the Nasonia genome assembly 1.0 on the linkage map, representing 63.6% of the assembled N. vitripennis genome. We estimated a genome-wide recombination rate of 1.4-1.5 cM/Mb for Nasonia, which is less than one tenth of the rate reported for the honeybee. The local recombination rate in Nasonia is positively correlated with the distance to the center of the linkage groups, GC content, and the proportion of simple repeats. In contrast to the honeybee genome, gene density in the parasitoid wasp genome is positively associated with the recombination rate; regions of low recombination are characterized by fewer genes with larger introns and by a greater distance between genes. Finally, we found that genes in regions of the genome with a low recombination frequency tend to have a higher ratio of non-synonymous to synonymous substitutions, likely due to the accumulation of slightly deleterious non-synonymous substitutions. These findings are consistent with the hypothesis that recombination reduces interference between linked sites and thereby facilitates adaptive evolution and the purging of deleterious mutations. Our results imply that the genomes of haplodiploid and of diploid higher eukaryotes do not differ systematically in their recombination rates and associated parameters.Publisher PDFPeer reviewe

The Global Ant Genomics Alliance (GAGA)

Peer reviewe

Advances in Genomics and Epigenomics of Social Insects

Social insects are among the most successful and ecologically important animals on earth. The lifestyle of these insects has fascinated humans since prehistoric times. These species evolved a caste of workers that in most cases have no progeny. Some social insects have worker sub-castes that are morphologically specialized for discrete tasks. The organization of the social insect colony has been compared to the metazoan body. Males in the order Hymenoptera (bees, ants and wasps) are haploid, a situation which results in higher relatedness between female siblings. Sociality evolved many times within the Hymenoptera, perhaps spurred in part by increased relatedness that increases inclusive fitness benefits to workers cooperating to raise their sisters and brothers rather than reproducing themselves. But epigenetic processes may also have contributed to the evolution of sociality. The Hymenoptera provide opportunities for comparative study of species ranging from solitary to highly social. A more ancient clade of social insects, the termites (infraorder Isoptera) provide an opportunity to study alternative mechanisms of caste determination and lifestyles that are aided by an array of endosymbionts. This research topic explores the use of genome sequence data and genomic techniques to help us explore how sociality evolved in insects, how epigenetic processes enable phenotypic plasticity, and the mechanisms behind whether a female will become a queen or a worker

Behavioral assays

Raw data on the behavioral assays, focussing on N. oneida and N. giraulti males (Fig. 4). Whether a copulation has occurred or not is given in the second column for each pairing in a binary coding (1 = yes, 0 = no), and the average number of occurred copulations is given for each pairing with untreated and treated female dummies. Species affiliation and treatment of female dummies indicated in the caption of each pairing. Male species affiliation can be found in the main caption on each spread sheet. Furthermore, the male arrestment time has been recorded (third column), but those data have not been used in this study. Mating results on two further N. giraulti strains are given as well

Polyandry in two South American harvester ants

Although monandry (single mating) is the ancestral state in social hymenopteran insects, effective mating frequencies greater than 2 have been confirmed for a fair amount of ant species: Cataglyphis cursor, the leaf-cutters of the genera Atta and Acromyrmex, army ants of the genera Eciton, Dorylus, Aenictus and Neivamyrmex, and some North American seed harvester species of the genus Pogonomyrmex. This last genus spreads throughout open arid habitats from Patagonia to southwestern Canada. Whereas some North American Pogonomyrmex species are thoroughly studied, we know much less about these ants in South America. The objective of this study was to estimate the effective mating frequency of Pogonomyrmex inermis and P. pronotalis, two Pogonomyrmex sensu stricto species from the central Monte desert of Argentina. A total of 477 P. pronotalis workers from 24 colonies and 402 P. inermis workers from 20 colonies were analyzed using six and four highly polymorphic microsatellites, respectively. The multilocus analysis revealed that all colonies were monogynous and all queens multiply-mated. The effective mating frequency was 8.75 and 6.52 for queens of P. pronotalis and P. inermis, respectively; those values increased up to 15.66 and 9.78, respectively, when corrected for sampling errors. This is the first demonstration that queens in at least some members of the South American Pogonomyrmex sensu stricto are strictly polyandrous, with mating numbers per queen at least as high as those previously found for North American species. We suggest that multiple mating probably arose early in the evolution of the genus Pogonomyrmex and may be the basis of its ecological success and wide distribution.Fil: Pol, Rodrigo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Lopez de Casenave, Javier Nestor. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Feldhaar, Heike. University of Würzburg; AlemaniaFil: Milesi, Fernando Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Gadau, Juergen. Arizona State University; Estados Unido