Male body size and brooding success under natural conditions in the freshwater Japanese goby, Rhinogobius sp. OR (orange type)

Males of the Japanese goby Rhinogobius sp. OR (orange type) establish nests under stones in streams. They provide care to egg masses until hatching. We carried out field observations and a field experiment in a natural stream to examine the effect of male body size on brooding success. An experiment excluding guarding males indicated that their presence has a positive effect on nest defense. Field data showed that male body size was positively correlated with the size of the egg mass that was initially found at the nest. Furthermore, a sequential increase in egg mass size seen in the nests of larger males indicated that multiple females spawned during a single breeding cycle of larger males. To examine male brooding success, two dependent variables, egg mass persistence (days from initial egg mass to disappearance or hatching) and hatching success were analyzed. The results indicated that the variation found in both dependent variables was significantly explained by two independent variables, namely, initial egg-mass size and the number of matings. It is also suggested that male body size indirectly influenced brooding success through positive correlations with these independent variables.     

Changes in male physiological condition during brooding activities in a natural population of a stream goby, <Emphasis Type="Italic">Rhinogobius</Emphasis> sp.

We investigated the change in physical condition of males during paternal care in a natural population of a stream goby Rhinogobius sp. LD. Hepatosomatic index (HSI) and Condition factor (K) of males guarding an egg mass were higher than those of non-breeding males. In the first brooding cycle, the HSI of males decreased with the progress of embryo development. Moreover, in the second brooding cycle, both the HSI and K decreased, suggesting that the energy reserves in the somatic tissue were used when the liver reserves were exhausted as a source of energy for paternal activities. After paternal care, males showed reduced K and were unable to recover HSI immediately. Comparisons of the physical condition between non-guarding males after the first brooding cycle and males guarding an early stage clutch in the second brooding cycle indicated that males which could recover HSI and K were able to have a second brooding cycle. This suggested that the physical condition determines participation in breeding activity and the number of brooding cycles, greatly influencing male reproductive success.     

Reproductive behavior and spawning success of female Amblyglyphidodon leucogaster (Pisces: Pomacentridae) from the Red Sea

The reproductive behavior of female whitebelly damselfish, Amblyglyphidodon leucogaster, was investigated in the Gulf of Aqaba, Red Sea over two breeding seasons. Females were promiscuous, mating with 7–10 different males throughout the season. Females lay eggs in distinct batches, defined as the total number of eggs laid in a day. Generally females deposit a batch of eggs with one male (87.2%) and are capable of laying a new batch every other day. Egg batch size averaged 4009 eggs and females laid from 2 to 22 egg batches per season. The variation in spawning success was not correlated to body size. Females preferred to deposit eggs in nests that already contained early stage eggs (0–2 days old). Within a nest, females chose to lay eggs contiguous to the youngest egg batch, regardless if the nest contained either a single batch or multiple batches of different ages. Female within-nest spawning patterns appear to be a consequence of between nest preferences for nests with young eggs. It is proposed that the strong within-nest preference is a consequence of mate selection where females may use new egg batches as a visual cue as part of a copying style. Such a style may reduce the risk of predation and increase feeding opportunities, because less time is expended in mate selection, which would provide additional resources for egg production and ultimately increase female spawning success over the breeding season. This revised version was published online in July 2006 with corrections to the Cover Date.     

Large males have a mating advantage in a species of darter with smaller, allopaternal males Etheostoma olmstedi

Theory suggests that males that are larger than their competitors may have increased mating success, due to both greater competitive ability and increased attractiveness to females. We examined how male mating success varies with male size in the tessellated darter Etheostoma olmstedi. Previous work has shown that large males tend to move around and breed in vacant breeding sites, and consequently provide less care for their eggs, while smaller individuals can be allopaternal, caring for the eggs of other males as well as for their own. We studied female egg deposition in a natural breeding population using artificial breeding sites and in the laboratory, where female choice of spawning site was restricted to two breeding sites tended by two males of different sizes. In both the field and the laboratory, nests tended by larger males were more likely to receive new eggs. Additionally, the mean size of males associated with a nest was positively correlated with both the maximum coverage of eggs at the nest and the number of times new eggs were deposited. We discuss how the increased mating success of larger males, despite their decreased parental care, may help explain allopaternal care in this species [Current Zoology 56 (1): 1-5, 2010].     

