scholarly journals Size-dependent functional response of Xenopus laevis feeding on mosquito larvae

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5813 ◽  
Author(s):  
Corey J. Thorp ◽  
Mhairi E. Alexander ◽  
James R. Vonesh ◽  
John Measey
Keyword(s):  
Xenopus Laevis ◽  
Functional Response ◽  
Handling Time ◽  
Mosquito Larvae ◽  
Agricultural Pests ◽  
Food Web Structure ◽  
Predator Prey ◽  
Predator Attack ◽  
Considerable Individual Variation ◽  
And Function

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.

scholarly journals Size-dependent functional response of Xenopus laevis on mosquito larvae

2018 ◽  
Author(s):  
Corey J Thorp ◽  
Mhairi E Alexander ◽  
James R Vonesh ◽  
John Measey
Keyword(s):  
Body Size ◽  
Xenopus Laevis ◽  
Functional Response ◽  
Handling Time ◽  
Mosquito Larvae ◽  
Agricultural Pests ◽  
Food Web Structure ◽  
Predator Prey ◽  
Predator Attack ◽  
Considerable Individual Variation

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 size. 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 (15-30mm snout-vent length), medium (50-60mm) and large (105-120mm), 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 show that functional response of X. laevis changed with size: small predators exhibited a Type II response, while medium and large predators exhibited Type III responses. Both functional response and behavioural data showed an inversely proportional relationship between predator attack rate and predator size. Small and medium predators had highest and lowest handling time respectively. That the functional response changed 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 be a misrepresentation of the predator’s potential impact on a prey population.

scholarly journals Size-dependent functional response of Xenopus laevis on mosquito larvae

2018 ◽  
Author(s):  
Corey J Thorp ◽  
Mhairi E Alexander ◽  
James R Vonesh ◽  
John Measey
Keyword(s):  
Body Size ◽  
Xenopus Laevis ◽  
Functional Response ◽  
Handling Time ◽  
Mosquito Larvae ◽  
Agricultural Pests ◽  
Food Web Structure ◽  
Predator Prey ◽  
Predator Attack ◽  
Considerable Individual Variation

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 size. 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 (15-30mm snout-vent length), medium (50-60mm) and large (105-120mm), 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 show that functional response of X. laevis changed with size: small predators exhibited a Type II response, while medium and large predators exhibited Type III responses. Both functional response and behavioural data showed an inversely proportional relationship between predator attack rate and predator size. Small and medium predators had highest and lowest handling time respectively. That the functional response changed 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 be a misrepresentation of the predator’s potential impact on a prey population.

scholarly journals Rosenzweig-Macaurther Model with Holling type II Predator Functional Response for Constant Delayed Migration

2019 ◽  
pp. 1-14
Author(s):  
Apima B. Samuel ◽  
Lawi O. George ◽  
Nthiiri J. Kagendo
Keyword(s):  
Stability Analysis ◽  
Functional Response ◽  
Food Source ◽  
Type Ii ◽  
Human Settlement ◽  
Natural Habitats ◽  
Predator Prey ◽  
Migration Rates ◽  
Predator Attack ◽  
Predator Prey Models

Predator-prey models describe the interaction between two species, the prey which serves as a food source to the predator. The migration of the prey for safety reasons after a predator attack and the predator in search of food, from a patch to another may not be instantaneous. In this paper, a Rosenzweig-MacAurther model with a Holling-type II predator functional response and time delay in the migration of both species is developed and analysed. Stability analysis of the system shows that depending on the prey growth and prey migration rates either both species go to extinction or co-exist. Numerical simulations show that a longer delay in the migration of the species leads makes the model to stabilize at a slower rate compared to when the delay is shorter. Relevant agencies likethe Kenya Wildlife Service should address factors that slow down migration of species, for example, destruction of natural habitats for human settlement and activities, which may cause delay in migration.

scholarly journals Inferring Size-Based Functional Responses From the Physical Properties of the Medium

2022 ◽  
Vol 9 ◽  
Author(s):  
Sébastien M. J. Portalier ◽  
Gregor F. Fussmann ◽  
Michel Loreau ◽  
Mehdi Cherif
Keyword(s):  
Physical Properties ◽  
Functional Response ◽  
Aquatic Organisms ◽  
Handling Time ◽  
Real Data ◽  
Physical Factors ◽  
Functional Responses ◽  
Predator Prey ◽  
Natural Systems ◽  
Physical Principles

