The behaviour of Abudefduf zonatus (Pisces,pomacentridae) at Heron Island,Great Barrier Reef

Social organization and reproductive behaviour of Abudefduf zonatus were studied at Heron Island, Great Barrier Reef. This species is closely associated with the sand and coral substrate of the inner reef flat zone. Territorial, clustering, nest-digging, breeding and parental care behaviours are described. Mature males maintain territories for several weeks or longer around empty clam shells in which periodic spawning occurs. Females and sub-adult males hold territories interspersed among those of adult males. No pair bonds are formed, and eggs are guarded only by males. Breeding is roughly synchronized among fish of one area. Clustering behaviour may contribute to breeding syndrony in local populations.     

Single‐parentage assignments reveal negative‐assortative mating in an endangered salmonid

Understanding reproductive patterns in endangered species is critical for supporting their recovery efforts. In this study we use a combination of paired‐parent and single‐parent assignments to examine the reproductive patterns in an endangered population of sockeye salmon (Oncorhynchus nerka) that uses Redfish Lake in central Idaho as a spawning and nursery lake. Recovery efforts include the release of maturing adults into the lake for volitional spawning. The lake is also inhabited by a population of resident O. nerka that is genetically indistinguishable, but phenotypically smaller, to the maturing adults released into the lake. The resident population is difficult to sample and the reproductive patterns between the two groups are unknown. We used results of paired‐ and single‐parentage assignments to specifically examine the reproductive patterns of male fish released into the lake under an equal sex ratio and a male‐biased sex ratio. Assignment results of offspring leaving the lake indicated a reproductive shift by males under the two scenarios. Males displayed an assortative mating pattern under an equal sex ratio and spawned almost exclusively with the released females. Under a male‐biased sex ratio most males shifted to a negative‐assortative mating pattern and spawned with smaller females from the resident population. These males were younger and smaller than males that spawned with released females suggesting they were unable to compete with larger males for spawning opportunities with the larger, released females. The results provided insights into the reproductive behavior of this endangered population and has implications for recovery efforts.     

Reproductive behaviour of the filefishRudarius ercodes: male spawning parades and female choice

Synopsis The reproductive behaviour ofRudarius ercodes is described from undersea observations in Aburatsubo Bay, Japan. Reproductive behaviour can be separated into four parts: (1) Prespawning Search = searching for spawning sites by females and searching for gravid females by males, (2) Spawning Parade = males follow a gravid female in a line, competing with each other to reach the head of the queue, (3) Spawning = the female takes the spawning position, males rush to the side of the female, and mating occurs between one female and several anterior males of the spawning parade, (4) Parental Care = females attach adhesive eggs to seaweed with the mouth and guard them until embryos hatch. There is no male parental care. The reproductive season ranges from May to October and spawning occurs early in the morning every day. Females begin feeding early in the morning, but males feed little at this time.R. ercodes shows neither territorial behaviour nor fixed-pair spawning. One male might spawn several times in one morning. One female spawns at most once every 5 days. The mating system of this species is promiscuous. The probable function of the spawning parade as a style allowing female choice is discussed.     

Females solicit sneakers to improve fertilization success in the bitterling fish (Rhodeus sericeus)

In most species there is greater variance in reproductive fitness among males than females. A consequence is the evolution of alternative male mating tactics, including sneaking behaviour whereby males attempt to mate with females courted by other males, which could undermine female choice. In bitterling (Rhodeus sericeus), fish that lay their eggs on the gills of living freshwater mussels, sneaking is common and successful. Here we show that female bitterling can significantly improve their fertility with an increase in the number of spawning partners. Females perform conspicuous behaviours associated with spawning more frequently close to sneakers, and spawn more eggs close to high-quality sneakers. This is the first time that females have been shown to engage in behaviour that increases the probability of sneaking, and raises the possibility of a sexual conflict over the number and source of ejaculates during spawning in this species.     

