Cold/Warm stenothermic freshwater macroinvertebrates along altitudinal and latitudinal gradients in Western South America: A modern approach to an old hypothesis with updated data

DOS SANTOS, D.; MOLINERI, C.; NIETO, C.; ZUÑIGA, M. DEL C.; EMMERICH, DANIEL; FIERRO, P; PESSAQ, PABLO; RIOS-TOUMA, B.; MARQUEZ JAVIER; GOMEZ, DANIELA; SALLES, FREDERICO; ENCALADA, A; PRINCIPE, R; GOMEZ, GRACIELA CECILIA; VALDOVINOS, C; DOMINGUEZ, EDUARDO

JOURNAL OF BIOGEOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018 vol. 45 p. 1571 - 1581

0305-0270

Aim Traditionally,the South American aquatic insects have been divided into cold and warm adaptedforms. Cold adapted fauna inhabits freshwater systems from higher latitudes, orhigher altitudes even around the Equator. Warm adapted groups are those foundin lower latitudes and altitudes. This work aims to answer the questions: Arethere mayfly cold and warm assemblages geographically segregated according to geographical(latitude) and topographical (altitude) surrogates of temperature? If so, whereis this change located?Location South America.Methods We compiled a data set about the relative incidence of74 mayfly genera in 331 sampled communities. They span from 0 to 4320 m andfrom 47.77º S to 5.74º N latitude. By virtue of the compositional nature of thedata set, we applied the statistical procedures behind the Aitchisoncompositional data analysis. We delimited groups of assemblages based on theirAitchison distances and projected the data points onto a biplot obtainedthrough Principal Component Analysis adjusted to compositions (Aitchison PCA). Results A strong correspondence among biological andgeographical information is detected, the cold and warm adapted assemblages areclearly segregated. Andesiops and Meridialaris are typical representativesof cold-adapted fauna; Baetodes, Leptohyphes and Thraulodes represent the warm-group. Both groups can be separatedby a curved line of altitude in function of latitude expressed in terms of asuperellipse arc. Main conclusions The classical ecological bipartition into warm andcold freshwater groups is formalized quantitatively. The dividing line betweenwarm and cold assemblages levels off at high altitudes (~ 3300 m) around theEquator and falls to sea level at southern latitudes. The community bipartitionline is useful for tracking global change through records of altitudinaldisplacement below and above of the warm/cold line of involved ecologicalgroups.