scholarly journals Idea Paper: Effects of gonad type and body mass on the time required for sex change in fishes

2021 ◽  
Author(s):  
Soma Tokunaga ◽  
Tatsuru Kadota ◽  
Yuuki Y. Watanabe ◽  
Tetsuo Kuwamura ◽  
Yuuki Kawabata
Keyword(s):  
Sex Change ◽  
High Temporal Resolution ◽  
Scaling Exponent ◽  
Large Species ◽  
Teleost Fishes ◽  
Metabolic Scaling ◽  
Factors Influencing ◽  
Opposite Sex ◽  
Time Required ◽  
Male To Female

AbstractSex change is a well-known phenomenon in teleost fishes, and it takes several days to a few months depending on the species and direction of sex change. However, the underlying factors influencing the time required for sex change (TS) remain unclear. Given that the time for producing a new gonad largely determines TS, the gonad type (i.e., whether fish retain the gonad of opposite sex or not [delimited or non-delimited]) and metabolic rate are the ultimate determinants of TS. This study sought to test two hypotheses: (1) the delimited gonad shortens TS; and (2) TS scales with mass0.1–0.2, because the metabolic scaling exponent (β) in fishes is 0.8–0.9 and biological times scale with mass1−β in general. We compiled data on TS for 12 female-to-male and 14 male-to-female sex-changing species from the literature. Results of individual examinations of the effects of gonad type and mass were consistent with our hypotheses. However, upon simultaneous examination of the effects of gonad type and mass, these effects became unclear because of their strong multicollinearity. The compiled data for delimited and non-delimited gonads were biased toward the smaller and larger species, respectively, precluding us from being able to statistically distinguish between these effects. Small species with non-delimited gonads and large species with delimited gonads exist; however, their TS has not been measured with high temporal resolution thus far. Therefore, additional experiments on these species are required to statistically distinguish between, as well as to better understand, the effects of gonad type and mass on TS.

scholarly journals Biological scaling in green algae: the role of cell size and geometry

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Helena Bestová ◽  
Jules Segrestin ◽  
Klaus von Schwartzenberg ◽  
Pavel Škaloud ◽  
Thomas Lenormand ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Internal Diffusion ◽  
Scaling Exponent ◽  
Power Scaling ◽  
Nutrient Distribution ◽  
Metabolic Scaling ◽  
Key Factor ◽  
Size And Morphology

AbstractThe Metabolic Scaling Theory (MST), hypothesizes limitations of resource-transport networks in organisms and predicts their optimization into fractal-like structures. As a result, the relationship between population growth rate and body size should follow a cross-species universal quarter-power scaling. However, the universality of metabolic scaling has been challenged, particularly across transitions from bacteria to protists to multicellulars. The population growth rate of unicellulars should be constrained by external diffusion, ruling nutrient uptake, and internal diffusion, operating nutrient distribution. Both constraints intensify with increasing size possibly leading to shifting in the scaling exponent. We focused on unicellular algae Micrasterias. Large size and fractal-like morphology make this species a transitional group between unicellular and multicellular organisms in the evolution of allometry. We tested MST predictions using measurements of growth rate, size, and morphology-related traits. We showed that growth scaling of Micrasterias follows MST predictions, reflecting constraints by internal diffusion transport. Cell fractality and density decrease led to a proportional increase in surface area with body mass relaxing external constraints. Complex allometric optimization enables to maintain quarter-power scaling of population growth rate even with a large unicellular plan. Overall, our findings support fractality as a key factor in the evolution of biological scaling.

scholarly journals The earliest example of sexual dimorphism in bivalves—evidence from the astartid Nicaniella (Lower Jurassic, southern Germany)

2021 ◽  
pp. 1-10
Author(s):  
Baran Karapunar ◽  
Winfried Werner ◽  
Franz T. Fürsich ◽  
Alexander Nützel
Keyword(s):  
Principal Component Analysis ◽  
Life History ◽  
Shape Analysis ◽  
Principal Component ◽  
Sex Change ◽  
Lower Jurassic ◽  
Allocation Of Resources ◽  
Fourier Shape Analysis ◽  
Lower Height ◽  
Male To Female

