Nutritional versus genetic correlates of caste differentiation in a desert ant

1. In many ant species, caste differentiation stems from trophic differences at the larval stage. Adult workers that feed larvae have great control over the allocation of colony resources to growth (production of workers) versus reproduction (production of queens). However, larval caste fate may also be constrained very early on through direct genetic effects or non‐genetic maternal effects. 2. Here, we combined isotopic and genetic analyses to study the developmental origin of queens and workers in a desert‐dwelling ant, Cataglyphis tartessica (Amor & Ortega, 2014). Queens do not found new colonies alone but rather disperse with workers. As the latter are always wingless, selection pressures on specific queen traits such as flight ability have become relaxed. Though the phylogenetically related species, C. emmae (Forel, 1909) only produces winged queens much larger than workers, C. tartessica produces two types of small queens relative to workers: brachypterous (short‐winged) queens and permanently apterous ergatoid (wingless and worker‐like) queens. 3. Upon emergence, workers and ergatoids have similar δ15N isotopic values, which were lower than those of brachypters, suggesting the latter are fed more protein as larvae. Microsatellite analyses indicated that: (i) colonies are mostly monogynous and monandrous; (ii) both ergatoids and brachypters are equally related to workers; and (iii) in the few polyandrous colonies, patrilines were evenly represented across workers, brachypters and ergatoids. 4. Overall, there was no evidence of genetic caste determination. We suggest that, in contrast to brachypters, ergatoids are selfish individuals that escape the nutritional castration carried out by workers and develop into queens in spite of the colony's collective interests.     

Opportunities for mate choice in the fission‐performing ant Cataglyphis cursor

1. Sexual selection has been little studied in social insects. Nonetheless, because mating is generally for life, opportunities for selecting among mating partners should be exploited. 2. In some ants, males aggregate at nest entrances to mate with emerging gynes. Both males and females thus have access to multiple mates over a relatively protracted period, giving rise to opportunities for mate choice and multiple mating. 3. We provide data from field observations of the male mating biology of the ant, Cataglyphis cursor Fonscolombe. In this species, females mate with, on average, six males each at the nest entrance and found colonies with the help of workers. 4. Males were present at the field site for approximately 1 month in spring, with up to 40 males at a single nest entrance for, on average, 4.7 days. Individual males were observed to survive up to 3 days, and mate up to eight times. 5. Thus both males and females of this species have the ability to mate multiply and have a window permitting mate choice to occur. Workers actively attacked males and may take part in the mate choice process, making C. cursor an interesting model to study questions relating to sexual selection and male mating strategies.     

Characterization of nuclear DNA microsatellite markers in the ant Cataglyphis cursor

The ant Cataglyphis cursor is exceptional in that unmated workers are potentially able to lay both male and female eggs. We characterized eight pairs of primers for microsatellite loci, developed from genomic DNA for this species. Variability was tested with DNA from 19 workers and all eight loci were highly polymorphic, displaying 5–10 alleles and a high level of heterozygosity. Cross‐species amplifications indicate that these microsatellites might be useful in genetic studies of other species belonging to the genus Cataglyphis.