Social Behaviour of Individual Oval Squids (Cephalopoda,Teuthoidea, Loliginidae,Sepioteuthis lessoniana) within a Captive School

The social behaviour of individually identified squids was observed over a period of 4 mo. Squids were reared in captivity and maintained in a shoal of up to 18 animals. Distances between animals averaged 1.6 body lengths, similar to the 1.2 body lengths of wild teleost fish schools. Smaller animals schooled less frequently and were found at the periphery, and familiar and unfamiliar animals shoaled together. Eighty-six apparent reproductive events were observed. This species of squid, Sepioteuthis lessoniana, is not sexually dimorphic to the human eye and male squids copulated with both males and females but they directed their attention disproportionately towards females. Most copulations occurred more than a month before spawning, lasted only a few seconds and, unlike field observations on spawning grounds, were not followed by mate-guarding. Two body patterns are described that were used consistently in social interactions by both males and females; these patterns were both associated with reproductive behaviour but their exact function was unclear. A sister species, Sepioteuthis sepioidea, has been described as showing complex social behaviour; in S. lessoniana, no evidence for such behaviour was seen.     

The influence of discharge, photoperiod, and temperature on the reproductive ecology of cyprinids in the Paluxy River, Texas

The distributions and abundances of cyprinids in North America are declining at an alarming rate with almost half of all known species considered imperiled and in need of conservation. Much of this loss in biodiversity is a result of flow regulation and climate change, especially in streams in the southern Great Plains that are prone to large and rapid fluctuations in discharge. The overall objective of this study was to examine the influence of discharge, photoperiod, and temperature on the reproductive ecology of cyprinids in the Paluxy River, Texas. Our results support previous findings in that photoperiod and water temperature were influential in the initiation and termination of the annual reproductive season. Interannual differences in GSI for Cyprinella venusta and Notropis volucellus indicated that reproductive effort in certain cyprinids was directly linked to discharge. In 2010, mean gonadosomatic index values for C. venusta (9.60 %) and N. volucellus (9.15 %) were at least twice that of 2011 (4.61 and 3.14 %, respectively); discharge during the spawning season of 2010 averaged 1,965 cfs, whereas it averaged only 177 cfs in 2011. Indeed, yearly differences in streamflow (i.e., mean annual discharge) can significantly impact the production of ova in a variety of cyprinids, even those non-broadcast-spawning species such as C. venusta. Consequently, we suggest conservation efforts should focus on maintaining natural flow regimes to combat the overwhelming loss of cyprinid diversity, especially as water extraction and climate change continue to threaten the biodiversity of freshwater fishes.     

Mate-guarding in a promiscuous insect: species discrimination influences context-dependent behaviour

Mating strategy is often informed by social context. However, information on social environment may be sensitive to interference by nearby heterospecifics, a process known as reproductive interference (RI). When heterospecific individuals are present in the environment, failures in species discrimination can lead to sub-optimal mating behaviours, such as misplaced courtship, misplaced rivalry behaviours, or heterospecific copulation attempts. All aspects of mating behaviour that are influenced by social context may be prone to RI, including copulatory behaviours associated with mate-guarding in the presence of possible competitors. Here we investigate the effect of three heterospecifics on the mate-guarding behaviour of male Lygaeus equestris seed bugs. We find that, despite previously reported heterospecific mating harassment amongst these species of lygaeid bug, male L. equestris are able to effectively distinguish rival conspecific males from heterospecifics. Thus, heterospecific mating attempts in this group may reflect selection on males to mate opportunistically, rather than a failure of species discrimination.     

