rDNA (18S-28S and 5S) colocalization and linkage between ribosomal genes and (TTAGGG)(n) telomeric sequence in the earthworm,Octodrilus complanatus (Annelida: Oligochaeta: Lumbricidae), revealed by single- and double-color FISH

Spermatogonial and metaphase I chromosomes of the lumbricid earthworm Octodrilus complanatus (Annelida: Oligochaeta) were examined using fluorescent in situ hybridization (FISH) with three repetitive DNA probes-5S rDNA, 18S-26S rDNA, and (TTAGGG)(n). Single-color FISH consistently mapped one chromosome pair per spread using either 5S rDNA or 18S-26S rDNA as probes. Simultaneous (18S-26S)-5S and (18S-26S)-(TTAGGG)(n) FISH demonstrated that repeated units of the two ribosomal families were overlapped and closely associated with telomeric sequences.     

The biology of Psammoryctides barbatus (Grube) in English chalk streams

The tubificid Psammoryctides barbatus is common in the sediments of English chalk streams. The species is primarily a spring and summer breeder with the most intense period of reproduction from April to June throughout its distribution in the river. Recruitment of juveniles takes place chiefly from June to August and most of the worms attain maturity in the following spring. In culture at 15 °C worms had attained 38 mm within 90 days of hatching and showed early signs of maturity. Growth rates and rates of cocoon production in culture are presented.     

Studies on the Relationships Between Earthworms and Soil Fertility

The rate of cocoon production in British Lumbricidae differs considerably from species to species and is greatly affected by soil temperature, moisture and the food supply of the adult worms. Only two out of fourteen species studied frequently produced more than one worm per cocoon, and twins were only recorded once in many hundreds of observations on four species of the genus Lumbricus.
The incubation period of the cocoons and the growth period to sexual maturity varies from species to species and also depends on the time of year at which the cocoons are deposited and the young worms emerge.     

Effects of removal of chicks from hens on concentrations of prolactin, luteinizing hormone and oestradiol in plasma of brooding Gifujidori hens.

Gifujidori hens were allowed to repeat a breeding cycle in one season. In the first breeding cycle the duration of the brooding (raising chicks) stage was limited to 3 weeks, whereas in the second breeding cycle it was limited to 1 week by removing all chicks from mother hens. In the first breeding cycle, plasma prolactin (PRL) was high during the incubation period, but rapidly decreased on the day of hatching and reached minimum values about 1 week after hatching. In contrast, plasma luteinizing hormone (LH) concentrations were low during the incubation period, but after hatching they gradually increased and reached peak values immediately after removal of chicks. Concentrations of oestradiol in plasma were low in the incubation and brooding stages but increased significantly immediately after removal of chicks. In the second breeding cycle, changes in PRL and LH concentrations were similar to those observed in the first breeding cycle except that even greater increases in plasma LH and oestradiol concentrations were observed one week after hatching when the chicks were removed. These results suggest that coexistence of newly hatched chicks may suppress LH secretion from the pituitary of the hen in the natural breeding cycle.     

Life history of the oligochaete Enchytraeus coronatus (Annelida, Enchytraeidae) in agar culture

Abstract. Life-history attributes and the reproductive biology of Enchytraeus coronatus (Oligochaeta, Enchytraeidae) were studied in agar cultures, as a basis for using this species in toxicity tests and other experimental studies. The use of agar allows daily examination of the behavior, reproduction, and mortality of the worms. At 20°C, E. coronatus had a generation time of 21–22 days and an embryonic period of 7–10 days. Hatch rate was high (>80%) and worms became sexually mature 8–10 days after hatching. Cocoon production and number of eggs per cocoon were positively correlated. Mortality in the first stages of the life cycle (embryonic period and first week after hatching) was about 38%. Three different periods of cocoon production were distinguished: a period characterized by a regular increase in the number of cocoons produced (weeks 4–9), a period of production at a constant high rate of ∼5 cocoons per week (weeks 10–20), and a period of decline in production rate (weeks 21–32), down to a mean value of 1.6 cocoons per adult in the last week. This study showed that synchronized agar cultures of cohorts can provide adults for long-term experimental tests, with the age for optimum reproduction being 8–20 weeks.     

