scholarly journals Predation risk indirectly enhances survival of seaweed recruits but not intraspecific competition in an intermediate herbivore species

2011 ◽  
Vol 99 (3) ◽  
pp. 807-817 ◽  
Author(s):  
Markus Molis ◽  
Inken Preuss ◽  
Annika Firmenich ◽  
Julius Ellrich
Keyword(s):  
Predation Risk ◽  
Intraspecific Competition ◽  
Herbivore Species

scholarly journals The interactive effects of competition and predation risk on dispersal in an insect

2014 ◽  
Vol 10 (6) ◽  
pp. 20140287 ◽  
Author(s):  
Celina B. Baines ◽  
Shannon J. McCauley ◽  
Locke Rowe
Keyword(s):  
Predation Risk ◽  
Intraspecific Competition ◽  
Aquatic Insects ◽  
Ecological Factors ◽  
Factorial Experiment ◽  
Interactive Effects ◽  
Factorial Experiments ◽  
Evolutionary Processes ◽  
Factors Affecting ◽  
Ecological Conditions

Dispersal dynamics have significant consequences for ecological and evolutionary processes. Previous work has demonstrated that dispersal can be context-dependent. However, factors affecting dispersal are typically considered in isolation, despite the probability that individuals make dispersal decisions in response to multiple, possibly interacting factors. We examined whether two ecological factors, predation risk and intraspecific competition, have interactive effects on dispersal dynamics. We performed a factorial experiment in mesocosms using backswimmers ( Notonecta undulata ), flight-capable, semi-aquatic insects. Emigration rates increased with density, and increased with predation risk at intermediate densities; however, predation had minimal effects on emigration at high and low densities. Our results indicate that factorial experiments may be required to understand dispersal dynamics under realistic ecological conditions.

scholarly journals Animal body size distribution influences the ratios of nutrients supplied to plants

2020 ◽  
Vol 117 (36) ◽  
pp. 22256-22263 ◽  
Author(s):  
Elizabeth le Roux ◽  
Laura S. van Veenhuisen ◽  
Graham I. H. Kerley ◽  
Joris P. G. M. Cromsigt
Keyword(s):  
Body Size ◽  
Predation Risk ◽  
Size Distribution ◽  
Food Availability ◽  
N:P Ratio ◽  
Nitrogen And Phosphorus ◽  
Herbivore Community ◽  
Herbivore Species ◽  
Herbivore Communities ◽  
Average Body

Nutrients released through herbivore feces have the potential to influence plant-available nutrients and affect primary productivity. However, herbivore species use nutrients in set stoichiometric ratios that vary with body size. Such differences in the ratios at which nutrients are used leads to differences in the ratios at which nutrients are deposited through feces. Thus, local environmental factors that affect the average body size of an herbivore community (such as predation risk and food availability) influence the ratios at which fecal nutrients are supplied to plants. Here, we assess the relationship between herbivore body size and the nitrogen-to-phosphorus ratios of herbivore feces. We examine how shifts in the average body size of an herbivore community alter the ratios at which nitrogen and phosphorus are supplied to plants and test whether such differences in the stoichiometry of nutrient supply propagate through plants. We show that dung from larger-bodied herbivores contain lower quantities of phosphorus per unit mass and were higher in N:P ratio. We demonstrate that spatial heterogeneity in visibility (a proxy for predation risk and/or food availability) and rainfall (a proxy for food availability), did not affect the overall amount of feces deposited but led to changes in the average body size of the defecating community. Feces deposited in areas of higher rainfall and reduced visibility originated from larger herbivores and were higher in N:P ratios. This indicates that processes that change the size distribution of herbivore communities, such as predation or size-biased extinction, have the potential to alter the nutrient landscape for plants.

scholarly journals Host-mediated, cross-generational intraspecific competition in a herbivore species

2021 ◽  
Vol 1 ◽  
Author(s):  
Bastien Castagneyrol ◽  
Inge van Halder ◽  
Yasmine Kadiri ◽  
Laura Schillé ◽  
Hervé Jactel
Keyword(s):  
Intraspecific Competition ◽  
Herbivore Species

Elevated nest predation risk promotes offspring size variation in birds with prolonged parental care.

2019 ◽  
Author(s):  
Gretchen F. Wagner ◽  
Emeline Mourocq ◽  
Michael Griesser
Keyword(s):  
Predation Risk ◽  
Reproductive Cycle ◽  
Perceived Risk ◽  
Nest Predation ◽  
Bird Species ◽  
Size Variation ◽  
Egg Laying ◽  
Offspring Size ◽  
Natural Predation ◽  
Risk Spreading

Predation of offspring is the main cause of reproductive failure in many species, and the mere fear of offspring predation shapes reproductive strategies. Yet, natural predation risk is ubiquitously variable and can be unpredictable. Consequently, the perceived prospect of predation early in a reproductive cycle may not reflect the actual risk to ensuing offspring. An increased variance in investment across offspring has been linked to breeding in unpredictable environments in several taxa, but has so far been overlooked as a maternal response to temporal variation in predation risk. Here, we experimentally increased the perceived risk of nest predation prior to egg-laying in seven bird species. Species with prolonged parent-offspring associations increased their intra-brood variation in egg, and subsequently offspring, size. High risk to offspring early in a reproductive cycle can favour a risk-spreading strategy particularly in species with the greatest opportunity to even out offspring quality after fledging.

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