scholarly journals Electrocommunication signals indicate motivation to compete during dyadic interactions of an electric fish

2021 ◽  
Author(s):  
Till Raab ◽  
Sercan Bayezit ◽  
Saskia Erdle ◽  
Jan Benda
Keyword(s):  
Body Size ◽  
Electric Fish ◽  
Relative Size ◽  
Limited Resources ◽  
Agonistic Interactions ◽  
Apteronotus Leptorhynchus ◽  
Communication Signals ◽  
Detailed Evaluation ◽  
Physical Attributes ◽  
Competition Behavior

Animals across species compete for limited resources. While in some species competition behavior is solely based on own abilities, others assess their opponents to facilitate these interactions. Using cues and communication signals, contestants gather information about their opponent, adjust their behavior accordingly, and can thereby avoid high costs of escalating fights. We tracked electrocommunication signals, in particular “rises”, and agonistic behaviors of the gymnotiform electric fish Apteronotus leptorhynchus instaged competition experiments. A larger body-size relative to the opponent was the sole significant predictor for winners. Sex and the frequency of the continuously emitted electric field were only mildly influencing competition outcome. In males, correlations of body-size and winning were stronger than in females and, especially when losing against females, communication and agonistic interactions were enhanced, hinting towards males being more motivated to compete. Fish that lost competitions emitted the majority of rises, whereby their quantity depended on the competitors’ relative size and sex. The emission of rises was costly since it provoked ritualized biting or chasing behaviors by the other fish. Despite winners being accurately predictable based on rise numbers already after the initial 25 minutes, losers continued to emit rises. The number of rises emitted by losers and the duration of chasing behaviors depended in similar ways on physical attributes of contestants. The detailed evaluation of these correlations hint towards A. leptorhynchus adjusting their competition behavior according to mutual assessment, where rises could signal a loser's motivation to continue assessment through ritualized fighting.

scholarly journals Electric fish use electrocommunication signals to fine tune relative dominance and access to resources

2021 ◽  
Author(s):  
Till Raab ◽  
Sercan Bayezit ◽  
Saskia Erdle ◽  
Jan Benda
Keyword(s):  
Electric Fish ◽  
Dominance Hierarchy ◽  
Dominance Rank ◽  
Relative Size ◽  
Access To Resources ◽  
Dominance Hierarchies ◽  
Communication Signals ◽  
Relative Dominance ◽  
Gymnotiform Fish ◽  
Fine Tune

AbstractSocial animals establish dominance hierarchies to regulate access to resources. Although communication signals could reduce costs in negotiating dominance, their detailed role and emergence in non-mammalian vertebrates is not well researched. We tracked electrocommunication signals and agonistic behaviors of the gymnotiform fish Apteronotus leptorhynchus in staged competition experiments. Subordinates emitted the majority of so called “rises” in dependence on the competitor’s relative size and sex. Rises provoked ritualized biting or chasing behaviors by dominant fish. Already after 25 minutes losers were accurately predictable based on rise numbers, but they continued to emit rises. We suggest the interplay between communication and aggression to fine tune relative dominance without questioning dominance rank. This communication system regulates the skewness of access to resources within a dominance hierarchy and allows A. leptorhynchus to populate neotropical rivers with high abundances.

Effect of phenology on agonistic competitive interactions between invasive and native sheet-web spiders

2016 ◽  
Vol 94 (6) ◽  
pp. 427-434 ◽  
Author(s):  
Jeremy D. Houser ◽  
Adam H. Porter ◽  
Howard S. Ginsberg ◽  
Elizabeth M. Jakob
Keyword(s):  
Competitive Advantage ◽  
Native Species ◽  
Negative Impact ◽  
Relative Size ◽  
Agonistic Interactions ◽  
Resident Species ◽  
The Third ◽  
Linyphia Triangularis ◽  
Size Interaction ◽  
Very High

