scholarly journals Spatial variability in sexual and asexual reproduction of the fissiparous seastar Coscinasterias muricata: the role of food and fluctuating temperature

2002 ◽  
Vol 233 ◽  
pp. 143-155 ◽  
Author(s):  
M Sköld ◽  
MF Barker ◽  
PV Mladenov
Keyword(s):  
Spatial Variability ◽  
Asexual Reproduction ◽  
Fluctuating Temperature ◽  
Sexual And Asexual Reproduction

Reproduction of Cnidaria

2002 ◽  
Vol 80 (10) ◽  
pp. 1735-1754 ◽  
Author(s):  
Daphne Gail Fautin
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Somatic Tissue ◽  
Class Level ◽  
Sexual And Asexual Reproduction ◽  
Analytical Tools ◽  
Reproductive Characters ◽  
Analytical Frameworks ◽  
Shed Light

Empirical and experimental data on cnidarian reproduction show it to be more variable than had been thought, and many patterns that had previously been deduced hold up poorly or not at all in light of additional data. The border between sexual and asexual reproduction appears to be faint. This may be due to analytical tools being insufficiently powerful to distinguish between the two, but it may be that a distinction between sexual and asexual reproduction is not very important biologically to cnidarians. Given the variety of modes by which it is now evident that asexual reproduction occurs, its ecological and evolutionary implications have probably been underestimated. Appropriate analytical frameworks and strategies must be developed for these morphologically simple animals, in which sexual reproduction may not be paramount, that during one lifetime may pass though two or more phases differing radically in morphology and ecology, that may hybridize, that are potentially extremely long-lived, and that may transmit through both sexual and asexual reproduction mutations arising in somatic tissue. In cnidarians, perhaps more than in any other phylum, reproductive attributes have been used to define taxa, but they do so at a variety of levels and not necessarily in the way they have conventionally been considered. At the species level, in Scleractinia, in which these features have been most studied, taxa defined on the basis of morphology, sexual reproduction, and molecular characters may not coincide; there are insufficient data to determine if this is true throughout the phylum. At the class level, transverse fission occurs in members of all three major taxa but is rare outside Scyphozoa, the group of which it is considered characteristic (pending more research, its absence in Cubozoa should be ascribed to poor knowledge). Understanding the role of transverse fission in the ecology and reproductive biology of hydrozoans and anthozoans could shed light on scyphozoan evolutionary history, and elucidating its morphogenesis in all groups is essential to determining if it is homologous across the classes. Only by comparing aspects of reproduction among cnidarians of various taxa will idiosyncratically adaptive strategies be distinguished from reproductive characters that reflect evolution and so are phylogenetically informative.

scholarly journals EVOLUTION OF POPULATION WITH SEXUAL AND ASEXUAL REPRODUCTION IN CHANGING ENVIRONMENT

2004 ◽  
Vol 15 (02) ◽  
pp. 289-299 ◽  
Author(s):  
MINGFENG HE ◽  
CHANGLIANG YU ◽  
HONGBO RUAN ◽  
LEI YAO
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Asexual Reproduction ◽  
Birth Rate ◽  
Changing Environment ◽  
Mutation Probability ◽  
Sexual And Asexual Reproduction ◽  
Reproduction Pattern ◽  
Low Birth Rate

Using a lattice model based on Monte Carlo simulations, we study the role of the reproduction pattern on the fate of an evolving population. Each individual is under the selection pressure from the environment and random mutations. The habitat ("climate") is changing periodically. Evolutions of populations following two reproduction patterns are compared, asexual and sexual. We show, via Monte Carlo simulations, that sexual reproduction by keeping more diversified populations gives them better chances to adapt themselves to the changing environment. However, in order to obtain a greater chance to mate, the birth rate should be high. In the case of low birth rate and high mutation probability there is a preference for the asexual reproduction.

Gemmae in Tetralophozia setiformis (Anastrophyllaceae, Marchantiophyta) and their second record in Eurasia

2017 ◽  
Vol 51 ◽  
pp. 242-250
Author(s):  
M. V. Dulin
Keyword(s):  
British Columbia ◽  
Asexual Reproduction ◽  
Leaf Shape ◽  
Leaf Size ◽  
Komi Republic ◽  
The Other ◽  
Widespread Species ◽  
Northern Urals ◽  
Sexual And Asexual Reproduction ◽  
Murmansk Region

Tetralophozia setiformis is a widespread species occurring usually without organs of sexual and asexual reproduction. Gemmae of Tetralophozia setiformis were observed for the second time in Russia and Eurasia in the Northern Urals, Komi Republic. They form compact masses over upper leaves. The compact masses consist largely (70 %) of immature gemmae. Description of gemmae and gemmiparous shoots from the Northern Urals and their comparison with those from the other known localities, namely British Columbia (Canada) and the Murmansk Region (European Russia) were carried out. The gemmiparous plants of T. setiformis from the Northern Urals have approximately the same width as plants without gemmae but they are shorter. The leaves of gemmiparous plants from the Northern Urals are similar to leaves of gemmiparous plants from British Columbia. The leaf shape in upper part of the gemmiparous shoots varies from the typical to ± modified from gemmae production. These leaf shape transitions include reduction of leaf size and lobe number from 4 to 2–3, suppression of development and disappearance of characteristic teeth at the base of sinus. Gemmae size (17 × 22 μm) of plants from the Northern Urals is within variability recorded for plants from the Murmansk Region and British Columbia.

The role of rainfall spatial variability in estimating areal reduction factors

2019 ◽  
Vol 568 ◽  
pp. 416-426 ◽  
Author(s):  
Jongho Kim ◽  
Jaehyeon Lee ◽  
Dongkyun Kim ◽  
Boosik Kang
Keyword(s):  
Spatial Variability ◽  
Reduction Factors
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