Highest Number Of Eggs Research Articles

A Stockpile of Ova in the Grass Frog Rana temporaria is Established Once for the Life Span. Do Ovaries in Amphibians and in Mammals Follow the Same Evolutionary Strategy?

Most anuran amphibians produce high numbers of eggs during several consecutive breeding seasons. The question is still open whether oocytes are formed anew as a result of oogonial proliferation after each spawning or the definitive pool of oocytes is established during the juvenile period and is sufficient for the whole reproductive life span of a female. Our quantitative studies show that primary oogonia in adult female frogs can proliferate, but they fail to differentiate further and do not enter meiosis, and thereby there is no supplementation of new generations of oocytes after each spawning. Ovaries of one-year-old grass frogs contain (median) 53,447 diplotene oocytes, in two-years-old frogs this number decreased to 33,583 and eventually reached 25,679 in virgin mature females. More than 50% decrease in the total oocyte number was accompanied by massive degeneration (atresia) of oocytes. The final number of oocytes in a female forms a stock for 11-12 breeding seasons and exceeds the number of eggs produced during the potential reproductive life span of this species. The phylogenetic context of oocyte recruitment modes in the major clades of vertebrates is discussed in respect to their ability to replenish the stock (a renewable stock in ovaries named "open" vs. a non-renewable stock in ovaries named "closed").

Taxonomy and Identification of Finfish Eggs from Muthupettai, South East Coast of India

The fish seed resource is a major input for fish farming. There is a playing important role for increasing fisheries production, providing food and income as well as contributing to national economy. Fishes is a delicious and most important source of animal protein food. Since, the fish seed resource is an essential for food security, rural development and poverty alleviation. In the present investigation fin fish eggs belonging to 43 species of finfishes belong to 31 genera, 19 families, 8 orders, have been collected, identified and described in detail. Among the various finfish eggs collected, higher number of eggs were recorded for Cluepeids fishes, followed by Engraulids, Carangids, Cynoglossids, Tetraodontids, Teraponis, Mugilids, Atherinids, Synodontids, Ophichthids, Pristigastrids, Chirocentrids, Scombrids, Gerreids, Soleids, Bothids, Pleuronectids and Hemiramphids from Muthupettai waters.

Antixenosis and antibiosis of some melon (Cucumis melo) genotypes to the two-spotted spider mite (Tetranychus urticae) and a possible mechanism for resistance

SummaryThe existence of antixenotic resistance to the two-spotted spider mite [Tetranychus urticae Koch (Acari: Tetranychidae)] was investigated in 36 melon (Cucumis melo L.) genotypes using choice tests. The results revealed significant genetic diversity for this trait, and resistant (‘Dastanbu 1’, ‘’Darunghermez’, ‘Zard-Jalali’, and ‘Kharboze’) and susceptible (‘Garmsari’, ‘Zard-khareji’, ‘Bargney’, and ‘Sabz’) genotypes were identified. These four resistant and four susceptible genotypes were used in follow-up experiments in order to assess their mechanisms of antibiosis and related enzyme activities. Antibiosis data against T. urticae were collected by assessing the fecundity of mated female mites on melon leaf discs in the laboratory. The number of eggs laid by each female per day showed significant differences between genotypes. The lowest numbers of eggs were laid on ‘Darunghermez’ and ‘Dastanbu 1’, while the highest numbers of eggs were laid on ‘Garmsari’ and ‘Zard-khareji’. The activities of both peroxidase and polyphenol oxidase increased in response to infestation by T. urticae in the resistant genotypes (‘Dastanbu 1’ and ‘Darunghermez’). The resistant melon genotypes identified in this study may provide new sources of resistance against T. urticae in breeding programmes.

