Paleogenetic and microscopic studies of Eimeria spp. (Apicomplexa: Eimeriidae) as a tool to reveal the zoological origin of coprolites: The case of study of artiodactyl coprolites from an archeological site from Patagonia, Argentina

Coprolites are one of the sources of evidence most commonly used in paleoparasitological studies. However, the zoological origin identification is not always possible. Parasites of the genus Eimeria (Apicomplexa: Eimeriidae) are obligate protozoan which have evolved to exhibit a great diversity of host range, and present strict host specificity. Usually, the identification of Eimeria spp. can be done by morphological characteristics such as size and shape of the oocysts. Moreover, molecular diagnostic methods such as PCR have proven to be very useful methodologies for an accurate taxonomic identification. In recent years, molecular techniques have started to be applied in paleoparasitological studies. Here, we provide the first integrative approach that combine light microscopic studies and ancient DNA (aDNA) in order to detect and identify Eimeria spp. on artiodactyl coprolites recovered from an archeological context from northwestern Patagonia, Argentina. The main objective is to discuss the advantages of complementing these two approaches as a promising tool to identify the zoological origin of coprolites. Furthermore, we provide paleoparasitological data about the presence of Eimeria spp. in coprolites of South American ungulates. Light microscopic studies allowed the identification of oocysts attributed to Eimeria spp. in 13 of the 40 coprolites. Amplification and sequencing of the aDNA ITS1 detected the presence of Eimeria spp. in 5 of the 10 samples, and allowed the taxonomic identification of these sequences as belonging to Eimeria arloingi. Furthermore, the results obtained from cytochrome b gene (Cytb) analysis confirmed the identity of the host as Capra hircus. Results displayed the presence of coccidiosis in goats from historical times. This study highlights that both techniques are complementary and promotes the use of the identification of Eimeria spp. in ancient samples in order to identify the zoological origin.

Automated summary

Coprolites are commonly used as evidence in paleoparasitological studies, but it is not always possible to identify their zoological origin. Eimeria parasites are obligate protozoa with a diverse host range and strict host specificity. Morphological characteristics and molecular diagnostic methods can be used to identify Eimeria spp. This study combines light microscopic and ancient DNA methods to detect and identify Eimeria spp. in artiodactyl coprolites from Argentina. The results demonstrate the complementary nature of these techniques and their potential for identifying the zoological origin of coprolites.