Twinning in a wild breeding population of Gharials (Gavialis gangeticus) in India

document twinning in wild reptilian populations, likely attributable to methods of examination, large clutch sizes, and synchronous hatching, especially in communally nesting species (Piovano et al. 2011;Di Marzio et al. 2023).Twins in an egg usually start development at the same time, but can result in hatchlings of equal or unequal sizes, or one developed and one in an embryonic phase (Hirasawa et al. 2019).In crocodiles, twinning occurs as twins, double yolks, or axial bifurcation (Ferguson 1985).One-egg twins are usually undersized compared to normal hatchlings due to the competition for resources inside the egg (Acharjyo and Singh 1989;Platt et al. 2000), which can also compromise post-hatching survival.Causes of twinning are not known but some assumed mechanisms have been reported.Low genetic variation in bottlenecked populations can result in an