Animal personality studies rely on collecting repeated behavioural data either in the field or under laboratory conditions. Conditions in the field should be far less stable than controlled ...laboratory conditions, and hence represent a potential source of variation in behaviour. Here we report on the first experiment to our knowledge that formally compares the repeatability of identical behaviours in the laboratory and the field, and across the transition from laboratory to field. Using a design that controls for observation number we compared two groups of sea anemones, observed across two experimental phases, either (1) in the field followed by the laboratory or (2) in the laboratory only. We analysed differences in behaviour across a range of levels including repeatability and its between- and within-individual variance components. Although mean startle response durations varied between the laboratory and field, there was no significant difference in repeatability across situations. Within-individual variance differed between the two periods of the experiment for animals observed only in the laboratory but this effect was not present for those that transitioned from field to laboratory. Furthermore, the rank order of individual responses was stable for animals observed only in the laboratory but changed for those that transitioned from field to laboratory. These results show that although repeatability estimates in the laboratory can yield results like those obtained in the field, the underlying components of consistent variation in behaviour might be influenced by an interaction between prior experiences and the current situation in which the animals are observed.
•We compared behaviour in sea anemones in the laboratory and the field.•We analysed repeatability and its between- and within-individual variance components.•Mean startle response durations differ between the laboratory and field.•Within-individual variation but not repeatability differed between situations.•Consistent variation in behaviour might be influenced by prior experiences.
Equinatoxin II (EqT II) is a ~20kDa cytotoxic and cytolytic protein isolated from the sea anemone Actinia equina. When injected intravenously to rats the toxin has been reported to produce a rapid ...cardiorespiratory arrest. In the present study, we show that EqT II increases the tension of spontaneous contractions and induces long-lasting contracture of guinea pig taenia caeci muscle. In taenia caeci, dissociated smooth muscle cells, microspectrofluorometric measurements, using the Ca super(2) super(+) indicator fura-2/AM, revealed that the toxin causes a marked increase in intracellular calcium, provided Ca super(2) super(+) is present in the external medium. The increase in intracellular Ca super(2) super(+) by EqT II was not blocked or diminished by the calcium channel blocker verapamil. Furthermore, pre-treatment of smooth muscle cells with Ca super(2) super(+)-ATPase inhibitor thapsigargin, or exposure of the cells to a high K super(+) (75mM) medium did not prevent EqT II-induced intracellular Ca super(2) super(+) increases. Replacement of external sodium by sucrose markedly modified the time course of Ca super(2) super(+) signals suggesting the involvement of the Na super(+)/Ca super(2) super(+) exchanger in EqT II action. Our results strongly suggest that EqT II-induced increase in intracellular Ca super(2) super(+) and muscle tension are both dependent on the ability of EqT II to insert into the membrane and form pores allowing Ca super(2) super(+) influx into the cells. To our knowledge this is the first report showing that EqT II causes contraction and contracture of taenia caeci muscles and increases intracellular Ca super(2) super(+) in smooth muscle cells.
Abstract
Theoretical models of animal contests such as the Hawk-Dove game predict that variation in fighting behavior will persist due to mixed evolutionarily stable strategies (ESS) under certain ...conditions. However, the genetic basis for this variation is poorly understood and a mixed ESS for fighting can be interpreted in more than one way. Specifically, we do not know whether variation in aggression within a population arises from among-individual differences in fixed strategy (determined by an individual’s genotype—direct genetic effects DGEs), or from within-individual variation in strategy across contests. Furthermore, as suggested by developments of the original Hawk-Dove model, within-individual variation in strategy may be dependent on the phenotype and thus genotype of the opponent (indirect genetic effects—IGEs). Here we test for the effect of DGEs and IGEs during fights in the beadlet sea anemone Actinia equina. By exploiting the unusual reproductive system of sea anemones, combined with new molecular data, we investigate the role of both additive (DGE + IGE) and non-additive (DGE × IGE) genetic effects on fighting parameters, the latter of which have been hypothesized but never tested for explicitly. We find evidence for heritable variation in fighting ability and that fight duration increases with relatedness. Fighting success is influenced additively by DGEs and IGEs but we found no evidence for non-additive IGEs. These results indicate that variation in fighting behavior is driven by additive indirect genetic effects (DGE + IGE), and support a core assumption of contest theory that strategies are fixed by DGEs.
We show that for beadlet sea anemones, the likelihood of winning a fight depends on both the genotype of the individual and the genotype of its opponent. We find heritable variation in fighting success and evidence that fights last longer between more related opponents. Our results indicate that an individual’s ability to win will vary from fight to fight depending on the genetic identity of its opponent.