Octopus joubini (Mollusca: Cephalopoda): a detailed study of growth through the full life cycle in a closed seawater system

Twenty individual pygmy octopuses, Octopus joubini , were reared at 25°C from hatching to maturity on a quantified diet of live crabs in closed (recirculating) natural seawater systems. At 24 week intervals the animals were narcotized, weighed and measured. There was 85% survival to sexual maturity.
Growth rates were highest during the first four weeks of exponential growth. Beyond four weeks, growth rates steadily declined and growth became logarithmic in form. Female octopuses grew slightly faster than males and attained a larger size at maturity. The length-weight relationship showed male Octopus joubini to weigh more than females at a given mantle length. This species displays slight allometric growth resulting in changing body proportions through the life cycle. Relative food intake is highest at hatching and decreases with age. Mean gross growth efficiency over the life span was approximately 40%.     

Reproduction of Lumbricillus rivalis (Levinsen) in laboratory cultures and in decaying seaweed

The cocoon production of 144 Lumbricillus rivalis cultured in pairs at 10 ± 1 °C was high over the first 2 weeks of breeding activity and then declined, chiefly because of high mortality. Cocoon deposition lasted for between 1 and 16 weeks, eight pairs of worms producing cocoons for 9 weeks and one pair for 16 weeks. During the total period of cocoon deposition over 9000 eggs (mean 17·4 per cocoon) were deposited. Two decaying wrack bed populations of L. rivalis showed a low level of cocoon and egg production in autumn, rising to an annual maximum in late winter/early spring. In these populations the mean egg content varied seasonally from 17·1 to 47·8 eggs per cocoon. When cocoons in the laboratory were transferred from the site of deposition to incubation dishes 31% hatched, but those left in the substrate showed a 92% hatch. In the naturally occurring populations 19% of the cocoons detached from seaweed fronds hatched, but 62% of those left in situ. Eggs and worm embryos developed to relatively late stages in most cocoons, whatever the rate of hatching; development often continued for up to 2 months after deposition without hatching. Over 50% of the fertile eggs in cocoons from decaying wrack hatched and developed to 5 mm worms.     

Cocoon production,morphology, hatching pattern and fecundity in seven tropical earthworm species — a laboratory-based investigation

Data on the reproductive biology of seven Indian species of earthworms, viz.Perionyx excavatus Perrier,Lampito mauritii Kinberg,Polypheretima elongata (Perrier),Pontoscolex corethrurus (Muller),Eutyphoeus gammiei (Beddard),Dichogaster modiglianii (Rosa) andDrawida nepalensis Michaelsen are presented. The peregrine earthworms such asPerionyx excavatus, Pontoscolex corethrurus, Dichogaster modiglianii, andPolypheretima elongata are considered to be continuous breeders with high fecundity. NativeLampito mauritii andDrawida nepalensis are semi-continuous andEutyphoeus gammiei discrete breeders. There is a dramatic increase in cocoon production by most earthworm species of Tripura in the summer and monsoon with a corresponding peak during April and July. Cocoon production decreased or ceased during winter. Temperature affected the incubation period of cocoons. With increase in temperature, incubation period increased in the endogeic worms,Pontoscolex corethrurus, Polypheretima elongata andDrawida nepalensis and decreased in the epigeic worms,Perionyx excavatus andDichogaster modiglianii, within a temperature range between 28–32°C under laboratory conditions. There was a significant(P < 0.05) positive correlation between number of hatchlings per cocoon and incubation period inLampito mauritii. High rate of cocoon production, short development time with high hatching success, as well as continuous breeding strategies in the epigeic speciesPerionyx excavatus andDichogaster modiglianii and the top soil endogeic species,Pontoscolex corethrurus,Drawida nepalensis andLampito mauritii, indicate their possible usefulness in vermiculture. The giant anecic worm,Eutyphoeus gammiei, which has a very long cocoon development time, discrete breeding strategy and very low rate of cocoon production, is not a suitable species for vermiculture.     

