The Leptynia hispanica stick-insect species complex includes bisexuals, triploid and tetraploid parthenogenetic populations. Analyses of karyotypes, mtDNA (cox2) and nuclear DNA (ef1-a) markers were carried out to trace phylogenetic relationships as well as microevolutionary and phylogeographic patterns of the complex. Our analyses gave a subdivision of bisexual populations into four groups, tentatively proposed as incipient species. Moreover, triploids and tetraploids showed independent origins, the latter being far more ancient than the former. From (cox2) haplotypes the maternal ancestors of the polyploids were traced out; from the ef1-a sequences the triploids showed a clear hybrid constitution, while the hybrid constitution of tetraploids, although certain, could be only indirectly inferred. Moreover the wide distribution of polyploid parthenogens, likely linked to diploid ancestor displacement or extinction, appear to substantiate their competitive advantage over sexuals. WE suggest that L. hispanica is a case of "geographic parthenogenesis", since parthenogens colonize large peripheral ranges with bisexual being confined to glacial refuge areas. All this seems to demonstrate a major role of parthenogenesis and polyèloidy in the evolution of the L. hispanica species complex.

The Leptynia hispanica species complex (Insecta, Phasmida): hybridization, parthenogensis, polyploidy and more.

GHISELLI, FABRIZIO;MILANI, LILIANA;SCALI, VALERIO;PASSAMONTI, MARCO
2007

Abstract

The Leptynia hispanica stick-insect species complex includes bisexuals, triploid and tetraploid parthenogenetic populations. Analyses of karyotypes, mtDNA (cox2) and nuclear DNA (ef1-a) markers were carried out to trace phylogenetic relationships as well as microevolutionary and phylogeographic patterns of the complex. Our analyses gave a subdivision of bisexual populations into four groups, tentatively proposed as incipient species. Moreover, triploids and tetraploids showed independent origins, the latter being far more ancient than the former. From (cox2) haplotypes the maternal ancestors of the polyploids were traced out; from the ef1-a sequences the triploids showed a clear hybrid constitution, while the hybrid constitution of tetraploids, although certain, could be only indirectly inferred. Moreover the wide distribution of polyploid parthenogens, likely linked to diploid ancestor displacement or extinction, appear to substantiate their competitive advantage over sexuals. WE suggest that L. hispanica is a case of "geographic parthenogenesis", since parthenogens colonize large peripheral ranges with bisexual being confined to glacial refuge areas. All this seems to demonstrate a major role of parthenogenesis and polyèloidy in the evolution of the L. hispanica species complex.
Paradox of sex, theory and data.
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Ghiselli F.; Milani L.; Scali V.; M. Passamonti.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/46907
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