How to approach the study of syndromes in macroevolution and ecology

Abstract

Syndromes, wherein multiple traits evolve convergently in response to a shared selective driver, form a central concept in ecology and evolution. Recent work has questioned the utility and indeed the existence of some of the classic syndromes, such as pollination and seed dispersal syndromes. Here, we discuss some of the major issues that have plagued research into syndromes in macroevolution. First, observation of co-evolving traits (sometimes called “trait syndromes'') is often used as evidence of adaptation to a particular driver, even when the link between traits and adaptation is not well-tested. Second, the study of syndromes often uses a biased sampling approach, focusing on the most extreme examples, which may obscure significant continuous variation between traits. Finally, researchers often focus on the traits that are easiest to measure even though these may not be the most directly relevant to adaptive hypotheses. We argue that these issues can be avoided by combining macroevolutionary studies of trait variation across entire clades with explicit tests of adaptive hypotheses, and that taking this approach will lead to a better understanding of syndrome-like evolution and its drivers.

Linking mode of seed dispersal and climatic niche evolution in flowering plants

“…Field observations of frugivore-mediated seed dispersal are not available for most of the analysed species and so, to score as many species as possible as being either dispersed by frugivores or not, we used the concept of dispersal syndrome (Valenta & Nevo, 2020). Syndromes are a combination of traits that are shared among unrelated species due to convergent evolution in response to similar selective pressures over time (Sinnott-Armstrong et al, 2021). In the context of seed dispersal, species that rely on frugivores to disperse their seeds typically present fruits that are fleshy and visually attractive when ripe, a syndrome called endozoochory (Gautier-Hion et al, 1985).…”