菲牛蛭交配及卵茧人工孵化初步研究

人工饲养条件下,比较观察了不同养殖模式(水体、土壤)和不同温度(24℃、26℃、28℃、30℃、32℃和34℃)对菲牛蛭(Hirudinaria manillensis)交配率的影响,并进行了不同卵茧质量(＜0.6 g、0.6～1.0 g、1.0～1.5g、1.5～2.0 g、＞2.0 g)及不同温度(22℃、24℃、...     

Population dynamics and feeding behavior of Triatoma brasiliensis and Triatoma pseudomaculata, main vectors of chagas disease in Northeastern Brazil

Biological parameters of Triatoma brasiliensis and T. pseudomaculata that could influence the epidemiological importance of these insects as vectors of Trypanosoma cruzi were compared. The parameters studied were incubation period, interval between hatching or moulting and first feeding, number of blood meals, development time, mortality, net reproductive rate, instantaneous daily reproductive rate, time-lapse before starting feeding, duration of feeding, blood ingestion capacity, occurrence of defecation and blood ingestion velocity. Most aspects of feeding were similar for the two species, although T. pseudomaculata had a longer life cycle than T. brasiliensis producing one and two generations per year, respectively. The two species had similar instantaneous daily rates of population growth.     

Biology of Triatoma flavida Neiva, 1911 (Hemiptera: Reduviidae) under laboratory conditions

The complete life cycle of Triatoma flavida, weekly fed on hens, was studied at 28+/-2 degrees C and 80+/-10% RH. Aspects related to hatching, life span, mortality and feeding behavior for each stage of its life cycle were evaluated. The hatching rate observed for 100 eggs was 93% with an average incubation period of 27.2 days. Sixty-two nymphs completed the cycle and the mean egg to adult development time was 230.4 days. Mean duration of 1st, 2nd, 3rd, 4th and 5th instar nymphs was 22.1, 25.3, 36.7, 49.7 and 69.4 days, respectively. The number of blood meals on each nymphal stage varied from 1 to 7. The mortality rate was 6.5% for NI, 23% for NIII and 7.5% for NV nymphs. Mean number of laid eggs per female was 283.1. Adult survival rates were 344.8 +/- 256.4 days for males and 285.3 +/- 201.8 days for females.     

Reproduction and growth of Craterocephalus marjoriae and C. stercusmuscarum (Pisces: Atherinidae) in south-eastern Queensland, Australia

SUMMARY. 1. The reproductive cycle and growth of Craterocephalus marjoriae and Craterocephalus stercusmuscarum (Atherinidae) were studied in Brisbane, south-eastern Queensland, over a 17-month period (1981–82).
2. Both species had a 5-month breeding season in spring and summer, with a breeding peak in spring (September-October). Multiple spawning occurred but life time fecundity was not determined.
3. Gonosomatic index values and mean fecundity per female were higher in Craterocephalus marjoriae than in C. stercusmuscarum. Fecundity increased with body length in both species according to the relationship, F=aL^b. Growth rates were similar and growth was adequately described by the von Bertalanffy equation. Both species grew rapidly during the first year and reached maturity the following season. Reproductive strategies are considered in relation to seasonal flooding in the streams inhabited.     

Body size as an estimator of production costs in a solitary bee

Abstract 1. Body weight is often used as an estimator of production costs in aculeate Hymenoptera; however, due to differences between sexes in metabolic rates and water content, conversion of provision weight to body weight may differ between males and females. As a result, the cost of producing female progeny may often have been overestimated.
2. Provision weight and body weight loss throughout development were measured in a solitary bee, Osmia cornuta (Latreille), to detect potential differences between sexes in food weight/body weight conversion.
3. Male O. cornuta invest a larger proportion of larval weight in cocoon spinning, and presumably have higher metabolic rates than females during the larval period; however, this is compensated by a slightly longer larval period in females.
4. Overall, body weight loss throughout the life cycle does not differ significantly between sexes. As a result, cost production ratios calculated from provision weights and from adult body weights are almost identical.
5. The validity of other weight (cocoon, faeces) and linear (head width, intertegular span, wing length, cocoon length, and cell length) measures as estimators of production costs is also discussed.
6. Valid estimators of production costs vary across species due to differences in sex weight ratio, cocoon shape, provision size in reference to cell size, and adult body size.     

