Introduction
Alarm signals are cues emitted by individuals in the presence of predators. These signals may not only divert predator attention or discourage it to attack but also alert conspecifics1. Alarm signals can be transmitted via different communication pathways: alarm calls are widespread among social terrestrial animals (rodents2, birds3 and primates4). Other animal species use alarm pheromones for the same purpose (insects5,6 or mice7). In aquatic species, chemical alarm signals are widespread especially due to the large number of water-soluble compounds8 (insects9, crustaceans10, asteroids11,12, gastropods13,14, amphibians15,16 and fishes17). Alarm signaling is usually costly for the individual sender18 and often appears to primarily benefit the receivers. However, to evolve and be maintained by natural selection, the fitness benefits for the signaling individual must override its costs. One hypothesis proposed to explain the evolution of alarm signals is that senders benefit via reciprocal cooperation19. By this mechanism, the higher risk taken upon an individual during signaling is reciprocated by one of the receivers. On the other hand, many animals live in kin groups20 and it has been suggested that the process of kin selection is a major factor during the evolution of alarm signals. The term ‘kin selection’, coined by Maynard-Smith21 summarizes one aspect of Hamilton’s inclusive fitness theory, which predicts that individuals can increase their fitness indirectly by supporting the survival of genetically related individuals22. This process facilitates the evolution of costly communication23 and it may contribute to the evolution of alarm signals. For instance, it has been suggested that kin selection plays an important role in the evolution of mammalian alarm calls2,25–27 (but see28). Furthermore, kin-specific alarm responses have been reported during the chemical alarm communication of plants. Karban et al.24 describe that sagebrush plants induce increased protection mechanisms against herbivores when exposed to the volatile cues of wounded close relatives in comparison to plants exposed to cues from distantly related individuals.
The evolution of chemical alarm cues which are widespread in fishes29 is a particularly puzzling example of alarm signaling whose evolution has intrigued evolutionary ecologists since the 1960ies30,31 until today32. Chemical alarm cues, also termed ‘Schreckstoff’33,34, are assumed to be located in specialized enclosed epidermal ‘club cells’ without external ducts29,35,36 (but see37) and are passively released following injuries by predators, a likely lethal event. Because alarm cues are energetically costly to produce38 and reciprocal cooperation is unlikely because most senders will not survive a predator attack (leaving them unable to become a recipient of a reciprocal action), the evolution and maintenance of such communication remains obscure. Receivers benefit greatly because the presence of alarm cues reliably indicates high predation risk, thus allowing them to respond to predator presence and thereby increasing their survival probability39,40. Nevertheless, the benefits to the signaler often remain unclear considering its low survival probability when attacked. Still, most hypotheses proposed to explain the evolution of alarm cues in fishes focus on direct benefits to the sender41,42. Alarm cues might increase the survival of the producing individual. In this context, it has been suggested that alarm pheromones may function to attract secondary predators43. During the following interference between competing predators prey might be able to escape. Mathis et al.43 showed that pike Esox lucius and predatory diving beetles (Dytiscidae) were indeed attracted by minnow alarm cues. In the presence of such secondary predators (pike), escape probabilities of minnows were actually increased44. Accordingly, the signaling individual can increase its own fitness by producing alarm cues, provided that it survives an initial predator attack. Other authors proposed that the alarm function is a mere by-product and instead suggested the primary function of alarm cues to be anti-pathogenic agents45 or promote the healing of injuries46. A recent study by Chivers et al.47 supported this hypothesis; club cell production was unrelated to predation risk but stimulated by skin penetrating pathogens and parasites (but see48). Moreover, Chivers et al.47 found that UV radiation also affected club cell production, providing evidence for a general immune function of club cells.
Similar to mammalian alarm calls2,25–27 and plant volatile alarm cues24, kin selection has been proposed to explain the evolution of alarm cues in fishes42. Nevertheless, this hypothesis has received little attention49. Previous studies have shown that in aquatic species that use chemical alarm cues to detect predator signals such as gastropods50, amphibians51,52 and fish53, the magnitude of the response to heterospecfic alarm cues was positively correlated to the sender – receiver phylogenetic similarity. Accordingly, graded responses dependent on the degree of genetic relatedness within a species might appear as well. Furthermore, alarm cues are a mixture of many different substances54 and as only single active components have been identified to date54–56, their exact composition remains elusive. That leaves the potential that the substances emitted from injured fish contain kin-specific cues. Earlier studies have indeed suggested that alarm cues vary between senders57 and that individuals differentially respond to different alarm signals. For instance, familiarity with specific alarm calls58 or chemical cues59,60 was shown to lead to improved responses. Higher sensitivity to alarm cues released by kin may thus result in an improved response to predation, and thus higher survival of individuals related to the sender which in turn may increase the indirect fitness of the sender.
