Spermatophore Production Research Articles

On the reproduction of Octopus vulgaris off the coast of the Canary Islands

The common octopus, Octopus vulgaris Cuvier, 1797 is the most important cephalopod species in catches of the artisanal trap fishery in Canary Islands waters. Based on monthly samplings carried out off Gran Canaria (Canary Islands), 760 specimens of the common octopus, ranging from 4.8 to 165 mm ventral mantle length, were studied from June 1996 to July 1997, and from December 1997 to June 1999. The length–weight relationships found were W=0.0007×VML 3.096 ( n=760; r=0.95 ), W=0.0007×VML 3.112 ( n=481; r=0.86 ), W=0.0007×VML 3.098 ( n=247; r=0.77 ), for all the specimens caught, males and females, respectively. The proportion of males was significantly higher than females. Males predominated in all size intervals. Males and females become sexually mature at 105 and 113 mm of VML, respectively. Maturation and spawning occur all year around, with more intensity from January to July, with a peak in April. There is a second spawning period in October–November. The number of spermatophores produced increased with length and maturity stage. The production of spermatophores by individual body weight fluctuated from 0.29 to 0.03 spermatophores/g. The number of oocytes per gram of body weight fluctuated from 108 to 465. The real fecundity oscillated between 31 and 106 eggs spawned per gram of female body weight.

Gamete production and sexual size dimorphism in an insect (Orchesella cincta) with indeterminate growth

Abstract 1. The relationship of growth and body size with reproductive effort in animal species has been studied much less for males than for females. This imbalance applies to Orchesella cincta (L.) (Collembola), an insect with indeterminate growth, in which egg production is related positively to body size and negatively to growth.2. To allow a comparison of the reproductive effort of male and female O. cincta, development and growth in immature stages of both sexes, and growth and spermatophore production for adult males were studied.3. Embryonic development time and hatchling size did not differ between prospective males and females, but from hatching on the trajectories diverged, with males growing more slowly and maturing earlier and at a much smaller body size than females.4. Neither the number of spermatophores deposited in the first adult instar (= inter‐moult period) nor the total number of spermatophores deposited during seven instars was related to body size or growth.5. Differences in growth rate between instars with and without spermatophore deposition indicated that the physiology of spermatophore production inhibits growth, which, however, was compensated for during the next instar.6. The difference in the relationship of gamete production with body size and growth between males and females explains the divergence of their size at maturity.

Maturation in the male giant crab, Pseudocarcinus gigas, and the potential for sperm limitation in the Tasmanian fishery

The onset of sexual maturity of male giant crabs (Pseudocarcinus gigas) from Tasmania, Australia was assessed to determine the extent of protection of mature males provided by the minimum legal catch size of 150 mm carapace length (CL). Maturity was assessed by morphometric analysis of chela development, change in vaso-somatic index (VSI) with size and production of spermatophores. Males develop through three morphological groups based on development of the molariform chela relative to CL, termed `small-chela', `intermediate-chela', and 'large-chela'. The onset of morphological change to intermediate-chela occurs at approximately 120 mm CL at both sample sites (eastern and western Tasmania). Males with small-chela morphology were able to produce spermatophores and the mid vas deferens of all animals greater than 90 mm CL contained numerous well-formed spermatophores. Vaso-somatic index increases with CL, particularly for small-chela animals. Tank trials demonstrated that female giant crabs carry broods in successive years without moulting and stored sperm remains viable for at least four years under these conditions. Observation of functional maturity of males is required to fully assess the potential for sperm limitation in the fishery. Nonetheless, factors that appear to reduce the risk of sperm limitation include: both females and males are harvested; females do not moult every year thereby raising the operational sex ratio; and females can store sperm for extended periods.

Mating asymmetry and the direction of evolution in the Hawaiian cricket genus Laupala.