Reproductive endocrinology of free living Pied flycatchers (Ficedula hypoleuca): prolactin and FSH secretion in relation to incubation and clutch size

Plasma levels of prolactin and FSH in free-living Pied flycatchers were studied in relation to breeding stage, clutch size and diurnal variations. In the female, the concentration of prolactin started to increase during the egg-laying and reached maximal values at the end of the incubation period. After hatching prolactin levels decreased. Male Pied flycatchers showed an increase in plasma levels of prolactin at the time when they returned to their home-territories, i.e. at the end of the incubation period. Males still occupying secondary territories at this time had low levels of prolactin. In the males, as in the females, plasma levels of prolactin decreased after hatching.
Male Pied flycatchers showed at all times higher plasma levels of FSH than did females. In both sexes FSH levels were high during the early part of the breeding season and started to decrease after the egg-laying period. After hatching time plasma levels of FSH were below the sensitivity of the assay. No differences in FSH were found between males occupying secondary territories and males in home-territories.
In incubating females FSH, but not prolactin, showed a distinct unimodal daily cycle.
No differences were found in plasma levels of prolactin and FSH between females incubating different sized clutches.     

Natural growth and reproduction in Triops granarius (Lucas) (Crustacea: Notostraca)

Field sampling during successive inundations was followed by laboratory studies on growth, egg production and hatching of Triops granarius from temporary pans in southern Africa.The species was common where mean inundation was less than one month. Sexual maturity was reached in as little as six days at a carapace length of 6.5 mm. A biomass of 2.0 g, at carapace length of 25 mm was achieved in two months. Males and females occurred in similar numbers and mating was a prerequisite for sustained fertile egg production. Eggs were in similar numbers in both pouches, while successive clutches were larger. Hatching was light-dependent. Desiccation of eggs was not necessary but a period of up to 20 days was required before undesiccated eggs would hatch. In the event of desiccation, no minimum period thereof was necessary and hatching occurred within as little as a day of rehydration. Hatching success seldom exceeded 50 percent.As a candidate for aquaculture, the species has failings such as low hatching rate and cannibalism, but it grows rapidly and produces eggs over an extended period.     

Thermal constraints on embryonic development as a proximate cause for elevational range limits in two Mediterranean lacertid lizards

Local adaptation and range restrictions in alpine environments are central topics in biogeographic research with important implications for predicting impacts of global climate change on organisms. Temperature is strongly coupled to elevation and greatly affects life history traits of oviparous reptiles in mountain environments. Thus, species may encounter barriers for expanding their ranges if they are unable to adapt to the changing thermal conditions encountered along elevational gradients. We sought to determine whether thermal requirements for embryonic development provide a plausible explanation for elevational range limits of two species of lacertid lizards that have complementary elevational ranges in a Mediterranean mountain range (Psammodromus algirus is found at elevations below 1600 m and Iberolacerta cyreni is found at elevations above 1600 m). We combined experimental incubation of eggs in the laboratory with modelled estimates of nest temperature in the field. In both species, increasing temperature accelerated development and produced earlier hatching dates. The species associated with warmer environments (P. algirus) experienced an excessive hatching delay under the lowest incubation temperature. Moreover, newborns from eggs incubated at low temperatures showed poor body condition and very slow rates of postnatal growth. In contrast, eggs of the strictly alpine species I. cyreni exhibited shorter incubation periods than P. algirus that allowed hatching before the end of the active season even under low incubation temperatures. This was countered by lower reproductive success at higher temperatures, due to lower hatching rates and higher incidence of abnormal phenotypes. Elevational range limits of both species coincided well with threshold temperatures for deleterious effects on embryonic development. We suggest that incubation temperature is a major ecophysiological factor determining the elevational range limits of these oviparous lizards with predictable consequences for mountain distributions under future warmer climates.     

