Aeglidae is the only freshwater family in the infraorder Anomura. Aegla uruguayana Schmitt, 1942 is one of the most widely distributed species in southern South America and is found in different environments, which makes it an interesting object for population genetic studies. The main objective of this work was to analyse the genetic population structure of A. uruguayana along a sea distance gradient for four populations that were studied in the La Plata Basin with an 1100-km range in relation to an east-west transect. The populations studied were the Río Tercero Reservoir, the Setúbal Lagoon, the Doll Stream and the Urquiza Stream. Aeglid DNA was extracted using a commercial kit that was amplified with ISSR markers. Of the 10 primers tested, we selected four that showed the best resolution and reproducible results. Our studies revealed a of 0.3479 ± 0.1383 (mean ± SD) and a global of 0.3583 (), demonstrating genetic differentiation among populations with low gene flow. The Urquiza Stream population showed a genetic structure clearly different from that of the other populations. However, the Río Tercero, Setúbal and Doll populations were well grouped with one effective connection among them. The geomorphologic history of the basin provides evidence for the isolation hypothesis. These data demonstrate the importance of geoclimatic history in the study region and the importance of using complete population distribution data where the species live. These data permit us to interpret that different populations have independent histories that are delineated by the geomorphological events that occurred on earth.

The yacare caiman (Caiman yacare) is a reptile from South America and 1 of the 2 crocodilian species present in Argentina. The degradation of their natural habitat and strong hunting pressure led to a sharp numerical decline of wild populations. Nowadays, C. yacare is included in Appendix II of CITES, and ranching practices in some areas in Argentina are helping hatching success. In this context, it is important to better understand the population structure and mating system of the species. To do this, we amplified 10 microsatellite markers (SSRs) in 148 individuals of 13 C. yacare nests. All of the markers were polymorphic with 2–12 alleles per locus, with allelic sizes ranging between 154 and 400 bp and medium levels of polymorphism (Ho = 0.152–0.551 and He = 0.221–0.621). We were able to determine the maternal genotype in 9 out of 13 nests. In 6 of them we found more than 1 paternal genotype, with a maximum of 3 fathers for a single nest. This study is the first to provide evidence of multiple paternity behavior. These findings will be useful to improve management and conservation strategies for the species.

ABSTRACT. Sometimes, commercial products obtained from wild animals are sold as if they were from domestic animals and vice versa. At this point of the productive chain, legal control of possible wildlife products is difficult. Common in the commerce of northern Argentina, skins of two wild species, the carpincho and the collared peccary, look very similar to each other and to those of the domestic pig; it is extremely difficult to differentiate them after they have been tanned. Because there was no an adequate methodology to discriminate between leather of these three species, we developed a new methodology of DNA extraction from skin and leather. This new method involves digesting a leather sample using proteinase K, followed by precipitation of proteins with 5 M NaCl, cleaning with absolute isopropanol and DNA precipitation with 70% ethanol. DNA is hydrated in Tris-EDTA buffer. This protocol provided good-quality DNA suitable for analysis with molecular markers. This new protocol has potential for use in DNA extraction from animal skins using a novel protocol identifying leather products of these species using molecular markers based on RAPDs.

Surubim (Pseudoplatystoma corruscans, Pimelodidae) are migratory catfish native to the rivers in the La Plata and São Francisco basins. They are piscivores that attain considerable body sizes and are a valuable economic resource. Surubim exhibits extensive migrations during its life cycle that may affect the population structure at vast geographic scales. The authors examined the genetic diversity and population genetic structure of P. corruscans using microsatellite markers from a comprehensive sampling of 260 individuals from the Upper and Lower Paraná River. They identified two well-differentiated genetic clusters corresponding to a natural geographic barrier historically separating Upper and Lower Paraná regions. They also demonstrated temporal variation in population genetic structure at a site in Lower Paraná close to the confluence with the Paraguay River, most likely explained by the influx of migrant fishes at certain times of the year.