Oral Presentation- Symposium 12th International Mammalogical Congress

Who killed the wolf spider? Intraguild predation among taxonomically disparate micro-carnivores (#202)

Tamara I Potter 1 , Aaron C Greenville 1 , Christopher R Dickman 1
  1. School of Life and Environmental Science, University of Sydney, Sydney, New South Wales, Australia

Successful foraging is important for animals to fulfil their specific energy and nutrient requirements. However, as these resources are generally limited, competition often arises. Intraguild predation (IGP) is a distinctive form of interference competition where a dominant predator selectively kills subordinate species and thereby gains increased access to resources. This asymmetrical interaction has been documented primarily among carnivores, with few examples from different taxonomic levels. We present such an example here. The lesser hairy-footed dunnart (Sminthopsis youngsoni) is a common generalist insectivore in arid Australia that has been shown to consume wolf spiders (Family Lycosidae) disproportionately often relative to their availability. In this study, we tested three hypotheses to uncover the underlying mechanisms driving this selective predation. Lycosids were not found to contain more energy, water or nutrients than other available arthropod prey, discrediting the hypothesis that S. youngsoni forages to optimise nutritional or caloric intake. However, we found a high degree of spatial and temporal overlap in resources (diet and microhabitat), providing support for the hypothesis of competition. This latter hypothesis, and the operation of IGP, was further supported by the results of cafeteria-style trials showing that S. youngsoni selectively targets lycosids when alternative prey types are equally available. This study is the first to uncover IGP between such taxonomically disparate groups, and its consequences extend beyond simple predator-prey relationships to suggest that IGP can have substantial impacts on community structure and ecosystem processes.