Two possible mechanisms could cause such beneficial kin-specific alarm responses. Kin alarm cues could be identified directly (when alarm cues include a kin-specific component) or indirectly (when alarm cues do not include such kin-specific components but are perceived simultaneously with the kin cues of the sender). Little is known about the molecular basic of alarm cues in general; consequently, even less concerning potential kin-specific patterns. On the other hand, kin recognition based on chemical cues is widespread in animals61. Such kin-cues are often more or less continuously emitted by individuals, e.g. via the urine. As fish readily associate alarm cues with other cues such as chemical cues62–65 or visual cues66 from heterospecifics, a successful association between alarm cues and concurrently present kin-related cues might be possible. This combination might then trigger stronger responses than alarm cues perceived with unknown cues.
The aim of the present experiment was to test whether the cichlid fish Pelvicachromis taeniatus responds more strongly to alarm cues produced by kin than to those produced by non-kin. P. taeniatus is a socially monogamous small cave-breeder with biparental brood care67 which inhabits streams in Western Africa68. Previous studies revealed that this species possesses alarm cues, recognizes conspecific alarm cues and adjusts its behavior in the presence of alarm cues (DM, SAB, Theo C. M. Bakker, TT, unpublished data). Furthermore, P. taeniatus is capable of kin recognition69–71 which is most likely based on chemical cues72–75. In the experiment we measured the change in activity in individual P. taeniatus after the addition of alarm cues derived from kin and non-kin, respectively.
Material and methods
Ethics statement
This study conforms to the Association for the Study of Animal Behaviour’s Guidelines for the Use of Animals in Research and was carried out according to the German laws for experimentation with animals (§ 8 Abs. 1 TierSchG, V.m. § 2 Abs. 1.1 TierSchZustV NW 26.9.1989). No additional licenses were required.
Animal collection and maintenance
We conducted an experiment using female F2 progeny of the cichlid species P. taeniatus, whose ancestors (F0) were collected from the Moliwe river near Limbe, Cameroon (04°04'N, 09°16'E). Female P. taeniatus were used exclusively due to their consistent activity levels relative to males76. Prior to experiments, fish were kept in mixed-sex 50 × 30 × 30 cm (L × W × H) stock tanks at densities up to 20 individuals and were fed daily with frozen invertebrate larvae ad libitum. These tanks were illuminated in a 12:12 h light:dark cycle; water temperature was kept at 25 ± 1°C.
Experimental setup
During experiments, we exposed individual fish to one of the following extracts: (1) Alarm cues derived from kin (from familiar and unfamiliar siblings); (2) Alarm cues derived from unfamiliar, unrelated conspecifics (non-kin); (3) Distilled water to control for disturbance effects upon introduction. We produced alarm cues from 26 lab-bred donor cichlids which were previously starved for two days to exclude any effects caused by the individual’s selective diet. Each alarm cue consisted of a male and a female cichlid to control for sex effects. Fish were anaesthetized with a blow to the head and afterwards euthanized by cervical dislocation in accordance to § 4 of the German animal welfare act (BGB l. I S. 1207, 1313). The whole fish were then grinded in a mortar using a pestle. This procedure ruptured cells and thus allowed alarm pheromones to be released. By using whole fish, we additionally accounted for the possible existence of alarm cues located outside the skin (e.g. blood cues37). Furthermore, such assays are also likely to contain kin-specific chemical cues (e.g. in the urinary system). The homogenate was diluted with distilled water, passed through filter floss and frozen in 1 ml aliquots at -20°C until use. The final concentration each fish was exposed to during trials was 3.6 mg/l donor wet fish weight. Likewise, we prepared 1 ml aliquots of pure distilled water for control experiments.