Abstract Protandrous sex change (sex change from male to female) is one of the diverse sexual expressions exhibited by bivalves, but its expression in the shell is quite rare. Previous studies on living and fossil astartids suggest a relationship between protandrous sex change and the formation of crenulations on the ventral shell margin at later ontogenetic stages. Here we report the formation of such crenulations in the Early Jurassic astartid Nicaniella rakoveci (Kuhn, 1935) from the Amaltheenton Formation at Buttenheim, Franconia. This is the earliest known record of protandrous hermaphroditism in fossil bivalves, predating previous reports by at least 13 Myr. A principal component analysis of linear size measurements and Fourier shape analysis of the shell outlines revealed that the outline of Nicaniella rakoveci specimens varies from subquadrate to subcircular, but this variation is independent of the presence or absence of crenulations and therefore not associated with sex. Crenulated specimens exhibit a lower height/inflation ratio than non-crenulated ones, suggesting that the protandrous females have more inflated valves than the males. The formation of crenulations was probably related to allocation of resources for reproduction. The most likely function of the crenulations was to increase the internal shell volume in the female stage to accommodate more eggs rather than being an adaptation against predation as often assumed for other bivalves. The formation of crenulations is part of the protandrous life history and probably is controlled by a genetic mechanism that is also responsible for sex change.

Transsexualism

2011 ◽  
pp. 1463-1468
Author(s):  
Louis J. G. Gooren
Keyword(s):  
Sexual Differentiation ◽  
External Genitalia ◽  
The Other ◽  
Stria Terminalis ◽  
Bed Nucleus ◽  
Psychological Phenomenon ◽  
Opposite Sex ◽  
Male To Female ◽  
The Brain

Transsexualism is the condition in which a person with apparently normal somatic sexual differentiation is convinced that he/she is actually a member of the opposite sex. It is associated with an irresistible urge to be hormonally and surgically adapted to that sex. Traditionally transsexualism has been conceptualized as a purely psychological phenomenon, but research on the brains of male-to-female transsexuals has found that the sexual differentiation of the brain—the bed nucleus of the stria terminalis (BSTC) and the hypothalamic uncinate nucleus—had followed a female pattern (1). This finding may lead to a concept of transsexualism as a form of intersex, where the sexual differentiation of the brain (which in mammals also undergoes sexual differentiation) is not consistent with the other variables of sex, such as chromosomal pattern, nature of the gonad and nature of internal/external genitalia. Thus it can be argued that transsexualism is a sexual differentiation disorder.

scholarly journals Comparative growth, age at maturity and sex change, and longevity of Hawaiian parrotfishes, with bomb radiocarbon validation

2018 ◽  
Vol 75 (4) ◽  
pp. 580-589 ◽  
Author(s):  
Edward E. DeMartini ◽  
Allen H. Andrews ◽  
Kathrine G. Howard ◽  
Brett M. Taylor ◽  
Dong-Chun Lou ◽  
...  
Keyword(s):  
Fork Length ◽  
Logistic Models ◽  
Growth Curves ◽  
Sex Change ◽  
Terminal Phase ◽  
Large Species ◽  
Small Species ◽  
Bomb Radiocarbon ◽  
Current Minimum ◽  
Fishery Species

Growth rates and longevities were estimated for five major fishery species of parrotfishes (“uhu”) at Oahu, Hawai’i. All species grew rapidly with von Bertalanffy growth formula k values ≥0.4·year−1. Longevities were found to range broadly among the three small species, 4 years in Calotomus carolinus and 6 and 11 years in Scarus psittacus and Chlorurus spilurus, and to 15–20 years in Scarus rubroviolaceus and Chlorurus perspicillatus for the two large species. Age reading and growth curves for the latter two large species were validated using bomb radiocarbon dating. Median ages at sexual maturity as females (AM50) and at sex change (from female to terminal phase male, AΔ50) were estimated using logistic models. Sexual maturation occurred at 1–2 years for the small species and at 3–3.5 years in the large species. AΔ50 estimates ranged from 2 to 4 years in the small species and were about 5 and 7 years in S. rubroviolaceus and C. perspicillatus, respectively. Estimated milestones poorly corresponded to the current minimum legal size for uhu in Hawai’i (12 in. or 30.5 cm fork length). Pooling these parrotfishes for management seems generally inappropriate, especially for the two large species. Age-based metrics are more informative than size-based metrics for these fishes.