Fighting experience (specifically winning or losing a fight) can significantly alter boldness, a component of resource-holding potential (RHP). Previous studies have shown that both the repeatability ...of boldness and mean-level boldness can be affected by fighting experience and that these effects are strongest in the recipients of agonistic behaviour. However, whether these postfight changes in boldness impact future contest success and whether subsequent contests further affect boldness remain unknown. Furthermore, little is known about the effects of the specific tactics used within a fight (within-fight experience) and how these might influence future fight performance and boldness. Here, we investigated the relationship between fighting success and boldness (measured as recovery time when startled) across repeated contests in the beadlet sea anemone, Actinia equina, measuring boldness on five occasions before, between and after two contests. We found that boldness (both repeatability and mean-level) was generally robust to the effects of fighting experience, apart from a decrease in the immediate boldness of losers after their second fight. Furthermore, we found that while prefight boldness significantly predicted fighting success and the level of aggression used in an individual's first fight, it did not predict victory or aggression in the second fight. Our findings thus indicate that different traits may be important in determining fighting success in consecutive fights and, moreover, that fighting experience may alter which traits contribute to an individual's RHP.
•Fighting experience can alter components of resource-holding potential.•We explore the link between boldness and fighting success across repeated contests.•Contrary to previous work we find that boldness is robust to fighting experience.•We find that boldness predicts success in the first but not the second fight.•Victory in consecutive contests may thus be determined by different traits.
Anemones of the genus Actinia are ecologically important and familiar organisms on many rocky shores. However, this genus is taxonomically problematical and prior evidence suggests that the North ...Atlantic beadlet anemone, Actinia equina, may actually consist of a number of cryptic species. Previous genetic work has been largely limited to allozyme electrophoresis and there remains a dearth of genetic resources with which to study this genus. Mitochondrial DNA sequencing may help to clarify the taxonomy of Actinia. Here, the complete mitochondrial genome of the beadlet anemone Actinia equina (Cnidaria: Anthozoa: Actinaria: Actiniidae) is shown to be 20,690 bp in length and to contain the standard complement of Cnidarian features including 13 protein coding genes, two rRNA genes, two tRNAs and two Group I introns, one with an in-frame truncated homing endonuclease gene open reading frame. However, amplification and sequencing of the standard mtDNA barcoding region of the cytochrome oxidase I gene revealed only two haplotypes, differing by a single base pair, in widely geographically separated A. equina and its congener A. prasina. COI barcoding shows that whilst A. equina and A. prasina share the common mtDNA haplotype, haplotype frequency differed significantly between A. equina with red/orange pedal discs and those with green pedal discs, consistent with the hypothesis that these morphotypes represent incipient species.
•The complete mitochondrial genome of the anemone Actinia equina is deduced.•Variability in the barcoding gene COI is low with just two haplotypes detected.•The frequency of haplotypes differs significantly between colour morphs.
Between‐individual variation in behavioural phenotype, termed personality, is an important determinant of how populations cope with acute environmental fluctuation related to climate change.
...Personality in the beadlet sea anemone Actinia equina is linked to genetically distinct morphotypes, which are associated with different heights on the shore. In the intertidal zone, high‐shore environments experience more environmental fluctuation due to longer periods of exposure, and animals adapted to live in these environments are predicted to deal more effectively with environmental perturbation than their low‐shore counterparts.
We collected beadlet anemones of two different morphotypes from three different shore heights. We investigated variation in two behaviours at three different temperatures and in a temporal control treatment where the temperature was not changed: startle response time, the time it took an anemone to re‐extend its tentacles after a threatening stimulus, and immersion response time, the time to re‐extend tentacles after simulated tidal immersion. These behaviours reflect risk‐taking and allow individuals to be categorized as bold, shy or intermediate based upon response times.
Both behaviours showed significant changes as the temperature increased. For immersion response, the morphotype associated with the low‐shore‐lengthened response times at high temperatures. For startle response, all animals lengthened their response times at high temperatures but animals collected from the low‐shore lengthened theirs to the greatest degree. At the individual level, although control individuals exhibited temporal changes in their response times, a clear effect of temperature was present in both behaviours. Shy and bold individuals became more intermediate at higher temperatures in immersion response (this effect was present to a lesser degree in control individuals), while intermediate individuals raised their response times at higher temperatures for startle response.
Given that prolonged tentacle retraction reduces foraging opportunities and can negatively impact respiratory efficiency, our data suggest that some individuals within a single population of A. equina, particularly those associated with the lower shore, may exhibit less effective behavioural responses to temperature shifts than others. These findings demonstrate that acute temperature changes influence risk‐taking, and could have profound short and long‐term implications for survival in the face of climate change.