Trials were run in 30 × 20 × 20 cm tanks which were supplemented with a 0.5 × 0.5 × 15 cm grey square plastic tube leading 5 cm below the water level at the middle of their short side. This duct allowed the direct addition of chemical cues into the tanks while minimizing fish disturbance. Furthermore, experimental tanks were surrounded on all sides (except the top) with white polystyrene to prevent fish agitation by neighboring fish or the experimenter. A video camera (QuickCam 9000, Logitech, China) viewing the tanks from the top enabled recording of fish behavior for evaluation. Tanks were filled with substrate-treated water at 24°C76; individual fish were then introduced and acclimatized for 1 h, this period is referred to as the pre-stimulus phase from now on. Experimental stimuli were thereafter temperature-adjusted to tank conditions and introduced at the point of 1 h 15min. Subsequently, fish behavior was recorded for another hour. Afterwards, the experimental subjects were sized accurate to the nearest millimeter (standard length: body size from snout to the beginning of the tail fin) and weighed accurate to one milligram on a digital precision scale (LC 2215, Sartorius, Germany). Between trials, tanks were cleaned with 3% hydrogen peroxide and then rinsed with tap water to remove remaining olfactory traces77,78. Furthermore, experimental stimuli assigned to individual tanks were alternated between trials.
In total, we tested 51 individuals from 8 families; extracts from the same donor fish were used throughout different treatments and thus represented – based on the family identity of the focal fish – either kin or non-kin alarm cues. Also, individuals from the same family were evenly distributed among the three extracts. In two cases the fish exhibited no activity during the pre-stimulus phase and were excluded from analysis. Hence, the final sample size consisted of 49 individuals; 12 received alarm cues from familiar siblings, 9 from unfamiliar siblings, 14 from unrelated fish and 14 individuals were exposed to the control stimulus. Because sibling familiarity did not significantly affect focal fish activity (familiar vs. unfamiliar kin: χ2 = 0.090, p = 0.764), their activity scores were pooled to represent 21 fish receiving alarm cues derived from kin.
Statistical analysis
We evaluated fish activity by tracking its movement during the 1 h pre-stimulus phase and the following 1 h post-stimulus phase with animal tracking software (Biobserve Viewer2 3.0.0.119, St. Augustin, Germany). Subsequently, we assigned an activity index to each fish by calculating the difference between the distances covered during the two experimental phases. All statistical analyses were conducted using R 3.0.179. Neither body size nor weight nor activity indices deviated significantly from normal distribution according to the Kolmogorov-Smirnov test with Lilliefors significance correction (Lillie.test, R library ‘nortest’), thus we applied linear-mixed effect models (LME, R library ‘nlme’) for analysis. All test fish were only used once but to account for the repeated use families, we entered ‘family identity’ as a random factor. All results were based on likelihood ratio tests (LRT); hence degrees of freedom differed by two in analyses involving all three treatments and by one in the analyses testing for differences between two treatments.
Results
Fish activity before the introduction of the three treatments was not significantly different among the three groups (χ2 = 4.398, p = 0.111). Moreover, neither fish standard length (χ2 = 0.648, p = 0.723) nor body mass (χ2 = 0.498, p = 0.780) differed significantly between treatments. However, the change in activity of female P. taeniatus was significantly affected by the treatment (χ2 = 10.057, p = 0.007, Figure 1). Activity indices of both alarm-cue treatment groups (kin/non-kin) were significantly different from those of the water-control group (Kin vs. water: χ2 = 8.346, p = 0.004; Non-kin vs. water: χ2 = 8.693, p = 0.003, Figure 1). Fish of the control group showed on average an increase of 6.7 m in covered distance during the post-stimulus period, whereas fish of both alarm cue treatments showed reduced activity in the post-stimulus phase (on average 3.1 m less compared to the pre-stimulus phase). However, fish did not respond differently to alarm cues derived from related and unrelated individuals (χ2 = 0.233, p = 0.630, Figure 1).

Figure 1. Activity indices of female P. taeniatus (mean±SE) exposed to distilled water (gray open bar) and alarm cues derived from related conspecifics (kin, black hatched bar) or unrelated conspecifics (non-kin, black open bar).
Activity indices were calculated by subtracting the distance covered during the 1 h prestimulus phase from the following 1 h poststimulus period. Asterisks above the bars indicate ** p < 0.01; ns p > 0.6.
Discussion
Generally, activity of female P. taeniatus was affected by the presence of conspecific alarm cues. Fish of the alarm cue treatment significantly decreased their activity relative to control fish. However, P. taeniatus did not respond differentially to alarm cues derived from kin or non-kin in terms of activity changes.
