Reproductive characteristics and gamete development of the soft coral Sclerophytum cf. heterospiculatum in Okinawa Island,Japan

Sexual reproduction data are important to understand how organisms can replenish their populations and proliferate on coral reefs. Despite the importance of such data, the reproductive characteristics of most soft coral species are still unknown. Here, we examined the reproductive strategies of a species from the often-dominant genus Sclerophytum in a coral reef on subtropical Okinawa Island, Japan. DNA barcoding and histological examinations of the tissues were conducted to confirm colony conspecificity and identify reproductive characteristics, respectively, between March 2020 and March 2021. Results indicated that the studied species, identified as Sclerophytum cf. heterospiculatum, exhibits gonochorism with longer oogenesis and shorter spermatogenesis. Female colonies produced immature oocytes throughout the year, with mature oocytes observed from late July to early September, and thus, extended spawning is likely characteristic of this species. In male colonies, spermatogenesis took place over ~5 months, with spermaries present from April through August. Mature spermaries were noted beginning in July and the inferred peak of sperm release was between late August and early September, which suggests that spermatogenesis duration was ~5 months. The largest mean oocyte and spermary sizes (628.45 ± 61.36 and 240.04 ± 49.49 μm, respectively) were both recorded in August. Gamete spawning presumably occurred during the summer season, which suggests seasonality in reproduction as influenced by changes in seawater temperature. However, the proximate cue for exact dates of spawning could be the lunar period because the inferred release of spawning materials seemed to occur between full moon and last-quarter moon phases in both the months of August and September. The results of this study represent the first detailed report of reproductive characteristics of the genus Sclerophytum in Japan.     

Gametogenesis, spawning and fecundity of Platygyra daedalea (Scleractinia) on equatorial reefs in Kenya

The reproductive ecology of the hermaphroditic broadcast spawning scleractinian reef coral Platygyra daedalea was studied on lagoonal reefs in Kenya. While single annual gametogenic cycles occurred in 84% of colonies, biannual gametogenic cycles were recorded in 16% of colonies and these patterns occurred in two morphotypes. In colonies with a single annual cycle, oogenesis occurred for 6–7 months from September to March and spermatogenesis for 5 months from November to March. In biannually spawning colonies, oogenic cycles overlapped for at least 2 months prior to gamete release. The major spawning period occurred in February and March, with minor spawning also occurring in August–October in biannually spawning colonies. Reproductive effort was lower during the minor winter compared to the major summer spawning, with fewer colonies reproducing (12.5–19.2%), not all mesenteries producing oocytes (32.5%) and less than half of the mesenteries with mature oocytes had associated spermaries (48.1%).     

Colony structure and reproduction in the thelytokous parthenogenetic ant Platythyrea punctata (F. Smith) (Hymenoptera, Formicidae)

Summary: An important evolutionary characteristic of the formicine subfamily Ponerinae is the occurrence of various alternative reproductive tactics within single species. In Platythyrea punctata Smith, 1858, queens, gamergates and parthenogenetic workers co-occur in the same species. Morphological queens, both alate and dealate, were present in only 29 percent of the colonies collected in Florida, but absent from colonies collected in Barbados and Puerto Rico. One of the six queens which were dissected (three alate and three dealate) was found to be inseminated but not fertile. Instead, in most queenless colonies, a single uninseminated worker monopolized reproduction by means of thelytokous parthenogenesis, i.e., it produced female offspring from unfertilized eggs. A single mated, reproductive worker (gamergate) was found dominating reproduction in the presence of an inseminated alate queen in one of the Florida colonies. Thelytokous parthenogenesis was examined in artificial groups of virgin laboratory-reared workers, where one worker typically monopolized reproduction despite the presence of several individuals with elongated ovaries. In 16 colonies collected in Florida, a total of 66 individuals differed morphologically from queens and workers. Their thorax morphology varied from a worker-like to an almost queen-like structure. We refer to these individuals as "intercastes" (sensu Peeters, 1991a). The remarkable complexity of reproductive strategies renders P. punctata unique within ants.     

