Abstract
Predator-prey body mass relationships are a vital part of food webs across ecosystems and provide key information for predicting the susceptibility of carnivore populations to extinction. Despite this, there has been limited research on the minimum and maximum prey size of mammalian carnivores. Without information on large-scale patterns of prey mass, we limit our understanding of predation pressure, trophic cascades and susceptibility of carnivores to decreasing prey populations. The majority of studies that examine predator-prey body mass relationships focus on either a single or a subset of mammalian species, which limits the strength of our models as well as their broader application. We examine the relationship between predator body mass and the minimum, maximum and range of their prey's body mass across 108 mammalian carnivores, from weasels to baleen whales (Carnivora and Cetacea). We test whether mammals show a positive relationship between prey and predator body mass, as in reptiles and birds, as well as examine how environment (aquatic and terrestrial) and phylogenetic relatedness play a role in this relationship. We found that phylogenetic relatedness is a strong driver of predator-prey mass patterns in carnivorous mammals and accounts for a higher proportion of variance compared with the biological drivers of body mass and environment. We show a positive predator-prey body mass pattern for terrestrial mammals as found in reptiles and birds, but no relationship for aquatic mammals. Our results will benefit our understanding of trophic interactions, the susceptibility of carnivores to population declines and the role of carnivores within ecosystems.
Highlights
Examining patterns in predator-prey relationships provides information on predation pressure [1,2], the impact of decreasing prey species on predators [3] and the potential for trophic cascades and the collapse of prey populations [4,5,6]
Previous research on predator-prey body mass relationships in mammalian carnivores has focused upon the mean mass of prey, largely ignoring the minimum and maximum body mass of prey consumed by predators
Phylogenetic Generalized Least Squares Regression The model including an interaction between body mass and environment was the best supported model for minimum prey mass, maximum prey mass and prey mass range (Table 2)
Summary
Examining patterns in predator-prey relationships provides information on predation pressure (e.g. on specific size guilds) [1,2], the impact of decreasing prey species on predators [3] and the potential for trophic cascades and the collapse of prey populations [4,5,6]. Larger-sized predators can utilise a wide variety of prey types because they have large home ranges [7] that provide access to a diversity prey species [8], as well as a wide gape size that allows them to feed on prey of a variety of sizes. Large predators tend to eat larger-sized prey [13] It is not always profitable for large species to feed on small-sized prey due to capture inefficiency as it is costly to pursue small-sized prey in relation to the small energetic benefit gained [9]. If maximum prey size scales positively with predator mass and minimum prey size does not this will result in a larger diversity of prey size for larger predators (i.e. wider DNB)
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