Stegomyia albopicta skuse, 1894 (Diptera: Culicidae) on Lustica Peninsula 2011-2012 (Montenegro)

Lustica Peninsula in Montenegro was chosen as a study area to provide data about the distribution and population density of Stegomyia albopicta. This research is a preliminary step in the possible application of the sterile male technique (SIT). Fifty-four ovitraps were placed at 9 sites in August-September 2011-2012 to check peak seasonal activity. All of the nine sites were positive for St. albopicta in 2011; while in 2012, two of the nine places were negative. The most continuous presence of adults was registered at the locality of Tici, where they were collected throughout the entire sampling period. The highest number of eggs per trap (674) and in total was collected at Krasici in September 2011. At the localities Mrkovi and Begovici with a rare incidence of adults, the smallest number of eggs was counted. The two-year-long study showed that a well-established population of St. albopicta is persistently present on the peninsula, pointing to the possibility of testing the potential of SIT strategy in suppressing populations.

人工巢箱条件下两种山雀鸟类的同域共存机制

Birds adjust their survival strategies in the face of interspecific competition.Integrative analysis is important for understanding the main factors accounting for coexistence mechanism of different species.Parus major and Parus varius are long-term coexistence avian species in eastern mountainous area of Liaoning province.However,we still know little about the mechanism accounting for their coexistence.During March to July in each year from 2009 to 2011,we attracted both species with artificial nest boxes.With the aim to reveal the mechanism of their coexistence,we analyze the breeding habitat selection and reproduction strategy for both species. The results showed that niche separation was the underlying mechanism for the long-term coexistence.Both of those two species immediately started to breed when breeding season arrival.Both of them showed two breeding peaks in each year.When environmental quality was poor,they chose brood reduction strategy in order to improve reproductive success.The breeding strategies for those two species belonged to k-choice,with that of Parus major was slightly close to r.Parus major had high egg number but low reproductive success,whereas Parus varius had low nest egg number and high reproductive success. Based on step discriminant analysis,we found that the average height of trees,nest height from ground,and tree abundance were important factors accounting for nest site selection of Parus major.For Parus varius,the average height of trees,vegetation types,and the average height of shrubs were important factors.Comparing the nest site selection activities of those two species,they both like their nest boxes in old forest and have some angle and vegetation around growth lush.Parus major often paid more attention to the safety performance of their nest sites as indicated by the fact that their nest sites were usually apart from the ground.In contrast,Parus varius usually located their nest sites in mixed wood,which may be closely related to its food structure.

Immune Function in an Avian Brood Parasite and Its Nonparasitic Relative

Organisms that breed multiple times must trade off resources between current and future reproduction. In many species, sexual selection can lead to reduced levels of immune function in males because they invest heavily in current reproduction at the expense of self-maintenance. Much less is known about whether the same trend is seen in species such as the brood-parasitic brown-headed cowbird Molothrus ater (hereafter "cowbird"), in which females invest heavily in current reproduction. We examined two measures of immune function (bactericidal capacity of the plasma and the phytohemagglutinin swelling response) and baseline levels of corticosterone in both sexes of the cowbird and its nonparasitic relative the red-winged blackbird Agelaius phoeniceus (hereafter "redwing") during the breeding and subsequent nonbreeding seasons. We found that female cowbirds exhibited significantly lower levels of both measures of immune function than did male cowbirds and female redwings during the breeding season but had comparable levels during the nonbreeding season. Female redwings, in contrast, exhibited higher or comparable levels of immune function when compared with male redwings during the breeding season. In conjunction with published accounts documenting significantly higher rates of mortality for female cowbirds compared with male cowbirds and the fact that female cowbirds produce very high numbers of eggs (25-65) in a single breeding season, our results suggest that female cowbirds invest heavily in current reproduction at the expense of self-maintenance.

