Co-variation of life history characters in the family Lophoziaceae: a multivariate analysis

Abstract

The particular combinations of life history traits that organisms display are a product of trade-offs between conflicting demands on finite energy budgets. Organisms are, therefore, expected to display combinations of co-evolved life history traits, sometimes referred to as tactics or strategies, that overall maximize fitness within the constraints imposed by environmental and/or genetic limitations. This study uses a combination of Principal Component and Cluster analyses to examine patterns of life history co-variation in the family Lophoziaceae, based on data obtained from literature. We also evaluate the relationship between sexuality, reproductive mode and sporophyte/gemma frequency among members of this family. The species studied are resolved into more or less coherent groups that have specific life history trait combinations. No evidence of either phylogenetic constraint or close relationship to habitat parameters could be demonstrated. The results suggest trade-offs between spore frequency and gemma frequency. Dioicous species dominate the family, with about 90% of the species being dioicous. The relationship between sexuality and sporophyte frequency is statistically significant: monoicous species produce sporophytes more frequently than dioicous species. Mode of reproduction and gemmae production were both independent of sexuality. For species that can reproduce both ways, sexuality was independent of diaspore frequency. The data are consistent with the idea of coevolved life history “strategies” as in most others organisms studied.