Is Silene acaulis (Caryophyllaceae) a trioecious species? Reproductive biology of two subspecies

1998 ◽  
Vol 76 (3) ◽  
pp. 478-485 ◽  
Author(s):  
Sandrine Maurice ◽  
Christine Desfeux ◽  
Agnes Mignot ◽  
Jean-Pierre Henry
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Natural Populations ◽  
Morphological Characters ◽  
Fruit Production ◽  
Breeding Systems ◽  
Pollen Production ◽  
French Alps ◽  
Silene Acaulis ◽  
Dioecious Populations

Based on morphological characters, Silene acaulis subsp. exscapa and Silene acaulis subsp. cenisia have been previously described as dioecious and trioecious, respectively. Here we examine whether these subspecies are truly dioecious (subsp. exscapa) and trioecious (subsp. cenisia) based on individual seed and pollen production. Nine populations of subsp. cenisia and five populations of subsp. exscapa were studied in the French Alps. The ratio of staminate to female plants within populations did not in general differ from 1:1, the sex ratio expected in dioecious populations. Staminate plants of both subspecies were found to set fruits. In subsp.exscapa, the ratio of fruit production in female versus staminate plants is around 900; in subsp. cenisia, this ratio is around 10. The advantage of female plants in fruit production is not always sufficient to explain their frequencies in natural populations. Staminate plants cannot be divided in two distinct categories: males and hermaphrodites. The two subspecies can be best described as subdioecious, although S. a. exscapa is effectively closer to exhibiting true dioecy than S. a. cenisia.Key words: breeding systems, trioecy, subdioecy, Silene acaulis.

scholarly journals Natural variation in social conditions affects male mate choosiness in the amphipod Gammarus roeselii

2021 ◽  
Author(s):  
Konrad Lipkowski ◽  
Sophie Steigerwald ◽  
Lisa M Schulte ◽  
Carolin Sommer-Trembo ◽  
Jonas Jourdan
Keyword(s):  
Population Density ◽  
Sex Ratio ◽  
Natural Variation ◽  
Natural Populations ◽  
Social Background ◽  
Social Conditions ◽  
Background Information ◽  
Male Mating ◽  
Natural Environments ◽  
Male Mate

Abstract The extent of male mate choosiness is driven by a trade-off between various environmental factors associated with the costs of mate acquisition, quality assessment and opportunity costs. Our knowledge about natural variation in male mate choosiness across different populations of the same species, however, remains limited. In this study, we compared male mate choosiness across 10 natural populations of the freshwater amphipod Gammarus roeselii (Gervais 1835), a species with overall high male mating investments, and evaluated the relative influence of population density and sex ratio (both affecting mate availability) on male mate choosiness. We investigated amplexus establishment after separating mating pairs and presenting focal males with a novel, size-matched female from the same population. Our analysis revealed considerable effects of sex ratio and (to a lesser extent) population density on time until amplexus establishment (choosiness). Male amphipods are able to perceive variable social conditions (e.g., sex ratio) and modify their mating strategy accordingly: We found choosiness to be reduced in increasingly male-biased populations, whereas selectivity increases when sex ratio becomes female biased. With this, our study expands our limited knowledge on natural variations in male mate choosiness and illustrates the importance of sex ratio (i.e., level of competition) for male mating decisions in natural environments. Accounting for variation in sex ratios, therefore, allows envisioning a distinctive variation of choosiness in natural populations and highlights the importance of considering social background information in future behavioral studies.

scholarly journals Sex Chromosome Meiotic Drive in Stalk-Eyed Flies

Genetics ◽  
1997 ◽  
Vol 147 (3) ◽  
pp. 1169-1180 ◽  
Author(s):  
Daven C Presgraves ◽  
Emily Severance ◽  
Gerald S Willrinson
Keyword(s):  
Sex Ratio ◽  
Sex Chromosome ◽  
Sex Ratios ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Operational Sex Ratio ◽  
Genetic Modifiers ◽  
Ratio Distortion ◽  
The Impact ◽  
Sex Ratio Distortion

Meiotically driven sex chromosomes can quickly spread to fixation and cause population extinction unless balanced by selection or suppressed by genetic modifiers. We report results of genetic analyses that demonstrate that extreme female-biased sex ratios in two sister species of stalk-eyed flies, Cyrtodiopsis dalmanni and C. whitei, are due to a meiotic drive element on the X chromosome (Xd). Relatively high frequencies of Xd in C. dalmanni and C. whitei (13–17% and 29%, respectively) cause female-biased sex ratios in natural populations of both species. Sex ratio distortion is associated with spermatid degeneration in male carriers of Xd. Variation in sex ratios is caused by Y-linked and autosomal factors that decrease the intensity of meiotic drive. Y-linked polymorphism for resistance to drive exists in C. dalmanni in which a resistant Y chromosome reduces the intensity and reverses the direction of meiotic drive. When paired with Xd, modifying Y chromosomes (Ym) cause the transmission of predominantly Y-bearing sperm, and on average, production of 63% male progeny. The absence of sex ratio distortion in closely related monomorphic outgroup species suggests that this meiotic drive system may predate the origin of C. whitei and C. dalmanni. We discuss factors likely to be involved in the persistence of these sex-linked polymorphisms and consider the impact of Xd on the operational sex ratio and the intensity of sexual selection in these extremely sexually dimorphic flies.