Reproductive characteristics of the ocean leatherjacket, Nelusetta ayraudi

The ocean leatherjacket (Nelusetta ayraudi) is one of the largest members of the family Monacanthidae. Distributed throughout inshore waters around the southern half of Australia, this schooling species supports substantial commercial and recreational fisheries. N. ayraudi do not conform to either of the general reproductive modes reported within the family, but exhibit characteristics of both strong social reproductive behaviour and of being promiscuous and polygynous. Sexual dimorphism, with males and females exhibiting differing colouration and body shapes, and ripe ovaries being an order of magnitude larger than ripe testes, are characteristic of social reproductive behaviour and pair spawning. In contrast, high batch fecundity (mean of 320 oocytes per gram of body weight), similar sizes and ages at sexual maturity (350 mm and 2.5 years respectively) and the formation of large spawning aggregations in offshore waters are characteristic of being promiscuous and polygynous. Similar to many other coastal marine species off the east and west coasts of Australia, N. ayraudi are partial spawners during the austral winter months with spawning restricted to the part of their distribution that is towards the upper area of the prevailing currents. It is hypothesized that N. ayraudi off eastern Australia have evolved a life-history strategy whereby fish move northwards through time, spawning occurs in these more northern waters and the southerly flowing Eastern Australian Current facilitates dispersal of eggs and larvae southwards. The reproductive characteristics described provide various options to fishery managers who wish to enhance the sustainability of the fishery through increased egg production. These include spatial and temporal fishing closures to protect breeding fish during the spawning period, the protection of juveniles through either inshore area closures, improving the selectivity of fishing gears and/or regulated minimum legal lengths.     

Energy expenditures during spawning by chum salmon Oncorhynchus keta (Walbaum) in British Columbia

Physiological telemetry and proximate tissue analyses were used to assess energy expended by chum salmon Oncorhynchus keta on various behaviours during spawning in Kanaka Creek, British Columbia, Canada, and results were compared with published data on Fraser River sockeye salmon Oncorhynchus nerka , the only other species for which both types of measurements have been taken. Chum salmon arrived at the spawning grounds with body energy densities of 4·84 MJ kg⁻¹ in males and 4·62 MJ kg⁻¹ in females, lower than most sockeye salmon populations, and died with energy densities of c . 4 MJ kg⁻¹, similar to that observed in sockeye salmon and other salmonids. Moisture levels generally increased in body tissues over the spawning life, particularly in female gonads, and lipid levels decreased. Declines in protein observed over the spawning life of other Pacific salmon Oncorhynchus sp. were less evident in Kanaka Creek chum salmon. Holding behaviour constituted the dominant component of the activity schedule and energy budget of both sexes. After holding, the most expensive behaviours were nest digging in females and aggressive displays in males. Dominant males expended the most energy on behaviours each day, as indexed by oxygen consumption (3600 mgO₂ kg⁻¹), while satellite males expended nearly as much (3504 mgO₂ kg⁻¹) but females expended considerably less (2327 mgO₂ kg⁻¹). Kanaka chum salmon engaged more frequently in energetically expensive reproductive behaviours than Stuart River sockeye salmon.     

Effect of density on the reproductive behaviour of the territorial male demoiselle Chromis dispilus (Pisces: Pomacentridae)

Synopsis Characteristics of nest sites and reproductive behaviour of territorial male demoiselles Chromis dispilus were examined at sites of low, medium and high population density in northeastern New Zealand, by use of SCUBA diving and a remote underwater video system. Nest territories were closer together at high density (relative to areas of low population density) and this was accompanied by an increase in the frequency of spawning sequences and territorial defence against conspecifics. Territorial males were more aggressive during periods of display and spawning than during egg guarding. Fish from areas of low density spent more time on courtship display (signal jumps) and territorial defence against fish of other species, than demoiselles from areas of high population density. Territories and nest sizes tended to be largest in areas of medium population density. As in other damselfishes, population density is a major determinant of the frequency and intensity of reproductive behaviours.     

Shifting reproductive success in a shoal of Atlantic Cod, Gadus morhua L.