Critical periods in the life cycle and the effects of a severe spate vary markedly between four species of elmid beetles in a small stream

1. The chief objectives were: (i) to describe quantitatively the life cycles of four species of Elmidae, Elmis aenea, Esolus parallelepipedus, Oulimnius tuberculatus and Limnius volkmari; (ii) to use life tables to identify critical periods for survival in the life cycle of each species; (iii) to evaluate the immediate and longer‐term effects of a severe spate on densities of the four species. Monthly samples were taken over 63 months at two contrasting sites in a small stream: one in a deep section with macrophytes abundant, and the other in a shallow stony section. 2. There were five larval instars for O. tuberculatus, seven for L. volkmari and six for the other two species. The life cycle of each species took 1 year from egg hatching (chiefly in June for E. aenea and O. tuberculatus, and July for the other species) to pupation in the stream bank and a further year before the adults in the stream matured and laid their eggs. Mature adults were present in most months, but were rare or absent in January and February and attained maximum densities in April for O. tuberculatus and May for the other species. 3. Laboratory experiments provided data on egg hatching and pupation periods and the number of eggs laid per female. Life tables compared maximum numbers per square metre for key life‐stages. Within each species, mortality rates between adjacent life‐stages were fairly constant among six cohorts and between sites, in spite of large differences in numbers. The only exception for all species was the high adult, but not larval, mortality during a severe spate. 4. Standardised life tables, starting with 1000 eggs, identified key life‐stages with the highest mortality, namely the early life‐stages for E. aenea (36% mortality), start of the overwintering period to pupation for O. tuberculatus (41%) and L. volkmari (51%), start of pupation to the maximum number of immature adults for E. parallelepipedus (41%) and between the maximum numbers of immature and mature adults for O. tuberculatus (41%). Therefore, critical periods for survival in the life cycle differed between species, presumably because of their different ecological requirements. Similarly, the effects of the spate on adult mortality, and hence egg production, varied between species, being most severe and long‐term for E. aenea and O. tuberculatus, less severe for E. parallelepipedus and least severe with a rapid recovery for L. volkmari. Possible reasons for these discrepancies are discussed, but more data are required on the food and microhabitat requirements of the elmids before satisfactory explanations can be found.     

The sooner the better: reproductive phenology drives ontogenetic trajectories in a temperate squamate (Podarcis muralis)

Understanding variations in individual trajectories is a crucial evolutionary issue. Terrestrial ectotherms from temperate regions typically face thermal constraints and limited activity periods. Developmental conditions (i.e. embryonic life) and reproductive timing (laying date) should induce phenotypic variations and influence subsequent ontogenetic trajectories (growth and survival). We studied these combined influences in an oviparous squamate, the wall lizard (Podarcis muralis), comprising a multiple clutch species with natural variations in laying date for the first clutch. We experimentally manipulated maternal basking opportunities during gravidity (3, 6 or 9 h per day) and incubation temperature (23 or 29 °C). Early laying date positively influenced winter survival in both incubation treatments. Survival was significantly lower in cool than warm‐incubated individuals (14.8% and 73.6%, respectively) because of delayed hatching date and reduced activity period before winter. Individuals from cool incubation temperature were slightly smaller but had a higher body condition and grew faster during the first month of life. Offspring behaviour was driven by complex interactions between gravidity and incubation treatments. Under cool incubation temperature, defensive behaviour was high, independently of gravidity treatment. Warm incubated individuals showed low defensive response except when maternal basking opportunities were restricted to 3 h. Defensive behaviour at birth had a positive influence on survival in cool‐incubated individuals. The results of the present study highlight the long‐term influence of hatching date that integrates female reproductive timing and incubation conditions. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 00, 000–000.     

Biological studies upon Enchytraeus variatus Bouguenec & Giani 1987 in breeding cultures

The life history of an enchytraeid worm, Enchytraeus variatus, was studied under laboratory conditions at 18–22 °C. This species can reproduce simultaneously by asexual (architomy) or sexual reproduction. The number of ova per cocoon varies from 5 to 20 (x = 10.9). The generation period (from cocoon to next cocoon) varies from 14 to 39 days (x = 26.1) according to the period of the year. The number of generations per year is between 7.3 and 26.1 (x = 14). A mature worm can lay between 23.7 and 25.8 cocoons during its life (254 days as maximum observed) at a mean rate of 0.12 cocoon worm^–1 day^–1. Experimental cultures were carried out to determine the structure, density and biomass of the populations. A maximal density of 1 396 314 worms was recorded after 85 days of culture. Net production reached 21.48 g m^–2 day^–1 after 26 days in a culture initiated from cocoons.