scholarly journals Reproductive Biology of Round Sardinella (Sardinella Aurita) (Valenciennes, 1847) in Senegalese Coastal Waters

2018 ◽  
Vol 9 (1) ◽  
pp. 31
Author(s):  
Ismaïla NDIAYE ◽  
Alassane SARR ◽  
Alioune FAYE ◽  
Modou THIAW ◽  
Malick DIOUF ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Coastal Waters ◽  
Sexual Maturity ◽  
Reproductive Parameters ◽  
Monthly Variation ◽  
Relative Fecundity ◽  
The Mean ◽  
Sardinella Aurita ◽  
Somatic Index

In this study, a total of 1068 specimens Sardinella aurita of which 553 females and 515 males were examined. The objectif of this study was to determine the reproductive parameters of Sardinella aurita. The sex ratio was significantly in favor of females (55%). The size at first sexual maturity was estimated at 18.9 cm for females and 18.0 cm for males. The monthly variation of sexual maturity stages and gonado-somatic index (GSI) allowed to locate the reproduction periods from February to June and from September to December. The mean absolute fecundity was estimated at 110.794 ± 7582 oocytes whereas relative fecundity was about 422 ± 26 oocytes per gram of female.

Biology of lake sturgeon (Acipenser fulvescens) spawning below a dam on the Richelieu River, Quebec: behaviour, egg deposition, and endocrinology

2013 ◽  
Vol 91 (3) ◽  
pp. 175-186 ◽  
Author(s):  
J.D. Thiem ◽  
D. Hatin ◽  
P. Dumont ◽  
G. Van Der Kraak ◽  
S.J. Cooke
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Residence Time ◽  
Lake Sturgeon ◽  
Blood Sampling ◽  
Acipenser Fulvescens ◽  
Spawning Ground ◽  
Egg Deposition ◽  
Daily Spawning ◽  
Gill Netting

Knowledge of the reproductive biology of wild sturgeon populations is critical to ensure the survival of this unique group of animals. We combined gill-netting surveys, nonlethal blood sampling, radiotelemetry, and egg collection to examine the reproductive biology of lake sturgeon (Acipenser fulvescens Rafinesque, 1817) at a suspected spawning ground below a dam on the Richelieu River, Quebec. Lake sturgeon were present at the beginning of sampling in early May, and spawning took place from 26 May to 5 June when water temperature averaged 13.4 ± 0.1 °C (range 11.5–15.5 °C). Daily spawning population estimates ranged from 285 to 1282 individuals and the sex ratio of spawners was estimated at 2.1 males per female. The presence of radio-tagged individuals on the spawning grounds peaked from 20 to 28 May, corresponding with known spawning bouts. Residence time of spawners on the spawning ground ranged from 1 to 27 days (median = 5 days) and there were no differences in residence time between sexes. Nonlethal blood sampling enabled the quantification of steroid levels to determine the spawning population sex ratio, and steroid levels were highest before spawning was known to occur and decreased concurrently with, and after, known spawning events.

Variation in leaf characteristics among provenances of Eucalyptus camaldulensis Dehn. grown in Zambia

1971 ◽  
Vol 19 (2) ◽  
pp. 237
Author(s):  
J Burley ◽  
PJ Wood ◽  
AS Hans
Keyword(s):  
Principal Component Analysis ◽  
Leaf Shape ◽  
Natural Populations ◽  
Eucalyptus Camaldulensis ◽  
Principal Component ◽  
Morphological Characters ◽  
Leaf Length ◽  
Maximum Temperature ◽  
Ecotypic Variation ◽  
Old Trees

Eight morphological characters of leaves were examined in 2-year-old trees of 25 provenances of Eucalyptus camaldulensis Dehn, grown in a replicated trial in Zambia. Provenances differed significantly in leaf length and width, base angle, and oil gland density but significant effects were attributed to trees within provenances. Leaf curvature also varied between provenances, trees, and branches. The tip angle and the number of veins did not vary significantly. Leaf length and oil gland density were related to maximum temperature at seed source rather than to latitude but the reverse occurred for leaf width. Significant amounts of variation were explained by a linear combination of temperature and latitude but not by longitude, altitude, or rainfall. Information on seven traits was combined in principal component analysis in which the first component (a measure of leaf shape) accounted for 36% of total observed variation while the second (weighted largely on leaf length) accounted for 26%. Mapping of both univariate and multivariate results indicated that there are two major ecotypes and gave some evidence of clinal and ecotypic variation within them. The conclusions support those of other workers both in natural populations in Australia and in exotic populations elsewhere.