Spawning detection device for the black tiger shrimp Penaeus monodon broodstock

This research is aimed at developing an automatic spawning detection system for the black tiger shrimp, Penaeus monodon. This system is composed of instruments which are attached to the inner wall of the spawning tank that contains light sensing circuits which change light intensity into electrical signals. The detection unit is composed of a polyvinyl chloride (PVC) pipe containing a light emitting diode (LED) bulb that serves as a light source transmitter, and a light-dependent resistor (LDR) that serves as a light receiver which transforms light intensity into electrical resistance. Placed between the LED bulb and the LDR is a 135μm nylon mesh screen that is stretched horizontally inside the pipe to filter out shrimp eggs. Changing signals from the LDR turns on (or off) a 220V bulb. This device detects spawning activity as early as 22s after the onset of spawning. There is a correlation that exists between the number of spawned eggs and the time of the onset of spawning, with earliest detection occurring with the highest number of eggs.

Patch area of macrophyte Stratioites aloides as a critical resource for declining dragonfly Aeshna viridis

Currently, many rare and endangered species occur in fragmented habitats. Habitat patch size is often used as an easily measured surrogate of habitat quality and local population size. We investigated whether habitat patch size affects the presence and density of larvae of the endangered dragonfly Aeshna viridis, which for a large part of their life history depend on the macrophyte Stratiotes aloides rosette. The study was performed in four populations, two from Finland and two from Latvia. Our main result was that density of A. viridis and patch occupation increased with area of S. aloides patch. The results may be due to larvae actively avoiding enemies (higher survival) and/or to the possibility that females laid higher number of eggs in the large S. aloides patches. Our results indicate that local abundance and persistence of A. viridis population may depend on the few, large S. aloides patches rather than several small patches of equal total area.

Abbreviation of larval development and extension of brood care as key features of the evolution of freshwater Decapoda

The transition from marine to freshwater habitats is one of the major steps in the evolution of life. In the decapod crustaceans, four groups have colonized fresh water at different geological times since the Triassic, the freshwater shrimps, freshwater crayfish, freshwater crabs and freshwater anomurans. Some families have even colonized terrestrial habitats via the freshwater route or directly via the sea shore. Since none of these taxa has ever reinvaded its environment of origin the Decapoda appear particularly suitable to investigate life-history adaptations to fresh water. Evolutionary comparison of marine, freshwater and terrestrial decapods suggests that the reduction of egg number, abbreviation of larval development, extension of brood care and lecithotrophy of the first posthatching life stages are key adaptations to fresh water. Marine decapods usually have high numbers of small eggs and develop through a prolonged planktonic larval cycle, whereas the production of small numbers of large eggs, direct development and extended brood care until the juvenile stage is the rule in freshwater crayfish, primary freshwater crabs and aeglid anomurans. The amphidromous freshwater shrimp and freshwater crab species and all terrestrial decapods that invaded land via the sea shore have retained ocean-type planktonic development. Abbreviation of larval development and extension of brood care are interpreted as adaptations to the particularly strong variations of hydrodynamic parameters, physico-chemical factors and phytoplankton availability in freshwater habitats. These life-history changes increase fitness of the offspring and are obviously favoured by natural selection, explaining their multiple origins in fresh water. There is no evidence for their early evolution in the marine ancestors of the extant freshwater groups and a preadaptive role for the conquest of fresh water. The costs of the shift from relative r- to K-strategy in freshwater decapods are traded-off against fecundity, future reproduction and growth of females and perhaps against size of species but not against longevity of species. Direct development and extension of brood care is associated with the reduction of dispersal and gene flow among populations, which may explain the high degree of speciation and endemism in directly developing freshwater decapods. Direct development and extended brood care also favour the evolution of social systems, which in freshwater decapods range from simple subsocial organization to eusociality. Hermaphroditism and parthenogenesis, which have evolved in some terrestrial crayfish burrowers and invasive open water crayfish, respectively, may enable populations to adapt to restrictive or new environments by spatio-temporal alteration of their socio-ecological characteristics. Under conditions of rapid habitat loss, environmental pollution and global warming, the reduced dispersal ability of direct developers may turn into a severe disadvantage, posing a higher threat of extinction to freshwater crayfish, primary freshwater crabs, aeglids and landlocked freshwater shrimps as compared to amphidromous freshwater shrimps and secondary freshwater crabs.