Individual and temporal variability in the spawning behaviour of Atlantic Cod (Gadus morhua L.) was examined by studying wild and reared individuals from the same putative population in a common spawning arena. The number of eggs fertilized per male was best explained by the number of aggressive interactions initiated by each male. A strong skew in male reproductive success and a temporal shift in male fertilization success were also observed. The latter co-occurred with an apparent similar temporal shift in the reproductive behaviour of the individual males. We hypothesize that energetic costs associated with reproduction, potentially mediated by sperm depletion in dominant individuals, may be responsible for temporal shifts in mating behaviour and reproductive success of male Atlantic Cod. We suggest that this hypothesis merits further study.     

The spawning behaviour of the endangered Eastern Cape rocky, Sandelia bainsii (Anabantidae), in South Africa

Sandelia bainsii is an endangered freshwater fish species which only occurs in short sections of several Eastern Cape river systems in South Africa. The spawning behaviour of S. bainsii is described for the first time. Female S. bainsii remained a light grey colour. Males exhibited distinctive nuptial coloration consisting of an intense black with a white bar on their caudal fin and white windows on the posterior areas of their dorsal and anal fins. There was a darkened post orbital contact organ of ctenoid scales on the reproductively active males. The spawning behaviour was recorded on a video recorder and analyzed during frame by frame replay. Sandelia bainsii are uniparental substrate breeders. The male prepared a spawning area by clearing the substrate with rapid body movements (sweeps). There were a number of preliminary courtship movements, several trial embraces by the male before the actual final embrace. The male underwent a U bend around the female, anchored himself with the contact organ, squeezed the abdominal area of the female with a quick head movement. Courtship and spawning all took place near the substratum. Twenty one separate mating bouts were filmed and analyzed. The duration varied from 1.44 to 5.11 seconds with an average embrace of 3.39 seconds. During the mating clench the female was not normally turned over, as in some anabantoids, but remained upright. The male then guarded the spawning area. Eggs were light yellow, adhesive, demersal and 1.28 mm in diameter with 0.61 mm oil globules. The breeding behaviour of S. bainsii has some similarities with both breeding behaviourial groups, the bubble nesters and the free spawners, within the other African anabantid genus, Ctenopoma. Sandelia bainsii have acquired some temperate specializations with regard to their reproductive style. Free spawning and the release of buoyant eggs is the plesiomorphic anabantid reproductive style. The demersal eggs and male substratum nest sites of S. bainsii are considered apomorphic.     

A molecular genetic examination of the mating system of pumpkinseed sunfish reveals high pay-offs for specialized sneakers

Intrasexual variation in reproductive behaviour and morphology are common in nature. Often, such variation appears to result from conditional strategies in which some individuals (e.g. younger males or those in poor condition) adopt a low pay-off phenotype as a 'best of a bad job'. Alternatively, reproductive polymorphisms can be maintained by balancing selection, with male phenotypes having equal fitnesses at equilibrium, but examples from nature are rare. Many species of sunfish (genus Lepomis) are thought to have alternative male reproductive behaviours, but most empirical work has focused on the bluegill sunfish and the mating systems of other sunfish remain poorly understood. We studied a population of pumpkinseed sunfish (Lepomis gibbosus) in upstate New York. Field observations confirm the existence of two male reproductive strategies: 'parentals' were relatively old and large males that maintained nests, and 'sneakers' were relatively young and small males that fertilize eggs by darting into nests of parentals during spawning. The sneaker and parental male strategies appear to be distinct life-history trajectories. Sneaker males represented 39% of the males observed spawning, and sneakers intruded on 43% of all mating attempts. Microsatellite analyses revealed that sneaker males fertilized an average of 15% of the eggs within a nest. This level of paternity by sneaker males appears to be higher than seen in most other fishes, and preliminary analyses suggest that the two male reproductive strategies are maintained as a balanced polymorphism.     

Phylogenetic relationships of Iberian cyprinids: systematic and biogeographical implications.