Colonial Nesting and the Importance of the Brood Size in Male Parasitic Reproduction of the Mediterranean Damselfish Chromis chromis (Pisces: Pomacentridae)

We investigated male parasitic spawning in a protected natural population of Mediterranean damselfish. Chromis chromis nested in colonies, inside which males showed a high variability in mating success. Our field observations indicate that the egg batches obtained by the most successful fish were five times bigger than the ones obtained by the less successful fish and many males never received ovipositions. On the other hand, reproductive parasitism was a common tactic within the colony. Successful nesting males sneaked into their neighbours' nests depending on the amount of eggs in their nest, with small clutch size inducing the males to parasitic reproduction. Males failing to receive egg depositions on their nests showed a significantly higher parasitism rate than successful males. Non-territorial males occupied stations in the water column above the breeding grounds and whenever the opportunity arose, they disrupted spawning in progress, stealing copulation with females. We observed that the likelihood of males being parasitized by sneakers was not correlated with the size of their own clutch; on the contrary, it depended both on the number of neighbouring nests and on the number of neighbouring males with barren nests (i.e. unsuccessful males). No correlation was found between parasitic behaviour and male size, suggesting males may switch between spawning in their own and in their neighbour's nests depending on mating opportunity. The hypothesis that colonial nesting facilitates parasitic reproduction is here discussed.     

Correlates of male reproductive success in Padogobius martensi (Gobiidae)

Factors affecting male reproductive success were investigated in a natural population of Padogobius martensi , a small freshwater goby showing paternal care. Males were found to be polygynous and their mating success was related both to their body length and to the size of the nest occupied. Body size was a good predictor for the presence of eggs in the nest. The number of egg batches guarded by a male was highly correlated with the area of his nest. Mature males with a total length of 48 mm or less (1-year-old individuals) occupied nest sites in breeding areas but were never found with eggs in their nests. The components of sexual selection which may determine the variance in mating success are discussed.     

Reproductive success in male sunbleak, a recent invasive fish species in the U.K.

The spawning behaviour of male nest guarding sunbleak Leucaspius delineatus , a recent invasive species in southern England, was studied and quantified for the first time. In the absence of physical differences between territorial and non‐territorial males ( i.e . colour, size, etc .), the reproductive behaviour of territorial males was analysed and related to reproductive success. The results showed that females preferred high‐courting and highly aggressive males. The initial cue in female mate choice, however, was based on courtship, while aggression was the decisive behavioural trait in influencing mate choice, providing a direct signal of physical condition and 'paternal competence'. Some males picked nest sites which were subsequently preferred by other males taking over the nest of a previous male ('communal nest'), with the new territorial male adopting the eggs already present at the nest. It appears that either due to female preference for nests already containing eggs or lower rates of sired egg predation by dilution among unrelated eggs, sunbleak males have adopted the mating strategy of allopaternal care.     

Male mating success and female mate choice in the river sculpin,Cottus nozawae (Cottidae)

Synopsis Mating success of males and its correlates were investigated in a natural population of the polygynous fluvial sculpinCottus nozawae. Furthermore, the female mate preference of this species was examined experimentally under alternative conditions for mating in a stream. The mating success of individual males (the number of females with which a male mated) ranged between 0 and 8 with a mean of 2.41 in 1983 and 2.52 in 1989, in a population of which the sex ratio was about 1 : 2 in both years, skewed toward females. Mainly due to the excess of nests without egg masses and the few nests with one egg mass, the distribution of male mating success did not fit a Poisson distribution, indicating its non-randomness. Male mating success was not correlated either with the size of the nest rocks or with the male size, suggesting that these two variables are not determinants of mating success. The mate choice experiments demonstrated that females of this species more frequently chose smaller males as mates whose nests already contained eggs than large males without eggs. Additionally, an analysis of stomach contents of guarding males suggested that the parental males ate their own eggs during egg guarding (filial-cannibalism). Based on these results and on a comparison of reproductive characteristics with congeneric species, it is suggested that one of the most important determinants for female mate choice inCottus species may be whether or not parental males are filial egg cannibals.     

