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|Evolution without sex|
Research sponsored by
the Spanish Ministry of Science and Innovation (Plan Nacional 2008-2011).
sex: Historical circumstances and
Research team: Anabela Cardoso (research assistant, IBE), Daniel J. Funk (co-investigator, Vanderbilt University), Jesús Gómez-Zurita (IP, IBE), Adela González-Megías (co-investigator, Universidad de Granada), and Tinguaro Montelongo (PhD student, IBE).
Keywords: Phylogeny, phylogeography, molecular systematics, evolution, ecology, asexuality, interspecific hybridization, Coleoptera.
Unisexuality is paradoxically an unstable and rare reproductive mode in animals. Paradoxically because it is after all the most efficient, economic way to produce offspring. Its limitations to generate genetic variation able to cope and buffer environmental (biotic and abiotic) change supposedly explain the prevalence of sexual reproduction. Understanding an essential biological phenomenon such as sex thus benefits immensely from insight gained from the study of biological systems lacking it.
Unisexuality appears in Nature in a variety of forms and as the result of various mechanisms. Apomixis product of interespecific hybridisation is seemingly the most widespread in animals, but suitable models to investigate it in a comparative fashion are scarce. Within this context, we advocate in this proposal for the study of Calligrapha, a leaf beetle genus with several unisexual species hypothesised to be descendant of multiple independent interspecific hybridisation events. The comparative approach is granted with this model, providing several independent natural experiments of hybridisation (and subsequent unisexuality) and closely related lineages with alternative reproductive modes.
Finally, we will investigate the ecological implications that surround hybrid speciation and evolution, including trophic specialisation, female and larval performance, and mating preference. Hybridisation in Calligrapha involves parentals with different trophic selection; thus, unisexual hybrids inherit in theory a double trophic potentiality and broader niche, which can be interpreted as an ecologic advantage. For the same reason, different host selection by putative parentals, interspecific mating is in principle an unlikely outcome, unless parental and hybrid habitat tolerance are relaxed. Ultimately, we want to show that hybridisation is a crucial, almost unavoidable phenomenon in the evolution of this group of beetles, definitely of great scientific interest.