Body size variation in hybrids among populations of European water frogs (Pelophylax esculentus complex) with different breeding systems

2020 ◽  
Vol 41 (3) ◽  
pp. 361-371
Author(s):  
Adam Hermaniuk ◽  
Magdalena Czajkowska ◽  
Anetta Borkowska ◽  
Jan R.E. Taylor
Keyword(s):  
Body Size ◽  
Sex Ratio ◽  
Parental Species ◽  
Size Variation ◽  
Breeding Systems ◽  
European Water ◽  
Water Frogs ◽  
Population Type ◽  
Pelophylax Esculentus ◽  
European Water Frogs

Abstract In some populations, hybrids reproduce with a parental species by eliminating the genome of this species from their own germline and produce gametes that only contain the genome of the other parental species (sexual host). This mode of reproduction, known as hybridogenesis, leads to a conflict of interest between the two parties because the sexual host should avoid mating with the hybrid to prevent a reduction in reproductive success, whereas the hybrid depends on such matings for survival. We investigated European water frogs (Pelophylax esculentus complex), including hybrids (P. esculentus, genotype LR) and two sexual host species (P. lessonae, LL and P. ridibundus, RR). We hypothesized that to maximize fitness, hybrid males should be morphologically more similar to the sexual host that is preferred by females for successful reproduction. To test this hypothesis, we compared hybrid males in two different population types, L-E (hybrids coexist with LL) and L-E-R (hybrids coexist with both LL and RR). The latter was described in terms of genome composition, sex ratio, and mate choice preferences; the sex ratio of hybrids was significantly male-biased. We found that LR males from the L-E-R populations were significantly larger than those from the L-E, which makes them more similar to P. ridibundus, the largest species within the P. esculentus complex. We suggest that a larger body size of hybrid males may provide a reproductive advantage in the L-E-R population type, where the most common type of pair caught in the breeding season was LR males × RR females.

A quantitative assessment of the reproductive biology of Cyclonaias tuberculata (Bivalvia: Unionidae)

1995 ◽  
Vol 73 (1) ◽  
pp. 83-88 ◽  
Author(s):  
Thomas M. Haggerty ◽  
Jeffrey T. Garner ◽  
George H. Patterson ◽  
Lannis C. Jones Jr.
Keyword(s):  
Sex Ratio ◽  
Reproductive Biology ◽  
Reproductive Performance ◽  
Quantitative Assessment ◽  
Late Summer ◽  
Early Spring ◽  
Short Term ◽  
Tennessee River ◽  
Early Fall

Two hundred and thirty-three purple wartyback unionids (Cyclonaias tuberculata) were collected approximately monthly over a 31-month period from Kentucky Reservoir (Tennessee river mile 201.3), Tennessee, between August 1988 and February 1991. An equal sex ratio and only one case of hermaphroditism were discovered. Histological examinations showed that spermatogenesis and oogenesis occurred throughout the year except during late summer and early fall. "Typical" spermatogenesis was most evident between May and July. Spawning occurred between early spring (March–April) and late summer (August). Brooding variation among females was shown by the presence of embryos in the suprabranchial chambers and gills between early April and late August. Brooding was short term, as indicated by mature larvae being found in the outer demibranchs between early July and late August. Full demibranchs were never found, possibly indicating that the study took place during years of poor reproductive performance.

scholarly journals Reproductive biology and embryonic development of Centroscymnus coelolepis in Portuguese mainland waters

2003 ◽  
Vol 60 (6) ◽  
pp. 1335-1341 ◽  
Author(s):  
Ana Veríssimo ◽  
Leonel Gordo ◽  
Ivone Figueiredo
Keyword(s):  
Sex Ratio ◽  
Embryonic Development ◽  
Reproductive Biology ◽  
Sexual Maturity ◽  
Sampling Period ◽  
Yolk Sac ◽  
Pregnant Female ◽  
Reproductive Parameters ◽  
Reproductive Characteristics ◽  
Total Length

Abstract A total of 871 females (76–122 cm) and 86 males (68–100 cm) of Centroscymnus coelolepis caught in Portuguese mainland waters were examined for reproductive characteristics. One hermaphroditic individual of 95 cm was found. Males were few in numbers and dominated by immature specimens. Female length at first sexual maturity was 98.5 cm. Mean ovarian and uterine fecundity were 13.2 oocytes per female and 9.9 embryos per pregnant female, respectively. Total length of embryos with completely absorbed external yolk sacs ranged between 233 and 300 mm. Sex ratio (F/M) of embryos with completely absorbed external yolk sac was 0.9. All stages of reproduction were found during the 12-month sampling period. Results were compared with those from other regions. A hypothesis is formulated on the existence of several regional populations based on morphometric and reproductive parameters observed in different areas.

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