Lifetime mating success of males in a natural population of the papilionid butterfly,Atrophaneura alcinous (Lepidoptera: Papilionidae)

Lifetime mating success of males in a natural population of the papilionid butterfly, Atrophaneura alcinous, was investigated and causes of the variation were examined. The most successful males mated with 5 females, whereas about 73% of the males failed to mate. Body size of males was not correlated with their eclosion date, longevity and lifetime mating success. There was no trade-off between mating success and longevity, and long-lived males had a disproportionately high mating success. Although number of available females per male per day was not variable among males with different longevities, long-lived males had higher mating efficiency. Time interval between matings by non-virgin males was shorter than that from eclosion to the first mating. High lifetime mating success of long-lived males was strongly related to their mating experience, not to their age per se.     

Sex‐specific differences in Sand Martin Riparia riparia nest attentiveness

Capsule Nest attentiveness during the night is significantly lower in males but varies with the activities of the breeding cycle. Male nest attentiveness shows minima during the burrowing and egg‐laying phases, and also during the brooding of chicks in second or re‐nest broods.     

Alternative male mating tactics in Gobius niger

In the field, parental males of the black goby Gobius niger were always >9 cm L _T, showed a conspicuous elongation of the first dorsal fin, and were darkly coloured. Larger parental males did not occupy larger nests or obtain more eggs, suggesting that over a threshold size reproductive success was not correlated with male size. The mating system was polygynous with different egg clutches simultaneously present in a nest. Smaller sexually mature males were observed around and inside nests in which spawning was occurring. These opportunistic males ranged in body size between 6 to 8 cm L _T. In contrast to parental males, they did not show an exaggeration of the first dorsal fin and were cryptically coloured, thus resembling small females in their external morphology. Aquarium experiments confirmed that smaller males perform a sneaking behaviour, releasing sperm when parental males spawn. As a consequence, it is possible to define three male types: type I are small, without an elongated dorsal fin and adopt a sneaking mating tactic; type III are large, have a pronounced elongation of the dorsal fin and perform parental behaviour; type II are intermediate both in size and elongation of the first dorsal fin and behave as either as sneakers or, possibly, as parental males according to nest availability and male competition.     

Repeated Mating and Female Fecundity in the Simultaneously Hermaphroditic Land Snail Arianta arbustorum

Summary

To evaluate the influence of repeated mating on female fecundity in the simultaneously hermaphroditic, self-incompatible land snail Arianta arbus-torum, the number and size of clutches, egg size and hatching success of individuals from 3 populations were determined under conditions of isolation and grouping during one breeding season in a field cage experiment. Only adult snails which had mated and oviposited in the preceding year were used.

Sperm storage enabled isolated individuals to continue with the production of fertilized eggs. Snails kept singly or in groups differed neither in number of clutches laid nor in egg size. But isolated snails laid smaller clutches than did grouped snails. As a result isolated snails produced fewer eggs per breeding season. Hatching success varied greatly between populations and rearing conditions. In general, isolated snails had fewer hatchlings than grouped snails, indicating that individuals prevented from remating suffered a reduced fitness.     

Effects of delayed mating and male mating history on the reproductive potential of Leucoptera coffeella (Lepidoptera: Lyonetiidae)

Abstract 1 Despite the importance of Leucoptera coffeella (Guérin‐Mèneville) in coffee production worldwide, there is a lack of information on its reproduction. This knowledge will help in mass rearing, and support the development of behavioural control techniques for this insect. The present study determined the effects of delayed mating and previous matings of male L. coffeella on fecundity, egg viability and frequency of female remating. 2 The highest levels of fecundity and egg viability were obtained from matings of 1–3‐day‐old females. When females mated at 5 days of age, there were reductions of 40% in oviposition and of 43% in egg viability. 3 Females mated with 2‐day‐old virgin males were more fecund than those mated with older males; egg viability was also low (18%) from females mated with older males. 4 Virgin females that mated with virgin males laid a greater number of eggs than those mated with previously copulated males. Egg viability decreased with the increase in the number of previous male matings. 5 Five‐day‐old females remated in greater proportion than 2–3‐day‐old females. Females that copulated with males that had previously mated three times had higher rates of remating than those that copulated with virgin males. 6 The results obtained indicate that 1–3 days after emergence is the optimum age for mating. The implications of these findings for the control of L. coffeella by synthetic sex pheromone are discussed.     

