A comparison of the life cycles, reproductive ecologies, and size–weight relationships of Helisoma anceps, H. campanulatum, and H. trivolvis (Gastropoda, Planorbidae)

1975 ◽  
Vol 53 (12) ◽  
pp. 1812-1824 ◽  
Author(s):  
Hans Boerger
Keyword(s):  
Life Span ◽  
Life Histories ◽  
Live Weight ◽  
Dry Weight ◽  
Life Cycles ◽  
Spawning Season ◽  
Minimum Size ◽  
Regression Equations ◽  
Shell Weight ◽  
Helisoma Anceps

Helisoma anceps, H. campanulatum, and H. trivolvis were studied separately in three ponds near Waterloo, Ontario, and were found to differ in the following parameters, respectively: life span, 2.1, and 2 years; mean growth rate during the first 2 months after hatching, 0.2, 1.0, and 0.06 mm/week; minimum size at which snails laid eggs, 8, 10, and 18 mm shell diameter; number of breeding periods during the life cycle, 2, 1, and 1: length of the spawning season, 18, 10, and 8 weeks; date by which 50% of the eggs had been laid, July 2, May 14, and May 15; mean number of eggs per egg capsule, 14, 14, and 24. Although mature H. trivolvis occurred throughout the pond during the spawning season, eggs were laid only along the margin. The average number of eggs laid during the life span of a snail was 300 for H. campanulatum and 590 for H. anceps. Linear regression equations relating size to live weight, shell weight, and shell-free dry weight were calculated for each species. Differences between the three species in geographic distribution, tolerance to environmental perturbations, and frequency of congeneric associations seem to be related to differences in their life histories.

A Method for Measuring Growth in Living Barnacles (Crustacea: Cirripedia)

1993 ◽  
Vol 73 (3) ◽  
pp. 723-726 ◽  
Author(s):  
Marilyn S. Darling ◽  
Karl M. Wilbur
Keyword(s):  
Sea Water ◽  
Shell Growth ◽  
Dry Weight ◽  
Regression Equations ◽  
Balanus Amphitrite ◽  
Shell Weight ◽  
Buoyant Weight ◽  
Weight Method ◽  
Total Dry Weight ◽  
Non Destructive

A buoyant-weight method is described for the non-destructive estimation of fresh weight, total dry weight, shell weight and dry weight of organic matter in living barnacles Balanus amphitrite amphitrite Darwin. The method involves developing regression equations relating weight in air of these parameters to the buoyant weight of living barnacles in sea water. Buoyant weights of barnacles can then be used with the regression equations to obtain the weight in air of these consitituents, making possible the measurement of rates of shell growth and growth in dry weight without disturbance to the living animal. The method has been developed for the analysis of groups of juvenile barnacles cultured on coverslips, ranging in total dry weight from 1 to 60 mg, and for single mature individuals from 75 to 800 mg total dry weight. The buoyant-weight method has been used to measure shell growth of 2–3 mg d-1 in barnacles of 48 mg mean initial total dry weight cultured at 28°C.

scholarly journals Production of Larval Tanypodinae (Insecta: Chironomidae) in the Mud at Loch Leven, Kinross

1976 ◽  
Vol 75 (3) ◽  
pp. 157-169 ◽  
Author(s):  
W. Nigel Charles ◽  
Kenneth East ◽  
Thomas D. Murray
Keyword(s):  
Life Histories ◽  
Dry Weight ◽  
Common Species ◽  
Average Density ◽  
Life Cycles ◽  
Fourth Instar ◽  
Individual Species ◽  
Seasonal Patterns ◽  
Loch Leven ◽  
Two Generations

SynopsisLife histories and production of the five common species of Tanypodinae (Pentaneura monilis, Procladius simplicistilus, P. crassinervis, P. choreus and Psilotanypus rufovittatus) in the mud at Loch Leven were measured from March 1971 to March 1972. The methods used to identify each species of larva are described. All were univoltine except Pentaneura monilis which had two generations per year, but the seasonal patterns of the life cycles were different. The average density of third and fourth instar Tanypodinae was 3100/m2 and densities of individual species exceeded 2500/m2 for short periods in Procladius crassinervis and P. choreus. Net annual dry weight production by this subfamily was 2·6 g/m2(57 kJ/m2), with individual species ranging from 1·1 g/m2 (P. crassinervis) to 0·16 g/m2 (Pentaneura monilis). These results are discussed briefly and compared with production estimates for other zoobenthos.

scholarly journals Robustness of life histories to environmental variability in complex versus simple life cycles