Based on studies from native Hawaiian Drosophila, a model was proposed to explain sexual isolation and mating asymmetry, from which one could potentially infer the 'direction of evolution'. We examined sexual isolation between allopatric cricket species of the genus Laupala, another endemic Hawaiian insect with an elaborate mating system, to begin to explore the nature of sexual isolation and mating asymmetry in closely related Hawaiian organisms. We studied sexual isolation and mating asymmetry in two contrasts. First, an inter-island comparison, including L. makaio from the older island of Maui and L. paranigra from the younger island of Hawaii, and second, an intra-island (Hawaii) comparison, including L. nigra from the older volcano of Mauna Kea and L. paranigra with a primary distribution on the younger volcanoes of Mauna Loa and Kilauea. We used a 'no-choice' experimental design, pairing individual males and females in homospecific or heterospecific combinations. Several behavioural aspects of courtship (proportion of male singing, latency to male singing, production of spermatophores and courtship initiation speed) were quantified as well as the success or failure of matings. We demonstrate asymmetry in sexual isolation between reciprocal combinations of L. makaio and L. paranigra. This result is examined in light of the differences in courtship behaviour manifest in the experiments with these two species. We did not find evidence of asymmetry in sexual isolation between L. nigra and L. paranigra, although differences in courtship initiation speed were evident between reciprocal combinations of these two species. In addition to the geological argument that species on older islands and older volcanoes give rise to species on younger islands and younger volcanoes, we discuss phylogenetic evidence consistent with these biogeographic hypotheses of relationships among the focal taxa. The patterns of asymmetrical sexual isolation and mating asymmetry are consistent with those found in the native Hawaiian Drosophila.

Variation of distal genitalia in the simultaneously hermaphroditic land snail Arianta arbustorum (Pulmonata, Stylommatophora) caused by sexual selection?

The most likely explanation for genitalic extravagance may be sexual selection acting either before, during, or after copulation. In promiscuous species, the intensity of postmating sexual selection may be a function of population density. In this study we examined the variability of the distal genitalia involved in spermatophore production, reception and manipulation of 113 adult individuals of the simultaneously hermaphroditic land snail Arianta arbustorum (L.) from six natural populations in the Eastern Alps (Gesause, Austria). We investigated the hypothesis that these genitalia increase in relation to shell size with increasing population density (range: 0.9 to 39.8 individuals/m2) and expected a higher variance of the genitalia compared to shell dimensions due to sexual selection. Genitalic size was unexpectedly inversely related to population density, probably due to increased inhibitory effects of snail mucus. Patterns of variation of female and male characters did not differ. Coefficients of variation of the genitalia were significantly higher than those of the shell dimensions as predicted. This was due to a higher dispersion around the regression lines rather than higher allometric values. However, the influence of sexual selection on genitalic size and variance cannot be unambiguously determined. We discuss different scenarios emphasizing the importance of sexual selection to differing degrees and conclude that sexual selection has probably played only a minor role.

Variation of distal genitalia in the simultaneously hermaphroditic land snail Arianta arbustorum (Pulmonata, Stylommatophora) caused by sexual selection?

The most likely explanation for genitalic extravagance may be sexual selection acting either before, during, or after copulation. In promiscuous species, the intensity of postmating sexual selection may be a function of population density. In this study we examined the variability of the distal genitalia involved in spermatophore production, reception and manipulation of 113 adult individuals of the simultaneously hermaphroditic land snail Arianta arbustorum (L.) from six natural populations in the Eastern Alps (Gesäuse, Austria). We investigated the hypothesis that these genitalia increase in relation to shell size with increasing population density (range: 0.9 to 39.8 individuals/m2) and expected a higher variance of the genitalia compared to shell dimensions due to sexual selection. Genitalic size was unexpectedly inversely related to population density, probably due to increased inhibitory effects of snail mucus. Patterns of variation of female and male characters did not differ. Coefficients of variation of the genitalia were significantly higher than those of the shell dimensions as predicted. This was due to a higher dispersion around the regression lines rather than higher allometric values. However, the influence of sexual selection on genitalic size and variance cannot be unambiguously determined. We discuss different scenarios emphasizing the importance of sexual selection to differing degrees and conclude that sexual selection has probably played only a minor role.

