Overview of the frequency of factors included in 92 macroecological studies of plants and vertebrates. The figure shows that the majority of studies in all taxonomic groups focus on traits, but that there is a difference among plants and animals in the frequency of studies addressing propagule and colonisation pressure, that is greater in the latter. On the contrary, plant studies more commonly address the role of residence time. Based on studies listed in Appendix I ; note that studies on invertebrates, fungi, and cross-taxonomic studies are not shown here (n = 10).