The phylogenetic relationships among all Iberian endemic cyprinids were inferred using the complete nucleotide sequence of the cytochrome b gene. The inferred molecular phylogeny included representatives from Central European, Asian and North African species, and is highly congruent with previous phylogenies based on osteological characters. Iberian cyprinids were grouped into only five, very speciose lineages (with the exception of the monotypic Anaecypris): Barbus, Luciobarbus, Chondrostoma, Leuciscus and Anaecypris. The existence of such a relatively small number of Iberian cyprinid lineages can be explained by the historical isolation of the Iberian Peninsula. North African and Asian barbels are the sister group of Iberian Luciobarbus, supporting a south-eastern route of colonization of the Iberian Peninsula for this subgenus. With leuciscins, Anaecypris hispanica was considered a relict species as it could not be related to any other Iberian cyprinid. The phylogenetic relationships among the main lineages of Iberian cyprinids based on cytochrome b sequence data supported the traditional division of the Cyprinidae into two subfamilies: Cyprininae and Leuciscinae.     

Preference for the presence of substrate in male cichlid fish: Effects of social dominance and context

Many cichlid species dig spawning pits or nests in soft bottoms and exhibit many substrate oriented activities. Despite this fact being of general knowledge, captive cichlids in laboratory and aquaculture set-ups are often kept in the absence of a soft substrate that they can manipulate. This raises a potential welfare issue, depending on how the substrate is valued by cichlid fish. The aim of this study is to assess the importance of substrate for male Mozambique tilapia (Oreochromis mossambicus) in social and non-social contexts. Preferences were established as a measure of time spent in two choice compartments, before and after the presence of a female. Locomotory activity, social interactions and substrate-related behaviours were recorded. Results show that dominant males prefer the area with substrate regardless of social context, and that female's presence strengthens this preference. The same preference is not apparent in the subordinate males, except for foraging. To draw conclusions on the importance of substrate to subordinates, preferences should also be assessed in agonistic contexts, during which substrate may serve to displace aggression. These results, together with related previous studies, show that the lack of substrate is particularly deleterious in a reproductive context, and thus it is likely to decrease the welfare state of breeding males of Mozambique tilapia.     

Sexual interactions in red-spotted newt populations

Two alternative reproductive tactics (amplexus and spermatophore transfer interference) and three sexual interference tactics (spermatophore transfer interference, pseudofemale behaviour, amplexus interference) are described for male red-spotted newts, Notophthalmus viridescens. The two reproductive tactics yield equal insemination rates for males displaying these behaviours. The three sexual interference tactics decrease the potential fitness of amplectic males either directly, by displacing them from receptive females and/or duping them into fruitless spermatophore depositions, or indirectly, by increasing the time spent in amplexus with no concomitant increase in probability of successful insemination.     

Evidence for sexual attraction pheromones released by male tropical donkey's ear abalone (Haliotis asinina), (L.)

Abstract

The tropical donkey's ear abalone (Haliotis asinina) is routinely collected in many parts of the Indo-Pacific and has significant potential for commercial aquaculture. Although its reproductive cycle has been investigated, no studies have reported the use of chemical signals to coordinate reproduction and spawning. Using a bioassay designed with one caged individual, whilst the other is free to roam, we investigated the presence of attraction pheromones released from mature individuals. Only mature females were attracted to caged mature males with all other treatments showing no significant attraction. Those mature females also took significantly less time to reach the mature males than other pairings. Temperature influenced the response with the maximum number of positives occurring between 25 and 31°C, which coincides with the optimum physiological temperatures and the spawning times for this species. We have also shown that the attraction pheromone is present in mature male testes and induces stereotypical pre-spawning behaviours (sweeping epipodial and cephalic tentacles) as well as attracting females. Some individuals also moved towards the surface of the water, this may also be a pre-spawning behaviour. This is the first time that a sexual attraction pheromone has been reported for any haliotid species and is likely to have a critical function in the synchronization of spawning in the wild between sexes.