Specialists and generalists fulfil important and complementary functional roles in ecological processes

DEHLING, D. MATTHIAS; BLENDINGER, PEDRO G.; MUÑOZ, MARCIA C.; NEUSCHULZ, EIKE LENA; SCHLEUNING, MATTHIAS; BENDER, IRENE M.A.; BÖHNING?GAESE, KATRIN; QUITIÁN, MARTA; SAAVEDRA, FRANCISCO; SANTILLÁN, VINICIO; STOUFFER, DANIEL B.

FUNCTIONAL ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2021 vol. 35 p. 1810 - 1821

0269-8463

1. Species differ in their resource use and their interactions with other species and,consequently, they fulfil different functional roles in ecological processes. Species withspecialized functional roles (specialists) are considered important for communitiesbecause they often interact with species with which few other species interact, therebycontributing complementary functional roles to ecological processes. However, thecontribution of specialists could be low if they only interact with a small range ofinteraction partners. In contrast, species with unspecialized functional roles (generalists)often do not fulfil complementary roles but their contribution to ecological processescould be high because they interact with a large range of species.2. To investigate the importance of the functional roles of specialists versus generalists, wetested the relationship between species? degree of specialization and their contribution tofunctional-role diversity for frugivorous birds in Andean seed-dispersal networks. Weused two measures for the specialization of birds?one based on the size, and one basedon the position of their interaction niche?and measured their effect on the birds?contribution to functional-role diversity and their functional complementarity, a measureof how much a species? functional role is complementary to those of the other species.3. In all networks, there were similar log-normal distributions of species? contributions tofunctional-role diversity and functional complementarity. Contribution to functional-rolediversity and functional complementarity increased with both increasing niche-positionspecialization and increasing niche size, indicating that the composition of functionalroles in the networks was determined by an interplay between specialization andgeneralization. There was a negative interaction between niche-position specializationand niche size in both models, which showed that the positive effect of niche-positionspecialization on functional-role diversity and functional complementarity was strongerfor species with a small niche size, and vice versa.4. Our results show that there is a continuum from specialized to generalized functionalroles in species communities, and that both specialists and generalists fulfil importantfunctional roles in ecological processes. Combining interaction networks with functionaltraits, as exemplified in this study, provides insight into the importance of an interplay ofredundancy and complementarity in species? functional roles for ecosystem functioning.