Age at sexual maturity of males and timing of the mating season of polar bears (Ursus maritimus) in Greenland

Age at sexual maturity among male polar bears (Ursus maritimus) and timing of the mating season were studied by microscopic and macroscopic analysis of the reproductive organs from 165 male and 92 female Greenland polar bears. Males became sexually mature in the spring following their fifth birthday. Testes sampled during the spring reached 95% of their asymptotic length at 5.8 years. Some spermatozoa were found in 2- to 4-year-old bears during the spring, but only in low concentrations in a mixture of other cell types. The first corpus luteum was found on 1 April and most ovulations were estimated to occur before mid-May which indicate that the peak of the mating season begins in late March and ends in May. These findings are somewhat different from a similar study from Svalbard, where the mating season is estimated to peak later and male polar bears are found to become mature earlier. We hypothesize that these differences occur because adolescent males have their peak testicular activity after the main breeding period and therefore appear to be fully sexually mature during summer and not during spring.     

Size and composition of swarming colonies in Provespa anomala (Hymenoptera, Vespidae), a nocturnal social wasp

Summary: Ninety-eight nests of various growing stages of Provespa anomala were found in the lowlands of Sumatra, Indonesia, from August to January. Its colony cycle is considered to be annual, with nests built throughout the year. There were two types of early nests before the emergence of workers, one with a worker number of less than 63 and the other of more than 231. The former were new nests, each containing a new queen and were built by reproductive swarming, whereas each of the latter was possibly re-built by an old queen and an absconding swarm. Ten swarming colonies were attracted by an oil-lamp light; these consisted of a copulated queen with immature oocytes in the ovary and 55 workers on average. No males, or workers stylopized by Xenos provesparum were observed either in colonies before worker emergence or in swarms coming flying into the light. Differences between swarming in Provespa, polygyny and nest relocation in Vespa, and those in swarm-founding Polistinae are discussed.     

Comparative study of the effects of the late pack-ice break-off on chinstrap and Adélie penguins' diet and reproductive success at Laurie Island,South Orkney Islands,Antarctica

The effects of ice cover on diet and breeding chronology of Adélie (Pygoscelis adeliae) and chinstrap penguins (P. antarctica) were studied in the colonies located at Point Martin, South Orkney Islands. Reproductive success and diet parameters were measured as described in the CCAMLR Environmental Monitoring Program protocols. It was found that late pack-ice break-off in 1998 resulted in lower reproductive success than in 1999 for chinstrap penguins, while Adélie penguin parameters were rather insensitive. This species has shown to be able to cope with this environmental factor, as suggested by its circumpolar and more southerly range. Significant differences in stomach contents' weights and in the proportion of whole krill were found between ice-covered and open-sea periods within and between years. Foraging trips of both species became longer, resulting in underfeeding of chicks and nest desertion by chinstrap-penguin parents. Simultaneous analysis of reproductive parameters of both species and their diets have proven to be useful in discriminating between variation in reproductive success parameters due to prey accessibility and prey abundance.     

Reproductive activity of two dominant Antarctic copepod species, Metridia gerlachei and Ctenocalanus citer, in late autumn in the eastern Bellingshausen Sea

The main reproductive period of herbivorous Antarctic copepods is coupled to the phytoplankton bloom in spring, while omnivorous or carnivorous species apparently reproduce year round. However, our knowledge of the reproduction during autumn and winter is limited. Therefore this study during a cruise with RV "Polarstern" aimed to measure reproductive activity in two dominant copepod species, Metridia gerlachei and Ctenocalanus citer, in late autumn (April/May). For this purpose, gonad development stages were determined from both species, taken with Bongo net in the eastern Bellingshausen Sea (Antarctic Peninsula region), and related to the ambient feeding conditions represented as chlorophyll a concentration. In addition, experiments were conducted with M. gerlachei to study the influence of feeding and starvation on gonad development. Gonad maturity of M. gerlachei differed considerably between stations and decreased over time. The correlation of chlorophyll a and the proportion of mature females, though significant, was weak and highly variable. In experiments, the gonads of feeding females were in better condition than those of their starving counterparts, showing that reproductive activity in M. gerlachei was related to ambient feeding conditions. Mature females of C. citer were found at each station (17-67%). The gonad stage composition was rather similar at all stations, showing no clear temporal and spatial trend. In this species, the proportion of mature females was not related to the chlorophyll a concentration, indicating either that the ambient phytoplankton stock was sufficient to fuel maturation or that other food sources were used. Our study shows that both species are reproducing during the austral autumn, indicating that their reproduction is partially decoupled from the spring phytoplankton bloom.     