2021 ◽  
Author(s):  
Annie Jonsson
Keyword(s):  
Growth Rate ◽  
Life Histories ◽  
Environmental Variability ◽  
Life Cycles ◽  
Relative Advantage ◽  
Complex Life Cycle ◽  
Life Stages ◽  
Vital Rates ◽  
Habitat Separation ◽  
Simple Life

AbstractMost animal species have a complex life cycle (CLC) with metamorphosis. It is thus of interest to examine possible benefits of such life histories. The prevailing view is that CLC represents an adaptation for genetic decoupling of juvenile and adult traits, thereby allowing life stages to respond independently to different selective forces. Here I propose an additional potential advantage of CLCs that is, decreased variance in population growth rate due to habitat separation of life stages. Habitat separation of pre- and post-metamorphic stages means that the stages will experience different regimes of environmental variability. This is in contrast to species with simple life cycles (SLC) whose life stages often occupy one and the same habitat. The correlation in the fluctuations of the vital rates of life stages is therefore likely to be weaker in complex than in simple life cycles. By a theoretical framework using an analytical approach, I have (1) derived the relative advantage, in terms of long-run growth rate, of CLC over SLC phenotypes for a broad spectrum of life histories, and (2) explored which life histories that benefit most by a CLC, that is avoid correlation in vital rates between life stages. The direction and magnitude of gain depended on life history type and fluctuating vital rate. One implication of our study is that species with CLCs should, on average, be more robust to increased environmental variability caused by global warming than species with SLCs.

Rice bran as a supplement to elephant grass for cattle and buffalo in Indonesia: 2. Carcass development, energy accretion and its effect on feed efficiency: 2. Carcass development, energy accretion and its effect on feed efficiency

1983 ◽  
Vol 100 (3) ◽  
pp. 717-722
Author(s):  
J. B. Moran
Keyword(s):  
Weight Gain ◽  
Rice Bran ◽  
Feed Efficiency ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Regression Equations ◽  
Elephant Grass ◽  
Live Weight Gain ◽  
Fat Depots ◽  
Gross Energy

SUMMARYIndonesian Ongole and swamp buffalo bulls that had previously been given 0, 1·2, 2·4, 3·6 or 4·8 kg/head/day rice bran plus ad libitum elephant grass were slaughtered after 161 days feeding. Abdominal depot fat, full and empty reticulo-rumen and cold carcass weights were recorded. Various carcass variables were measured and the 9–10–11 rib joints were dissected into bone, muscle and fat. Carcass gross energy was calculated from rib-fat content using previously determined regression equations. Feed efficiency was expressed in terms of the ratios of live-weight gain or carcass-energy accretion to metabolizable energy available for growth.Increasing supplementation with rice bran resulted in larger abdominal fat depots, higher dressing percentages, increased carcass fatness (and hence carcass gross energy) and improved rib muscle to bone ratios. Carcass conformation was unaffected by dietary treatment. When feed efficiency was expressed per unit live-weight gain, there was a decrease with increasing rice-bran feeding. Feed efficiency, expressed per unit of carcass energy accretion, improved with rice-bran supplementation and was generally higher in buffalo than in Ongole bulls. Dietary and species differences in feed efficiency could be primarily explained by the differential energy cost of deposition of, and the availability of energy from, carcass protein and lipid.

Growth, Development, and Morphological Differences among Native and Nonnative Prickly Nightshades (Solanum spp.) of the Southeastern United States

2012 ◽  
Vol 5 (3) ◽  
pp. 341-352 ◽  
Author(s):  
Charles T. Bryson ◽  
Krishna N. Reddy ◽  
John D. Byrd
Keyword(s):  
Dry Weight ◽  
Life Cycles ◽  
Natural Habitats ◽  
Solanum Torvum ◽  
Southeastern Us ◽  
Solanum Mammosum ◽  
Weedy Species ◽  
Growth Development ◽  
Average Plant ◽  
Morphological Differences

