Do mayflies (Ephemeroptera) support a biogeographic transition zone in South America?

MOLINERI, CARLOS; NIETO, CAROLINA; DOS SANTOS, DANIEL A.; EMMERICH, DANIEL; ZÚÑIGA, M. DEL CARMEN; FIERRO, PABLO; PESSACQ, PABLO; GOMEZ, DANIELA; MÁRQUEZ, JAVIER A.; PRÍNCIPE, ROMINA E.; VALDOVINOS ZARGES, CLAUDIO; DOMÍNGUEZ, EDUARDO

JOURNAL OF BIOGEOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020

0305-0270

Aim: South America is considered a biologically hybrid continent. To the south, thePatagonian region harbours a unique biota strongly related to other southern continents.To the northern portion, tropical and subtropical areas from the Neotropicalregion show a more complex taxocoenosis related to the Nearctic and Afro-Orientalregions. The South American Transition Zone (STZ) has been proposed to belong simultaneouslyto both regions. This work aimed to test the validity of STZ in the lightof the distributions of an ancient freshwater taxon.Location: South America.Taxon: Ephemeroptera.Methods: We compiled a dataset including all mayfly species having at least one recordin South America (8,268 records for 661 species). By using the Network AnalysisMethod (NAM), we analysed the validity and delimitation of the STZ.Results: The distributions of Ephemeroptera give rise to groups of cohesively sympatricspecies with a clear distinction between Patagonian and Neotropical regions.Although some degree of overlap occurs between them, the overlapping area doesnot match the STZ to a significant extent. The units of co-occurring species recoveredshow that Neotropical groups mainly occupy the STZ.Main conclusions: Almost the entire provinces of Puna, Desert and Paramo are notsupported as part of the STZ by mayfly distribution. The transition zone betweenPatagonian and Neotropical mayfly fauna involves Southern Puna and high Andes(south to 17° S latitude), Monte province, and a narrow portion of Patagonian steppewith Chubut River being the southern limit.