Sex, drugs and rock iguanas: testicular dynamics and plasma testosterone concentrations could predict optimal semen collection times in Cyclura
Sean M. Perry
A B D , Ty Park C and Mark A. Mitchell A
+ Author Affiliations
- Author Affiliations
A Department of Veterinary Clinical Sciences, Louisiana State University School of Veterinary Medicine, Skip Bertman Drive, Baton Rouge, LA 70803, USA.
B Mississippi Aquarium, 2100 E Beach Blvd, Gulfport, MS 39501, USA.
C Iguanaland, 33900 Bermont Road, Punta Gorda, FL 33982, USA.
D Corresponding author. Email: seanmperry87@gmail.com
Reproduction, Fertility and Development 34(5) 417-427 https://doi.org/10.1071/RD21032
Submitted: 2 February 2021 Accepted: 13 July 2021 Published: 17 August 2021
Abstract
Iguanas are the most endangered family of reptiles, with 77% categorised as threatened or near threatened. Further, Cyclura is the most endangered reptile genus, with all 12 species considered threatened. Therefore, it is vital that we develop assisted reproductive technologies for Cyclura spp. to enhance their conservation efforts. The goals of this study were to collect semen, and to measure testicle size and testosterone concentrations in Grand Cayman rock iguana hybrids (Cyclura lewisi × nubila (CLN)) and rhinoceros rock iguanas (Cyclura cornuta (CC)). A prospective longitudinal study was performed in 9.0 CLN and 9.0 CC during their reproductive season in southern Florida (February–July). Serial testicle ultrasound measurements and plasma testosterone concentrations were collected monthly. Testicle measurements (length (L), width (W), height (H)) were collected and testicle volume (V) was estimated using the equation V = 0.52(LW2). There were significant differences in testicle L, W, H and V for both species. Testicle size peaked for CLN and CC in April and May respectively. Plasma testosterone concentrations increased from baseline during February, March and April in CLN and in March, April and May in CC. Ultrasound testicle measurements could be used to predict when to collect semen in these seasonally monocyclic iguanas.
Keywords: rock iguanas, Cyclura, semen, electrostimulation, testicles, ultrasound, testosterone.
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