Diurnal mating behaviour of a Nisitrus sp. cricket (Orthoptera: Gryllidae) from Sumatra

The sexual behaviour of a diurnally active cricket in the genus Nisitrus is described from observations made in its natural habitat. Courtship consists of both auditory and visual elements. The male transfers up to five spermatophores to an individual female during a single reproductive sequence lasting more than 3 h. Males guard females during the intervals between successive production of spermatophores. The visual signal-one or more hind-leg waves-given by the male to indicate to the female that she can eat the old spermatophore, and that a new one is now ready, appears to be unique among gryllids studied so far. Females are very co-operative, as they stand to receive and then eat as many as five spermatophores in relatively quick succession. Inter-male rivalry does not occur in the absence of females, but possible 'spoiling' behaviour may occasionally interrupt mating sequences.

Fluctuating asymmetry and sperm transfer in male decorated field crickets ( Gryllodes sigillatus )

Fluctuating asymmetry (FA) in limb size in female decorated field crickets (Gryllodes sigillatus) was associated with a reduction in the size of the spermatophore and the amount of sperm transferred by males and an increase in the time taken to transfer a spermatophore following introduction of a female. There was a weaker negative relationship between limb asymmetry in males and sperm number but no significant relationship between asymmetry in either sex and spermatophylax size. In line with a previous study, female size did not appear to influence spermatophore production or mating decisions by males. The results imply that developmental instability affects both gamete production and mating decisions among males, although the relationships between spermatophore size, sperm number and asymmetry in females are unlikely to be the result of males perceiving differences in female FA.

First evidence of some dinoflagellates reducing male copepod fertilization capacity

Evidence is presented that hatching failure in Temora stylifera eggs can depend on poor sperm quality. Three dinoflagellate diets, Prorocentrum micans, Gymnodinium sanguinium, and Gonyaulax polyedra, significantly modified spermatophore production and reduced the fertilization capacity of male sperm after 6–12 d of continuous feeding. Two other diets, the dinoflagellate P. minimum and the prymnesiophycean Isochrysis galbana, had no effect on hatching success, which remained high (>;89%) and stable with time. A reduction in fertilization capacity was neither due to maternal effects nor to male age since hatching success returned to normal upon the introduction of freshly caught wild males or males conditioned with a good diet such as P. minimum for the same length of time as couples fed with the poor diets, P. micans, G. sanguinium, and G. polyedra. Confocal microscope images of unhatched eggs colored with a nucleus‐specific fluorescent dye confirmed that these eggs had not been fertilized. Experiments with Calanus helgolandicus females, which did not require reinsemination and which were fed the same diets that induced hatching failure in T. stylifera, showed no change in hatching success with time.

Reproduction, larval development and functional relationships of the burrowing, spionid polychaete Dipolydora armata with the calcareous hydrozoan Millepora complanata

Dipolydora armata (Langerhans, 1880) is a small (4 to 5 mm) spionid polychaete found burrowing in the calcareous hydrozoan Millepora complanata Lamarck, 1816, on coral reefs at Barbados, West Indies. It excavates complex networks of interconnecting burrows and forms aggregations of worms in cavities within branches of the coral. Adult worms have a mixed feeding mode (suspension feeding and deposit feeding). Size–frequency distributions of worms in branch samples suggest that they mature in a single year and that reproduction occurs throughout the year. Burrow openings on the surface of the coral develop distinctive, erect spines caused by combined growth of worm tubes and host tissue. Millepore zooids were absent in the vicinity of tube openings and on spines, and thus the potential feeding surface of the coral will be reduced in heavily colonized branches. Burrows and openings were densest at the bases of millepore branches where weakening of the skeleton would be expected to occur. The absence of openings near the branch tips suggests difficulty in larval settlement there, amongst stinging zooids. Reproduction␣and larval development of the worms were examined, and a sequence of larval stages from one to 20 segments and a juvenile stage of 22 segments are described. Eggs are deposited in brood sacs attached to the burrow wall, and the larvae feed upon nurse eggs (adelphophagy). The presence of larvae and juveniles occurring free in the burrows suggests that larval development may be completed within the host coral as an alternative or in addition to a planktonic larval phase. Lack of provisional larval setae, early development of adult capillary setae, production of special spermatophores and a protracted breeding cycle in D. armata are all traits which would favour complete development within the host skeleton.

