Reproduction, egg morphology and development observed in two Australian penicillate millipedes, Lophoturus queenslandicus (Lophoproctidae) and Phryssonotus novaehollandiae (Synxenidae) (Diplopoda)

2016 ◽  
Vol 64 (2) ◽  
pp. 138 ◽  
Author(s):  
Cuong Huynh ◽  
Anneke A. Veenstra
Keyword(s):  
Sexual Reproduction ◽  
Reproductive Strategies ◽  
Anterior Region ◽  
Harsh Environment ◽  
Web Structure ◽  
Egg Morphology ◽  
Protective Membrane

Lophoproctid and synxenid millipede species observed in this study showed clear differences in their sexual reproduction, including sperm web structure, egg morphology and development compared with species from Polyxenidae. Male Lophoturus queenslandicus (Lophoproctidae) produce a single spermatophore on a sperm web without signal threads due to their lack of silk-producing coxal glands. Females of this species lay fewer eggs and differ in their egg cluster arrangement, which includes nest trichomes for protection. Lophoproctid chorion has a thin protective membrane and the pupoid has fused papillae covering the entire anterior region and an aperture bordered by protective papillate sensilla is present at the apex of the pupoid. Lophoproctid millipedes have a comparatively short intermoult period between stadia. In contrast, male Phryssonotus novaehollandiae (Synxenidae) produce two spermatophores separated by a large gap on their sperm web, with signal threads that are less obvious. Synxenid chorion and pupoid stages were unique; the chorion was tough and thick and the pupoid had anterior projections without an aperture bordered by sensilla, unlike those observed in lophoproctid and polyxenid millipedes. This study extends knowledge of the reproduction of species from three major millipede families from the Suborder Polyxenida (Penicillata: Diplopoda). Additionally, the results indicate that the reproductive strategies of Australian lophoproctid and synxenid species are adapted to their harsh environment.

scholarly journals Reproductive Strategies of the Seagrass Zostera japonica Under Different Geographic Conditions in Northern China

2020 ◽  
Vol 7 ◽  
Author(s):  
Shidong Yue ◽  
Xiaomei Zhang ◽  
Shaochun Xu ◽  
Yu Zhang ◽  
Peng Zhao ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Reproductive Strategies ◽  
Geographic Location ◽  
Dry Weight ◽  
Northern China ◽  
Shoot Density ◽  
Zostera Japonica ◽  
Sexual And Asexual Reproduction ◽  
Density And Biomass

Seagrasses form a unique group of submerged marine angiosperms capable of both sexual and asexual reproduction. The amounts of sexual and asexual reproduction differ within some species relying on geographic location and environmental factors. Here, we studied the reproductive strategies of different geographic Zostera japonica populations, S1 and S2 at Swan Lake lagoon (SLL), and H1 and H2 at Huiquan Bay (HQB), in northern China. The duration of flowering at SLL was longer than at HQB, whereas flowering initiation at HQB occurred earlier than at SLL. In addition, the timing of seed maturation at HQB occurred earlier than at SLL. The allocation to sexual reproduction at SLL was greater than at HQB. The maximum potential seed production was greatest at S1 (22228.52 ± 8832.46 seeds ⋅ m–2), followed by S2 (21630.34 ± 9378.67 seeds ⋅ m–2), H2 (7459.60 ± 1779.33 seeds ⋅ m–2), and H1 (2821.05 ± 1280.57 seeds ⋅ m–2). The seasonal changes in total shoot density and biomass were small at HQB. There was a relatively large number of overwintering shoots at HQB because of the higher average temperature during winter. The allocation to sexual reproduction was lower than at SLL, and no seedlings were observed at HQB during our study. Thus, the population of Z. japonica at HQB was maintained by asexual reproduction. Compared with HQB, the biomass of overwintering shoots at SLL was less than 30 g dry weight ⋅ m–2. The Z. japonica at SLL relied on asexual and sexual reproduction to maintain the population. The results show the necessity of understanding local reproductive strategies before starting restoration and management projects. The study provides fundamental information and guidance for the conservation and restoration of seagrass beds.

Atypical reproduction in a syllid worm: the stolon of Syllis rosea (Annelida, Syllidae) takes care of its offspring

2020 ◽  
Vol 100 (2) ◽  
pp. 221-227
Author(s):  
Joachim Langeneck ◽  
Michela Del Pasqua ◽  
Margherita Licciano ◽  
Adriana Giangrande ◽  
Luigi Musco
Keyword(s):  
Parental Care ◽  
Sexual Reproduction ◽  
Reproductive Strategy ◽  
Reproductive Strategies ◽  
Congeneric Species ◽  
Reproduction Mode ◽  
Laboratory Rearing ◽  
Larval Stages ◽  
The Family ◽  
Reproductive Cycles