Latitudinal trends in within-year reoccupation of nest boxes and their implications

Multiple brooding can substantially increase the annual reproductive output of birds, and the propensity for multiple brooding can vary geographically. Thus, studies attempting to understand the evolution of geographic variation in nesting success need to account for variation in re‐nesting potential. However, direct assessment of rates of multiple brooding requires individually recognizable breeding adults, which are not generally available. We explore the possibility of comparing relative indices of multiple broodedness across a latitudinal gradient from studies of un‐banded birds locally restricted to nest boxes. We analyzed nest box reoccupation by a multiple‐brooding species, the eastern bluebird Sialia sialis, reported by volunteers in a citizen‐participation project (1998–2002) in which nest boxes were monitored throughout much of the breeding range of the bluebirds. We found nest boxes in the southern portion of the bluebird range (30° latitude) had, on average 17–33% higher likelihood of repeated egg‐laying, brooding, and successful fledging events than boxes in the north (48° latitude). Latitudinal variation in the reoccupation of nest boxes may indicate that either (1) the number of broods per female varies with latitude, (2) female breeding dispersal/site fidelity varies with latitude, (3) the density, distribution, and/or availability of suitable nest sites varies with latitude, or (4) observer bias varies with latitude. Various lines of evidence suggest that nest re‐occupancy is a useful index of latitudinal variation in re‐nesting. During the time‐frame of second attempts, first‐time box occupancy was as likely as second occupancy and approximately 45% more likely in the south than north, suggesting that, despite considerable breeding dispersal, observed trends in box reoccupation conservatively reflect latitudinal trends in the number of nest attempts/broods per female. Furthermore, despite a compressed nesting cycle in the north (shorter incubation and re‐nesting interval), the shorter duration of the breeding season in the north restricted the potential number of broods. Studies of banded birds are necessary to confirm the behavior underlying the latitudinal trends in box reoccupation.     

Space use by the Japanese fluvial sculpin, Cottus pollux, related to spatio-temporal limitations in nest resources

Space use by the Japanese fluvial sculpin, Cottus pollux, as related to nest availability was studied in a Japanese mountain stream. Males had larger home ranges than females before breeding. A measure of nest resource limitation was L < 1 and the same nest rock was used by two males successively in three cases, indicating a limited supply of suitable nest rocks for males. All males included the nest rocks in their home ranges, but the timing of nest occupation was apparently dependent on male size, suggesting the presence of male-male competition for the nest rocks. Females, on the other hand, exhibited two different patterns in space use, independent of body size: (1) they spawned in their home ranges, or (2) they spawned out of their home ranges and returned. Nest cavity area did not affect male reproductive success. Spatial separation between female home ranges and nest location was the main reason for the females' movement out of their home ranges. The limitation in the male mating phase (5.7 days on average) might also have forced the females to move out of their home range to spawn. The reason behind such temporal limitation in the male mating interval was discussed from the viewpoint of the energy cost accompanying male parental care.     