Prickly nightshades are troublesome weeds of natural habitats, pastures, feedlots, right-of-ways, and croplands. Native and nonnative invasive weedy species of prickly nightshades were compared to determine growth, development, and morphological differences. Six (Solanum bahamense, Solanum capsicoides, Solanum carolinense, Solanum dimidiatum, Solanum donianum, and Solanum pumilum) of the 18 species of prickly nightshades studied are native to the US. Two species, Solanum citrullifolium and Solanum rostratum, are annuals; the others are perennials or are short lived perennials or annuals in northern extremes of their range in North America. Tables were developed from new and existing data to differentiate vegetative and reproductive characteristics among 18 species of prickly nightshade found in the southeastern US. In greenhouse experiments, average plant height ranged from 24 and 26 cm (9.45 and 10.24 inch) for S. carolinense and Solanum jamaicense, respectively, to 100 and 105 cm for Solanum tampicense and Solanum sisymbriifolium, respectively at 10 wk after emergence (WAE). By 10 WAE, the average number of leaves per plant ranged from < 10 for S. carolinense and Solanum torvum to > 40 leaves/plant for S. rostratum and S. dimidiatum. Average number of nodes/plant main stem ranged from 11, 12, and 14 nodes in S. jamaicense, S. torvum, and S. carolinense, respectively, to 54 nodes in S. rostratum. Average plant dry weights were collected at 10 WAE and were greatest for Solanum mammosum and (> 17 g/plant) (0.6001 oz/plant) and least for S. carolinense (1 g/plant). Based on these data, nightshade growth rate and dry weight were variable among some species and variability may be a result of phenology and life cycles, annual or perennial. Plants of S. rostratum, an annual, were relatively tall and produced high number of nodes and leaves and had the shortest period from emergence to flower among the prickly nightshades evaluated.

scholarly journals Community structure, life histories and secondary production of stoneflies in two small mountain streams with different degree of forest cover

2015 ◽  
Author(s):  
Pavel Beracko ◽  
Andrea Kušnírová ◽  
Michaela Partlová ◽  
Jana Ciceková
Keyword(s):  
Community Structure ◽  
Secondary Production ◽  
Life Histories ◽  
Forest Cover ◽  
Adult Emergence ◽  
Life Cycles ◽  
Mountain Streams ◽  
Annual Life Cycle ◽  
Forested Stream ◽  
The Difference

<p>Our study examines community structure and nymphal biology (life cycles and secondary production) of stoneflies in two adjacent mountain streams with different degree of forest cover in the Prosiečanka River Basin (Chočské Vrchy Mts., West Carpathians). One of the streams has non-forested catchment, converted to meadows and pastures, while the other one has catchment with 60% covered by spruce forest. Differences in forest cover and in thermal regime of the streams were reflected by the difference of stonefly communities at their structural and functional level. Species <em>Nemoura cinerea and Leuctra aurita </em>created stonefly assemblage in non-forested stream, whereas <em>Nemoura cinerea</em> also occurred in naturally forested stream together with species <em>Leuctra armata, Leuctra nigra, Leuctra prima, Siphonoperla neglecta</em> and <em>Arcynopteryx dichroa</em>. All examined species had maximally annual life cycle and in eudominant species <em>Nemoura cinerea</em> one month shift was found in nymphal hatching and adult emergence between streams. Total secondary production of stoneflies in undisturbed stream (126.46 mg DW m<sup>-2</sup> y<sup>-1</sup>) was more than two times higher than the production in non-forested stream (47.39 mg DW m<sup>-2</sup> y<sup>-1</sup>). </p>

FAT THICKNESS MEASURED WITH THREE ULTRASONIC INSTRUMENTS ON LIVE RAM LAMBS AS PREDICTORS OF CUTABILITY

1980 ◽  
Vol 60 (4) ◽  
pp. 857-867 ◽  
Author(s):  
ANDRÉ FORTIN
Keyword(s):  
Multiple Regression ◽  
Live Weight ◽  
Optimal Location ◽  
Regression Equations ◽  
Longissimus Muscle ◽  
Fat Thickness ◽  
Ram Lambs

Fat thickness at four locations over the longissimus muscle was measured ultrasonically on 33 live ram lambs ranging in live weight from 16.0 to 37.0 kg. Simple and multiple regression equations were developed to assess the effectiveness of fat thickness as measured by three different ultrasonic instruments (Krautkrämer USM #2, Scanoprobe Model 731A and Scanogram Model 722) to predict cutability. Weight of trimmed or boneless cuts (shoulder + loin + rack + leg) was predicted with more precision than percentage of cuts. Fat thickness alone or combined with weight at scanning was of no significant value (P > 0.05) in the prediction of percentage of trimmed cuts. Percentage of boneless cuts was predicted more efficiently from weight at scanning alone than from fat thickness alone or combined with weight at scanning. Weight of cuts (trimmed or boneless) was also estimated from the fat measurement (P < 0.01), the weight at scanning (P < 0.01) or a combination of both variables. For the latter, fat thickness did not contribute significantly (P > 0.05). The optimal location of the fat measurement depended on the ultrasonic instrument used. Fat thickness measured with the Krautkrämer was more efficient in its prediction of cutability than fat thickness measured with the Scanoprobe or Scanogram. However, over the range of liveweights studied, the usefulness of fat thickness measured on live ram lambs to predict cutability is questionable.

