High recombination frequency creates genotypic diversity in colonies of the leaf-cutting ant Acromyrmex echinatior.

Honeybees are known to have genetically diverse colonies because queens mate with many males and the recombination rate is extremely high. Genetic diversity among social insect workers has been hypothesized to improve general performance of large and complex colonies, but this idea has not been tested in other social insects. Here, we present a linkage map and an estimate of the recombination rate for Acromyrmex echinatior, a leaf-cutting ant that resembles the honeybee in having multiple mating of queens and colonies of approximately the same size. A map of 145 AFLP markers in 22 linkage groups yielded a total recombinational size of 2076 cM and an inferred recombination rate of 161 kb cM(-1) (or 6.2 cM Mb(-1)). This estimate is lower than in the honeybee but, as far as the mapping criteria can be compared, higher than in any other insect mapped so far. Earlier studies on A. echinatior have demonstrated that variation in division of labour and pathogen resistance has a genetic component and that genotypic diversity among workers may thus give colonies of this leaf-cutting ant a functional advantage. The present result is therefore consistent with the hypothesis that complex social life can select for an increased recombination rate through effects on genotypic diversity and colony performance.

cagA, vacA and iceA virulence genes of Helicobacter pylori isolates of children in Finland.

cagA, vacA s and m genotypes and iceA alleles were analyzed from Helicobacter pylori strains isolated from 17 Finnish children and 32 children of non-Finnish origin living in Finland. Twelve children in the latter group were eastern European and 15 were of African origin. Only three children of non-Finnish origin were born in Finland. The vacA sla subtype was more prevalent in the isolates from Finnish children than African children (76% vs. 7%, P<0.001); vacA s1b frequencies were 5% and 67%, respectively (P<0.001). The iceA1 allele was significantly more prevalent in African than Finnish isolates (93% vs. 35%, P< 0.01). Considerable variation was noted in the frequency of vacA s1 subtypes and iceA alleles in children originating from different geographic regions, but the geographic variation of s1 subtypes resembled that described in other reports.