First, these results are in accordance to numerous studies showing that the presence of conspecific alarm cues decreases prey activity in general80,81. Reduced activity concurrently decreases prey conspicuousness, which is an effective strategy against visual predators and enhances survival81. Furthermore, our results add to an earlier study, showing that males of P. taeniatus reduce territorial aggression in the presence of conspecific alarm cues (DM, SAB, Theo C. M. Bakker, TT, unpublished data). Thus both sexes of P. taeniatus are capable of recognizing alarm cues and adjust their behavior accordingly.
Against the expectations of the kin selection hypothesis, fish did not discriminate between kin and non-kin alarm cues. These results are also in contrast to other studies that found kin-biased responses concerning alarm signals in plants24 or mammals2,25–27 (but see28). As alarm cues are assumed to be located inside enclosed epidermal ‘club cells’ without external ducts29,35,36 (but see37), they constitute a passively released discrete signal probably sent only once during an individual’s lifetime. This makes reciprocal cooperation unlikely in the case of fish alarm cues. Consequently, this result rather suggests that the evolutionary origin of alarm cues in fishes is based on direct benefits to the sender42, including those hypotheses highlighting that alarm cues might have primarily evolved as an immune enhancing mechanism, making the alarm signal function a by-product47.
The missing discrimination between different alarm cues suggests that a) cues signaling the presence of kin are not part of the alarm system b) that fish did not link concurrently present alarm cues to kin cues or c) that kin cues were not recognized. As P. taeniatus have been shown to be capable of kin recognition69–71, it is likely that they have detected the presence of kin during trials (e.g. via urine, which was included in the fish extract). Thus, instead of missing kin recognition, our results rather suggest that kin-related cues and alarm cues are neither linked directly nor indirectly in P. taeniatus. The fitness benefits of kin discrimination in the context of alarm cue perception might be too small in order to generate selection on either senders or receivers. In fact, these benefits might be unable to outweigh possible additional production (kin-related information as an alarm cue component) or sensory costs (receiver coupling between concurrently present alarm cues and kin cues).
Alternatively, kin discrimination in alarm cues might simply not have evolved in P. taeniatus due to the lack of necessity. Many fishes are capable of identifying kin and live in kin-shaped groups82. This is also true for P. taeniatus which lives the first weeks after hatching in family groups guarded by their parents67. Afterwards they live in shoals without defined territories throughout the juvenile stage68. Laboratory experiments showed that they prefer to shoal with familiar kin (TT, Saskia Hesse, Theo C. M. Bakker, SAB, unpublished data) and that kin form tighter shoals83. Furthermore, P. taeniatus prefers to mate with kin69 which is most likely also true for the natural population84. Accordingly, throughout their life the social environment of P. taeniatus is probably largely kin-structured in nature. In this case, individuals receiving the information transmitted by alarm cues are most likely kin due to the nature of the spatial distribution. As a consequence, signaling individuals might still increase their inclusive fitness according to the kin selection theory.
In conclusion, our study found no evidence for differences in response between alarm cues derived from kin or non-kin. However, under natural conditions behavioral mechanisms may lead to kin-biased alarm cue perception. Thus, kin selection potentially plays a role in alarm signaling in our model system. Still, further research is required determining the direct fitness benefits and costs for the signaling individual as well as the benefits for the receivers which are fundamental parameters to understand the evolution and maintenance of alarm cues.
Data availability
figshare: Fish activity data: Update 1, doi: 10.6084/m9.figshare.103154485
Author contributions
TT and DM conceived the study. DM, SAB and TT designed the experiments. DM carried out the research. DM, SAB and TT analysed the data. DM and TT wrote the paper. All authors had read and improved the manuscript and agreed to the final content.
Competing interests
No competing interests were disclosed.
Grant information
This research was funded by the Deutsche Forschungsgemeinschaft (TH 1615/1-1).
Acknowledgements
We are grateful to the Bakker research group for discussion.
Faculty Opinions recommendedReferences
- 1.
Smith RJF:
Evolution of alarm signals: Role of benefits of retaining group members or territorial neighbors.
Am Nat.
1986; 128(4): 604–610. Reference Source
- 2.
Sherman PW:
Nepotism and evolution of alarm calls.
Science.
1977; 197(4310): 1246–1253. PubMed Abstract
| Publisher Full Text
- 3.
Klump GM, Shalter MD:
Acoustic behavior of birds and mammals in the predator context; 1. Factors affecting the structure of alarm signals. 2. The functional significance and evolution of alarm signals.
Z Tierpsychol.
1984; 66(3): 189–226. Publisher Full Text
- 4.
Macedonia JM, Evans CS:
Essay on contemporary issues in ethology: Variation among mammalian alarm call systems and the problem of meaning in animal signals.