Nutritional function of replete workers in the pharaoh's ant, Monomorium pharaonis (L.)

Summary: Queens of the pharaoh's ant Monomorium pharaonis (L.), like several other ant species, feed on larval secretions as their main nourishment and their fecundity is positively correlated with the number of large larvae present in the nest. The surplus of secretions produced by larvae is stored in a temporary caste of replete workers, which comprises young workers who remain in the nest and store liquid nourishment. Repletes are characterised by a conspicuously large gaster, caused by large amounts of liquid food stored in the crop, from which it may be regurgitated and distributed among colony members. In this study, repletes of pharaoh's ants were demonstrated to be functioning as buffers, smoothing fluctuations in availability of high quality food to the reproductive queens when larvae are scarce or missing, thus temporarily keeping up the egg production of queens.¶In undisturbed two-queen colonies with 20 large worker larvae and 30 workers (15 young and 15 old workers), approximately 10 repletes developed (one replete per two larvae). Development of older workers into repletes, when some or all repletes had been removed from the colonies, demonstrated that their temporal polyethism exhibits great plasticity in this trait.¶This study confirmed that, in pharaoh's ants, the regulation of fecundity depends not only on the food flow to the queen from larvae or from repletes but also on an unknown larval stimulus.¶The term crop repletes is suggested for replete workers which use their crop to store nourishment, as opposed to fat-body repletes, which store nourishment in their fat body.¶The presence of brood tending crop repletes in nests in several European ant species of Leptothorax, Myrmica, and Lasius, show that repletism is a common trait in ants, and that it may play an important role in regulation of nutrition in ant colonies, as demonstrated in Monomorium pharaonis.     

Changes in Adélie penguin breeding populations in Lützow-Holm Bay, Antarctica, in relation to sea-ice conditions

The Adélie penguin, Pygoscelis adeliae, an important component of the Antarctic marine ecosystem, is closely associated with sea ice. Using data collected by Japanese Antarctic Research Expeditions since the 1960s, we examined trends in breeding populations of this species around Lützow-Holm Bay. Ten colonies ranging in size from 10 to 2,500 individuals were counted along the Soya Coast. Populations fluctuated synchronously, and overall increased at most colonies, except for two: one located deep inside the bay and another where human disturbance was substantial. Populations tended to increase during, or after, periods of sparse sea ice in summer, a condition that occurred once every decade. An increase in population size also occurred 5 years after a winter of extensive sea ice and after a winter of especially reduced sea ice.     

Reproduction Strategy of the Deep-sea Hermit Crabs Pagurus alatus and Pagurus excavatus of the Central-Western Mediterranean Sea

Some aspects of the reproductive biology of two hermit crabs Pagurus alatus (Fabricius, 1775) and P. excavatus (Herbst, 1791) were studied. Specimens were collected monthly from April 2000 to March 2001 on the continental shelf and the upper-middle slope off the Southwestern coasts of Sardinia, in the central-western Mediterranean Sea. Crab size (minimum and maximum shield length) was 1.7 and 9.5 mm for 1150 females of P. alatus; 4.0 and 10.4 mm for 347 females of P. excavatus, respectively. Females of P. alatus with ripe ovaries were only found in February-April and ovigerous females were observed throughout the year except in March, with the highest incidence in summer. Females of P. excavatus with fully developed ovaries were collected during all months of the year reaching a peak from April to June. Ovigerous females of P. excavatus occurred throughout the year and the main spawning period occurred in March and April. Fecundity of both species was calculated to assess seasonal variation of reproductive intensity and was positively correlated with the size of the individuals. Monthly fecundity did not reveal significant differences in P. alatus ovigerous females, whereas P. excavatus exhibited significant differences in monthly fecundity depending on the time of year. Difference in fecundity among P. alatus and P. excavatus can be related to the size of the ovigerous females and species of hermit crab, but their different reproductive strategies suggest that they are specifically related to different environmental conditions.     

