scholarly journals Asexual and puzzling sexual reproduction of the Mediterranean sponge Haliclona fulva (Demospongiae): life cycle and cytological structures

2017 ◽  
Vol 136 (4) ◽  
pp. 403-421 ◽  
Author(s):  
Alexander V. Ereskovsky ◽  
Alexia Geronimo ◽  
Thierry Pérez
Keyword(s):  
Life Cycle ◽  
Sexual Reproduction ◽  
The Mediterranean

Life cycle of Spirogyra decimina var. juergensii (Kütz.) O.V. Petlovany from Lake Baikal

2018 ◽  
pp. 1-7
Author(s):  
Ekaterina A. Volkova
Keyword(s):  
Life Cycle ◽  
Sexual Reproduction ◽  
Lake Baikal

Identification of Spirogyra species is based on the morphology of the fertile specimens. This work provides characteristics of growth and the time of reproduction of Spirogyra decimina var. juergensii in Lake Baikal and describes sexual reproduction and conditions for germination of new filaments of this species isolated from the lake.

The butterfly squid Stoloteuthis leucoptera in the Mediterranean

1991 ◽  
Vol 71 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Lidia Orsi Relini ◽  
Daniela Massi
Keyword(s):  
Life Cycle ◽  
Adult Male ◽  
The Other ◽  
Otter Trawl ◽  
Ligurian Sea ◽  
The Mediterranean ◽  
Unique Species ◽  
Recent Immigration

The presence of Stoloteuthis leucoptera in the Mediterranean is recorded on the basis of three specimens, including an adult male, caught by IKMT and by commercial otter-trawl in the Ligurian Sea. The hypothesis of a recent immigration is discussed.The list of Mediterranean cephalopods (Mangold Wirz, 1963; Torchio, 1968; Bello, 1986; Mangold & Boletzsky, 1987) includes the Sepiolidae of the subfamily Heteroteuthinae, whose members are supposed to be pelagic throughout their life cycle. Mangold Wirz (1963) recognizes in the Mediterranean fauna the unique species Heteroteuthis dispar, the other authors include H. atlantis Voss, which Voss himself (1955) reported at Messina. To this group may now be added Stoloteuthis leucoptera (Verrill, 1878) a species until now recorded in limited Atlantic areas. Verrill (1881) wrote “This species is an exceedingly beautiful one, when living, owing to the elegance and brilliancy of its colours and the gracefulness of its movements. In swimming it moves its fins in a manner analogous to the motion of the wings of a butterfly.”

Heterozygote advantage and the evolution of a dominant diploid phase.

Genetics ◽  
1992 ◽  
Vol 132 (4) ◽  
pp. 1195-1198 ◽  
Author(s):  
D B Goldstein
Keyword(s):  
Life Cycle ◽  
Sexual Reproduction ◽  
Genetic Factor ◽  
Higher Plants ◽  
Heterozygote Advantage ◽  
Seed Plants ◽  
Sexual Species ◽  
Evolutionary Forces ◽  
Eukaryotic Species ◽  
Selection For

Abstract The life cycle of eukaryotic, sexual species is divided into haploid and diploid phases. In multicellular animals and seed plants, the diploid phase is dominant, and the haploid phase is reduced to one, or a very few cells, which are dependent on the diploid form. In other eukaryotic species, however, the haploid phase may dominate or the phases may be equally developed. Even though an alternation between haploid and diploid forms is fundamental to sexual reproduction in eukaryotes, relatively little is known about the evolutionary forces that influence the dominance of haploidy or diploidy. An obvious genetic factor that might result in selection for a dominant diploid phase is heterozygote advantage, since only the diploid phase can be heterozygous. In this paper, I analyze a model designed to determine whether heterozygote advantage could lead to the evolution of a dominant diploid phase. The main result is that heterozygote advantage can lead to an increase in the dominance of the diploid phase, but only if the diploid phase is already sufficiently dominant. Because the diploid phase is unlikely to be increased in organisms that are primarily haploid, I conclude that heterozygote advantage is not a sufficient explanation of the dominance of the diploid phase in higher plants and animals.

scholarly journals The Role of Sea Surface Temperature Forcing in the Life-Cycle of Mediterranean Cyclones

