Direct observations of protandrous sex change in the patellid limpet Patella vulgata

2006 ◽  
Vol 86 (1) ◽  
pp. 161-162 ◽  
Author(s):  
W.J.F. Le Quesne ◽  
S.J. Hawkins
Keyword(s):  
Sex Change ◽  
Spawning Season ◽  
Indirect Methods ◽  
Patella Vulgata ◽  
Direct Observations ◽  
Protandrous Hermaphrodite

Direct observations of sex change were made on Patella vulgata, which has long been considered a protandrous hermaphrodite based on indirect methods. Thirty per cent of the male limpets that were marked during the spawning season in 2003 were female when they were re-examined during the spawning season in 2004. This confirms that protandry does occur within the superfamily Patellidae.

scholarly journals An Update on The Problem of Small Comets

1998 ◽  
Vol 11 (1) ◽  
pp. 237-238
Author(s):  
J.C. Brandt ◽  
M.F. A’Hearn
Keyword(s):  
Recent Work ◽  
Terrestrial Planets ◽  
Indirect Methods ◽  
Earth’S Atmosphere ◽  
Direct Observations ◽  
Icy Bodies ◽  
Earth's Atmosphere ◽  
Search Program ◽  
Volatile Materials

The evidence for a major population of small comets (SCs) is summarized in two steps. First, we briefly summarize our previous work. Second, we describe recent work that continues to find SCs. When new capabilities become available that can detect SCs, we expect to find them and this is occurring. At present, their detection is a haphazard process and we advocate a dedicated, optimized search program. We define SCs as those icy bodies (i.e., sublimating bodies) with radius less than 1000 meters. Often the existence of SCs is inferred from effects ascribed to them. These “effects” include: lunar cratering; cratering on Ganymede; excess interplanetary hydrogen; delivery of volatile materials to the terrestrial planets; and a source of fragile bodies entering the Earth’s atmosphere. While some of these indirect methods support the existence of SCs, direct observations are clearly preferred.

scholarly journals Observations on Patella Vulgata. Part I. Sex-Phenomena, Breeding and Shell-Growth

1928 ◽  
Vol 15 (3) ◽  
pp. 851-862 ◽  
Author(s):  
J. H. Orton
Keyword(s):  
Breeding Season ◽  
Shell Growth ◽  
Sex Change ◽  
Chromosome Constitution ◽  
Breeding Period ◽  
Patella Vulgata ◽  
The Future ◽  
Different Seasons ◽  
Metabolic Conditions

SUMMARYThe small individuals were examined before the height of the breeding season, and there is a probability that many or most of the indeterminate individuals would become male. Hermaphrodite individuals have been observed previously, and in certain samples 10% of the males contain doubtful young ova in the gonad. It is therefore concluded that Patella vulgata is apparently a protandric hermaphrodite, but that the evidence is not yet sufficiently good to prove protandry.It is suggested that possibly two kinds of male, which may be recognisable by chromosome constitution, may occur, one being pure male and one protandric, and also that sex-change may be controlled by as yet unknown metabolic conditions.The breeding period is discussed ; it may extend from August to March at Plymouth in different seasons, and spawning may occur within this period. A maximum of spawning appears to occur about January-February. The conditions controlling breeding and spawning in Patella are unknown, and as the course of seasonal shell-growth is unknown, although shell-growth is general at the end of the breeding season, it is suggested that research on the subjects in the future should be combined.

scholarly journals A comparison of fecal sampling and direct feeding observations for quantifying the diet of a frugivorous primate

2019 ◽  
Vol 66 (4) ◽  
pp. 333-343
Author(s):  
Jaya K Matthews ◽  
Amanda Ridley ◽  
Beth A Kaplin ◽  
Cyril C Grueter
Keyword(s):  
Indirect Evidence ◽  
Wild Animals ◽  
Indirect Methods ◽  
Fecal Samples ◽  
Fruit Species ◽  
Direct Observations ◽  
Food Species ◽  
Study Population ◽  
Very High ◽  
Fecal Sampling