Reproductive biology of a brooding Diopatra species: Diopatra marocensis

The reproductive cycle of Diopatra marocensisPaxton et al., 1995 has been studied in a population from Ria de Aveiro, Western Portugal with monthly samples, during a two-year period. This species presents a direct development with brooding in the parental tube and specimens with gametes inside the coelom and female tubes with eggs and/or larvae were observed in every sampling month. This suggested that the species reproduces during the whole year, with the main reproductive period from April to September. The male:female sex ratio ranged from 1:2 to 1:4, with females always dominating the population. A comparison with other Diopatra Audouin and Milne Edwards, 1833 (Onuphidae) showed that D. marocensis is the largest species with direct development and with the highest number of eggs and larvae inside the parental tube. With the exception of the colour, due to the presence of the gametes in the coelom cavity, no morphological differences between males and females were observed.

Effects of photoperiod on reproduction of Siamese fighting fish Betta splendens

This study investigated the effect of different photoperiods (24 h of light (L):0 h of darkness (D); 20L:4D; 16L:8D; 12L:12D; and 8L:16D) on the reproduction and growth of Betta splendens. The results showed that spawning frequency was significantly higher in couples reared under 16L:8D and 12L:12D, in comparison with other treatments. The highest number of eggs per spawn was obtained under 16L:8D (544.76±375.23) and 12L:12D (471.13±261.52), and the lowest values were detected for 24L:0D (128.55±58.14) and 20L:4D (187.87±103.84). Fertility and fecundity also showed significantly higher average values in 16L:8D and 12L:12D when compared with 24L:0D and 20L:4D treatments. Egg volume and perivitelline space were significantly higher in 24L:0D treatments that showed the lowest numbers of eggs per spawn, while the vitelline volume did not show significant differences. Other variables such as breeders weight gain and condition factor (K) were not statistically different. Moreover, the final length varies according to photoperiod and gender. These results demonstrated a key role for the photoperiod upon B. splendens reproduction. The best reproductive performance is achieved under the photoperiods that best approached those that occur in spring and summer (16L:8D and 12L:12D), coinciding with their best seasons for reproduction.

An Inexpensive, Efficient Method for Regular Egg Collection from Zebrafish in a Recirculating System

Zebrafish in our laboratory are usually bred by removing the fish from the recirculating aquatic system and placing them into 1-2 L spawning tanks. These spawning tanks consist of a bottom reservoir, a lid, and an insert that fits in closely into the bottom reservoir. When the fish breed, the eggs fall through holes of the insert and into the reservoir, thus preventing them from being cannibalized. Because fish in these spawning tanks are not fed and do not get fresh water, they are bred only once a week. During a period where we had high demand for embryos, we instead tried breeding the fish for multiple consecutive days on the recirculating system. Fish were placed into the spawning insert as usual, but the insert was placed into the home tank instead of into the bottom reservoir. We found that there was no significant difference in the number of fertilized eggs produced between the spawning tank and home tank breeding methods. Further, the fish in the home tanks regularly produced fertile embryos over a 28-day time course, with the highest number of eggs per pair produced by the tank with only one pair of adult fish. This method is time-saving as fish bred in home tanks only require to be set up once. It is also an effective way to collect embryos over long periods from the same pair or group of fish and to more easily obtain embryos from stocks with low spawning frequency.

Olive Fruit Fly (Diptera: Tephritidae) in California: Longevity, Oviposition, and Development in Canning Olives in the Laboratory and Greenhouse