Delayed mating and its cost to female reproduction in the butterfly,Eurema hecabe

The timing of mating of females under semi-natural condition, male ejaculate production and their effects on female fecundity were examined inEurema hecabe. Age of the first mating of females varied, and the number of matings increased with age. Male spermatophore production depended on age and body mass. The spermatophore mass at the second mating depended only on the interval between the first and second matings. The timing of the first mating and the spermatophore mass did not affect female fecundity. The timing of mating of females relative to the role of male spermatophores in female fecundity and male mating strategy are discussed.

Ejaculate expenditure by malebush crickets decreases with sperm competition intensity

Male bushcrickets transfer a spermatophore at mating that consists of a sperm-containing ampulla and a sperm-free mass, the spermatophylax, that is consumed by the female during insemination. The costs of spermatophore production for males and benefits of consumption for females result in reversals in courtship roles in nutrient limited populations that increase both the risk and intensity of sperm competition. Here we show that under conditions characteristic of courtship role reversal, male expenditure on the spermatophore is dependent on female size. When mating with small females, males increase the amount of spermatophylax material and sperm, as expected from the increased sperm competition risk associated with courtship role reversal. However, males reduce the amount of spermatophylax material and sperm transferred to larger females. Since larger females have a higher mating success when competing for nurturant males, the intensity of sperm competition covaries with female size. Reduced ejaculate expenditure under increased sperm competition intensity is in accord with theoretical expectation.

Ultrastructure and relationships of spermatozoa of the freshwater crabs Potamon fluviatile and Potamon ibericum (Crustacea, Brachyura, Potamidae)

The spermatozoa of Potamon fluviatile and P. ibericum are virtually indistinguishable and do not support separate subgeneric rank (Potamon and Pontipotamon, respectively). Synapomorphic with the spermatozoa of the South African freshwater crab Potamonautes perlatus Sidneyi are the elongation of the two centrioles and disposition of the centrioles almost parallel to each other, unknown elsewhere in the Brachyura, and reduction of the thickened ring (homoplasic with grapsids and gecarcinids). Other, probably synapomorphic, similarities of Potamon and Potamonautes include the wide inner acrosome zone, absence of a definite acrosome ray zone (homoplasic in other families) and the cleistospermial spermatophores. Further similarities, of questionable polarity, are the simple, not multilaminar, nuclear membrane and the tendency of the nuclear arms to wrap around the nucleus. Differences of Potamon from Potamonautes, which possibly support their present generic separation and give weak support to their former separate familial placement in the Potamidae and Potamonautidae respectively, are perforation of the operculum and the weak, rather than strong, development of a periopercular rim. Absence in Potamon and Potamonautes of an accessory opercular ring and a xanthid ring separates them from xanthids. No close affinities with other heterotreme families are seen but their assignment to the Helerotremata is not in doubt. Their spermatozoa lack two of the distinctive features of thoracotreme spermatozoa (apical button on the operculum and concentric lamellation of the outer acrosome zone). No clear correlates of spermatozoon structure with a freshwater existence are recognizable but reduction of the thickened ring possibly relates to peculiarities of the acrosome reaction. However, the production of spermatophores with single spermatozoa (cleistospermia) is possibly a device to prevent polyspermy and wastage of the small number of lecithotrophic eggs produced in potamids.