2020 ◽  
Vol 12 (5) ◽  
pp. 825 ◽  
Author(s):  
Christos Stathopoulos ◽  
Platon Patlakas ◽  
Christos Tsalis ◽  
George Kallos
Keyword(s):  
Life Cycle ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Early Warning Systems ◽  
Life Cycles ◽  
Heat Fluxes ◽  
Sea Surface ◽  
Mediterranean Cyclones ◽  
The Mediterranean ◽  
The Impact

Air–sea interface processes are highly associated with the evolution and intensity of marine-developed storms. Specifically, in the Mediterranean Sea, the air–ocean temperature deviations have a profound role during the several stages of Mediterranean cyclonic events. Subsequently, this enhances the need for better knowledge and representation of the sea surface temperature (SST). In this work, an analysis of the impact and uncertainty of the SST from different well-known datasets on the life-cycle of Mediterranean cyclones is attempted. Daily SST from the Real Time Global SST (RTG_SST) and hourly SST fields from the Operational SST and Sea Ice Ocean Analysis (OSTIA) and the NEMO ocean circulation model are implemented in the RAMS/ICLAMS-WAM coupled modeling system. For the needs of the study, the Mediterranean cyclones Trixi, Numa, and Zorbas were selected. Numerical experiments covered all stages of their life-cycles (five to seven days). Model results have been analyzed in terms of storm tracks and intensities, cyclonic structural characteristics, and derived heat fluxes. Remote sensing data from the Integrated Multi-satellitE Retrievals (IMERG) for Global Precipitation Measurements (GPM), Blended Sea Winds, and JASON altimetry missions were employed for a qualitative and quantitative comparison of modeled results in precipitation, maximum surface wind speed, and wave height. Spatiotemporal deviations in the SST forcing rather than significant differences in the maximum/minimum SST values, seem to mainly contribute to the differences between the model results. Considerable deviations emerged in the resulting heat fluxes, while the most important differences were found in precipitation exhibiting spatial and intensity variations reaching 100 mm. The employment of widely used products is shown to result in different outcomes and this point should be taken into consideration in forecasting and early warning systems.

scholarly journals Observation of asexual reproduction with symbiont transmission in planktonic foraminifera

2020 ◽  
Vol 42 (4) ◽  
pp. 403-410 ◽  
Author(s):  
Haruka Takagi ◽  
Atsushi Kurasawa ◽  
Katsunori Kimoto
Keyword(s):  
Life Cycle ◽  
Sexual Reproduction ◽  
Vertical Transmission ◽  
Asexual Reproduction ◽  
Planktonic Foraminifera ◽  
Gamete Release ◽  
Symbiotic Algae ◽  
Laboratory Cultures ◽  
Symbiont Transmission

Abstract Gamete release has been frequently observed in laboratory cultures of various species of planktonic foraminifera. Those observations have been taken as evidence that these organisms produce new generations exclusively by sexual reproduction. We report here the first observation of asexual reproduction in Globigerinita uvula, a small, microperforate foraminifera. The asexual phase was associated with the release of ca. 110 offspring, all of which hosted symbiotic algae that must have been passed on directly from the parent. This event was also the first observation of vertical transmission of symbionts in planktonic foraminifera. Although the trigger of the observed asexual reproduction and its frequency in nature remain unknown, our observation indicates that among the planktonic foraminifera, at least G. uvula has not abandoned the asexual phase of its life cycle.

scholarly journals On the life-cycle of ameles spallanzania (Rossi, 1792) (Insecta, Mantodea)

2011 ◽  
Vol 152 (1) ◽  
pp. 25
Author(s):  
Roberto Battiston ◽  
Carlo Galliani
Keyword(s):  
Life Cycle ◽  
Mediterranean Area ◽  
Climatic Conditions ◽  
Northern Italy ◽  
General Distribution ◽  
Continental Area ◽  
The Mediterranean ◽  
Behavioural Strategies

The recent find of an <em>Ameles spallanzania</em> population in a continental area of northern Italy permitted to redraw the northernmost edge of the distribution of this species and to study its life cycle in extreme climatic conditions. A comparison with collecting records of adult specimens from the Mediterranean area has been performed to put in evidence how this species adapts its life-cycle timings in different latitudes: hatching earlier or using nymphs to overwinter in warmer localities or oothecae in colder ones. Overwintering strategies of <em>Ameles spallanzania</em> have been compared with strategies of other genera of mantids that share the same habitat but have different life-cycle strategies and general distribution. Different developing times in mantids seem to be linked to behavioural strategies more than physiological attitudes.

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