Abstract Both observational and indirect evidence are widely used to determine the diets of wild animals. Direct observations are often assumed to provide the most comprehensive reflection of diet, but many wild animals are logistically challenging to observe. Despite the regular use of observational and indirect methods for inferring diet in wild animals, they have rarely been compared in detail for the same study population. Over 12 months this study assessed the congruence of methods in estimating the diet of a montane community of eastern chimpanzees Pan troglodytes schweinfurthii in Nyungwe National Park, Rwanda using observational scan samples and macroscopic fecal inspection. The assessment of the number of food species consumed each month was comparable between methods, but the estimation of the composition of items in the diet differed significantly. Most notably, the fecal samples significantly underestimated the consumption of flowers, and certain fruit species, which based on direct behavioral observations were seasonally consumed at very high rates. Conversely, direct observations underestimated the consumption of leaves and pith in comparison to results present in the fecal samples. These results suggest that combining methods where possible is most useful for accurate monitoring of dietary trends, particularly for species that experience significant seasonal shifts in their diet.

scholarly journals Polymer tensiometers with ceramic cones: direct observations of matric pressures in drying soils

2010 ◽  
Vol 14 (10) ◽  
pp. 1787-1799 ◽  
Author(s):  
M. J. van der Ploeg ◽  
H. P. A. Gooren ◽  
G. Bakker ◽  
C. W. Hoogendam ◽  
C. Huiskes ◽  
...  
Keyword(s):  
Polymer Solution ◽  
Time Domain ◽  
Response Times ◽  
Measurement Range ◽  
Time Domain Reflectometry ◽  
Matric Potential ◽  
Indirect Methods ◽  
Direct Observations ◽  
The Relationship

Abstract. Measuring soil water potentials is crucial to characterize vadose zone processes. Conventional tensiometers only measure until approximately −0.09 MPa, and indirect methods may suffer from the non-uniqueness in the relationship between matric potential and measured properties. Recently developed polymer tensiometers (POTs) are able to directly measure soil matric potentials until the theoretical wilting point (−1.6 MPa). By minimizing the volume of polymer solution inside the POT while maximizing the ceramic area in contact with that polymer solution, response times drop to acceptable ranges for laboratory and field conditions. Contact with the soil is drastically improved with the use of cone-shaped solid ceramics instead of flat ceramics. The comparison between measured potentials by polymer tensiometers and indirectly obtained potentials with time domain reflectometry highlights the risk of using the latter method at low water contents. By combining POT and time domain reflectometry readings in situ moisture retention curves can be measured over the range permitted by the measurement range of both POT and time domain reflectometry.

scholarly journals Influence of Size, Age, and Spawning Season on Sex Change in Black Sea Bass

2017 ◽  
Vol 9 (1) ◽  
pp. 126-138 ◽  
Author(s):  
M. M. Provost ◽  
O. P. Jensen ◽  
D. L. Berlinsky
Keyword(s):  
Black Sea ◽  
Sex Change ◽  
Sea Bass ◽  
Spawning Season ◽  
Black Sea Bass

scholarly journals Experimental Investigation of Pore Structure and Movable Fluid Traits in Tight Sandstone

Processes ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 149 ◽  
Author(s):  
Dengke Liu ◽  
Wei Sun ◽  
Dazhong Ren
Keyword(s):  
Surface Water ◽  
Water Saturation ◽  
Bulk Water ◽  
Reservoir Quality ◽  
Tight Sandstone ◽  
Indirect Methods ◽  
Direct Observations ◽  
Pore Structures ◽  
Lower Limits ◽  
Porosity Measurements

Whether the variation of pore structures and movable fluid characteristics enhance, deteriorate, or have no influence on reservoir quality has long been disputed, despite their considerable implications for hydrocarbon development in tight sandstone reservoirs. To elucidate these relationships, this study systematically analyzes pore structures qualitatively and quantitatively by various kinds of direct observations, indirect methods, and imaging simulations. We found that the uncertainty of porosity measurements, caused by the complex pore-throat structure, needs to be eliminated to accurately characterize reservoir quality. Bulk water was more easily removed, while surface water tended to be retained in the pores, and the heterogeneity of pore structures was caused by the abundance of tiny pores. The rates of water saturation reduction in macropores are faster than those for tiny pores, and sandstones with poor reservoir quality show no marked descending of lower limits of movable pore radius, indicating that the movable fluid would advance exempted from the larger pores. This study suggests that the deterioration of reservoir quality is strongly affected by the reduction of larger pores and the aqueous phases tended to remain in the tiny pores in the forms of surface water.

