Morphological differentiation of crosses of two phenotipically divergent populations of Italian wall lizard Podarcis siculus (Rafinesque-Schmaltz,1810)

Abstract

Brza evolucija biološki je proces u kojem se promjene neke populacije događaju toliko brzo da su vidljive već unutar nekoliko generacija. Jedan od intrigantnijih primjera brze fenotipske divergencije je rezultat translokacijskog eksperimenta provedenog 1971. godine. Pet parova primorske gušterice (Podarcis siculus) prebačeno je s otočića Pod Kopište na Pod Mrčaru gdje do tada vrsta nije bila prisutna. 37 godina kasnije otkriveno je da je novo introducirana populacija na otoku Pod Mrčaru u to kratko vrijeme razvila razne fenotipske promjene u odnosu na izvornu populaciju. U ovom radu uspoređivani su potomci prve generacije unakrsnog križanja jedinki s oba otoka. Cilj ovog rada je bio ustvrditi nasljednost morfoloških svojstava kod križanaca jer se time indicira da utvrđene fenotipske razlike imaju genetsku osnovu. Kroz razvojni period od izlijeganja do navršene prve godine života mjerilo se osam morfoloških obilježja (mjere cijeloga tijela, s naglaskom na mjere glave obzirom da su najveće uočene razlike između populacija vezane za veličinu glave). Statistička obrada dobivenih podataka pokazala je da spol ima velik utjecaj na veličinu jedinke, a promatranjem trendova vidi se da križanci imaju mjere različite od čistih jedinki što je nagovještaj da postoji genetska osnova za prikazane rezultate, no potreban je puno veći uzorak kako bi se to moglo sa sigurnošću potvrditi.Rapid evolution is a biological process in which phenotypic and genetic changes happen so fast that they are noticeable within generations. One of the intriguing examples of rapid phenotypic divergence is a result of a translocating experiment conducted in 1971. Five pairs of Italian wall lizard (Podarcis siculus) were transferred from a small islet Pod Kopište onto Pod Mrčaru islet where the species was not present before. After only 36 years it was discovered that the new established, introduced population from Pod Mrčaru had developed diverse phenotypical changes compared to the native population. With the objective of determine the inheritance of those morphological traits we set a reciprocal cross-experiment with individuals from both islands. The crossbreeding was performed in common garden conditions to determine if the phenotypical differences between offspring have genetic background. We measured eight morphologic traits, emphasizing head measures, considering that the biggest observed differences between populations were in head shape. Those traits were measured every two months through the developmental period, from the moment of hatching until one year afterwards. In this work we present the results of the morphometric analysis of the the first generation of offspring. The results show that the sex has a big influence on the individual size. While observing the overall data pattern it seems that hybrids have different values than pure crosses which suggests that there is a genetic background for the differences. However, bigger sample size is needed to confirm it with certainty