Temporal changes in genetic variability in three bumblebee species from Rio Grande do Sul, South Brazil

In order to protect biodiversity, conservation genetics are of great importance. Until now, a few population genetic studies of Neotropical bumblebees are available but studies of temporal stability in genetic diversity are lacking. Here, genetic variability of three South Brazilian species Bombus bellicosus, B. pauloensis, and B. morio was investigated over time. Hereto, museum collection specimens of 1946 until 2012, from eight locations in Rio Grande do Sul, were genotyped at 16 microsatellite loci. During an additional sampling in the foraging season of 2015, no bumblebees could be collected possibly due to the super El Nio of 2015-2016. Our results on the collection specimens demonstrated a significantly higher genetic diversity in B. morio than in B. pauloensis. Genetic variability in B. pauloensis gradually and significantly decreased over time from 1946 until 2012; while in B. morio, genetic variability remained stable until the last time period (2010-2012). For B. bellicosus, not enough data was available. Although the studied populations became more vulnerable over time, for the conservation of Neotropical bumblebees, still more information is needed and could include more frequent monitoring of bumblebees. Adding B. bellicosus to the Brazilian list of threatened species is suggested