Field studies of the behavioral ecology and agonistic behavior of Cichlasoma meeki (Pisces: Cichlidae)

Synopsis The behavior and ecology of the firemouth cichlid were investigated in southern Mexico. Observations were conducted primarily at Laguna Bacalar, Quintana Roo. The fish bred throughout the year, nesting in small rocky crevices. Territories were established either by wandering pairs or by lone males which subsequently attracted mates. Stationary territories were maintained for two to three weeks by both pair members until the young were free-swimming, after which the parents defended the young as they foraged. Brood care lasted approximately three months. The distances at which fish were attacked and the behavior performed varied with the age of the defended young and the sex of the parent, as well as the species and size of the intruder. The sexes differed in their reproductive and agonistic activities. Predation on young was rapid if the parents were diverted from their defense. Serious injuries to adults were not observed to result from intraspecific contests. Such interactions were very common, but were ritualized with physical contact between animals rare. Color patterning varied with breeding interval, sex and behavior.     

A study of Aphyosemion schmitti (Romand, 1979) and a survey of the Aphyosemion of Liberia (Pisces, Cyprinodontidae)

Aphyosemion schmitti can be separated from neighbouring species on the basis of colour pattern, crossing experiments, cytogenetics, genetics and zoogeographical distribution. Three groups of Aphyosemion can be distinguished, based on morphological and meristic characters, colour patterns and geographical distribution; i.e. the liberiense group, the guineense group and the occidentalis group. A differentiation of the Liberian Aphyosemion is proposed, and its possible phylogenetic relationships are discussed.     

Sexual selection,reproductive behavior,and speciation in the mbuna species flock of Lake Malawi (Pisces: Cichlidae)

Synopsis The cichlid species flocks of the African Great Lakes represent the most extreme case of adaptive radiation among vertebrates. Recently, attention has focused on the potential for sexual selection to drive or accelerate speciation in these fishes. Cichlids as a whole are social in nature and display complex behavior, particularly during courtship and spawning; however, the extent to which changes in species recognition cues may account for species diversity among haplochromine lineages has remained speculative. Our investigations have indicated that oral incubating haplochromines show a reduction in diversity and extent of courtship relative to substrate brooding cichlids, and apparently retain aspects of a primitive specific mate recognition system. Laboratory observations of courtship in the Malawian endemicPseudotropheus zebra suggest that organization of the spawning bout is loose, and lacking in any well defined stimulus-response chain. Interspecific comparisons of in situ courtship behavior among male mbuna, lithophilous haplochromines of Lake Malawi, revealed only one potential example of species-specific behavior, and indicated that mate choice occurred prior to the onset of intense courtship. Courtship display by male mbuna does not appear critical to species recognition and may represent an evolutionary relict. Alternatively, male courtship display may have an indirect effect on successful reproduction or may be maintained through pleiotropic effects. The mbuna display no evidence of behavioral innovation and show limited interspecific differentiation in behavioral expression. More generally, there is no evidence at present to suggest that epigamic sexual selection, acting on courtship behavior, has been a major mechanism in the diversification of the haplochromine species flocks.     

The behavior of the African killifish,Aphyosemion gardneri: normative studies

Synopsis The behaviors of maleAphyosemion gardneri observed during interactions with female and maleA. gardneri are described. First order transition matrices based on data collected during these interactions were used to construct behavioral flow diagrams. These flow diagrams show that sequences of sexual behaviors are less variable than sequences of aggressive behaviors. The position of acts in a typical sequence may be used in determining the level of activation of the behavioral system associated with those acts. Complexity and energy expenditure of behaviors tends to increase within sequences.     

Development of the gonads and gonaducts in the polypterids (Pisces)]

No study of the development of the gonads and gonoducts in Polypterus has ever been made in a more or less complete way. The present study does not fill up this gap, but repairs several lacks of knowledge, by putting clear a few items that may contribute to a better understanding of this development. In larvae between 5,5 mm and 9,6 mm the primary gonocytes appear under the pronephric ducts in the anterior region of the opisthonephros. A genital crest is foreshadowed there; one of its characteristics is a cubial epithelium. The latter does not have any relation with peritoneal channels and it does not contribute to the formation of gonocytes. In the following stages the gonocytes get very numerous because of cellular multiplication. They cause a local transformation of the genital crest into a genital fold; when the number of gonocytes has increased very much, a part of the fold gets transformated into a gonad. At no stage is there any intrusion of medullary tissue into this gonad anlage.     