New insights into patterns of coral spawning on Western Australian reefs

On reefs around Australia, coral mass spawning typically occurs during the austral spring (October/November) on the east coast, and during autumn (March/April) on the west coast. However, to investigate the incidence of a secondary spawning event in spring on the west coast, the reproductive state of corals was assessed on two reefs. The results indicated that of the 29 species of Acropora investigated, multiple colonies of 11 species spawned in late spring or in early summer, in contrast to previous reports of spawning during autumn. Additionally, of four species that were followed through time at one reef, two spawned in both spring and autumn, however, individual colonies had only one gametogenic cycle. Within a single site, conspecific colonies were reproductively isolated and may not interbreed, potentially representing the initial stage of sympatric speciation in these populations.     

Batflies parasitic on some phyllostomid bats in southeastern Brazil: parasitism rates and host-parasite relationships

Ectoparasitic batflies were studied on 12 species of phyllostomid bats, by making 35 nightly collections of bats using mist nets at the "Panga" Ecological Reservation near Uberlandia, State of Minas Gerais, southeastern Brazil, from August 1989 to July 1990. Eleven species of Streblidae and one of Nycteribiidae were collected on 12 species of bats. Prevalence of ectoparasitic flies was lower than those reported by other authors for the New World and may be the result of the lack of caves in the study area, causing bats to roost in less favorable locations, forming smaller colonies. The fly, Trichobius joblingi Wenzel, was found on Carollia perspicillata (Linnaeus), showing preference for adult male bats. This could be explained by the predominance of males in the bat colonies, and by the fact that females rest in isolation during the reproductive period making them less exposed to the parasites. The streblid flies, Aspidoptera falcata Wenzel and Megistopoda proxima (Séguy), were found on Sturnira lilium (Geoffroy). A. falcata occurred mainly on young and adult females, whereas M. proxima did not show any preferences relative to the reproductive condition of the host. Ecological factors are important in determining differential numbers of parasites occurring on the different sexes, ages and reproductive state of the hosts.     

Diet composition of polar bears in Svalbard and the western Barents Sea

We estimated both the numerical and biomass composition of the prey of polar bears (Ursus maritimus) from 135 opportunistic observations of kills in Svalbard and the western Barents Sea collected from March to October 1984-2001. By number, the prey composition was dominated by ringed seals (Phoca hispida) (63%), followed by bearded seals (Erignathus barbatus) (13%), harp seals (P. groenlandica) (8%) and unknown species (16%). However, when known prey were converted to biomass, the composition was dominated by bearded seals (55%), followed by ringed seals (30%) and harp seals (15%). Results indicated that bearded seals are an important dietary item for polar bears in the western Barents Sea. We believe that different patterns of space use by different bears may result in geographic variation of diet within the same population.     

Coral reproduction in the world��s warmest reefs: southern Persian Gulf (Dubai, United Arab Emirates)

Despite extensive research on coral reproduction from numerous geographic locations, there remains limited knowledge within the Persian Gulf. Given that corals in the Persian Gulf exist in one of the most stressful environments for reef corals, with annual variations in sea surface temperature (SST) of 12°C and maximum summer mean SSTs of 36°C, understanding coral reproductive biology in the Gulf may provide clues as to how corals may cope with global warming. In this study, we examined six locally common coral species on two shallow reef sites in Dubai, United Arab Emirates (UAE), in 2008 and 2009 to investigate the patterns of reproduction, in particular the timing and synchrony of spawning. In total, 71% colonies in April 2008 and 63% colonies in April 2009 contained mature oocytes. However, the presence of mature gametes in May indicated that spawning was potentially split between April and May in all species. These results demonstrate that coral reproduction patterns within this region are highly seasonal and that multi-species spawning synchrony is highly probable. Acropora downingi, Cyphastrea microphthalma and Platygyra daedalea were all hermaphroditic broadcast spawners with a single annual gametogenic cycle. Furthermore, fecundity and mature oocyte sizes were comparable to those in other regions. We conclude that the reproductive biology of corals in the southern Persian Gulf is similar to other regions, indicating that these species have adapted to the extreme environmental conditions in the southern Persian Gulf.     