AbstractThe family Syllidae, aside from representing the most species-rich family in Annelida, is characterized by a number of sexual and asexual reproductive strategies. With the exception of a few viviparous species, the subfamily Syllinae is characterized by schizogamous reproduction with pelagic larval stages and without parental care. Laboratory rearing of ripe specimens of Syllis rosea showed a different reproductive strategy, hitherto unknown in this subfamily. While male stolons rapidly degenerated after fertilization, female ones released large eggs in a gelatinous cluster attached to the middle-posterior chaetigers. The gel mass progressively compacted as a cocoon wrapped by the stolon body; 7 days after the deposition the larvae hatched out from the cocoon at the metatrochophore stage and the female stolon died after a few days. After hatching the larvae remained associated to the stolon, and young specimens of S. rosea survived up to the 3-chaetiger stage. Until now cocoon brooding by the stolon has only been reported for some Autolytinae. The production of gelatinous egg masses and parental care are known in basally branching clades within Syllidae, suggesting that this reproduction mode might retain some ancestral features. The scarce knowledge about reproductive cycles in Syllinae does not allow clarification whether this strategy is unique for S. rosea, or it occurs in other congeneric species. Further research is needed to understand possible relationships between sexual reproduction and phylogeny, stolon morphology and its adaptation to parental care, and ultimately between reproductive strategies and ecology.

scholarly journals Reproductive strategies and dimorphic seeds germination in Trifolium argentinense Speg., an amphicarpic species

2019 ◽  
Vol 25 (3) ◽  
pp. 66-79
Author(s):  
Ionara Fátima Conterato ◽  
Maria Teresa Schifino-Wittmann ◽  
Diego Bitencourt David ◽  
Jorge Dubal Martins
Keyword(s):  
Sexual Reproduction ◽  
Reproductive Strategies ◽  
Vegetative Reproduction ◽  
Rio Grande ◽  
Soil Surface ◽  
Rio Grande Do Sul ◽  
Storage Roots ◽  
Depth Effect ◽  
Seeds Germination ◽  
Better Than

Native from Rio Grande do Sul natural pastures, Trifolium argentinense Speg. has sexual reproduction through aerial and subterranean seeds (amphicarpy) and vegetative reproduction by regrowth from storage roots. In this study the seeds produced at the soil-surface flowers, the depth effect and scarification on the aerial and subterranean seeds germination and the storage roots produced by plants derived from the two types of seeds were evaluated. The aerial (0.10 cm) and soil-surface (0.11 cm) seeds were similar in size, but smaller than the subterranean seeds (0.14 cm), with no significant variation in the production of the three types of seeds. Aerial and subterranean seeds scarified at and sowed 2.5 cm deep germinated better than the scarified and non-scarified seeds sowed on the soil-surface and at 7.0 cm, evincing a depth effect on seed germination. Although amphicarpic, T. argentinense first invests in the production of the storage roots making sure the cloning of specific genotypes and allowing the plants to persist vegetatively year after year without the need for regeneration by seeds in unfavorable environments for sexual reproduction, such as in Rio Grande do Sul natural pastures, where hard grazing and trampling can destroy the aerial part of the plants.  

scholarly journals Staying well connected – Lithistid sponges on seamounts

2015 ◽  
Vol 96 (2) ◽  
pp. 437-451 ◽  
Author(s):  
Merrick Ekins ◽  
Dirk Erpenbeck ◽  
Gert Wörheide ◽  
John N. A. Hooper
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Sexual Reproduction ◽  
Internal Transcribed Spacer ◽  
Reproductive Strategies ◽  
New Caledonia ◽  
The Third ◽  
Relative Contribution ◽  
Indirect Measures ◽  
Separate Population

Three species of lithistid sponges, Neoaulaxinia zingiberadix, Isabella mirabilis and Neoschrammeniella fulvodesmus were collected from deep seamounts off New Caledonia to address questions about their population structure, gene flow and the relative contribution of sexual and asexual reproductive strategies to their populations. The sponges were tested by sequencing the ITS (internal transcribed spacer) and CO1 regions of their genomes. These rare and presumably ancient sponges have a distribution restricted to seamounts in the south-western Pacific. Deep seamounts represent geographically separated islands. Although the sponges could be expected to have sexual reproduction restricted to near neighbours due to low sexual dispersal opportunities via larvae, this study found surprisingly high levels of gene flow between the seamounts. Amongst the specimens of N. zingiberadix taken from two seamounts there was no population structure; CO1 resulted in identical genotypes. For the population structure within N. fulvodesmus, as revealed by ITS, most of the variation was within each individual from the six seamounts on which it occurred and CO1 revealed no difference between individuals or seamounts. The third species I. mirabilis showed four genotypes based on CO1, which were distributed across all the seamounts. Indirect measures of different species showed a range of reproductive strategies from asexual to sexual, but with much higher connection between seamounts than previously thought. Individual seamounts did not show a separate population structure as one might expect from ‘islands’. The conclusion must be that these sponges have mechanisms to attain greater dispersal than previously thought.