Social behavior of the emperor tamarin in captivity: Components of agonistic display and the agonistic network

Agonistic behavior was studied longitudinally for 16 months in an intact family groups of captive emperor tamarins (Saguinus imperator subgrisescens) using methods from quantitative ethology and social network analysis. A motivational analysis of the components of agonistic display revealed the relative strength of each component along a continuum from strongly dominant to strongly subordinate. Tabulations of exchanges of strongly dominant and strongly subordinate components in interactions among the tamarins revealed an agonistic network (“dominance hierarchy”) that approached, but did not quite reach, the ideal state of a transitive order (“linear dominance hierarchy”). The frequency with which individual tamarins long called and scent marked was not closely correlated with their position (“dominance rank”) in the agonistic network. Instead, individuals undergoing change in status long called and scent marked frequently, irrespective of their rank.     

Sexual and agonistic behaviour in the killdeer (Charadrius vociferus)

Field studies suggest that killdeer pairs form on the breeding grounds. Males advertise both on the ground and in the air with loud ‘killdeer’ and other calls and with scraping (‘sham’ nesting). In scrape exchanges the scraper faces away, breast dipped, tail raised and spread over the incoming bird. On the ground killdeers chase with body horizontal, back feathers ruffled and trilled calls. Fleers are silent and may end runs with sudden crouched tilting of the dorsum toward the pursuer, exposing the reddish rump. Pairs defend their nest area and young from conspecifics.     

Origin of the coelomic cavities and the heart in the polypterids (Pisces)]

In polypterus the mesodermal cavities appear quite late during embryonic life. They are generally small and they only get somewhat more voluminous in the anterior mesomeres (where they establish the pronephrie chambers) and in the ventral anterior mesoderm (where they become an embryonic pericardial cavity). The anlage of the heart appears in the anterior part of the tissue that is situated between the paired mesodermal cavities of these stages. It assumes some unawaited dispositions that are truly confusing in the case of a superficial inspection. It is only during larval life that a coelomic cavity appears all along the truncal part of the mesoderm. In the beginning this is a pericardio-peritoneal cavity. But because of the coalescence between several membranes an anterior cavity gets isolated and this one is the pericardial cavity of the adult specimens; this cavity is much more limited than its homonymic counterpart of the embryonic stages.     

Development of the cloaca and its ulterior transformations in the polypterids (Pisces)]

Generally spoken cloacae have been but little studied. In Polypterus, a brachiopterygian fish, a cloaca only exists during parts of the embryonal and larval life and it gets replaced by structures consisting of an anus and an urinary sinus. In the beginning of embryonal life the posterior opening of the body seems to be nothing else than the original blastoporus. The wall of this opening acquires evaginations; the anlagen of the excretory ducts come in contact with them, establishing in that way a structure, that merits the name of cloaca. During the elongation of the post-vitellin body, the latter gets shifted from the level of metamere XII to that of metamere XXX. Another migration of the cloaca occurs when the digestive system acquires its development. Finally the cloaca may be found under the 47th and 48th muscular segments (at least in the species Polypterus senegalus senegalus Cuvier). During these stages the excretory ducts have build up an urinary sinus that gets separated from the gut. In adults no communication exists any more between the gut and the urinary sinus; the latter is a very destinct organ that may have an impair or pair aspect according to its being filled up. Because of the establishing of a communication with the genital ducts the sinus becomes an uro-genital sinus in the adult.     