Moult in relation to some aspects of reproduction and growth in swarms of Antarctic krill,Euphausia superba

In a 14-d period 38 swarms of Antarctic krill,Euphausia superba Dana, were sampled in an area 55.5 x 55.5 km to the southwest of Elephant Island, at the north of the South Shetland Islands. Moult stage, maturity stage, and size of ca. 100 krill from each swarm were measured. Each of the characteristics varied greatly between swarms. Moulting krill were found in most swarms, but in one swarm all of the krill were just about to moult. Ways in which moulting may act as a possible sorting mechanism are discussed. Data for all the analysed krill (ca. 3000 specimens) were used to investigate the interdependence of moult rate, sexual maturation and growth. While all immature krill moulted at approximately the saine rate in the study, there were significant differences in the moulting rates of mature male and female krill. Gravid female krill continued to moult, although less frequently than mature males. As a consequence males had to attach spermatophores to females after each moult. It is likely that variation in moult rate of females and males was related to the energy expenditure required for ovary development in females and spermatophore production and searching behaviour in males. Spawning and moulting were only partly coupled in gravid females. Spawning appeared to take place predominantly during Moult Stage D2. There was no evidence of intermoult growth by intersegmental dilation.

The spermatophore of the carrion beetle Thanatophilus sinuatus biochemical characterization of proteins and incorporation of radioactively labelled amino acids

Male Thanatophilus sinuatus (Coleoptera, Silphidae) transfer a spermatophore to females at mating, consisting on average of 40% protein based on dry mass. One-dimensional gel electrophoresis revealed several stainable proteins in the range of 14 kDa-70 kDa. The protein pattern was found constant for spermatophores of different individuals. One lipoprotein, two glycoproteins and one glyco-lipoprotein were detected by staining methods. Several isoforms of all proteins were detected after two-dimensional gel electrophoresis, varying in the isoelectric points. The majority of the proteins were slightly acidic. By immunodetection of chromosomal proteins, histone H2A/H2B and high mobility group protein HMG1 could he selectively demonstrated as compounds of the spermatophore. Autoradiographic studies showed, that radioactively labelled amino acids ( 3H or 14C:), injected into the male, were incorporated into proteins of the male accessory glands. Comparing the labelled protein pattern, the predominant proteins of the spermatophore seemed to derive mostly from the long accessory glands. In relation to whole body, labelled amino acids were preferentially incorporated into reproductive tissues. The highest accumulation of radioactivity was found for spermatophores. For the vasa deferentia, the place of sperm storage, and the long accessory glands, a high accumulation was detected. Based on incorporated radioactivity, about half of the proteinous accessory gland secretions were used in spermatophore production.

Female Sexual Interference in the Smooth Newt, Triturus vulgaris vulgaris

AbstractCompetition between unmated females for males was observed in the smooth newt, T. vulgaris, during the early part of the breeding season. Females interfered at the spermatophore‐transfer stage of courtship, preventing a rival female from picking up the sperm mass. Interference often resulted in the rival female abandoning the courtship encounter. In many of the encounters (70%), the interfering female was inseminated. However, interference between females was not observed after the commencement of ovulation.By contrast, the incidence of sexual interference between males was low during the preovulatory period and increased significantly post‐ovulation.Sexual interference in newts and salamanders has previously only been observed between males. During the greater part of the breeding season, when females are ovipositing, eggs are the limiting resource and males compete for access to receptive females. However, this study suggests that early in the breeding season, prior to commencement of ovulation, the limiting resource may temporarily be sperm, due to the physiological constraint of spermatophore production. This may lead to female competition for mates.

Mating strategies based on foraging ability: an experiment with grasshoppers

Female mate choice and the benefits of this behavior are critical aspects of Darwinian sexual selection, but they are seldom documented because it is difficult to identify the male trait(s) that females may be seeking. We conducted experiments with grasshoppers (Melanoplus sanguinipes: Orthoptera, Acrididae) to examine this behavior. Males that feed more intensively and select a diet mix that permits greater food intake (food intake per body mass per time) in laboratory trials were preferentially selected by females. These better foraging males on average provide greater paternal investment (greater spermatophore mass) to the female, which increases her reproductive rate (eggs produced per body mass per time). However, paternal investment may not entirely explain female choice of better foraging males, because these males were still selected even if they had their food intake restricted or had been allowed to recently mate, which reduces spermatophore production. Furthermore, males change their mating strategy in response to female choice and the foraging abilities of surrounding males. Poorer foraging males attempt forcible copulation rather than displaying and allowing female choice. A male will facultatively switch between these strategies depending on the foraging abilities of the surrounding males. While females attempt to reject forcible copulation, forcible copulation reduces the frequency with which females successfully copulate with better foraging males. Therefore, males that are less attractive to females adopt alternative mating strategies to counter female choice which would exclude them from mating.