Tree densities and sex ratios in breeding populations of dioecious Central Amazonian Myristicaceae

1990 ◽  
Vol 6 (2) ◽  
pp. 239-248 ◽  
Author(s):  
David D. Ackerly ◽  
Judy M. Rankin-De-Merona ◽  
William A. Rodrigues
Keyword(s):  
Adult Population ◽  
Sex Ratios ◽  
Abundant Species ◽  
Partial Explanation ◽  
Canopy Tree ◽  
Breeding Populations ◽  
The Face ◽  
Opposite Sex ◽  
The Mean ◽  
Male To Female

ABSTRACTThe densities of the breeding populations and the sex of all flowering individuals were recorded for five dioecious canopy tree species of Central Amazonian Myristicaceae, in 11 study areas of the Minimum Critical size of Ecosystems Project totalling 22.5 ha. Adult population densities were extremely low, ranging from 0.38 to 1.61 ha–1 for the five species studied. In a 10 ha study plot the mean distance to the nearest flowering conspecific ranged from 48 to 100 m, while the mean distance to the nearest opposite sex conspecific was 147 m. The two most abundant species, Iryanthera macrophylla and Virola calophylla, both showed male-biased sex ratios, of 23:9 and 20:6, respectively. The size class distribution of males, females and non-flowering individuals in V. calophylla suggests that earlier reproductive maturation of male plants may provide a partial explanation for this bias. In I. macrophylla, since 95% of the individuals were observed flowering, the observed ratio is representative of the population, and may be caused by sex shifts from male to female. The low reproductive densities, combined with the skewed sex ratios and overlapping generations of these species, create very small effective breeding populations, placing species such as these at great risk in the face of deforestation and habitat fragmentation.

Long-term follow-up of ?sex change? in 13 male-to-female transsexuals

1986 ◽  
Vol 15 (3) ◽  
pp. 187-210 ◽  
Author(s):  
Gunnar Lindemalm ◽  
Dag K�rlin ◽  
Nils Uddenberg
Keyword(s):  
Sex Change ◽  
Long Term Follow Up ◽  
Male To Female

Male-to-female sex change in widowed males of the protogynous damselfish Dascyllus aruanus

2015 ◽  
Vol 34 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Tetsuo Kuwamura ◽  
Shohei Suzuki ◽  
Tatsuru Kadota
Keyword(s):  
Sex Change ◽  
Female Sex ◽  
Dascyllus Aruanus ◽  
Male To Female

scholarly journals Under-24-hour mortality from acute coronary syndrome in emegrency hospital

2012 ◽  
Vol 93 (6) ◽  
pp. 859-864
Author(s):  
Z G Valeev ◽  
V G Belyakov ◽  
L Y Salyahova
Keyword(s):  
Acute Coronary Syndrome ◽  
Female Mortality ◽  
Total Rate ◽  
Emergency Hospital ◽  
Coronary Syndrome ◽  
Factors Influencing ◽  
Complex Approach ◽  
Mortality Ratio ◽  
The Impact ◽  
Male To Female

Aim. To identify the factors influencing the strategy and tactics of treating patients with acute coronary syndrome; to define the impact of various stages of emergency care in total rate of under-24-hour in-patients mortality. Methods. The retrospective analysis of the in-patients medical charts, ambulance accompanying sheets and autopsy protocols of 303 patients who died during the first 24 hours after admission to the department of cardiology at Municipal Emergency Hospital №1, Kazan from January 1st, 2009 to December 31th, 2011. Results. The level of under-24-hour in-patients mortality in the emergency hospital remains considerably high without a tendency to fall. In economically active group of population male to female mortality ratio exceeds 1,8. Most patients are being brought to the hospital by ambulance crews which are not enough qualified and equipped to care for patients in a critical condition. Only 48.3% of admitted patients get medical aid before admission, although the share of patients admitted in a poor, critical or agonal condition is 89.8%. Conclusion. Decreasing under-24-hour mortality is a multidimensional and multifactorial problem, which demands a complex approach in all stages of providing medical care to be solved.

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