Age, Growth, and Sexual Development in the Self-fertilizing Hermaphroditic Fish Rivulus marmoratus

We studied age, growth, and sexual development in the early life intervals of the self-fertilizing mangrove killi-fish, Rivulus marmoratus. Newly hatched (day 0) individuals had sagittal otoliths of 60m radius, with about 30 increments. Sequential sampling until about day 60 after hatching yielded otoliths with the number of increments outside the 60m radius equal to the daily age of the fish. Alizarin complexone marking of otoliths also confirmed the increments were daily, and demonstrated the applicability of this technique to field studies for capture-mark-recapture, or age and growth estimates. Individuals fed a restricted amount of food formed fewer daily otolith growth increments than fish fed to satiation each day. Using histological analysis for identifying gonad morphogenesis, we found no correlation between gonadal development and external appearance (caudal ocellus, orange fin colouration) in young fish of known ages. The caudal ocellus was not present until 9mm total length, and developed thereafter. Of 136 individuals examined, fish less than 17.2mm total length (TL, n = 124) were females. Testicular tissue first appeared among individuals 17–18mm TL (n = 3), while some individuals greater than 18mm TL (n = 8) were functional hermaphrodites. The single male in our study was relatively of small body size (9.6mm, day 37) with a distinct caudal ocellus, indicating that it is presumably a primary male.     

Spatio-temporal patterns of recruitment of labroid fishes (Pisces: Labridae and Scaridae) to damselfish territories

Recent studies have shown that recruitment variability is an important process structuring reef fish assemblages. The aim of this study is to describe the spatio-temporal patterns of recruitment of three abundant labroid taxa (Coris schroederi, Halichoeres melanurus and Scarus spp.), using damselfish territories as replicate units of habitat. Temporal recruitment patterns of each taxa were consistent among three sites along 2 km of reef tract, with small differences among sites probably the result of hydrological or random factors operating at that scale. Recruitment of only one species (C. schroederi) showed consistent differences in the magnitude of recruitment among sites, which was probably due to an overriding effect of habitat selection for the location of the territories on the reef profile at one site. Two taxa, C. schroederi and Scarus spp., recruited in low to moderate rates over many weeks with moderate recruitment peaks detected in one year only. This pattern may be characteristic of many labroid species that have protracted periods of production of larvae. In contrast, H. melanurus recruited in a single short pulse of high magnitude each summer, which suggests that production of larvae by this species may occur over a more restricted period of time. No strong pattern of lunar entrainment of recruitment was detected for any taxa, which may be due to a lack of lunar periodicity in production of larvae. Further studies are now required to identify the processes that are important in determining patterns of labroid recruitment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Intra- and interspecific agonistic behavior of the subterranean termite Microcerotermes crassus (Isoptera: Termitidae)

The aim of our study was to investigate the intra- and interspecific agonistic behaviors exhibited by the worker and soldier castes of the subterranean termite Microcerotermes crassus Snyder (Isoptera: Termitidae). Aggression between M. crassus colonies from different field locations and also against three termite species--Coptotermes gestroi (Wasmann), Globitermnes sulphureus Haviland, and Odontotermes sp.--were observed in the laboratory. Termite responses were tested in paired combination of castes (soldiers versus soldiers, soldiers versus workers, and workers versus workers) consisting of 10 individuals each. Significant agonistic behaviors were observed only in encounters between pairings of different termite species. M. crassus was aggressive toward individuals from different species but not toward individuals from different M. crassus colonies. Mortality of M. crassus reached 100% in most of the interspecific encounters. However, no or low mortality was recorded in the intraspecific pairings.     

Multilocus phylogeny of cichlid fishes (Pisces: Perciformes): evolutionary comparison of microsatellite and single-copy nuclear loci

Among vertebrates, cichlid fishes are the paradigmatic example of adaptive radiation and ecological specialization. In turn, molecular genetic studies of cichlids have focused primarily on more recently diverged groups. Here, we present an evolutionary hypothesis of the major lineages of cichlid fishes based on DNA sequence data from two nuclear loci. One marker, Tmo-4C4, is a single-copy locus containing a region of amino acid similarity to the muscle protein TITIN. Flanking sequence from a second, microsatellite, locus Tmo-M27, shows similarity to mammalian RAS guanine nucleotide-releasing factor. We compare and combine data from these loci to evaluate phylogenetic performance. In separate and combined analyses, the sequence data support and clarify previous morphological hypotheses of cichlid major-group relationships. Indian and Malagasy cichlids form a basal, paraphyletic group. Neotropical cichlids are the sister clade to an African assemblage composed of the paraphyletic west and Pan-African lineages and a group of east African rift lake taxa. We use a consensus phylogeny of the Cichlidae to trace evolutionary changes in the microsatellite repeat motif at Tmo-M27. Analysis reveals that the repeat region was nearly lost in the ancestor to cichlids and then amplified extensively in African taxa. Results demonstrate that the two new DNA markers could be widely applied in perciform systematics. Furthermore, the comparative approach can unveil mutational dynamics of simple-sequence repeat loci over long periods of fish evolution. Simple-sequence repeat regions are increasingly being found in introns of important regulatory genes. We address issues involving their function and suggest caution in making assumptions of strict neutrality.     

