Dispersal syndromes affect ecosystem functioning in ciliate microcosms

Abstract

Dispersal is a key process mediating ecological and evolutionary dynamics. Its effects on metapopulations dynamics, population genetics or species range distribution can depend on phenotypic differences between dispersing and non-dispersing individuals (i.e., dispersal syndromes). However, scaling up to the importance of dispersal syndromes for meta-ecosystems have rarely been considered, despite intraspecific phenotypic variability is now recognised as an important factor mediating ecosystem functioning. In this study, we characterised the intraspecific variability of dispersal syndromes in twenty isolated genotypes of the ciliate Tetrahymena thermophila to test their consequences for biomass productivity in communities composed of five Tetrahymena species. To do so, dispersers and residents of each genotype were introduced, each separately, in ciliate communities composed of four other competing species of the genus Tetrahymena to investigate the effects of dispersal syndromes. We found that introducing dispersers led to a lower biomass compared to introducing residents. This effect was highly consistent across the twenty T. thermophila genotypes despite their marked differences of dispersal syndromes. Finally, we found a strong genotypic effect on biomass production, confirming that intraspecific variability in general affected ecosystem functions in our system. Our study shows that intraspecific variability and the existence of dispersal syndromes can impact the functioning of spatially structured ecosystems in a consistent and therefore predictable way.

The moulding of intra-specific trait variation by selection under ecological inheritance

“…A broad-brush conclusion from our model is therefore that under ecological inheritance, correlational selection may associate dispersal with multiple traits that have environmental effects, leading to the emergence of dispersal syndromes (Ronce and Clobert, 2012). Such syndromes, which have been observed across a wide range of taxa (fish, Cote et al, 2010b; Fraser et al, 2001; mammals, Haughland and Larsen, 2004; lizards, Cote and Clobert, 2007; for reviews: Cote et al, 2010a; Spiegel et al, 2017), are ecologically and evolutionarily significant as they influence the demographic and genetic consequences of movement (Ronce and Clobert, 2012; Edelaar and Bolnick, 2012; Raffard et al, 2021). In the model presented in section 4 for instance, the association between dispersal and attack rate on a resource led to complex meta-population dynamics, with cycles occurring both on ecological and evolutionary timescales (Fig.…”