Ethology.
1993; 93(3): 177–197. Publisher Full Text
- 5.
Blum MS:
Alarm pheromones.
Annu Rev Entomol.
1969; 14: 57–80. Publisher Full Text
- 6.
Kunert G, Otto S, Rose USR, et al.:
Alarm pheromone mediates production of winged dispersal morphs in aphids.
Ecol Lett.
2005; 8(6): 596–603. Publisher Full Text
- 7.
Rottman SJ, Snowdon CT:
Demonstration and analysis of an alarm pheromone in mice.
J Comp Physiol Psychol.
1972; 81(3): 483–490. PubMed Abstract
| Publisher Full Text
- 8.
Steiger S, Schmitt T, Schaefer HM:
The origin and dynamic evolution of chemical information transfer.
Proc R Soc Lond B.
2011; 278(1708): 970–979. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 9.
Sih A:
Antipredator responses and the perception of danger by mosquito larvae.
Ecology.
1986; 67(2): 434–441. Publisher Full Text
- 10.
Laforsch C, Beccara L, Tollrian R:
Inducible defenses: The relevance of chemical alarm cues in Daphnia.
Limnol Oceanogr.
2006; 51(3): 1466–1472. Publisher Full Text
- 11.
Parker DA, Shulman MJ:
Avoiding predation: Alarm responses of Caribbean sea-urchins to simulated predation on conspecific and heterospecific sea-urchins.
Mar Biol.
1986; 93(2): 201–208. Publisher Full Text
- 12.
Lawrence JM:
A chemical alarm response in Pycnopodia helianthoides (Echinodermata, Asteroidea).
Mar Behav Physiol.
1991; 19(1): 39–44. Publisher Full Text
- 13.
Sleeper HL, Paul VJ, Fenical W:
Alarm pheromones from the marine opisthobranch Navanax inermis.
J Chem Ecol.
1980; 6(1): 57–70. Publisher Full Text
- 14.
Kempendorff W:
Über das Fluchtphänomen und die Chemoreception von Helisoma (Taphius) nigricans).
Arch Molluskenkd.
1942.
- 15.
Hews DK, Blaustein AR:
An investigation of the alarm response in Bufo boreas and Rana cascadae tadpoles.
Behav Neural Biol.
1985; 43(1): 47–57. PubMed Abstract
| Publisher Full Text
- 16.
Kats LB, Petranka JW, Sih A:
Antipredator defenses and the persistence of amphibian larvae with fishes.
Ecology.
1988; 69(6): 1865–1870. Publisher Full Text
- 17.
Wisenden BD:
Olfactory assessment of predation risk in the aquatic environment.
Philos Trans R Soc Lond B Biol Sci.
2000; 355(1401): 1205–1208. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 18.
Hughes AL:
Evolution of adaptive phenotypic traits without positive Darwinian selection.
Heredity (Edinb).
2012; 108(4): 347–353. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 19.
Trivers RL:
The evolution of reciprocal altruism.
Q Rev Biol.
1971; 46(1): 35–57. Publisher Full Text
- 20.
Krause J, Ruxton GD:
Living in groups (Oxford University Press, 2002). Reference Source
- 21.
Maynard-Smith J:
Group selection and kin selection.
Nature.
1964; 201: 1145–1147. Publisher Full Text
- 22.
Hamilton WD:
The genetical evolution of social behaviour I.
J Theor Biol.
1964; 7(1): 1–16. PubMed Abstract
| Publisher Full Text
- 23.
Tamura K, Ihara Y:
Classes of communication and the conditions for their evolution.
Theor Popul Biol.
2011; 79(4): 174–183. PubMed Abstract
| Publisher Full Text
- 24.
Karban R, Shiojiri K, Ishizaki S, et al.:
Kin recognition affects plant communication and defence.
Proc R Soc Lond B.
2013; 280(1756): 20123062. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 25.
Charnov EL, Krebs JR:
The evolution of alarm calls: Altruism or manipulation?
Am Nat.
1975; 109(965): 107–112. Publisher Full Text
- 26.
Sherman PW:
Alarm calls of Belding’s ground squirrels to aerial predators: Nepotism or self-preservation?
Behav Ecol Sociobiol.
1985; 17(4): 313–323. Publisher Full Text
- 27.
da Silva KB, Mahan C, da Silva J:
The trill of the chase: Eastern chipmunks call to warn kin.
J Mammal.