ツツガムシによるツツガムシ病リケッチアの伝播機序

Transovarial transmission of Rickettsia tsutsugamushi (Rt) was experimentally demonstrated after establishment of infected laboratory colonies of Leptotrombidium deliense, L. fletcheri, L. arenicola and L. pallidum. Even if Rt is acquired by uninfected trombiculid larvae while feeding on infected rodents, it is not transmitted to progeny of the trombiculids. From these observations, trombiculid mites are considered to be the reservoirs as well as the vectors of Rt. Transovarial and filial infection rates were generally about 100%, but infected female produce largely uninfected offspring in a few cases. The adults of infected colonie of 3 species other than L. pallidum were mostly female, and the sex ratio in the infected L. fletcheri seemed to be controlled by Rt. In the adult stage of L. pallidum individuals, although Rt was seen in all the organs and tissues, it was distributed most densely in the salivary gland and ovary. Because the density of Rt was markedly different among cells in the same organ, it is considered that Rt does not transfer from one cell to another in trombiculids. Rt was found in many cells in the early stages of spermiogenesis, but was excluded from cytoplasm of these cells during the maturation process, resulting in the production of Rt-free mature sperms and spermatophores in the infected male trombiculid.

Variation in the lipid content and composition of Antarctic krill Euphausia superba at South Georgia

Samples of Antarctic knll Euphausia superba Dana from 8 sites around South Georgia were analysed for total lipid and lipid class composition. Samples consisted predominantly of immature krill, and females were entirely absent from samples from 2 of the 8 sites studied Individual fresh mass varied from 0.16 to 1 72 g (median values of 0 47 g (0 16 to 0.94), 1 14 g (0.71 to 1.63) and 1.46 g (0.94 to 1.72) for immatures, males and females respectively). Lipid amounts varied from 5 to 147 mg ind.' (median values of 17.8 mg (5.1 to 64.2), 21.0 mg (9.3 to 87 7) and 70 3 mg (17 3 to 146 9) for immatures, males and females respectively) Triacylglycerol (TAG) and phosphatidylcholme were the 2 most abundant lipid classes in all krill. Multivariate analysis of lipid composition indicated significant over- lap between sex-maturity classes, although female kriU tended to be distinguished from males by higher proportions of TAG and lower proportions of phosphatidylserine plus phosphatidylinositol, Reproductive investment is implicated in the overall variability in lipid content and composition, with females containing high lipid levels as reserves for egg production, whilst males showed apparent lipid deficits resulting from short-term mobilisation of storage material for spermatophore production and attachment Significant and systematic site-to-site variability in hpid content and composition were evident in the samples and this could not be explained by the sex ratio or krill size

Age dependency and tissue distribution of ecdysteroids in adult male crickets, Gryllus bimaculatus de Geer (Ensifera, Gryllidae)

Ecdysteroid titers were determined in tissues (gut plus Malpighian tubules, carcass tissue, fat body, muscles, haemolymph, accessory reproductive glands, and testes) of male adult crickets, Gryllus bimaculatus, during the first 20 days of adult life as well as in spermatophores. In all tissues, except testes, total ecdysteroid titers are high on the day of imaginal moulting and then drop more or less continuously until day 8 after moulting. Distinctly higher levels are found on day 12 and 18 as well. Freshly moulted males contain high quantities of polar ecdysteroid conjugates in the digestive tract, testes, accessory reproductive glands, and haemolymph. Apolar ecdysteroid conjugates are mainly detectable in carcass tissue and fat body, but also in the haemolymph during entire adulthood. Free ecdysteroids represent the domineering class of moulting hormones in the gut during all stages of adult life. The significance of cycling ecdysteroid concentrations during adulthood is discussed in relation to spermatophore production and development of male accessory reproductive glands.