Comparison of the spatial distribution and reproductive cycle of Reticulitermes santonensis Feytaud and Reticulitermes lucifugus grassei Clément (Isoptera, Rhinotermitidae) suggests that they represent introduced and native species, respectively

Summary: The termites Reticulitermes santonensis (Rs) and R. lucifugus (Rl) were first regarded as different species (Feytaud, 1924) and then as the same species (Buchli, 1958). In later studies, Clément (1978, 1986) and Bagnères et al. (1990) used morphological and chemical (cuticular hydrocarbons) criteria to show that they actually are two distinct species. Feytaud (1924) and Bagnères et al. (1990) suggested that Rs could have originated from a North American population of R. flavipes that was introduced into Europe. The present study examined the distribution and reproductive cycle of Rs and an Rl sup-species, Rl grassei (Rlg), which are partly sympatric in southwest France. In the wild, Rs has an aggregated distribution related to human surroundings (past or present), i.e. populations are either dense or entirely absent. Conversely, Rlg is distributed randomly (from dense to few) throughout its range. For example, Rs is not found in towns within the Landes Forest, an area in southwest France that remained economically depressed and sparsely settled until after 1850 (Sargos, 1997), while Rlg is quite common there. Their respective reproductive strategies show that Rs populations spread through budding (swarms are scarce and many brachypterous nymphs and neotenics are found), whereas Rlg populations reproduce by both swarming and budding. It is likely that Rs is an introduced species and Rlg a native one that has reached its northern limits in France. A closer examination of North American Reticulitermes species, particularly R. flavipes, might reveal a relationship with the European species.     

Seasonal nest usurpation of European colonies by African swarms in Arizona,USA

Summary. Nest usurpation is a form of reproductive parasitism that may contribute to the ability of African bees to displace European honey bees in the Americas. We examined nest usurpation by African swarms over a two-year period in a southern-Arizona apiary that contained 76 five-frame European colonies. We observed a mean annual usurpation rate of 21% , with strong seasonal trends in usurpation activity. Most usurpations occurred from October–December, with a minor peak of usurpation activity in the spring-summer months. The seasonal patterns of usurpation corresponded with the reproductive swarming season in spring and summer and the absconding season in the fall-winter months. Queenless colonies, colonies that contained a queen confined in a cage, and those that had been recently requeened were 2–8 times more likely to be invaded than were colonies that contained an actively laying queen, suggesting that queen condition may have a major influence on host-colony susceptibility to usurpation. This trend was particularly pronounced in October–December, during which months the usurpation rates experienced by caged-queen and queenless colonies approached 20–50%. Our results show that nest usurpation is seasonally frequent among honey bees in the southwestern U.S., which suggests that reproductive parasitism contributes to the invasion success of African honey bees and possibly other introduced social insect species.Received 3 February 2004; revised 8 April 2004; accepted 17 April 2004.     

Physiological diversity and adaptations of aerobic heterotrophic bacteria from different depths of hypersaline, heliothermal and meromictic Ekho Lake (East Antarctica)

The hypersaline and meromictic Ekho Lake provides, with increasing depth, a large variety of different habitats to microorganisms. Out of 250 isolates, 51 bacterial strains were studied for physiological adaptations to their environment (i.e. to the depth layer from which they were obtained). Their salinity and temperature tolerance ranges for growth reflected the very conditions that were measured in the samples of their origin collected in the summer of 1989/1990. These observations indicated that the isolates are capable of growth at the depth of their origin and that they conceivably were endemics. Additionally, a separation of physiologically different populations of heterotrophic bacteria was indicated with respect to the utilization of C-compounds: the uppermost 4 m of the oxylimnion (with frequent water turnover and more extreme temperature conditions) supported primarily sugar-utilizing and halotolerant !-Proteobacteria and Gram-positives. The deeper, hypersaline and heliothermally heated layers (>4-24 m) had more moderately halophilic and amino acid-utilizing %-Proteobacteria possibly of marine origin.     