The authors' research demonstrates that some beadlet anemones may be less able to cope with extreme heat waves caused by climate change. Thus, population‐level conservation strategies may risk leaving the most vulnerable individuals behind, causing a loss of genetic diversity and increasing a population's susceptibility to further environmental change.
Global warming and connected acidification of the world ocean attract a substantial amount of research efforts, in particular in a context of their impact on behaviour and metabolism of marine ...organisms, such as Cnidaria. Nevertheless, mechanisms underlying Cnidarians’ neural signalling and behaviour and their (possible) alterations due to the world ocean acidification remain poorly understood. Here we researched for the first time modulation of GABA
A
receptors (GABA
A
Rs) in
Actinia equina
(Cnidaria: Anthozoa) by pH fluctuations within a range predicted by the world ocean acidification scenarios for the next 80–100 years and by selective pharmacological activation. We found that in line with earlier studies on vertebrates, both changes of pH and activation of GABA
A
Rs with a selective allosteric agonist (diazepam) modulate electrical charge transfer through GABA
A
R and the whole-cell excitability. On top of that, diazepam modifies the animal behavioural reaction on startle response. However, despite behavioural reactions displayed by living animals are controlled by GABA
A
Rs, changes of pH do not alter them significantly. Possible mechanisms underlying the species resistance to acidification impact are discussed.
An experimental decay methodology is developed for a cnidarian model organism to serve as a comparison to the many previous such studies on bilaterians. This allows an examination of inherent bias ...against the fossilisation of cnidarian tissue and their diagnostic characters, under what conditions these occur, and in what way. The decay sequence of Actinia equina was examined under a series of controlled conditions. These experiments show that cnidarian decay begins with an initial rupturing of the epidermis, followed by rapid loss of recognisable internal morphological characters. This suggests that bacteria work quicker on the epidermis than autolysis does on the internal anatomy. The data also show that diploblastic tissue is not universally decayed more slowly under anoxic or reducing conditions than under oxic conditions. Indeed, some cnidarian characters decay more rapidly under anoxic conditions than they do under oxic conditions. This suggests the decay pathways acting may be different to those affecting soft bilaterian tissue such as soft epidermis and internal organs. What is most important in the decay of soft polyp anatomy is the microbial community, which can be dominated by oxic or anoxic bacteria. Different Lagerstätte, even of the same type, will inevitably have subtle difference in their bacterial communities, which among other factors, could be a control on soft polyp preservation leading to either an absence of compelling soft anthozoans (Burgess Shale) or an astonishing abundance (Qingjiang biota).
The ability to mitigate the costs of engaging in a fight will depend on an individual's physiological state. However, the experience of fighting itself may, in turn, affect an individual's state, ...especially if the fight results in injury. Previous studies have found a correlation between immune state and fighting success, but the causal direction of this relationship remains unclear. Does immune state determine fighting success? Or does fighting itself influence subsequent immune state? Using the beadlet anemone,
, we disentangled the cause and effect of this relationship, measuring immune response once pre-fight and twice post-fight. Contrary to previous findings, pre-fight immune response did not predict fighting success, but rather predicted whether an individual used its weapons during the fight. Furthermore, weapon use and contest outcome significantly affected post-fight immune response. Individuals that used their weapons maintained a stable immune response following the fight, whereas those that fought non-injuriously did not. Furthermore, although winners suffered a reduction in immune response similar to that of losers immediately post-fight, winners began to recover pre-fight levels within 24 h. Our findings indicate that immune state can influence strategic fighting decisions and, moreover, that fight outcome and the agonistic behaviours expressed can significantly affect subsequent immunity.
Contest theory predicts the evolution of a stable mixture of different strategies for fighting. Here, we investigate the possibility that stable between-individual differences in startle-response ...durations influence fighting ability or ‘resource-holding potential’ (RHP) in the beadlet sea anemone, Actinia equina. Both winners and losers showed significant repeatability of pre-fight startle-response durations but mean pre-fight startle-response durations were greater for eventual losers than for eventual winners, indicating that RHP varies with boldness. In particular, individuals with short startle responses inflicted more attacks on their opponent. Both repeatability and mean-level responses were changed by the experience of fighting, and these changes varied with outcome. In losers, repeatability was disrupted to a greater extent and the mean startle-response durations were subject to a greater increase than in winners. Thus, following a fight, this behavioural correlate of RHP behaves in a way similar to post-fight changes in physiological status, which can also vary between winners and losers. Understanding the links between aggression and boldness therefore has the potential to enhance our understanding of both the evolution of animal personality and the ‘winner and loser effects’ of post-fight changes in RHP.
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