BIHAREAN BIOLOGIST;
Volume: 20 (No.1) - pp. 37 - 46 - Art no: e261302
Geometric morphometric analysis of head shape variation in Hemidactylus turcicus (Linnaeus, 1758) (Sauria: Gekkonidae) from the Aegean and Mediterranean regions of Türkiye
Research articles → Vertebrate Zoology
Authors
Cahit YILDIZ1,*, Cemal Varol TOK2
1. Çanakkale Onsekiz Mart University, School of Graduate Studies, Department of Biology, Çanakkale, 17100, Türkiye.
2. Çanakkale Onsekiz Mart University, Science Faculty, Department of Biology, Çanakkale, 17100, Türkiye.
* Corresponding author: C. Yildiz, E-mail: cyildiz.biology@gmail.com
DOI https://doi.org/10.61215/bb.2026.20.1.04
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Keywords
Mediterranean house gecko, sexual dimorphism, geographic variation, landmark-based methods, outline-based methods.
Abstract
In this study, shape variation in the heads of 41 adult Hemidactylus turcicus specimens (17 males, 24 females) was investigated using geometric morphometric methods. To better understand geographic variation, an additional 21 juvenile specimens (12 Aegean, 9 Mediterranean) were analyzed, with separate analyses conducted for juvenile groups. For adults, landmark-based analyses revealed no evidence of sexual dimorphism (F=0.700 p>0.5). However, significant geographic variation was detected between adult groups (29 Aegean, 12 Mediterranean) (F=7.353, p<0.01). Similar results were obtained for juveniles (12 Aegean, 9 Mediterranean) (F=3.416, p<0.01). While strong positive correlations were observed between centroid size and linear measurements, the first principal component (PC1), which accounted for the largest portion of shape variation, showed no strong correlation with traditional morphometric traits. Variation in the anterior postmental plates of 37 adult specimens (14 males, 23 females; 27 Aegean, 10 Mediterranean) was assessed using an outline-based method to examine sexual and populational differences. Analyses revealed no sexual dimorphism in the anterior postmental plates; however, significant inter-population variation was detected in the right anterior postmental plate (Pillai's Trace = 0.355, F(3, 31) = 5.697, p<0.01). Overall, the findings suggest the presence of geographic variation in head shape between the Aegean and Mediterranean groups in both adults and juveniles. This study represents a preliminary investigation of head morphology in Hemidactylus turcicus using geometric morphometric approaches. Since the present analysis included only specimens from the Aegean and Mediterranean regions, future research should apply these methods to larger samples representing all geographic regions of Türkiye.
Article history
Received: 22 July 2025 / Accepted: 10 November 2025 / Available online: January 2026 / Published online: 28 June 2026 / Printed: 30 June 2026
Authors` ORCID IDs
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