Reproductive strategies of the Macroptilium lathyroides (Papilionoideae: Phaseoleae) explain the success of ruderal species in anthropized environments

Rodriguésia ◽  
2021 ◽  
Vol 72 ◽  
Author(s):  
Letícia Koutchin Reis ◽  
Diego Rezende da Fonseca ◽  
Susan Roghanian ◽  
Bruna Castro de Barros ◽  
Maria Rosângela Sigrist
Keyword(s):  
Sexual Reproduction ◽  
Seed Production ◽  
Seed Bank ◽  
Reproductive Strategies ◽  
Pollination Mechanism ◽  
Human Food ◽  
Commercial Use ◽  
Self Pollination ◽  
Underground System ◽  
Macroptilium Lathyroides

Abstract Ruderal plants are important they are used for animal (e.g., beekeeping/pasture) and human food. Many of these plants present multiple reproductive strategies that ensure that they remain in disturbed environments. Therefore, we investigated the sexual reproduction and regeneration by regrowth of the forage ruderal Macroptillium lathyroides in an anthropized area to support management of this species after cutting or grazing and determine its requirements for seed production and conditions for commercial use. We assessed the occurrence of reproduction through regeneration and species dependence on pollinators. M. lathyroides has an axial underground system capable of regrowth but not propagation post-cut. Its flowers last about eight hours and are papilionate, asymmetrical, hermaphrodite, nectariferous, vinaceous and diurnal. They present secondary pollen that is transferred to the trichomes of the style. The species is self-compatible and presents spontaneous self-pollination. The small bee Exomalopsis cf. auropilosa, was the only pollinator since it activated the brush-type pollination mechanism while gathering nectar/pollen. The species depends on seeds to propagate or maintain a seed bank, since all plants do not regrow after cutting. Thus, sexual reproduction is necessary, but pollinators are not since it is not pollinator independent.

Trophoblast infiltration

1994 ◽  
Vol 3 (2) ◽  
pp. 137-157 ◽  
Author(s):  
Harvey J Kliman
Keyword(s):  
Sexual Reproduction ◽  
Aquatic Environment ◽  
Human Fetus ◽  
Reproductive Strategies ◽  
Small Rodent ◽  
Simple Diffusion ◽  
Gestational Period ◽  
Fetal Pig

Sexual reproduction in the ocean necessitates only the combination of gametes, followed by absorption of nutrients and oxygen from the surrounding watery medium. As life moved from the sea to the land, reproductive strategies required compensation for the loss of this aquatic environment. For the mammals, and scattered other animals, the solution to this problem was the development of the placenta, the means by which the fetus extracts nutrients from its environment. As the animals that utilized the placenta evolved from small rodent-like creatures with short gestations to larger animals with prolonged gestations, the demands of the developing fetus grew. Whereas the placenta of the fetal pig, with a gestational period of a little less than four months, can extract sufficient nutrients from the mother by simple diffusion across the uterus to the placenta, the human fetus needs a far more complex uteroplacental relationship.

Magnetostrictive Cold Spray Sensor for Long-Term or Harsh Environment Ultrasound

2019 ◽  
Author(s):  
S. W. Glass ◽  
◽  
J. P. Lareau ◽  
K. S. Ross ◽  
S. Ali ◽  
...  
Keyword(s):  
Cold Spray ◽  
Harsh Environment

Neonatal nutritional strategy of a viviparous elasmobranch with extremely low reproductive output

2020 ◽  
Vol 638 ◽  
pp. 107-121 ◽  
Author(s):  
BS Rangel ◽  
NE Hussey ◽  
Y Niella ◽  
LA Martinelli ◽  
AD Gomes ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Reproductive Strategies ◽  
Trophic Ecology ◽  
Essential Fatty Acids ◽  
Physiological State ◽  
Maternal Investment ◽  
Early Life History ◽  
Nutritional State ◽  
Disc Width ◽  
Biomarker Analysis

Throughout evolutionary history, elasmobranchs have developed diverse reproductive strategies. Little focused work, however, has addressed how neonatal nutritional state is affected by differing degrees of maternal investment associated with these markedly different reproductive strategies. To investigate the effect of maternal investment on the nutritional quality of pups during the early life history of an extremely viviparous elasmobranch, quantitative biomarker analysis including lipids, fatty acids and stable isotopes was conducted. Using the cownose ray Rhinoptera bonasus (histotrophic viviparous) as a model, we found that pups were initially born in a positive nutritional state, enriched in physiologically important essential fatty acids and nitrogen and carbon stable isotope values (δ15N and δ13C), a result of maternal intrauterine transfer. A systematic decrease in some fatty acids and δ15N values, as well as a decrease in cholesterol with growth, confirmed that these substrates were derived from maternal resources and used in initial metabolic processes following birth. An observed increase in condition factor, plasma essential fatty acids and triglyceride:cholesterol ratio with increasing body size identified a progression towards successful independent foraging with pups not displaying marked nutritional deficiency or fasting phases. Our multi-tracer approach allowed the identification of 2 size classes of young rays (<50 and <70 cm disc width) that displayed distinct physiological states. Since prenatal maternal investment is critical for offspring condition and to promote successful foraging post birth, understanding the trophic ecology and physiological state of pups during their first year is critical to guide management and conservation within nursery grounds.

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