Does living in streams with fish involve a cost of induced morphological defences?

2003 ◽  
Vol 81 (11) ◽  
pp. 1825-1828 ◽  
Author(s):  
Jonas Dahl ◽  
Barbara L Peckarsky
Keyword(s):  
Brook Trout ◽  
Chemical Cues ◽  
Additional Data ◽  
Field Survey ◽  
Larval Mortality ◽  
Negative Relationship ◽  
Relative Length ◽  
Inducible Defences ◽  
Morphological Defences ◽  
Morphological Defence

Previous studies have shown that chemical cues from brook trout (Salvelinus fontinalis) induce relatively longer caudal filaments and heavier exoskeletons in the mayfly Drunella coloradensis. These characters constitute morphological defences that reduce larval mortality from brook trout predation. There is also a potential fitness cost of living in streams with trout, as D. coloradensis females emerge at smaller sizes from streams with fish compared with females in streams without fish. In this study, we obtained additional data to evaluate the hypothesis that these costs of living in streams with fish could be attributed to inducible defences. A field survey of seven different streams showed that mature (black wing pad) female larvae from streams with fish invested a smaller proportion of their body mass in eggs than females maturing in streams without fish. Furthermore, a negative relationship between female allocation to eggs and to morphological defence characters (relative length of the caudal filament) provides evidence of a cost of inducible defences in this species.

scholarly journals Express yourself: bold individuals induce enhanced morphological defences

2014 ◽  
Vol 281 (1776) ◽  
pp. 20132703 ◽  
Author(s):  
Kaj Hulthén ◽  
Ben B. Chapman ◽  
P. Anders Nilsson ◽  
Johan Hollander ◽  
Christer Brönmark
Keyword(s):  
Crucian Carp ◽  
Personality Types ◽  
Interindividual Variation ◽  
Behavioural Plasticity ◽  
Inducible Defences ◽  
Morphological Defences ◽  
Risky Behaviours ◽  
Morphological Defence ◽  
Considerable Interindividual Variation ◽  
Defence Strategies

Organisms display an impressive array of defence strategies in nature. Inducible defences (changes in morphology and/or behaviour within a prey's lifetime) allow prey to decrease vulnerability to predators and avoid unnecessary costs of expression. Many studies report considerable interindividual variation in the degree to which inducible defences are expressed, yet what underlies this variation is poorly understood. Here, we show that individuals differing in a key personality trait also differ in the magnitude of morphological defence expression. Crucian carp showing risky behaviours (bold individuals) expressed a significantly greater morphological defence response when exposed to a natural enemy when compared with shy individuals. Furthermore, we show that fish of different personality types differ in their behavioural plasticity, with shy fish exhibiting greater absolute plasticity than bold fish. Our data suggest that individuals with bold personalities may be able to compensate for their risk-prone behavioural type by expressing enhanced morphological defences.

scholarly journals Knowing the Enemy: Inducible Defences in Freshwater Zooplankton

Diversity ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 147 ◽  
Author(s):  
Patricia Diel ◽  
Marvin Kiene ◽  
Dominik Martin-Creuzburg ◽  
Christian Laforsch
Keyword(s):  
Life History ◽  
Chemical Cues ◽  
Prey Species ◽  
Inducible Defences ◽  
Animal Kingdom ◽  
Predator Species ◽  
Freshwater Zooplankton ◽  
Taxonomic Range ◽  
Set Up ◽  
Made In

Phenotypic plasticity in defensive traits is an appropriate mechanism to cope with the variable hazard of a frequently changing predator spectrum. In the animal kingdom these so-called inducible defences cover the entire taxonomic range from protozoans to vertebrates. The inducible defensive traits range from behaviour, morphology, and life-history adaptations to the activation of specific immune systems in vertebrates. Inducible defences in prey species play important roles in the dynamics and functioning of food webs. Freshwater zooplankton show the most prominent examples of inducible defences triggered by chemical cues, so-called kairomones, released by predatory invertebrates and fish. The objective of this review is to highlight recent progress in research on inducible defences in freshwater zooplankton concerning behaviour, morphology, and life-history, as well as difficulties of studies conducted in a multipredator set up. Furthermore, we outline costs associated with the defences and discuss difficulties as well as the progress made in characterizing defence-inducing cues. Finally, we aim to indicate further possible routes in this field of research and provide a comprehensive table of inducible defences with respect to both prey and predator species.

