十年前,混合繁殖策略首先在白蚁中描述了无性女王继承(AQS)。在AQS物种中,工人们,士兵和分散繁殖是通过有性繁殖产生的,虽然非分散(新生)皇后是通过自生的毒性孤雌生殖产生的,取代开国女王,与开国国王交配。到目前为止,已在六个物种中记录了AQS,这些物种来自较低的(鼻甲科)和较高的(Termitinae:Termes组和Syntermitinae)白蚁的三个谱系。在三个分支中,自动机的不同机制支持对AQS的预适应能力的独立进化。这些开创性的发现促使人们对多样化的高级白蚁家族中的嗜好和AQS的程度提出了质疑。
这里,我们调查了来自新热带AQS物种Cavitermestuberosus(Termitinae:Termes组):Palmitermes冒名顶替者的系统发育接近性三个物种中AQS的容量和发生,刺五加,和Inquilinitermesinquilinus。我们证明了这三个物种的女王都能够产下未受精的卵,经历诱导性孤雌生殖(通过配子复制,如在结核杆菌中),并在吸食者的过渡阶段发展为替代的新皇后。
假单胞菌中的育种系统非常令人联想到在结核杆菌中描述的系统,并且可以表征为AQS。在剩下的两个物种中,我们有限的数据不允许将育种系统分类为AQS;然而,同样在这些物种中,新生雌性的毒性生产似乎是生殖策略的系统要素。在Termes组中,诱导性孤雌生殖的能力似乎曾经进化过,并可能最终被更广泛地发现,远远超出了这些新热带物种。
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.
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.
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.