The phenologies of introduced relative to native species can greatly influence the degree and symmetry of competition between them. The European spider Linyphia triangularis (Clerck, 1757) (Linyphiidae) reaches very high densities in coastal Maine (USA). Previous studies suggest that L. triangularis negatively affects native linyphiid species, with competition for webs as one mechanism. We documented phenological differences between L. triangularis and three native species that illustrate the potential for the reversal of size-based competitive advantage over the course of the year. To test whether relative size influences interaction outcome, we allowed a resident spider to build a web and then introduced an intruder. We examined whether the outcomes of agonistic interactions over the webs were influenced by the species of the resident (invasive or native), the relative size of the contestants, and the species × size interaction. We found that the importance of relative size differed among species. In interactions between L. triangularis and each of two native species, size played a greater role than resident species on the outcome of interactions, suggesting that competitive advantage reverses over the season based on phenology-related size differences. Linyphia triangularis had a negative impact on the third species regardless of relative size.

scholarly journals Changing the relative size of the body parts of Drosophila by selection

1962 ◽  
Vol 3 (2) ◽  
pp. 169-180 ◽  
Author(s):  
Forbes W. Robertson
Keyword(s):  
Body Size ◽  
Relative Size ◽  
Cell Number ◽  
High Ratio ◽  
Growth Patterns ◽  
The Body ◽  
Mass Selection ◽  
Body Parts ◽  
Wing Size ◽  
Thorax Length

1. Mass selection for both high- and low-ratio of wing to thorax length has been carried out on a population of Drosophila melanogaster. The response to selection was immediate and sustained. When the experiment was stopped after ten generations, the wing area in the two selected lines differed by about 30%. The heritability estimate worked out at 0·56 ± 0·08.2. Thorax length remained comparatively unchanged during selection nor was there any change in wing shape. There was some evidence of assymetry of response since there was a relatively greater change in favour of smaller rather than larger size.3. The tibia length of all pairs of legs showed correlated changes so that the lines with larger or smaller wing sizes had also larger and smaller legs.4. The normal allometric relation between wing and thorax length, associated with variation in body-size, apparently also changed, so that for a given change in thorax length there was a greater or smaller proportional change in wing size in the high- or low-ratio lines.5. The changes in relative wing size are due to changes in cell number.6. It is suggested that the genetic changes due to selection act in the early pupal period when the imaginal discs are undergoing differentiation and proliferation to form imaginal hypoderm and appendages.7. Tests of genetic behaviour failed to show any departure from additivity in crosses which involved the unselected population and the high-ratio line. But highly significant departures existed in the cross to the low-ratio line. Relatively smaller wing size behaves as largely recessive. Stability of the normal wing/thorax ratio involves dominance and probably also epistasis. The genetic properties of the relative size of the appendage are apparently similar to those which characterize body-size as a whole.8. It is suggested that selection provides a valuable tool for studying the constancy or lability of the growth patterns which determine morphology.

scholarly journals Quantitative genetic analysis of brain size variation in sticklebacks: support for the mosaic model of brain evolution

2015 ◽  
Vol 282 (1810) ◽  
pp. 20151008 ◽  
Author(s):  
Kristina Noreikiene ◽  
Gábor Herczeg ◽  
Abigél Gonda ◽  
Gergely Balázs ◽  
Arild Husby ◽  
...  
Keyword(s):  
Body Size ◽  
Brain Size ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Relative Size ◽  
Strong Support ◽  
Brain Evolution ◽  
Brain Regions ◽  
Independent Evolution ◽  
Mosaic Model

The mosaic model of brain evolution postulates that different brain regions are relatively free to evolve independently from each other. Such independent evolution is possible only if genetic correlations among the different brain regions are less than unity. We estimated heritabilities, evolvabilities and genetic correlations of relative size of the brain, and its different regions in the three-spined stickleback ( Gasterosteus aculeatus ). We found that heritabilities were low (average h 2 = 0.24), suggesting a large plastic component to brain architecture. However, evolvabilities of different brain parts were moderate, suggesting the presence of additive genetic variance to sustain a response to selection in the long term. Genetic correlations among different brain regions were low (average r G = 0.40) and significantly less than unity. These results, along with those from analyses of phenotypic and genetic integration, indicate a high degree of independence between different brain regions, suggesting that responses to selection are unlikely to be severely constrained by genetic and phenotypic correlations. Hence, the results give strong support for the mosaic model of brain evolution. However, the genetic correlation between brain and body size was high ( r G = 0.89), suggesting a constraint for independent evolution of brain and body size in sticklebacks.

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