Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
???displayArticle.abstract???
Predators can play an important role in regulating prey abundance and diversity, determining food web structure and function, and contributing to important ecosystem services, including the regulation of agricultural pests and disease vectors. Thus, the ability to predict predator impact on prey is an important goal in ecology. Often, predators of the same species are assumed to be functionally equivalent, despite considerable individual variation in predator traits known to be important for shaping predator-prey interactions, like body size. This assumption may greatly oversimplify our understanding of within-species functional diversity and undermine our ability to predict predator effects on prey. Here, we examine the degree to which predator-prey interactions are functionally homogenous across a natural range of predator body sizes. Specifically, we quantify the size-dependence of the functional response of African clawed frogs (Xenopus laevis) preying on mosquito larvae (Culex pipiens). Three size classes of predators, small (15-30 mm snout-vent length), medium (50-60 mm) and large (105-120 mm), were presented with five densities of prey to determine functional response type and to estimate search efficiency and handling time parameters generated from the models. The results of mesocosm experiments showed that type of functional response of X. laevis changed with size: small predators exhibited a Type II response, while medium and large predators exhibited Type III responses. Functional response data showed an inversely proportional relationship between predator attack rate and predator size. Small and medium predators had highest and lowest handling time, respectively. The change in functional response with the size of predator suggests that predators with overlapping cohorts may have a dynamic impact on prey populations. Therefore, predicting the functional response of a single size-matched predator in an experiment may misrepresent the predator's potential impact on a prey population.
Figure 1. Functional responses of X. laevis preying on mosquito larvae.(A) Functional responses of individual small (red), medium (blue) and large (green) size classes of X. leavis in different initial densities of mosquito larvae (per 500 l). Solid lines represent model curve and shaded areas represent 95% confidence intervals calculated by non-parametric bootstrapping. (B) Box plots and data points for each trial with small (red, open circles), medium (blue, closed circles) and large (green, closed triangles) size classes of X. leavis.
Figure 2. Search coefficient and handling time from functional response models.(A) Search coefficient (in seconds) and (B) handling time (in seconds) parameters derived from flexible functional response models for small, medium and large size classes of X. laevis. Points are original model values and error bars are bootstrapped 95% Confidence Intervals.
Asquith,
Effects of size and size structure on predation and inter-cohort competition in red-eyed treefrog tadpoles.
2012, Pubmed
Asquith,
Effects of size and size structure on predation and inter-cohort competition in red-eyed treefrog tadpoles.
2012,
Pubmed
Barr,
Occurrence and distribution of the Culex pipiens complex.
1967,
Pubmed
Brooks,
Predation, Body Size, and Composition of Plankton.
1965,
Pubmed
Brose,
Consumer-resource body-size relationships in natural food webs.
2006,
Pubmed
Courant,
Are invasive populations characterized by a broader diet than native populations?
2017,
Pubmed
,
Xenbase
De Villiers,
Overland movement in African clawed frogs (Xenopus laevis): empirical dispersal data from within their native range.
2017,
Pubmed
,
Xenbase
Englund,
Temperature dependence of the functional response.
2011,
Pubmed
Hassell,
The dynamics of arthropod predator-prey systems.
1978,
Pubmed
Jansson,
Terrestrial carbon and intraspecific size-variation shape lake ecosystems.
2007,
Pubmed
McCoy,
Predicting predation through prey ontogeny using size-dependent functional response models.
2011,
Pubmed
Measey,
Overland movement in African clawed frogs (Xenopus laevis): a systematic review.
2016,
Pubmed
,
Xenbase
Owen-Smith,
Predator-prey size relationships in an African large-mammal food web.
2008,
Pubmed
Persson,
Ontogenetic scaling of foraging rates and the dynamics of a size-structured consumer-resource model.
1998,
Pubmed
Rudolf,
Consequences of size structure in the prey for predator-prey dynamics: the composite functional response.
2008,
Pubmed
Samhouri,
Inter-cohort competition drives density dependence and selective mortality in a marine fish.
2009,
Pubmed
Schröder,
Invasion success depends on invader body size in a size-structured mixed predation-competition community.
2009,
Pubmed
Trexler,
How can the functional reponse best be determined?
1988,
Pubmed
Tucker,
Examining predator-prey body size, trophic level and body mass across marine and terrestrial mammals.
2014,
Pubmed
Turell,
Members of the Culex pipiens complex as vectors of viruses.
2012,
Pubmed
Vogt,
Competition and feeding ecology in two sympatric Xenopus species (Anura: Pipidae).
2017,
Pubmed
,
Xenbase
Vucic-Pestic,
Allometric functional response model: body masses constrain interaction strengths.
2010,
Pubmed