Some biochemical and physiological aspects of growth and gametogenesis inCrassostrea gigasandOstrea edulisgrown at sustained elevated temperatures

1979 ◽  
Vol 59 (1) ◽  
pp. 95-110 ◽  
Author(s):  
Roger Mann
Keyword(s):  
Crassostrea Gigas ◽  
Elevated Temperatures ◽  
Excretion Rate ◽  
Ammonia Excretion ◽  
Live Weight ◽  
Gonadal Development ◽  
Ostrea Edulis ◽  
Shell Weight ◽  
Histological Assessment ◽  
Ammonia Excretion Rate

Crassostrea gigas (Thunberg) andOstrea edulis L.were grown at sustained temperatures of 12°, 15°, 18° and 21°C for a period of 19 weeks. Regular assays of weight specific ammonia excretion rate were made, following which animals were sacrificed for estimation of dry meat weight, dry shell weight, biochemical composition (percentage carbon, nitrogen, carbohydrate, ash) and gonadal development (histological assessment). Crassostrea gigas grew from an intial live weight of 5·2 g to values of 23·5, 28·2, 34·6 and 38·7 g at 120, 150, 180 and 21 °C respectively.

scholarly journals Shell Growth Pattern and Percentage Flesh Yield of the West African Clam, Galatea paradoxa (Born, 1778) from Itu Creek, Niger Delta Nigeria

2020 ◽  
Vol 27 (2) ◽  
pp. 119-126
Author(s):  
V.F. Akinjogunla ◽  
R.O. Moruf
Keyword(s):  
Growth Pattern ◽  
Niger Delta ◽  
Shell Growth ◽  
Correlation Coefficients ◽  
Live Weight ◽  
Maximum Height ◽  
Maximum Width ◽  
Shell Weight ◽  
The Mean ◽  
Galatea Paradoxa

Shell Morphometry is a fundamental tool for the evaluation of phenotypic stocks. The shell growth pattern and percentage flesh yield of Galatea paradoxa from Itu Creek in Niger Delta were investigated using standard morphometric methods. The mean in centimeter (cm) of 9.71±0.09, 35.02±0.22, 23.21±0.12, 37.11±0.25, 29.31±0.16 and 7.32±0.04 were recorded for shell length, maximum width, maximum height, nacre length, nacre width and hinge length respectively. Mean live weight of 115.70±1.09 g, mean flesh weight of 37.91 ± 0.23g and mean shell weight of 66.82±0.97 g were recorded for this species. Galatea paradoxa showed negative allometric growth (b < 3) while the correlation coefficients (r) in all the shell variables were far below „1‟, indicating a week correlation between the parameters. About 19% of the live weight of the clam is made up of flesh by weight. Keywords: Bivalve, Clam, Shell dimension, Niger Delta.

Hybridization in leopard frogs (Rana pipiens complex): terrestrial performance of newly metamorphosed hybrid and parental genotypes in field enclosures

2001 ◽  
Vol 79 (9) ◽  
pp. 1552-1558 ◽  
Author(s):  
Matthew J Parris
Keyword(s):  
Growth Rates ◽  
Life Histories ◽  
Parental Species ◽  
Natural Populations ◽  
Life Cycles ◽  
Natural Hybridization ◽  
Evolutionary Potential ◽  
Leopard Frogs ◽  
Rana Blairi ◽  
Advanced Generation

Terrestrial ecology has been largely neglected in the study of amphibian life histories because it is difficult to manipulate most species during the terrestrial stage. I examined the terrestrial performance of Rana blairi, Rana sphenocephala, and four hybrid (two F1 and two advanced generation) genotypes in replicated experimental enclosures to test for differences in traits related to juvenile terrestrial fitness. I produced all genotypes by means of artificial fertilizations using frogs collected from natural populations in central Missouri, and juvenile frogs were obtained from larvae reared in experimental ponds. Following metamorphosis, froglets were raised in single-genotype groups in terrestrial enclosures through the first overwintering. The proportion surviving did not vary among genotypes, but the power to detect significant differences was low. F1 hybrid genotypes BS and SB demonstrated significantly higher growth rates than either parental species or advanced-generation hybrid genotypes. Observation of growth rates of advanced-generation hybrids equal to those of the parental species, and heterosis in F1 hybrids for growth rate, suggests that natural hybridization between R. blairi and R. sphenocephala can produce novel and relatively fit hybrid genotypes. Direct measurement of multiple fitness components for hybrid and parental genotypes is critical for assessing the evolutionary potential of natural hybridization in organisms with complex life cycles.

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