Sex ratio patterns and trade-off between sexual and asexual reproduction in the brown hydra

2018 ◽  
Vol 37 (3) ◽  
pp. 551-561 ◽  
Author(s):  
Anita Kaliszewicz
Keyword(s):  
Sex Ratio ◽  
Asexual Reproduction ◽  
Trade Off ◽  
Sexual And 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 effect of leguminous plant species onCallosobruchus maculatus(Coleoptera: Bruchidae) and its egg parasitoidUscana lariophaga(Hymenoptera: Trichogrammatidae)

1998 ◽  
Vol 88 (1) ◽  
pp. 93-99 ◽  
Author(s):  
A. van Huis ◽  
M. de Rooy
Keyword(s):  
Sex Ratio ◽  
Plant Species ◽  
Nutritional Quality ◽  
Development Time ◽  
Callosobruchus Maculatus ◽  
Egg Parasitoid ◽  
The Other ◽  
Leguminous Plant ◽  
Trade Off ◽  
Storage Pest

AbstractThe performance of the egg parasitoidUscana lariophagaSteffan was studied when reared on eggs of the bruchid storage pest,Callosobruchus maculatus(Fabricius) developing in seeds of cowpea, chickpea and pigeonpea. The beetle laid more and larger eggs on pigeonpea than on cowpea and chickpea, indicating that there was not a trade-off between number and size of the eggs. The bruchid larvae reared on pigeonpea exhibited a longer development time and a higher mortality than those reared on cowpea and chickpea. The resulting males weighed less than those reared on cowpea and chickpea. The trichogrammatidU. lariophagaparasitized more eggs whenC. maculatuswas reared on chickpea than when reared on the other hosts. Parasitoid larvae developed slowest and had the highest mortality in eggs ofC. maculatusreared on pigeonpea compared to those reared on cowpea and chickpea; the sex ratio (% of females) of the resulting adults was also higher. The high mortality and long development time ofC. maculatusreared on pigeonpea indicated that this legume was less favourable toC. maculatusthan chickpea or cowpea. This was probably also true for the parasitoid since the mortality was higher and development longer in eggs ofC. maculatusreared on pigeonpea compared to those reared on cowpea and chickpea. Therefore, when host eggs were larger and of lower nutritional quality, the proportion of female egg parasitoids was greater.

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.

scholarly journals Investigation of evolutionary effects on the relative frequency of sexual reproduction in freshwater diatoms

Phytotaxa ◽  
2013 ◽  
Vol 127 (1) ◽  
pp. 183 ◽  
Author(s):  
VIRGINIA M. CARD ◽  
MEEGEN CARRA
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Relative Frequency ◽  
Narrow Range ◽  
Size Class ◽  
Analysis Method ◽  
Costs And Benefits ◽  
Size Classes ◽  
Size Class Distribution ◽  
Sexual And Asexual Reproduction

There are substantial ecological and evolutionary costs to sexual reproduction and there is only a narrow range of conditions that favors the evolution of high rates of sexual reproduction in species that are capable of both sexual and asexual reproduction. Considering the evolutionary costs and benefits of sexual reproduction, it was hypothesized that the frequency of sexual reproduction relative to asexual reproduction in diatoms would be greater for attached pennates and lower for planktonic centrics. This was investigated by comparison of the size-class distributions of the attached pennate, Rhopalodia gibba (Ehrenberg) Müller 1895 and the planktonic centric Cyclotella meneghiniana Kützing 1844 collected from the littoral zone of Lake Phalen in St. Paul Minnesota, USA. Numerical combination of binomial functions was used to infer the number of significant occurrences of sexual reproduction contributing to the size-class distribution of each population, with the frequency of sexual reproduction relative to asexual reproduction inferred from the number of binomial curves contributing to the distribution. The size-class profile of C. meneghiniana was unimodal, dominated by a single peak at 12 µm, with additional contributing curves with peaks at 15 µm and 18 µm. The size-class profile of R. gibba was bimodal, dominated by peaks at 46 µm and 60 µm, with additional contributing curves with peaks at 36 µm, 73 µm, and 84 µm. The results of this investigation were robust with respect to difference between the species in sample size and number of size-classes, although the analysis method is sensitive to differences in the number of size-classes. The results supported the hypothesis, and demonstrate the principle that size-class analysis of diatom populations can be used to investigate evolutionary hypotheses about differences among taxa in the relative frequency of sexual and asexual reproduction.

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