Interaction between competitors and predators and its effects on morphological and behavioural defences in Scinax nasicus tadpoles

Behaviour ◽  
2013 ◽  
Vol 150 (8) ◽  
pp. 921-937 ◽  
Author(s):  
Valeria I. Gómez ◽  
Arturo I. Kehr
Keyword(s):  
Growth Rate ◽  
Experimental Design ◽  
Growth And Development ◽  
Chemical Cues ◽  
Development Rate ◽  
Larval Morphology ◽  
Induced Defences ◽  
Morphological Defences ◽  
Growth Development ◽  
Determinant Factor

Predation affects the behaviour of organisms, and the number of conspecifics can influence the perception of predation risk. Two main types of traits, morphological and behavioural, are involved in the induced defences of many organisms. Here, we examined the influence of chemical cues of the predators Belostoma elongatum (Hemiptera, Belostomatidae) and Moenkhausia dichroura (Characiformes, Characidae) on the morphology, growth, development and activity of Scinax nasicus larvae. Our main goal was to determine whether the investment in morphological or behavioural defences varied according to the number of conspecifics and to the chemical cues of predators. To this end, we performed two experiments under microcosm conditions. In experiment 1, we determined morphological defences in tadpoles by analysing changes in morphology, growth rate and development rate, whereas in experiment 2, we determined behavioural defences by analysing changes in the activity of tadpoles. The experimental design consisted of two tadpole densities, with and without chemical cues of predators. We found that: (1) larval morphology, growth and development were significantly affected by density; (2) the chemical cues of the predators did not influence the morphology, growth or development of tadpoles; (3) tadpoles at high densities were more active than those at low densities; (4) tadpoles decreased the activity in the presence of chemical cues of M. dichroura; and (5) tadpoles increased the activity in the presence of chemical cues of B. elongatum. Our results suggest that density is a determinant factor of tadpole morphology of and that Scinax nasicus larvae respond to predators with behavioural defences, which vary according to the type of predator.

scholarly journals Invasive predatory crayfish do not trigger inducible defences in tadpoles

2011 ◽  
Vol 278 (1723) ◽  
pp. 3364-3370 ◽  
Author(s):  
Ivan Gomez-Mestre ◽  
Carmen Díaz-Paniagua
Keyword(s):  
Invasive Species ◽  
Chemical Cues ◽  
Indigenous Species ◽  
Green Frog ◽  
Inducible Defences ◽  
Defensive Responses ◽  
Invasive Predator ◽  
Induced Defences ◽  
Invasive Crayfish ◽  
Cue Recognition

Invasive species cause deep impacts on ecosystems worldwide, contributing to the decline and extinction of indigenous species. Effective defences against native biological threats in indigenous species, whether structural or inducible, often seem inoperative against invasive species. Here, we show that tadpoles of the Iberian green frog detect chemical cues from indigenous predators (dragonfly nymphs) and respond by reducing their activity and developing an efficient defensive morphology against them (increased tail depth and pigmentation). Those defensive responses, however, were not activated against a highly damaging invasive predator (red swamp crayfish). Induced defences increased tadpole survival when faced against either indigenous dragonflies or invasive crayfish, so its inactivation in the presence of the invasive predator seems to be due to failure in cue recognition. Furthermore, we tested for local adaptation to the invasive predator by comparing individuals from ponds either exposed to or free from crayfish. In both cases, tadpoles failed to express inducible defences against crayfish, indicating that ca 30 years of contact with the invasive species (roughly 10–15 frog generations) have been insufficient for the evolution of recognition of invasive predator cues.

Threat-sensitive predator avoidance by slimy sculpins: understanding the importance of visual versus chemical information

2001 ◽  
Vol 79 (5) ◽  
pp. 867-873 ◽  
Author(s):  
Douglas P Chivers ◽  
Reehan S Mirza ◽  
Pamela J Bryer ◽  
Joseph M Kiesecker
Keyword(s):  
Field Experiment ◽  
Brook Trout ◽  
Predator Avoidance ◽  
Visual Cues ◽  
Laboratory Experiments ◽  
Chemical Cues ◽  
Salvelinus Fontinalis ◽  
Chemical Information ◽  
Cottus Cognatus ◽  
Predation Threat

The supposition that prey animals assess and behave flexibly in response to different degrees of predation threat is known as the threat-sensitive predator avoidance hypothesis. We completed a series of field and laboratory experiments to examine whether slimy sculpins (Cottus cognatus) exhibit threat-sensitive predator avoidance when exposed to sympatric predatory brook trout (Salvelinus fontinalis). In a field experiment we caged small and large trout in similar habitats and found that sculpins avoided areas containing trout that were large enough to pose a threat to them, but did not avoid areas containing trout that were small and hence not a threat. In a series of laboratory experiments we found that sculpins showed threat-sensitive predator avoidance when they could assess the predator visually. However, when only chemical cues from the predator were presented, sculpins responded to the predator regardless of its size. Chemical cues seem to function to warn the sculpin that the predator is in the vicinity, but visual cues are needed in order to accurately assess the risk posed by the predator.

scholarly journals New records of Darevskia armeniaca (Méhely, 1909) and Darevskia valentini (Boettger, 1892) (Squamata, Sauria, Lacertidae) from Armenia and updated geographic distribution maps