2002; 83(2): 546–552. Publisher Full Text
- 28.
Shelley EL, Blumstein DT:
The evolution of vocal alarm communication in rodents.
Behav Ecol.
2005; 16(1): 169–177. Publisher Full Text
- 29.
Pfeiffer W:
Distribution of fright reaction and alarm substance cells in fishes.
Copeia.
1977; 1977(4): 653–665. Reference Source
- 30.
Williams GC:
Measurement of consociation among fishes and comments on the evolution of schooling.
Pub Mus Michigan State Univ Biol Ser.
1964; 2(7): 349–384. Reference Source
- 31.
Williams GC:
Natural selection: Domains, levels, and challenges. (Oxford University Press, 1992). Reference Source
- 32.
Chivers DP, Brown GE, Ferrari MCO:
The evolution of alarm substances and disturbance cues in aquatic animals. In: Chemical ecology in aquatic systems. eds C. Brönmark & L. A. Hansson (Oxford University Press, 2012).
- 33.
von Frisch K:
Zur Psychologie des Fisch-Schwarmes.
Naturwissenschaften.
1938; 26(37): 601–606. Publisher Full Text
- 34.
von Frisch K:
Über einen Schreckstoff der Fischhaut und seine biologische Bedeutung.
Z Vgl Physiol.
1942; 29(1–2): 46–145. Publisher Full Text
- 35.
Kristensen EA, Closs GP:
Anti-predator response of naive and experienced common bully to chemical alarm cues.
J Fish Biol.
2004; 64(3): 643–652. Publisher Full Text
- 36.
Barreto RE, Barbosa A, Giassi ACC, et al.:
The ‘club’ cell and behavioural and physiological responses to chemical alarm cues in the Nile tilapia.
Mar Freshw Behav Physiol.
2010; 43(1): 75–81. Publisher Full Text
- 37.
Barreto RE, Miyai CA, Sanches FHC, et al.:
Blood cues induce antipredator behavior in Nile tilapia conspecifics.
PLoS One.
2013; 8(1): e54642. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 38.
Mathis A:
Alarm responses as a defense: Chemical alarm cues in nonostariophysan fishes. In: Fish defenses Volume 2: Pathogens, parasites and predators. eds G. Zaccone, C. Perriére, A. Mathis & B. G. Kapoor) 323–386 (Science Publishers, 2009). Reference Source
- 39.
Mathis A, Smith RJF:
Chemical alarm signals increase the survival time of fathead minnows (Pimephales promelas) during encounters with northern pike (Esox lucius).
Behav Ecol.
1993; 4(3): 260–265. Publisher Full Text
- 40.
Stabell OB, Lwin MS:
Predator-induced phenotypic changes in crucian carp are caused by chemical signals from conspecifics.
Environ Biol Fishes.
1997; 49(1): 139–144. Publisher Full Text
- 41.
Chivers DP, Smith RJF:
Chemical alarm signalling in aquatic predator-prey systems: A review and prospectus.
Ecoscience.
1998; 5(3): 338–352. Reference Source
- 42.
Smith RJF:
Alarm signals in fishes.
Rev Fish Biol Fish.
1992; 2(1): 33–63. Publisher Full Text
- 43.
Mathis A, Chivers DP, Smith RJF:
Chemical alarm signals: Predator deterrents or predator attractants?
Am Nat.
1995; 145(6): 994–1005. Publisher Full Text
- 44.
Chivers DP, Brown GE, Smith RJF:
The evolution of chemical alarm signals: Attracting predators benefits alarm signal senders.
Am Nat.
1996; 148(4): 649–659. Publisher Full Text
- 45.
Cameron AM, Endean R:
Epidermal secretions and the evolution of venom glands in fishes.
Toxicon.
1973; 11(5): 401–410. PubMed Abstract
| Publisher Full Text
- 46.
Al-Hassan JM, Thompson M, Criddle RS:
Composition of the proteinacous gel secretion from the skin of the Arabian Gulf catfish (Arius thallasinus).
Mar Biol.
1982; 70(1): 27–33. Publisher Full Text
- 47.
Chivers DP, Wisenden BD, Hindman CJ, et al.:
Epidermal ‘alarm substance’ cells of fishes maintained by non-alarm functions: possible defence against pathogens, parasites and UVB radiation.
Proc R Soc Lond B.
2007; 274(1625): 2611–2619. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 48.