Sexual harassment in live-bearing fishes (Poeciliidae): comparing courting and noncourting species

Sexual harassment by males has been reported from several live-bearingfishes (Poeciliidae) and has been shown to inflict costs onfemales. For example, poeciliid females have reduced feedingopportunities when accompanied by a male because females dedicateattention to avoiding male copulation attempts. Poeciliid speciesdiffer considerably in male mating behavior, such as the presenceor absence of courtship. Courting males display in front ofthe females, but males attempting to sneak-copulate approachfemales from behind, that is, in the blind portion of theirvisual field, and force copulations, which can be viewed asa male persistence trait. We predicted that poeciliid femalesneed to be more vigilant in the presence of noncourting males,and costs of harassment by noncourting males might be stronger.In a comparative approach we examined the costs of male sexualharassment for females as reduced feeding time in 9 speciesof live-bearing fishes, including courting (Poecilia latipinna,Poecilia reticulata, Xiphophorus cortezi, Xiphophorus variatus)and noncourting species (Poecilia mexicana [surface- and cave-dwellingform], Poecilia orri, Gambusia affinis, Gambusia geiseri, Heterandriaformosa). In all species examined except for the cave form ofP. mexicana, focal females spent significantly less time feedingin the presence of a male than when together with another female.The time females spent feeding was found to significantly declinewith increasing male mating activity (sum of all sexual behaviors),but there was no support for the idea that females would spendmore time feeding in the presence of courting males comparedwith noncourting ones.     

Stress and the development of agonistic behavior in golden hamsters

Aggressive behavior can be studied as either offensive or defensive responses to a stimulus. The studies discussed in this review are focused on the peripubertal development of offensive aggression in male golden hamsters and its responsiveness to repeated social stress. Quantitative and qualitative changes in offensive responses were analyzed during this period. Quantitative changes in offensive responses were observed as decreased frequency of attacks. Qualitative changes were observed as changes in attack types, as animals reorient their attacks gradually from the face to the lower belly and rump. These developmental changes were altered by repeated exposure to social stress during early puberty. Daily exposure to aggressive adults during early puberty accelerated the qualitative development of offensive responses and the onset of adult-like offensive responses. In contrast, social stress had little effect on the quantitative changes associated with early puberty. However, social stress was associated with higher attack frequency during adulthood. These effects of stress during early puberty contrast with those observed with animals in late puberty. At that time, repeated exposure to aggressive adults inhibits offensive aggression. These data constitute the basis for a new theory on the development of agonistic behavior that includes the following hypotheses. First, it is hypothesized that mid-puberty is marked by a change in responsiveness to repeated social stress. As such, differences in stress responsiveness from social interactions are interpreted as a basic distinction between play fighting and adult aggression. Second, it is also hypothesized that a common neural circuitry mediates the activation of offensive responses during play fighting and adult aggressive interactions.     

A review of damsel fishes (Pisces: Pomacentridae) of the genus Chromis from the central and eastern Atlantic and the Mediterranean

The specific status of the damsel fish Chromis chromis (L) is discussed and it is suggested that Chromis chromis is retained for Mediterranean specimens and that Chromis lirnbatus is re-introduced for the East Atlantic form. Behavioural and morphological differences which distinguish these two species are given. A key to these and other East Atlantic Chromis is provided, the species are described and their geographical range discussed.     

