Population density and testes size: more than meets the eye

13 agosto 2014

Changes in population density can affect the size of animals’ testes and therefore impact on reproduction, researchers have found. Across the animal kingdom, there is usually a positive relationship between sperm competing to fertilize eggs and the male reproductive effort in producing large ejaculates. This usually manifests in males evolving larger testes. However, demographic and ecological processes may drastically alter the level of sperm competition and therefore the evolution of testes size, it turns out.