Leszek Rychlik (Department of Systematic Zoology) and Krzysztof Kowalski (currently the Nicolaus Copernicus University in Toruń) published a review in the journal Toxins (Q1 in Zoology) on the evolution and ecological functions of venomousness in insectivorous mammals (order Eulipotyphla), to which most of the currently known venomous mammals belong. The authors provide an overview of the current knowledge about eulipotyphlan venoms and discuss how these venoms might have evolved under ecological pressures related to high metabolic rate, food acquisition, ecological interactions, defense and protection. They delineate six mutually nonexclusive functions of venom: prey hunting, food hoarding, food digestion, reducing intra- and interspecific conflicts, avoidance of predation risk, weapons in intraspecific competition. They also present several hypotheses explaining why, despite so many potentially beneficial functions, venomousness is rare even among eulipotyphlans.
The paper is available at: https://doi.org/10.3390/toxins13030231