Parental Care and Relative Issues

The evolution of maternal care in egg-laying terrestrial vertebrates remains unclear, particularly whether it arises from egg recognition or territorial behavior. Most species either lack care or show it consistently, limiting inference. However, in long-tailed skinks (Eutropis longicaudata) on Orchid Island, females uniquely exhibit nest guarding, unlike other populations. They remain with eggs during incubation and actively repel egg-eating snakes (Oligodon formosanus). Remarkably, females defend the original nesting site even when eggs are removed or replaced, guard any conspecific eggs, and show this behavior before laying. These findings suggest maternal care may originate from territorial instincts rather than egg recognition, with nest guarding representing an early stage in the evolution of parental care.