Check List ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 21-31
Author(s):  
Varos G. Petrosyan ◽  
Fedor A. Osipov ◽  
Vladimir V. Bobrov ◽  
Natalia N. Dergunova ◽  
Felix D. Danielyan ◽  
...  
Keyword(s):  
Geographic Distribution ◽  
Additional Data ◽  
Field Survey ◽  
New Records ◽  
Reticulate Evolution ◽  
Hybrid Speciation ◽  
Bisexual Species ◽  
Distribution Maps

During field survey in 2018, we recorded in Armenia the occurrences of the parthenogenetic lizard Darevskia armeniaca and its “paternal” bisexual species D. valentini. Based on our new data and records taken from publications and museums, we update the distribution maps of these species. The new records expand the geographical boundaries of sympatric habitats of these species and provide additional data for understanding the mechanisms of reticulate evolution and hybrid speciation.

scholarly journals The palliative function of climate change denial is stronger in more exposed countries

2020 ◽  
Author(s):  
Márton Hadarics
Keyword(s):  
Climate Change ◽  
Additional Data ◽  
Multilevel Models ◽  
Defense Mechanism ◽  
Local Level ◽  
Negative Relationship ◽  
Social Survey ◽  
Climate Change Denial ◽  
Low Levels ◽  
Representative Samples

In our multinational study, we tested whether the palliative effect of climate change denialdepends on the local level of climate change exposure. Building upon the literature of ecoanxiety and the palliative function of ideological beliefs, we assumed that the acknowledgement of climate change intensifies eco-anxiety while climate change denial eases it. More importantly, we also assumed that the extent of this ease is larger in countries beingmore threatened by the harmful consequences of climate change. To test this assumption, weanalyzed data collected from representative samples of 23 European countries withinEuropean Social Survey Programme, and additional data on the actual exposure of thesecountries to the effects of climate change. Results of our multilevel models showed thatclimate change denial is related to lower eco-anxiety, and this negative relationship is stronger at high (vs. low) levels of climate change exposure. Our results support the general principle stating that the harsher reality is, the larger emotional benefit can be achieved by its distorted perception and denial. This psychological defense mechanism can partly explain why many people are reluctant to fight against climate change even in countries that are threatened by it.

scholarly journals Costs and benefits of toxin production in a dinoflagellate

2020 ◽  
Author(s):  
Fredrik Ryderheim ◽  
Erik Selander ◽  
Thomas Kiørboe
Keyword(s):  
Chemical Cues ◽  
Toxin Production ◽  
Inducible Defences ◽  
Costs And Benefits ◽  
Alexandrium Minutum ◽  
Carbon And Nitrogen ◽  
Trade Offs ◽  
To Come ◽  
Carbon And Nitrogen Content ◽  
Different Levels

AbstractMany phytoplankton respond to chemical cues from grazers by upregulating defensive capabilities. Inducible defences like these are often assumed to come at a cost to the organism, but these trade-offs have not been experimentally established. A reason for this may be that costs only become evident under resource limiting conditions. Here, we exposed the toxin-producing dinoflagellate Alexandrium minutum to chemical cues from copepods under different levels of nitrogen limitation. Induced cells had higher cellular toxin content and a larger fraction of the cells were rejected by a copepod, demonstrating the clear benefits of toxin production. Induced cells also had a higher carbon and nitrogen content, despite an up to 25% reduction in cell size. Unexpectedly, induced cells seemed to grow faster than controls, likely owing to a higher nutrient affinity due to reduced size. We thus found no clear trade-offs, rather the opposite. However, we argue that indirect ecological costs that do not manifest under laboratory conditions are important and that the induction of toxins specific to particular defences prevents the cells from constantly synthesizing the large array of secondary metabolites that they are capable of producing.

Is the Personal Always Political?

2017 ◽  
Vol 38 (3) ◽  
pp. 133-143 ◽  
Author(s):  
Danny Osborne ◽  
Yannick Dufresne ◽  
Gregory Eady ◽  
Jennifer Lees-Marshment ◽  
Cliff van der Linden
Keyword(s):  
Survey Data ◽  
National Survey ◽  
Negative Relationship ◽  
Openness To Experience ◽  
Political Sophistication ◽  
Knowledge Based

Abstract. Research demonstrates that the negative relationship between Openness to Experience and conservatism is heightened among the informed. We extend this literature using national survey data (Study 1; N = 13,203) and data from students (Study 2; N = 311). As predicted, education – a correlate of political sophistication – strengthened the negative relationship between Openness and conservatism (Study 1). Study 2 employed a knowledge-based measure of political sophistication to show that the Openness × Political Sophistication interaction was restricted to the Openness aspect of Openness. These studies demonstrate that knowledge helps people align their ideology with their personality, but that the Openness × Political Sophistication interaction is specific to one aspect of Openness – nuances that are overlooked in the literature.

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