Prey type and temperature influence functional responses of threatened endemic Cape Floristic Ecoregion fishes

Broom, Casey J.; South, Josie; Weyl, Olaf L. F.

doi:10.1007/s10641-021-01111-w

Cited by 6 publications

(8 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the lower density of females at high temperatures may free up males and juveniles to forage at high temperatures. Our results on the temperature dependence of space clearance rates contrast with experimental examinations of temperature effects on functional responses in which individuals are often exposed to a uniform temperature and are typically in homogeneous arenas with no potential temperature refuges (Archer et al, 2019;Broom et al, 2021;Islam et al, 2021;Russell et al, 2021) This difference has potentially strong implications for the general way in which we conceive of temperature altering predator-prey interactions and thus food web dynamics given changing climates. Using more realistic temperature regimes and arenas in experiments will allow us to understand whether our result is unique to zebra jumping spiders or potentially more widespread in terrestrial ectotherms.…”

Section: Discussioncontrasting

confidence: 63%

Quantifying predator functional responses under field conditions reveals interactive effects of temperature and interference with sex and stage

Coblentz

Squires

Uiterwaal

et al. 2021

Preprint

View full text Add to dashboard Cite

Predator functional responses describe predator feeding rates and are a core component of predator-prey theory. Although originally defined as the relationship between predator feeding rates and prey densities, it is now well known that predator functional responses are shaped by a multitude of factors. Unfortunately, how these factors interact with one another remains unclear, as widely used laboratory methods for measuring functional responses are generally logistically constrained to examining a few factors simultaneously. Furthermore, it is also often unclear whether laboratory derived functional responses translate to field conditions. Our goal was to apply an observational approach for measuring functional responses to understand how sex/stage differences, temperature, and predator interference interact to influence the functional response of zebra jumping spiders on midges under natural conditions. We used field feeding surveys of jumping spiders to infer spider functional responses. We applied a Bayesian model averaging approach to estimate differences among sexes and stages of jumping spiders in their feeding rates and their dependencies on midge densities, temperature, and predator interference. We find that females exhibit the steepest functional responses on midges, followed by juveniles, and then males, despite males being larger than juveniles. We also find that sexes and stages differ in the temperature dependence of their space clearance (aka attack) rates. We find little evidence of temperature dependence in females, whereas we find some evidence for an increase in space clearance rate at high temperatures in males and juveniles. Interference effects on feeding rates were asymmetric with little effect of interference on male feeding rates, and effects of interference on females and juveniles depending on the stage/sex from which the interference originates. Our results illustrate the multidimensional nature of functional responses in natural settings and reveal how factors influencing functional responses can interact with one another through behavior and morphology. Further studies investigating the influence of multiple mechanisms on predator functional responses under field conditions will provide an increased understanding of the drivers of predator-prey interaction strengths and their consequences for communities and ecosystems.

show abstract

Section: Discussioncontrasting

confidence: 63%

Quantifying predator functional responses under field conditions reveals interactive effects of temperature and interference with sex and stage

Coblentz

Squires

Uiterwaal

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Laboratory experiments examining the effects of temperature typically occur in simplified arenas in which predators and prey are exposed to a constant temperature for the length of the feeding trial (e.g. Archer et al, 2019; Broom et al, 2021). This experimental design isolates the effects of temperature but prevents organisms from behaviourally thermoregulating by, for example, using thermal refugia as they might in the field (May, 1979).…”

Section: Introductionmentioning

confidence: 99%

Quantifying predator functional responses under field conditions reveals interactive effects of temperature and interference with sex and stage

Coblentz

Squires

Uiterwaal

et al. 2022

Journal of Animal Ecology

View full text Add to dashboard Cite

Predator functional responses describe predator feeding rates and are central to predator–prey theory. Originally defined as the relationship between predator feeding rates and prey densities, it is now well known that functional responses are shaped by a multitude of factors. However, much of our knowledge about how these factors influence functional responses is based on laboratory studies that are generally logistically constrained to examining only a few factors simultaneously and that have unclear links to the conditions organisms experience in the field. We apply an observational approach for measuring functional responses to understand how sex/stage differences, temperature and predator densities interact to influence the functional response of zebra jumping spiders on midges under natural conditions. We used field surveys of jumping spiders to infer their feeding rates and examine the relationships between feeding rates, sex/stage, midge density, predator density and temperature using generalized additive models. We then used the relationships supported by the models to fit parametric functional responses to the data. We find that feeding rates of zebra jumping spiders follow some expectations from previous laboratory studies such as increasing feeding rates with body size and decreasing feeding rates with predator densities. However, in contrast to previous results, our results also show a lack of temperature response in spider feeding rates and differential decreases in the feeding rates of females and juveniles with densities of different spider sexes/stages. Our results illustrate the multidimensional nature of functional responses in natural settings and reveal how factors influencing functional responses can interact with one another through behaviour and morphology. Further studies investigating the influence of multiple mechanisms on predator functional responses under field conditions will increase our understanding of the drivers of predator–prey interaction strengths and their consequences for communities and ecosystems.

