Kelly, Morgan. Multidimensional niche approach reveals constraints over the elemental content of animals. Retrieved from https://doi.org/doi:10.7282/t3-kcsf-8g40
DescriptionThe wide spectrum of phenotypic diversity found in life on Earth is a result of both environmental and evolutionary drivers. Functional traits are those elements of organismal phenotypes which have an effect on the organism’s performance. Specific trait combinations can reveal ecological strategies that evolved in response to selection pressures. The elemental content of living organisms (carbon (C), nitrogen (N), and phosphorus (P)), represent key functional traits that have a strong influence over organismal form and function. Using a global database of stoichiometric traits of animals from terrestrial, freshwater and marine habitats (n > 5000), I applied hypervolume trait approaches to quantify the overall size and shape of the stoichiometric space of animals to determine differences in stoichiometric niche between animals inhabiting different habitats and animals occupying different trophic guilds. I found that the observed multidimensional trait space of animals was significantly smaller than the potential niche space under null expectations and displayed an elliptical shape due to a significant correlation between C and N contents and independent variation of P content. The stoichiometric trait space of invertebrates and vertebrates occupying different habitats and from trophic guilds varied in their size and shape but displayed significant degrees of overlap suggesting evolutionary constraint over stoichiometric traits. These findings suggest that stoichiometric traits may be evolutionarily conserved in animals because regardless of the habitat in which the animals lived or the trophic guild they occupied, they did not evolve to occupy adjacent space, but overlapped in a large portion of their niche space. We argue that due to these evolutionary constraints, animals converge towards a limited amount of successful stoichiometric trait combinations resulting from trade-offs and covariance.