The biology of olive fruit fly, Bactrocera oleae (Rossi), was studied in the laboratory, greenhouse, and in canning olives, Olea europaea L., in relation to California regional climates. Adults survived in laboratory tests at constant temperatures and relative humidities of 5 degrees C and 83%; 15 degrees C and 59%; 25 degrees C and 30%; and 35 degrees C and 29% for 15, 6, 3, and 2 d without provisions of food and water and for 37, 63, 25, and 4 d with provisions, respectively. In a divided greenhouse, adults survived for 8-11 d in the warm side (36 degrees C and 31% RH daytime); and in the cool side (26 degrees C and 63% RH daytime) 10 d without provisions and 203 d with provisions. A significantly greater number of adults survived in the cool side than the warm side, and with provisions than without. First and last eggs were oviposited in olive fruit when females were 6 and 90 d old, respectively. The highest number of eggs was 55 per day in 10 olive fruit oviposited by 10 28 d-old females, with maximum egg production by 13-37 d-old females. A significantly greater number of ovipositional sites occurred in all sizes of immature green fruit when exposed to adults in cages for 5 d than 2 d. Adults emerged from fruit with a height of > or = 1.0 cm or a volume of > or = 0.2 cm3. More than seven adults per 15 fruit emerged from field infested fruit with a height of 1.1 cm and volume of 0.1 cm3. Larval length was significantly different among the first, second, and third instars and ranged from 0.7 to 1.6, 2.4-4.3, and 4.8-5.6 mm at 14 degrees C; 0.8-1.1, 1.9-2.9, and 3.9-4.4 mm at 21 degrees C, and 0.7-1.3, 2.4-2.9, and 4.4-4.8 mm at 26 degrees C, respectively. Survival of pupae to the adult stage was significantly lower at 26 degrees C than 14 degrees C or 21 degrees C. The period of adult emergence began at 38, 14, and 11 d over a period of 8, 5, and 1 d at 14, 21, and 26 degrees C, respectively. Findings were related to the occurrence and control of California olive fruit fly infestations.

Biological Studies on the Brown Dog Tick, Rhipicephalus sanguineus (Latreille)

Rhipicephalus sanguineus (Latreille, 1806) was reared under laboratory conditions of27± 3° C and 75± 5% R. H., for three generations. The mean of life cycle duration was 41- 73 days. The conversion efficiency index (CEI) was 0.3130± 0.173, the reproductive efficiency index (REI) was 33257.9± 14895.7 and the reproductive fitness index (RFI) was 9288.6 ± 4481.9. The males/ females ratio was 1.1 :1. Females fed for 9± 1.16 days. Pre-oviposition and oviposition periods were 4.0± 0.81 and 7.5± 1.72 days respectively. Number of oviposted eggs per female averaged 4598± 429.7. A positive correlation was observed between the weight of engorged female and number of its deposited eggs (r= 0.76). However, the highest number of eggs was recorded on the 4th day (1751 eggs/ female). Pre-hatching period was 15± 1.87 days and hatching rate was 92.4 %. Larvae and nymphs feeding periods were 4.5± 1.16 and 5.5± 1.12 days respectively.

Milho inteiro e moído em diferentes sistemas de alimentação para poedeiras semipesadas

Avaliaram-se o desempenho e a qualidade de ovos de poedeiras semipesadas alimentadas com dietas com diferentes granulometrias do milho em dois sistemas de alimentação (fatorial 4x2) utilizando-se 256 aves em 32 gaiolas, a partir da 46ª semana de idade. As granulometrias do milho utilizadas foram: milho inteiro, milho com 3.198µm, milho com 1254µm e milho com 663µm de diâmetro geométrico médio, e os dois sistemas de alimentação: completo e de livre escolha. O experimento teve duração de quatro períodos de 28 dias. Avaliaram-se consumo de ração (g/ave/dia), produção de ovos (%ovos/ave/dia), peso dos ovos (g), densidade específica (g/cm³), massa de ovos (g), consumo energético (kcal/ave/dia) e consumo proteico (g/ave/dia). No método de livre escolha, as diferentes granulometrias não influenciaram o desempenho. A qualidade do ovo não foi afetada pelas diferentes granulometrias do milho e pelos sistemas de alimentação. No método de livre escolha, houve redução no consumo proteico, com exceção do milho inteiro. Nas granulometrias média e grossa, o sistema completo resultou em maior número de ovos em relação ao de livre escolha.