Optimal numbers of matings: the conditional balance between benefits and costs of mating for females of a nuptial gift‐giving spider

In species where females gain a nutritious nuptial gift during mating, the balance between benefits and costs of mating may depend on access to food. This means that there is not one optimal number of matings for the female but a range of optimal mating numbers. With increasing food availability, the optimal number of matings for a female should vary from the number necessary only for fertilization of her eggs to the number needed also for producing these eggs. In three experimental series, the average number of matings for females of the nuptial gift‐giving spider Pisaura mirabilis before egg sac construction varied from 2 to 16 with food‐limited females generally accepting more matings than well‐fed females. Minimal level of optimal mating number for females at satiation feeding conditions was predicted to be 2–3; in an experimental test, the median number was 2 (range 0–4). Multiple mating gave benefits in terms of increased fecundity and increased egg hatching success up to the third mating, and it had costs in terms of reduced fecundity, reduced egg hatching success after the third mating, and lower offspring size. The level of polyandry seems to vary with the female optimum, regulated by a satiation‐dependent resistance to mating, potentially leaving satiated females in lifelong virginity.     

棕背黑头鸫繁殖习性初步观察

2008年和2009年的4～8月,在四川省雅江县帕姆岭对棕背黑头鸫Turdus kessleri的繁殖生态进行了初步观察.该鸟繁殖期在4月下旬至7月上旬,营树上巢,营巢树种为高山栎Quercus aquifolioides和鳞皮冷杉Abies squamata.窝卵数为2~3枚(n=7),平均卵重(7.96±0.03)g(n=8),卵长径(32.7±0.17)mm,短径(21.9±0.13)mm(n=13),雌雄共同孵卵,以雌性为主,孵化期为15~17 d(n=2),孵化率为83.3%(n=18).雌雄共同育雏,以雄性为主,雏鸟出飞后主要在巢周围的林下或灌从活动,这时亲鸟仍会对幼鸟喂食.在同一繁殖季对巢有重复利用的现象.     

Costs and Benefits of Mating in the Grasshopper Chorthippus parallelus (Caelifera: Acrididae)

Fitness consequences of different levels of mating benefits, viz., (1) virgin, (2) seldom mated, (3) free mating chances with the same male throughout the female's life span, and (4) free mating chances with three males always offered, were investigated in female meadow grasshoppers Chorthippus parallelus. No differences among the treatments were apparent in egg number per pod, total egg number per female, and hatching success of larvae. Seldom-mated females had offspring with the heaviest average larval dry weight. We did not find costs of mating in terms of reduced female longevity and residual dry weight between the treatments.     

Male Reproductive Success in a Promiscuous Armoured Catfish Corydoras Aeneus (Callichthyidae)

Among a variety of fish mating systems, promiscuity with random-mating seems to be most prevalent. However, detailed studies of promiscuity have been rare due partly to the peculiar difficulty in examination of male mating and reproductive success in the random mating. Females of the armoured catfish Corydoras aeneus (no sexual dimorphism other than size of males > females) spawn 10–20 egg-clutches with multiple males at a time, but an entire egg clutch is inseminated by sperm of a single male. We studied mating system of this fish in aquarium. Males had neither mating territories nor monopolized females, never being aggressive against rival males. Evidence of female preference for certain male traits including size was not detected. Females mated a male in proportion to his relative courtship frequency among males. Courtship frequency was not related to male size, and male mating success was not different between small and large males. Clutch size and insemination rate were different neither between small and large males nor between frequently and less frequently courting males. Thus, the male reproductive success will not be related to the male size, but directly to courtship frequency, indicating the random mating in this fish. There seemed to be fecundity advantage with size in female, and the consequent sexual difference in energy allocation will be responsible to the sexual dimorphism. We also discuss the low male-GSI in this promiscuous fish in which sperm competition hardly occurred.     

A link between sound producing musculature and mating success in Atlantic cod

Individual variability in the mating success of male Atlantic cod Gadus morhua was quantified within an aggregation ( n = 59) breeding undisturbed in a large (684 m³) mesocosm tank. Observational and morphometric data were examined to assess the degree to which this mating variation could be explained by aspects of morphology, condition and spawning behaviour. The number of ventral mounts initiated ( i.e. mating success) was highly variable; most mounts were initiated by a very small percentage of available males. The significant correlate of male mating success was mass of the sound producing musculature, i.e. drumming muscles. Neither body size, condition, pelvic and median fin morphology nor aggression influenced the number of ventral mounts initiated by a male. The present study suggests a possible link between sound production and mating success in Atlantic cod.