The ontogeny of agonistic behaviour in the blue gourami, Trichogaster trichopterus (Pisces,Anabantoidei)

The development of agonistic behaviour in the blue gourami, Trichogaster trichopterus, was studied from hatching to four months of age. Larval motor patterns appear first as simple, uncoordinated, and irregular movements and gradually become regular and well coordinated, forming integrated complex patterns, such as swimming, surfacing, and feeding. Most motor patterns used in agonistic interactions are first exhibited in non-social contexts. Initial interactions between young fish consist of Approach and investigation in a feeding context, in some cases followed by nibbling, Biting, and Chasing by one fish. Later, initial Approaches are separated from Biting and Chasing by Lateral Displays, circling, Tail Beating, and Fin Tugging, and by Appeasement behaviour that inhibits Chasing and Biting by the opponent.Agonistic behaviour of socially isolated fish, when paired in dyadic encounters as adults, indicates that the role of social experience as an integrator and regulator of social behaviour may change progressively during development and become more important as ontogeny proceeds.     

A biomechanical analysis of spitting in archer fishes (Pisces,Perciformes, Toxidae)

Summary The archer fish (Toxotes) is famous for its ability to shoot down prey from overhanging foliage. However, the biomechanics of the spitting act is relatively unknown. This study analyses the structures needed to generate the pressures involved in shooting water droplets up to 1.20 m above the water surface. The results of motion pictures (300 frames/s), combined with electromyographic techniques reveal that the spit is monophasic. The results of a three-dimensional mathematical model incorporating the relevant structural dimensions, show that the tongue plays a dominant role. The mouth valves act as a flutter valve, directing the course of the trajectory. The mathematical model is formulated generally and is applicable to other studies of closed kinematic spatial systems encountered in fishes or higher vertebrates.Abbreviations c-br. ceratobranchial - cent. central - centr. centroid - c-hy. ceratohyal - cl caudal - cleit. cleithrum - cond. condyle - cop. copula - corac. coracoid - dent. dental - dist. distance - dl dorsal - e-br. epibranchial - ectopt. ectopterygoid(al) - e-hy. epihyal - entopt. entopterygoid(al) - epax. epaxial - e-scap. extrascapula - fct facet - gl-hy. glossohyal - h-br. hypobranchial - h-hy. hypohyal - hy. hyoid - hyom. hyomandibula - hyp. hypaxial - if-orb. infraorbital - i-hy. interhyal - ins. insertion - i-op. interoperculum - i-orb. interorbital - l. ligamentum - lacr. lacrimal - m. musculus - m.add.arc.pal. m. adductor arcus palatini - m.add.mand. m. adductor mandibulae - m.add.op. m. adductor operculi - m.dil.op. m. dilatator operculi - m. geniohy. m. geniohyoideus - m.hyohy.inf. m. hyohyoideus inferior - m.i-mand. m. intermandibularis - m.lev.arc.pal. m. levator arcus palatini - m.lev.op. m. levator operculi - m.protr.pect. m. protractor pectoralis - m.sternohy. m. sternohyoideus - mand. mandibula, mandibular - max. maxilla(ry) - metapt. metapterygoid - musc. musculature - nas. nasal - neur. neurocranium - N V mand. mand. branch of trigeminal nerve - op. operculum - or. origin - pal. palatinum, palatinal - par. parietal - pect. pectoral - ph.br. pharyngobranchial - p.p. pro parte - p-pect. postpectoral - pr. process - premax. premaxilla - preop. preoperculum - p-sphen. parasphenoid - p-temp. posttemporal - quadr. quadratum - rad. radial - rl rostral(is) - scap. scapula - s-cleit. supracleithrum - s-op. suboperculum - susp. suspensorium - symph. symphysis - sympl. symplecticum - t. tendon - u-hy. urohyal - vert. vertebra - vl ventral - vom. vomer(ine)     

Conceptual and methodological issues in the genetics of mouse agonistic behavior

Currently, 36 genes have been reported to affect offensive behavior in male mice. Potentially, these genes could be used to analyze the mechanism of this behavior. But there are methodological flies in this conceptual ointment. The studies with these genes varied in the genetic background, the maternal environments, the postweaning housing, the strain or type of opponent, and the type of test. The effects of each of these on the genetics of offense are reviewed with examples. It is concluded that between-study variation in these environmental or experiential circumstances may make it difficult to impossible to relate the effect of one genetic variant to another and to use these to identify and relate the pathways for gene effects on offensive behaviors. For this reason, standardization of these conditions is recommended.