 Another centipede order, the Geophilomorpha, the number of segments varies in different species between 27 and 191, but the number is always odd, making this an absolute constraint; almost all the odd numbers in that range are occupied by one or another species.Ecological evolutionary developmental biology () integrates research from developmental biology and ecology to examine their relationship with evolutionary theory.Researchers study concepts and mechanisms such as developmental plasticity, epigenetic inheritance, genetic assimilation, niche construction and symbiosis.