James CT, Wisenden BD, Goater CP:
Epidermal club cells do not protect fathead minnows against trematode cercariae: A test of the anti-parasite hypothesis.
Biol J Linn Soc.
2009; 98(4): 884–890. Publisher Full Text
- 49.
Wisenden BD, Smith RJF:
The effect of physical condition and shoalmate familiarity on proliferation of alarm substance cells in the epidermis of fathead minnows.
J Fish Biol.
1997; 50(4): 799–808. Publisher Full Text
- 50.
Dalesman S, Rundle SD, Bilton DT, et al.:
Phylogenetic relatedness and ecological interactions determine antipredator behavior.
Ecology.
2007; 88(10): 2462–2467. PubMed Abstract
| Publisher Full Text
- 51.
Schoeppner NM, Relyea RA:
Damage, digestion, and defence: the roles of alarm cues and kairomones for inducing prey defences.
Ecol Lett.
2005; 8(5): 505–512. PubMed Abstract
| Publisher Full Text
- 52.
Schoeppner NM, Relyea RA:
When should prey respond to consumed heterospecifics? Testing hypotheses of perceived risk.
Copeia.
2009; 2009(1): 190–194. Publisher Full Text
- 53.
Mitchell MD, Cowman PF, McCormick MI:
Chemical alarm cues are conserved within the coral reef fish family Pomacentridae.
PLoS One.
2012; 7(10): e47428. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 54.
Mathuru AS, Kibat C, Cheong WF, et al.:
Chondroitin fragments are odorants that trigger fear behavior in fish.
Curr Biol.
2012; 22(6): 538–544. PubMed Abstract
| Publisher Full Text
- 55.
Brown GE, Adrian JC, Smyth E, et al.:
Ostariophysan alarm pheromones: Laboratory and field tests of the functional significance of nitrogen oxides.
J Chem Ecol.
2000; 26(1): 139–154. Publisher Full Text
- 56.
Pfeiffer W, Riegelbauer G, Meier G, et al.:
Effect of hypoxanthine-3(N)-oxide and hypoxanthine-1(N)-oxide on central nervous excitation of the black tetra Gymnocorymbus ternetzi (Characidae, Ostariophysi, Pisces) indicated by dorsal light response.
J Chem Ecol.
1985; 11(4): 507–523. Publisher Full Text
- 57.
Roh E, Mirza RS, Brown GE:
Quality or quantity? The role of donor condition in the production of chemical alarm cues in juvenile convict cichlids.
Behaviour.
2004; 141(10): 1235–1248. Publisher Full Text
- 58.
O’Connell-Rodwell CE, Wood JD, Kinzley C, et al.:
Wild African elephants (Loxodonta africana) discriminate between familiar and unfamiliar conspecific seismic alarm calls.
J Acoust Soc Am.
2007; 122(2): 823–830. PubMed Abstract
| Publisher Full Text
- 59.
Coopersmith R, Leon M:
Enhanced neural response to familiar olfactory cues.
Science.
1984; 225(4664): 849–851. PubMed Abstract
| Publisher Full Text
- 60.
Brown GE, Smith RJF:
Fathead minnows use chemical cues to discriminate natural shoalmates from unfamiliar conspecifics.
J Chem Ecol.
1994; 20(12): 3051–3061. PubMed Abstract
| Publisher Full Text
- 61.
Mateo JM:
Recognition systems and biological organization: The perception component of social recognition.
Ann Zool Fenn.
2004; 41: 729–745. Reference Source
- 62.
Berejikian BA, Smith RJF, Tezak EP, et al.:
Chemical alarm signals and complex hatchery rearing habitats affect antipredator behavior and survival of chinook salmon (Oncorhynchus tshawytscha) juveniles.
Can J Fish Aquat Sci.
1999; 56(5): 830–838. Publisher Full Text
- 63.
Brown GE, Adrian JC, Patton T, et al.:
Fathead minnows learn to recognize predator odour when exposed to concentrations of artificial alarm pheromone below their behavioural-response threshold.
Can J Zool.
2001; 79(12): 2239–2245. Publisher Full Text
- 64.
Brown GE:
Learning about danger: Chemical alarm cues and local risk assessment in prey fishes.
Fish Fish.
2003; 4(3): 227–234. Publisher Full Text
- 65.
Holmes TH, McCormick MI:
Smell, learn and live: The role of chemical alarm cues in predator learning during early life history in a marine fish.
Behav Processes.
2010; 83(3): 299–305. PubMed Abstract
| Publisher Full Text
- 66.