First derivations of the functional response were mechanistic, but subsequent uses of these functions tended to be phenomenological. Further understanding of the mechanisms underpinning predator-prey relationships might lead to novel insights into functional response in natural systems. Because recent consideration of the physical properties of the environment has improved our understanding of predator-prey interactions, we advocate the use of physics-based approaches for the derivation of the functional response from first principles. These physical factors affect the functional response by constraining the ability of both predators and prey to move according to their size. A physics-based derivation of the functional response should thus consider the movement of organisms in relation to their physical environment. One recent article presents a model along these criteria. As an initial validation of our claim, we use a slightly modified version of this model to derive the classical parameters of the functional response (i.e., attack rate and handling time) of aquatic organisms, as affected by body size, buoyancy, water density and viscosity. We compared the predictions to relevant data. Our model provided good fit for most parameters, but failed to predict handling time. Remarkably, this is the only parameter whose derivation did not rely on physical principles. Parameters in the model were not estimated from observational data. Hence, systematic discrepancies between predictions and real data point immediately to errors in the model. An added benefit to functional response derivation from physical principles is thus to provide easy ways to validate or falsify hypotheses about predator-prey relationships.

scholarly journals Prey body mass and richness underlie the persistence of a top predator

2019 ◽  
Vol 286 (1902) ◽  
pp. 20190622 ◽  
Author(s):  
Laura Melissa Guzman ◽  
Diane S. Srivastava
Keyword(s):  
Food Web ◽  
Functional Response ◽  
Body Mass ◽  
Prey Species ◽  
Handling Time ◽  
Predator Prey ◽  
Prey Diversity ◽  
Prey Interaction ◽  
Range Of Values ◽  
Food Web Model

Predators and prey often differ in body mass. The ratio of predator to prey body mass influences the predator's functional response (how consumption varies with prey density), and therefore, the strength and stability of the predator–prey interaction. The persistence of food chains is maximized when prey species are neither too big nor too small relative to their predator. Nonetheless, we do not know if (i) food web persistence requires that all predator–prey body mass ratios are intermediate, nor (ii) if this constraint depends on prey diversity. We experimentally quantified the functional response for a single predator consuming prey species of different body masses. We used the resultant allometric functional response to parametrize a food web model. We found that predator persistence was maximized when the minimum prey size in the community was intermediate, but as prey diversity increased, the minimum body size could take a broader range of values. This last result occurs because of Jensen's inequality: the average handling time for multiple prey of different sizes is higher than the handling time of the average sized prey. Our results demonstrate that prey diversity mediates how differences between predators and prey in body mass determine food web stability.

Combining scientific and fishers’ knowledge to co-create indicators of food web structure and function

2019 ◽  
Author(s):  
Jacob W Bentley ◽  
David E Hines ◽  
Stuart R Borrett ◽  
Natalia Serpetti ◽  
Gema Hernandez-Milian ◽  
...  
Keyword(s):  
Food Web ◽  
Integrated Management ◽  
Irish Sea ◽  
Food Web Structure ◽  
Predator Prey ◽  
Before And After ◽  
Commercial Species ◽  
Ecosystem Level ◽  
The Irish Sea ◽  
And Function

Abstract In this study, we describe the approach taken by the International Council for the Exploration of the Seas Irish Sea benchmark working group (WKIrish), to co-create diet information for six commercial species using fishers' and scientists knowledge and incorporate it into an existing Ecopath food web model of the Irish Sea. To understand how the co-created diet information changed the model we compared a suite of food web indicators before and after the addition of fishers' knowledge (FK). Of the 80 predator–prey interactions suggested by fishers during workshops, 50 were already included in the model. Although the small number of changes made to the model structure had an insignificant impact on the ecosystem-level indicators, indicators of species hierarchical importance and mixed trophic impacts were significantly changed, particularly for commercial species. FK heightened the importance of discards as a source of food for rays, plaice, and whiting and reduced the importance of cod, toothed whales, and plaice as structural components of the food web. FK therefore led to changes which will influence pairwise advice derived from the model. We conclude by providing lessons from WKIrish which we believe were key to the positive co-production experience and development of integrated management.

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