Abstract
Clinal variation is defined as gradual variation in a character associated with geographic distance among sites. Microlophus atacamensis is a medium large lizard species which inhabits the intertidal zone of northern Chile, distributed from Antofagasta (23° 39' S) to Arrayán, La Serena (29° 41' S) in a gradient which could show clinal variation. Geometric morphometrics analyzes differences in shape independent of size; information about shape allows a more complete biological interpretation than information on morphological variation. This studyevaluated clinal variation in the head shape of M.atacamensis fromfive localities (Antofagasta, Paposo, Pan de Azúcar, Caldera, and Tres Playitas) using dorsal and lateral views, comparing form variation with latitudinal distribution. The heads of adults collected were photographed in lateral and dorsal views. The analysis did not find significant differences in form among the five localities, in contrast to the proposal of earlier studies, and no differences were recorded between the sexes. Possible reasons why these populations are not differentiated in the latitudinal gradient are discussed. Our results show that there are no differences between the studied, among the explanations are that populationsof this species are subjected to similar environments that promote convergence of the structures analyzed.
Highlights
Clinal variation is defined as gradual variation in a character associated with geographic distance among sites
No significant differences were detected among localities, either in dorsal view (Wilk’s lambda = 0.23; p = 0.45) or lateral view (Wilk’s lambda = 1.77; p = 0.24), and no sexual dimorphism was found in dorsal (Wilk’s lambda = 0.31; p = 0.67) and lateral (Wilk’s lambda = 0.05; p = 0.63) views
In the dorsal view (Figure 3), PC1 expresses a change in the shape of the head laterally (90.1% of the total Procrustes form variance), while in lateral view (Figure 4) it expresses the change in the posterior region (68.4% of the total Procrustes form variance)
Summary
Clinal variation is defined as gradual variation in a character associated with geographic distance among sites. Based on a molecular phylogeny of data from many genes, Benavides et al (2007) proposed that the origin of the Chilean clade was a migration from Peru to the interior desert; M. theresioides diverged and dispersed along the Río Loa to the coast, giving rise to M. quadrivittatus in the north and M. atacamensis farther south. This last proposal is questionable, since the limit of distribution between M. quadrivittatus and M. atacamensis is near Antofagasta (Victoriano et al 2003).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