Natural aquatic plant colonisation in a newly constructed Irish Canal

In January 1989 a major breach in a section of the Grand Canal occurred. As a consequence, a 2.5 km long section required reconstruction. The channel was built up using peat material, lined with an impermeable membrane and overlayed with Puddle Clay. The section was rewatered in March 1990. For the next 30 months the course of natural aquatic plant colonisation was monitored. The first coloniser was the charophyte Tolypella glomerata, which appeared in September 1990. This occurred with low abundance until April 1991, when it disappeared. Between September 1991 and April 1992 charophytes, mainly T. glomerata and Chara vulgaris, proliferated. Their abundance diminished significantly during the summer of 1992. It was not until August 1991, 18 months after rewatering, that the first naturally colonising phanerogams were recorded. Principal among these was Myriophyllum verticillatum. In September of that year an aggressive coloniser in Irish canal and river habitats, Potamogeton pectinatus, was first observed. This became a permanent constituent of the flora and ultimately dominated the vegetation at the site. In total, 28 plant species were recorded from the newly constructed section. Nine of these species were either purposely or accidentally introduced during bankside stabilisation operations when live roots and rhizomes were planted along the exposed canal margins. By the end of the study period an abundant and diverse macroinvertebrate community had colonised the vegetation.     

Morphology of the female reproductive system and reproductive cycle of the mangrove land crab Ucides cordatus (L.) in the Baía de Antonina,Paraná, Brazil

Ucides cordatus is a species of considerable ecological and socioeconomic importance. The goal of this study is to contribute to the understanding of the reproduction biology of this species by describing the macroscopic anatomy, the histology of the female reproductive system and the reproductive cycle of U. cordatus. A total of 367 females were obtained from October of 2002 to March of 2005 during monthly collections in the Baía de Antonina, Paraná, Brazil. Specimens were submitted to necropsy and their reproductive systems (ovary and spermathecae) were analysed histologically. Permanent slides were stained with Harris' hematoxylin and eosin, Mallory's trichromic and the periodic acid‐Schiff reaction. Ovarian analysis allowed for the determination of five developmental stages based on the prevalence of oocytes in different phases of vitellogenesis. During stage V, when ovaries recover from spawning, the presence of oocytes in advanced stages of vitellogenesis was detected, suggesting that there could be more than one spawning in a single reproductive period. Females in stage IV were most common in the spring (November through February), whereas females with their egg mass exposed were most frequent from November through March. The reproductive period of U. cordatus in mangroves of the study region occurred from October to March. The reproductive events observed in the present study suggest that spermatophores acquired during copulation, which takes place during the ‘andada’, are only used in the reproductive period of the following year.     

Social organization, reproductive behavior and ecology of Leptothorax acervorum (Hymenoptera, Formicidae) from the Sierra de Albarracin in central Spain

Summary: Leptothorax acervorum, an ant species with holarctic range, occurs in an isolated population in the Spanish Sierra de Albarracin. Dissection of dealate females and laboratory observations revealed that in contrast to other European populations, the colonies are monogynous, with one reproductive queen each and a variable number of virgin or mated dealate but not laying females. Most of the latter probably just hibernate in the mother nests, leaving them in the following spring, but a few remain there for longer time, without reproducing. Such colonies then are functionally monogynous. Alate females exhibit a stationary sexual calling, and mating behavior could be studied in the laboratory. Mated females return to the mother nest where they soon shed wings. When developing fertility before or after hibernation they are evicted from the nests; in nature they probably form daughter colonies. Patchy habitat and rough climatic conditions in the Sierra de Albarracin may be responsible for the particular reproductive behavior of L. acervorum in this area. The generally small size difference between queens and workers in the subgenus Leptothorax entails high costs of dispersal and colony foundation by single queens who have to forage for their first brood. Some kind of dependent colony foundation therefore is frequently met with in the subgenus. Notwithstanding the marked biological and a few slight morphological differences between central European L. acervorum and the Spanish population its taxonomic status as yet is unsettled. We refer to this population provisionally as "L. acervorum Albarracin".