Chivers DP, Smith RJF:
Fathead minnows, Pimephales promelas, acquire predator recognition when alarm substance is associated with the sight of unfamiliar fish.
Anim Behav.
1994; 48(3): 597–605. Publisher Full Text
- 67.
Thünken T, Meuthen D, Bakker TCM, et al.:
Parental investment in relation to offspring quality in the biparental cichlid fish Pelvicachromis taeniatus.
Anim Behav.
2010; 80(1): 69–74. Publisher Full Text
- 68.
Lamboj A:
Die Cichliden des westlichen Afrikas. (Birgit Schmettkamp Verlag, 2004). Reference Source
- 69.
Thünken T, Bakker TC, Baldauf SA, et al.:
Active inbreeding in a cichlid fish and its adaptive significance.
Curr Biol.
2007; 17(3): 225–229. PubMed Abstract
| Publisher Full Text
- 70.
Thünken T, Bakker TC, Baldauf SA, et al.:
Direct familiarity does not alter mating preference for sisters in male Pelvicachromis taeniatus (Cichlidae).
Ethology.
2007; 113(11): 1107–1112. Publisher Full Text
- 71.
Thünken T, Meuthen D, Bakker TC, et al.:
A sex-specific trade-off between mating preferences for genetic compatibility and body size in a cichlid fish with mutual mate choice.
Proc R Soc Lond B.
2012; 279(1740): 2959–2964. PubMed Abstract
| Publisher Full Text
| Free Full Text
- 72.
Thünken T, Waltschyk N, Bakker TC, et al.:
Olfactory self-recognition in a cichlid fish.
Anim Cogn.
2009; 12(5): 717–724. PubMed Abstract
| Publisher Full Text
- 73.
Thünken T, Baldauf SA, Kullmann H, et al.:
Size-related inbreeding preference and competitiveness in male Pelvicachromis taeniatus (Cichlidae).
Behav Ecol.
2011; 22(2): 358–362. Publisher Full Text
- 74.
Hesse S, Bakker TCM, Baldauf SA, et al.:
Kin recognition by phenotype matching is family- rather than self-referential in juvenile cichlid fish.
Anim Behav.
2012; 84(2): 451–457. Publisher Full Text
- 75.
Thünken T, Bakker TCM, Baldauf SA:
“Armpit effect” in an African cichlid fish: Self-referent kin recognition in mating decisions of male Pelvicachromis taeniatus.
Behav Ecol Sociobiol.
2014; 68(1): 99–104. Publisher Full Text
- 76.
Meuthen D, Baldauf SA, Bakker TCM, et al.:
Substrate-treated water: A method to enhance fish activity in laboratory experiments.
Aquat Biol.
2011; 13(1): 35–40. Publisher Full Text
- 77.
McLennan DA:
Male brook sticklebacks’ (Culaea inconstans) response to olfactory cues.
Behaviour.
2004; 141(11): 1411–1424. Publisher Full Text
- 78.
Mehlis M, Bakker TCM, Frommen JG:
Smells like sib spirit: Kin recognition in three-spined sticklebacks (Gasterosteus aculeatus) is mediated by olfactory cues.
Anim Cogn.
2008; 11(4): 643–650. PubMed Abstract
| Publisher Full Text
- 79.
R Core Team: R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. 2014. Reference Source
- 80.
Bourdeau PE, Johansson F:
Predator-induced morphological defences as by-products of prey behaviour: A review and prospectus.
Oikos.
2012; 121(8): 1175–1190. Publisher Full Text
- 81.
Kats LB, Dill LM:
The scent of death: Chemosensory assessment of predation risk by prey animals.
Ecoscience.
1998; 5(3): 361–394. Reference Source
- 82.
Ward AJW, Hart PJB:
The effects of kin and familiarity on interactions between fish.
Fish Fish.
2003; 4(4): 348–358. Publisher Full Text
- 83.
Hesse S, Thünken T:
Growth and social behavior in a cichlid fish are affected by social rearing environment and kinship.
Naturwissenschaften.
2014; 101(4): 273–283. PubMed Abstract
| Publisher Full Text
- 84.
Langen K, Schwarzer J, Kullmann H, et al.:
Microsatellite support for active inbreeding in a cichlid fish.
PLoS One.
2011; 6(9): e24689. PubMed Abstract
| Free Full Text
- 85.
Meuthen D, Baldauf SA, Thünken T:
Fish activity data: Update 1.
figshare.
2014. Data Source
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