Mémoire
| Résumé : | Genome sizeisafundamentalbiologicaltraitthatshapestheevolutionarypathof speciesandtheirabilitytoadapttopotentialthreats.Inearly-branchinglineages ofanimalssuchassponges,genomesizedataremainscarceandintraspecificvariationisunderstudied.Inthisstudy,theintra-andinterspecificvariationingenomesizesofthespongegenus Stylissa collected fromIndonesiaand Saudi-Arabiawasinvestigated.A3.6-foldvariationwasobservedinthegenome sizevaluesestimatedusingarefinedFeulgenImageAnalysisDensitometry (FIAD)protocol,rangingfrom0.075pgto0.27pg.Geneticanalyses usingtheITS2ribosomalgenefragmentrevealedtwoputativespeciesamong the26analysedsamplesusingthehaplowebmethod.However,spiculelength, oneimportantmorphologicalcharacterinspongetaxonomy,didnotdiffer significantlybetweenthetwospecies.Thehighestgenomesizemeanwasrecordedin Stylissacarteri (0.22 pg,1.59-foldvariation),followedby Stylissamassa ( 0.20pg,3.3-foldvariation).Apositiveassociationwasobservedbetweennucleotidepolymorphism(π) andgenomesizevariance.Thisstudyprovidesafirstexplorationofgenomesizevariationsin Stylissa spongesfromthe tropics,andshouldbeextended,inthefuture,toamoreextensivedatasetof marinesponges,formoregeneralisedpertinentconclusions |