scholarly journals Faster juvenile growth promotes earlier sex change in a protandrous hermaphrodite (barramundi Lates calcarifer)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Brien H. Roberts ◽  
John R. Morrongiello ◽  
David L. Morgan ◽  
Alison J. King ◽  
Thor M. Saunders ◽  
...  
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Sex Change ◽  
Maximum Size ◽  
Growth Potential ◽  
Lates Calcarifer ◽  
Individual Level ◽  
Trade Offs ◽  
Animal Populations ◽  
Protandrous Hermaphrodite

AbstractThe relationship between growth and sexual maturation is central to understanding the dynamics of animal populations which exhibit indeterminate growth. In sequential hermaphrodites, which undergo post-maturation sex change, the size and age at which sex change occurs directly affects reproductive output and hence population productivity. However, these traits are often labile, and may be strongly influenced by heterogenous growth and mortality rates. We analysed otolith microstructure of a protandrous (i.e., male-to-female) fish (barramundi Lates calcarifer) to examine growth in relation to individual variation in the timing of sex change. Growth trajectories of individuals with contrasting life histories were examined to elucidate the direction and extent to which growth rate influences the size and age individuals change sex. Then, the relationships between growth rate, maturation schedules and asymptotic maximum size were explored to identify potential trade-offs between age at female maturity and growth potential. Rapid growth was strongly associated with decreased age at sex change, but this was not accompanied by a decrease in size at sex change. Individuals that were caught as large females grew faster than those caught as males, suggesting that fast-growing individuals ultimately obtain higher fitness and therefore make a disproportionate contribution to population fecundity. These results indicate that individual-level variation in maturation schedules is not reflective of trade-offs between growth and reproduction. Rather, we suggest that conditions experienced during the juvenile phase are likely to be a key determinant of post-maturation fitness. These findings highlight the vulnerability of sex-changing species to future environmental change and harvest.

scholarly journals Epigenetics underpins phenotypic plasticity of protandrous sex change in fish

2021 ◽  
Author(s):  
Alyssa Budd ◽  
Julie Robins ◽  
Olivia Whybird ◽  
Dean Jerry
Keyword(s):  
Phenotypic Plasticity ◽  
Epigenetic Modification ◽  
Strong Association ◽  
Sex Change ◽  
Ecological Processes ◽  
Sea Temperature ◽  
Protandrous Hermaphrodite ◽  
Female Specific ◽  
Response To Environmental Change ◽  
Male To Female

Phenotypic plasticity is an important driver of species resilience. Often mediated by epigenetic changes, phenotypic plasticity enables individual genotypes to express variable phenotypes in response to environmental change. Barramundi (Lates calcarifer) is a protandrous (male-first) sequential hermaphrodite that exhibit plasticity in length-at-sex change between geographic regions. This plasticity is likely to be mediated by changes in DNA methylation (DNAm), a well-studied epigenetic modification. However, region-specific relationships between length, sex and DNAm in sequential hermaphrodites were previously unreported. To investigate these relationships, here we compare DNAm in four conserved vertebrate sex-determining genes in male and female barramundi of differing lengths from three regions of northern Australia. Despite a strong association between increasing length and male-to-female sex change, the data reveal that DNAm becomes more sex-specific (rather than more female-specific) with length. Significant differences in DNAm between males and females of similar lengths suggest that female-specific DNAm arises rapidly during sex change, rather than gradually with growth. The findings also reveal that region-specific differences in length-at-sex change are accompanied by differences in DNAm, and were concurrent with variability in remotely sensed sea temperature and salinity. Together, these findings provide the first in situ evidence for epigenetically and environmentally mediated sex change in a protandrous hermaphrodite, and offer significant insight into the molecular and ecological processes governing the marked and unique plasticity of sex in fish.

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