show abstract

“…DeLong, 2020; Uszko et al, 2017). Importantly, species respond differently to temperature, in ways not always related to body size (Broom et al, 2021;Walker et al, 2020). In our case, each of the four predators has a different thermal niche, and their activity level and proportion of time spent foraging ( forage ) varies with temperature (B.…”

Section: Box 1 How To Empirically Estimate Parameter Valuesmentioning

confidence: 81%

“…For example, these interactions occur across a range of temperatures and it is well known that temperature alters functional responses and trophic interactions (Broom et al., 2021; da Silva Nunes et al., 2020; Davidson et al., 2021; Grigaltchik et al., 2012; Islam et al., 2021; Jalali et al., 2010; Rall et al., 2012; Uiterwaal & DeLong, 2020; Uszko et al., 2017). Importantly, species respond differently to temperature, in ways not always related to body size (Broom et al., 2021; Walker et al., 2020). In our case, each of the four predators has a different thermal niche, and their activity level and proportion of time spent foraging (

φ_{forage}

) varies with temperature (B. Feit & M. Jonsson, pers.…”

Section: A Worked‐through Examplementioning

confidence: 99%

“…Temperature can also affect handling time and mobility due to its effect on metabolism (e.g. Broom et al., 2021; da Silva Nunes et al., 2020; Jalali et al., 2010; Sentis et al., 2012; Vucic‐Pestic et al., 2011), but here we focus on the effect on foraging time as the driving factor affecting interaction strength. With field‐measured data on the optimum and standard deviation of each predator's thermal niche, we can as a first approximation, use the probability density function of a normal distribution to determine the effect of temperature (temp) on

φ_{forage}

(Rall et al., 2012):

φ_{forage} false(temp false) \propto \frac{1}{σ \sqrt{2 π}} e^{‐ \frac{1}{2} {()(, \frac{temp ‐ μ}{σ})}^{2}},

where temp is the temperature, μ is the species optimum temperature and σ is the standard deviation of the predator's temperature niche.…”

Section: A Worked‐through Examplementioning

confidence: 99%

See 1 more Smart Citation

Towards a modular theory of trophic interactions

et al. 2021

View full text Add to dashboard Cite

1. Species traits and environmental conditions determine the occurrence and strength of trophic interactions. If we understand the relationship between these factors and trophic interactions, we can make more accurate predictions and build better trophic-interaction models.2. We can compare traits and conditions by considering their effect on different parts (steps) of a trophic interaction, such as the steps search and pursuit. By linking traits to relevant steps, we can use these relationships to build trophicinteraction models. Currently, this is done ad hoc, defining steps based on the species and traits of interest. This makes it difficult to compare across traits and species and gain an overarching understanding of how traits and the environment drive trophic interactions.3. We present a comprehensive approach for the explicit choice of interaction steps and species traits or environmental conditions, which is readily integrated into existing models. The core of this framework is that it is modular; we present eight steps that occur in all trophic interactions and use them to build a modular, general dynamic model. When applying the framework, one explicitly selects only the most relevant steps and uses those to build a specific model. 4. To build our modular framework, we revisit and expand the functional and numerical response functions, dividing the trophic interaction into eight steps: (1) search, (2) prey detection, (3) attack decision, (4) pursuit, (5) subjugation, (6) ingestion, (7) digestion and (8) nutrient allocation. Together these steps form a general dynamical model where trophic interactions can be explicitly parameterized for multiple traits and environmental factors. We then concretize this approach by outlining how a specific community can be modelled by selecting key modules (steps) and parameterizing them for relevant factors. This we exemplify for a community of terrestrial arthropods using empirical data on body size and temperature responses.5. With species interactions at the core of community dynamics, our modular approach allows for quantification and comparisons of the importance of different steps, traits, and abiotic factors across ecosystems and trophic-interaction types, and provides a powerful tool for trait-based prediction of food-web structure and dynamics.

show abstract

Prey type and temperature influence functional responses of threatened endemic Cape Floristic Ecoregion fishes

Cited by 6 publications

References 49 publications

Quantifying predator functional responses under field conditions reveals interactive effects of temperature and interference with sex and stage

Quantifying predator functional responses under field conditions reveals interactive effects of temperature and interference with sex and stage

Quantifying predator functional responses under field conditions reveals interactive effects of temperature and interference with sex and stage

Towards a modular theory of trophic interactions

Contact Info

Product

Resources

About