BACKGROUND: A decade ago, the mixed reproductive strategy Asexual Queen Succession (AQS) was first described in termites. In AQS species, the workers, soldiers and dispersing reproductives are produced through sexual reproduction, while non-dispersing (neotenic) queens arise through automictic thelytokous parthenogenesis, replace the founding queen and mate with the founding king. As yet, AQS has been documented in six species from three lineages of lower (Rhinotermitidae) and higher (Termitinae: Termes group and Syntermitinae) termites. Independent evolution of the capacity of thelytoky as a preadaptation to AQS is supported by different mechanisms of automixis in each of the three clades. These pioneering discoveries prompt the question on the extent of thelytoky and AQS in the diversified family of higher termites. RESULTS: Here, we investigated the capacity of thelytoky and occurrence of AQS in three species from the phylogenetic proximity of the neotropical AQS species Cavitermes tuberosus (Termitinae: Termes group): Palmitermes impostor, Spinitermes trispinosus, and Inquilinitermes inquilinus. We show that queens of all three species are able to lay unfertilized eggs, which undergo thelytokous parthenogenesis (via gamete duplication as in C. tuberosus) and develop through the transitional stage of aspirants into replacement neotenic queens. CONCLUSIONS: The breeding system in P. impostor is very reminiscent of that described in C. tuberosus and can be characterized as AQS. In the remaining two species, our limited data do not allow classifying the breeding system as AQS; yet, also in these species the thelytokous production of neotenic females appears to be a systematic element of reproductive strategies. It appears likely that the capacity of thelytokous parthenogenesis evolved once in the Termes group, and may ultimately be found more widely, well beyond these Neotropical species.

Chemistry of Social Insects Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences Flemingovo n 2 CZ 166 10 Prague 6 Czech Republic

Evolutionary Biology and Ecology Université Libre de Bruxelles Avenue F D Roosevelt 50 CP 160 12 B 1050 Brussels Belgium

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