Feeding Ration, Genetics, and Reproductive Traits in Female Coho Salmon: Is Bigger Better?

We assessed the effects of different feeding regimes on reproductive traits in coho salmon, Oncorhynchus kisutch. Ration treatments subjected fish to different energy levels during oocyte proliferation (Year 1) and oocyte maturation (Year 2). Fish from 10 full-sibling families were fed at either the recommended feeding rate or double the recommended ration during the first year. At the beginning of the second year, each ration group was split again into recommended and double ration tanks for a total of four dietary treatments. At the end of the second year, 365 females from the four treatment groups were spawned and body weight, egg weight, and egg number were measured. Overall, the fish fed the double ration during both years grew the fastest (50.1% larger than controls), had the highest egg number (46.3% larger), and had the largest eggs (9.6% larger), although similar increases were observed feeding at the double ration level during the second year alone. Ration modification produced significant changes in some reproductive traits, especially egg number, while family effects had a greater influence on relative fecundity (eggs/g female body weight) and egg weight. In fact, family effects were significant for all of the traits. Results indicate that reproductive traits can be manipulated through changes in ration and/or via genetic selection, either directly or indirectly.

Vertical distribution of sympagic meiofauna in sea ice in the Canadian Beaufort Sea

This is the first study to determine vertical distribution patterns of sympagic meiofauna, including metazoans, protozoans and eggs >20 μm, in the Amundsen Gulf (southeastern Beaufort Sea, Arctic). Full sea-ice cores were sampled from mid of March to end of May 2008 (Circumpolar Flaw Lead system study). Investigations were performed on first-year ice from three pack- and three fast-ice stations. Additionally, 5-cm bottom-ice sections were sampled at 13 pack-ice and 5 fast-ice stations. The metazoan community was composed of nematodes, rotifers, copepods, copepod nauplii, platyhelminthes and a few rare taxa such as mollusks, cnidarians and nemerteans. High numbers of eggs, between 50 and 2,188 eggs L−1, particularly of nematodes and copepods, were present in the ice. Investigations revealed also eggs of the pelagic species Calanus hyperboreus and Sagitta spp. within the ice, so that further research is needed to clarify whether more organisms than expected might use this habitat as a reproduction ground. Many different morphotypes of protozoans were observed in the samples, especially ciliates of the order Euplotida. The highest abundance was always found in the lowermost 5 cm of the ice cores, nevertheless sympagic meiofauna was not restricted to that part of the ice. Integrated meiofauna abundance ranged between 41 and 4,738 × 102 Ind. m−2 and was highest in the fast ice in early May. Differences between pack and fast ice in terms of integrated meiofauna communities and vertical distribution were not significant, while the analysis of the bottom-ice sections indicated both a temporal development and ice-type-specific differences.

Foraging Behavior of the CoccinellidNephus includens(Coleoptera: Coccinellidae) in Response toAphis gossypii(Hemiptera: Aphididae) With Particular Emphasis on Larval Parasitism

This study assessed the effect of parasitism of Nephus includens (Col.: Coccinellidae) larvae by Homalotylus flaminius (Hym.: Encyrtidae) on the predation rates of the predator on the cotton aphid, Aphis gossypii Glover (Hem.: Aphididae) by deriving functional responses for second- and fourth-instar predators at prey densities ranging from 10 to 80 aphids per arena. The relationship between the functional and numerical responses of adult females of N. includens also was determined for prey densities ranging from 10 to 140 aphids per arena. Predation rates of unparasitized and parasitized second-instar N. includens were both fit by a type II functional response model with parameters as follows: unparasitized (a = 0.0768 hours(-1) and T(h) = 0.975 h) and parasitized (a = 0.0787 hours(-1) and T(h) = 0.8823 hours). Predation rates of unparasitized and parasitized fourth-instar N. includens were fit by type III and II models, respectively, with the following parameters: unparasitized (b = 0.1702 hours(-1) and T(h) = 0.2369 hours) and parasitized (a = 0.038 h(-1) and T(h) = 0.539 h). The unparasitized fourth-instar was the most voracious stage, having the highest attack rate and lowest handling time. Considering these attributes, it would seem to be the most effective stage of this predator against A. gossypii. Adult female lady beetles (N. includens) showed a type III functional response and their numerical response increase to prey density was curvilinearly related to prey density, with the highest number of eggs being produced at highest prey densities. The maximum saturation level for both predation and egg production for adult females occurred at a prey density of 120 aphids. Thus, a ratio 1:120 (predator:prey) should be used when releasing this species for augmentative biological control. Release of either fourth-instar or adult stage N. includens should be minimized the potentially negative effect of parasitism by H. flaminius on early developmental stages, and hence increase its efficiency in biocontrol programs.

