DNA barcoding and methods to uncover freshwater biodiversity: some examples from the neotropics

Water@Wayne: February 10, 2022 DNA barcoding and methods to uncover freshwater biodiversity: some examples from the neotropics Dr. Manuel Elias-Gutierrez, Professor of Zoology, National Autonomous University of Mexico Mexico is the fourth country with the most biodiversity in the world. Here, the two main biogeographical regions of the Americas meet (Nearctic and Neotropics). However, little was known about freshwater life until the end of the 20th century. From the 1990's, a new generation of limnologists started systematically documenting several systems, mainly located from the north to the country's central plateau. Among several exciting discoveries is the first and unique blind cladoceran from the continent, Spinalona anophtalma. After the proposal of DNA barcoding by Paul Hebert in 2003, we started in 2005 to work with Mexican freshwater fauna. The first steps were not easy; in most cases amplifying the standardized gene for animals was extremely difficult, with a failure of 60 to 70% of the material studied. Despite this problem, the first publication about freshwater zooplankton and DNA barcodes from Mexico appeared in 2008, including some material from Guatemala. The same year, the first cladoceran, Leberis chihuahuensis, and the first copepod, Leptodiaptomus garciai were described, based on integrative taxonomy. Since then, we have been documenting the striking diversity from this region, and we compared it with the rest of North America. From the main freshwater groups, we have the first place in the world for rotifers, with 606 specimens sequenced, 142 species, and 147 BINS. In the case of acarii, we have 1335 sequences of Trombidiformes. Nevertheless, most of them are unidentified and unique for Mexico, most probably new species for science. For Anomopoda, we have 3804 specimens sequenced, being the second most studied country globally, accounting for 95 species identified and 171 BINS; from these, we have described three new species, and only 21 are distributed in USA and Canada as well. Ctenopods are represented by 28 species and 31 BINS in North America; 11 species are found in Mexico. Only two species are shared with the USA and Canada. Moreover, Latonopsis australis s.l. seems to be represented by two different species in Mexico and one more in the United States. Cyclopoids are represented by 29 species and 83 BINS, with only nine shared with Canada and the USA. The exotic Mesocyclops pehpeiensis being one of them and Acanthocylops americanus the most widely distributed in the USA and Mexico. Finally, Calanoida has 26 species identified and 54 BINS. Only three species are shared with the USA. Currently, we know that the taxonomic impediment should not stop our knowledge on freshwater diversity, so we are currently working on baselines with DNA barcodes and a reference collection of the material sequenced. This work will allow the biomonitoring of our systems by using metabarcoding, allowing us to detect any change due to exotic species introduction or alteration of the ecosystem.