Courant J et al. (2017), Are invasive populations characterized by a bro...

XB-ART-53705

PeerJ 2017 Apr 19;5:e3250. doi: 10.7717/peerj.3250.

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Are invasive populations characterized by a broader diet than native populations?

Courant J , Vogt S , Marques R , Measey J , Secondi J , Rebelo R , De Villiers A , Ihlow F , De Busschere C , Backeljau T , Rödder D , Herrel A .

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BACKGROUND: Invasive species are among the most significant threats to biodiversity. The diet of invasive animal populations is a crucial factor that must be considered in the context of biological invasions. A broad dietary spectrum is a frequently cited characteristic of invasive species, allowing them to thrive in a wide range of environments. Therefore, empirical studies comparing diet in invasive and native populations are necessary to understand dietary requirements, dietary flexibility, and the associated impacts of invasive species. METHODS: In this study, we compared the diet of populations of the African clawed frog, Xenopus laevis in its native range, with several areas where it has become invasive. Each prey category detected in stomach contents was assigned to an ecological category, allowing a comparison of the diversity of ecological traits among the prey items in the diet of native and introduced populations. The comparison of diets was also performed using evenness as a niche breadth index on all sampled populations, and electivity as a prey selection index for three out of the six sampled populations. RESULTS: Our results showed that diet breadth could be either narrow or broad in invasive populations. According to diet and prey availability, zooplankton was strongly preferred in most cases. In lotic environments, zooplankton was replaced by benthic preys, such as ephemeropteran larvae. DISCUSSION: The relative proportions of prey with different ecological traits, and dietary variability within and between areas of occurrence, suggest that X. laevis is a generalist predator in both native and invasive populations. Shifts in the realized trophic niche are observed, and appear related to resource availability. Xenopus laevis may strongly impact aquatic ecosystems because of its near complete aquatic lifestyle and its significant consumption of key taxa for the trophic relationships in ponds.

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Species referenced: Xenopus laevis
Genes referenced: pigy

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References [+] :

Broennimann, Evidence of climatic niche shift during biological invasion. 2007, Pubmed

	Figure 1. Principal components of the diet of the native (South Africa) and invasive populations of Xenopus laevis, with prey categories as individuals (dots, squares, triangles and crosses) and populations as variables (black arrows).
	Figure 2. Occurrence of the main ecological traits among the native population (South Africa) and the five populations of Xenopus laevis.Terrestrial prey (black), benthic prey (dark blue), nektonic items (sky blue) and planktonic prey (cyan).
	Figure 3. Niche breadth calculated for diet data in native and colonized ranges of Xenopus laevis.Calculated with the Evenness J′ (A) and relationship between J′ and the number of sites NS used in localities (B).
	Figure 4. Electivity index for each aquatic prey category consumed in the native population of Xenopus laevis in South Africa (brown) and the invasive populations of Wales (dark-orange) and France (light-orange).