Geographical expansion of the invader Caprella scaura (Crustacea: Amphipoda: Caprellidae) to the East Atlantic coast

Caprella scaura (Templeton in Trans Entomol Soc Lond 1:185–198, 1836) is a native species to the western Indian Ocean. It was first described from Mauritius and later reported from several regions of the world. During the last decade, the species spread out of the Adriatic Sea, and in 2005, C. scaura was reported in Gerona, on the north-eastern coast of Spain. The present study shows the recent rapid expansion of the species to the East Atlantic. During a sampling survey of harbours along the Strait of Gibraltar (Dec 2009–June 2010), we found high densities of C. scaura associated with the bryozoans Zoobotryon verticillatum Della Chiaje, 1822, in Chipiona and Bugula neritina (L.) in Cadiz, Atlantic coast of southern Spain; on the other hand, during May 2009, an important population of C. scaura was also found in the Canary Islands (Tenerife) associated with aquaculture resources. A total of 1,034 individuals of C. scaura were studied, and we confirm that the populations are effectively established, with high densities and reproducing females during the whole year. The population from Cadiz was characterised by smaller specimens but a higher number of eggs per female. These differences could be related to environmental conditions, mainly sea water temperature and to other factors such as competition with other species, or availability of food or substrate. Significant correlation was found between female size and number of eggs in the three populations, but egg size did not vary with female body length. The morphometric relation length/width of the second gnathopod was also calculated and compared between sexes: larger males presented longer gnathopods at the three sites. The most probable introduction vector of this species is shipping; in fact, the Strait of Gibraltar is characterised by an intense shipping traffic. Also, we have observed that the native Caprella equilibra Say, 1818, is being displaced by C. scaura in the harbour of Cadiz, where this species reach densities of 35,945 ind/1,000 g of B. neritina. Further experimental studies are necessary to explore the potential danger of this species, which might spread into natural habitats too.

Long‐term fitness consequences for offspring of female oviposition decisions in the rose bitterling (Rhodeus ocellatus)

Agbali, M. and Smith, C. 2012. Long‐term fitness consequences for offspring of female oviposition decisions in the rose bitterling (Rhodeus ocellatus). —Acta Zoologica (Stockholm) 93: 367–372.AbstractFemale oviposition decisions can have immediate consequences for offspring fitness as well as longer‐term effects, either through irreversible disruption to normal development, inducing alternative adult phenotypes, or through ‘coping’ whereby challenges to development are compensated in the short term, but carry a fitness cost in the adult. We investigated the long‐term impacts of oviposition decisions on offspring fitness parameters in the rose bitterling fish (Rhodeus ocellatus). Bitterling lay their eggs in the gills of living freshwater mussels, which complete development inside the mussel gill chamber. Bitterling embryo mortality in mussels is density dependent, and consequently, there are immediate costs associated with using mussels containing high numbers of eggs and embryos. We raised embryos at high and low densities for the first 4 weeks of development and then at a common low density until sexual maturity. Our results showed no effect of density on offspring survival or growth. However, there was an impact of density on age and size at maturity, with embryos raised at high densities becoming sexually mature earlier and at a smaller size. This effect may arise through embryos coping with low oxygen conditions during development. The results are discussed in the context of development and mating system evolution.