Similar composition of functional roles in Andean seed‐dispersal networks, despite high species and interaction turnover

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

ECOLOGY

ECOLOGICAL SOC AMER

Año: 2020 vol. 101 p. 1 - 11

0012-9658

The species composition of local communities varies in space, and its similaritygenerally decreases with increasing geographic distance between communities, a phenomenonknown as distance decay of similarity. It is, however, not known how changes in local speciescomposition affect ecological processes, that is, whether they lead to differences in the localcomposition of species' functional roles. We studied eight seed-dispersal networks along theSouth American Andes and compared them with regard to their species composition and theircomposition of functional roles. We tested (1) if changes in bird species composition lead tochanges in the composition of bird functional roles, and (2) if the similarity in species composi-tion and functional-role composition decreased with increasing geographic distance betweenthe networks. We also used cluster analysis to (3) identify bird species with similar roles acrossall networks based on the similarity in the plants they consume, (i) considering only the speciesidentity of the plants and (ii) considering the functional traits of the plants. Despite strongchanges in species composition, the networks along the Andes showed similar composition offunctional roles. (1) Changes in species composition generally did not lead to changes in thecomposition of functional roles. (2) Similarity in species composition, but not functional-rolecomposition, decreased with increasing geographic distance between the networks. (3) Thecluster analysis considering the functional traits of plants identified bird species with similarfunctional roles across all networks. The similarity in functional roles despite the high speciesturnover suggests that the ecological process of seed dispersal is organized similarly along theAndes, with similar functional roles fulfilled locally by different sets of species. The high spe-cies turnover, relative to functional turnover, also indicates that a large number of bird speciesare needed to maintain the seed-dispersal process along the Andes.