scholarly journals The effect of life stages on needs satisfied by credit used, according to Alderfer’s existence relatedness growth theory

2016 ◽  
Vol 6 (4) ◽  
pp. 324-333
Author(s):  
A. Botha ◽  
J.M.P. Venter
Keyword(s):  
Family Life ◽  
Early Life ◽  
Life Stage ◽  
Early Life Stage ◽  
Growth Theory ◽  
Life Stages ◽  
Early Life Stages ◽  
Product Usage ◽  
The Past ◽  
Educational Programmes

The increase in household debt in South Africa over the past decade illustrates the importance of analysing credit usage. This study investigated the individual’s financial needs satisfied when using credit and the effect of life stage on the needs satisfied. The financial needs satisfied when using credit were analysed according to life stages using Alderfer’s existence relatedness growth (ERG) theory as a framework. The results indicated that credit usage is influenced by an individual’s life stage. This study found that individuals across all life stages mainly use credit to satisfy their existence needs. Although individuals in their single life stages used less credit products than individuals in their family life stages, it was worrisome to ascertain that mature couples had the highest average credit product usage. The findings suggest that individuals fall into the debt trap in their early life stage, resulting in them being unable to save income in the high-income-producing years in order to be able to dissave after retirement. It is suggested that educational programmes targeting the early life stages should be introduced to prevent individuals from becoming overindebted.

Lethality of Low pH and Al to Early Life Stages of Six Fish Species Inhabiting PreCambrian Shield Waters in Ontario

1989 ◽  
Vol 46 (7) ◽  
pp. 1188-1202 ◽  
Author(s):  
K. E. Holtze ◽  
N. J. Hutchinson
Keyword(s):  
Largemouth Bass ◽  
Early Life ◽  
Life Stage ◽  
Early Life Stage ◽  
Low Ph ◽  
Smallmouth Bass ◽  
Life Stages ◽  
White Sucker ◽  
Lake Whitefish ◽  
Early Life Stages

Lethality of low pH and Al to egg and fry stages of common shiner (Notropis cornutus), white sucker (Catostomus commersoni), walleye (Stizostedion vitreum), lake whitefish (Coregonus clupeaformis), smallmouth bass (Micropterus dolomieui), and largemouth bass (M. salmoides) was determined in a series of laboratory tests in soft (Ca = 4.0 mg/L) water. Low pH was lethal to cleavage eggs in the first 4 d of exposure, to eyed eggs in the immediate prehatch period and to fry following their transition to branchial respiration. Early life stage response to Al was determined by their sensitivity to low pH. Al prolonged survival of cleavage eggs at pH = 4.2, was detrimental to eyed eggs and fry at pH 4.4–5.4 and was most lethal within 0.3 pH units of the pH which was lethal in the absence of Al. In situ distribution of four of the six species was adequately explained by lethality of low pH alone to cleavage eggs or fry. Sensitivity to low pH and Al produced estimates of pH > 5.9 (common shiner), pH > 5.4 (lake whitefish, white sucker, walleye), and pH > 5.1 (smallmouth and largemouth bass) for survival of early life stages in acidified waters.

scholarly journals Differences among families in craniofacial shape at early life-stages of Arctic charr (Salvelinus alpinus)

2020 ◽  
Author(s):  
Samantha Victoria Beck ◽  
Katja Räsänen ◽  
Camille A. Leblanc ◽  
Skúli Skúlason ◽  
Zophonías O. Jónsson ◽  
...  
Keyword(s):  
Early Life ◽  
Egg Size ◽  
Developmental Stages ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Life Stage ◽  
Early Life Stage ◽  
Offspring Size ◽  
Life Stages ◽  
Early Life Stages

Abstract Background Organismal fitness can be determined at early life-stages, but phenotypic variation at early life-stages is rarely considered in studies on evolutionary diversification. The trophic apparatus has been shown to contribute to sympatric resource-mediated divergence in several taxa. However, processes underlying diversification in trophic traits are poorly understood. Using phenotypically variable Icelandic Arctic charr (Salvelinus alpinus), we reared offspring from multiple families under standardized laboratory conditions and tested to what extent family (i.e. direct genetic and maternal effects) contributes to offspring morphology at hatching (H) and first feeding (FF). To understand the underlying mechanisms behind early life-stage variation in morphology, we examined how craniofacial shape varied according to family, offspring size, egg size and candidate gene expression. Results Craniofacial shape (i.e. the Meckel’s cartilage and hyoid arch) was more variable between families than within families both across and within developmental stages. Differences in craniofacial morphology between developmental stages correlated with offspring size, whilst within developmental stages only shape at FF correlated with offspring size, as well as female mean egg size. Larger offspring and offspring from females with larger eggs consistently had a wider hyoid arch and contracted Meckel’s cartilage in comparison to smaller offspring.Conclusions This study provides evidence for family-level variation in early life-stage trophic morphology, indicating the potential for parental effects to facilitate resource polymorphism.

scholarly journals Differences among families in craniofacial shape at early life-stages of Arctic charr (Salvelinus alpinus)

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Samantha V. Beck ◽  
Katja Räsänen ◽  
Camille A. Leblanc ◽  
Skúli Skúlason ◽  
Zophonías O. Jónsson ◽  
...  
Keyword(s):  
Early Life ◽  
Egg Size ◽  
Developmental Stages ◽  
Salvelinus Alpinus ◽  
Arctic Charr ◽  
Life Stage ◽  
Early Life Stage ◽  
Offspring Size ◽  
Life Stages ◽  
Early Life Stages

Abstract Background Organismal fitness can be determined at early life-stages, but phenotypic variation at early life-stages is rarely considered in studies on evolutionary diversification. The trophic apparatus has been shown to contribute to sympatric resource-mediated divergence in several taxa. However, processes underlying diversification in trophic traits are poorly understood. Using phenotypically variable Icelandic Arctic charr (Salvelinus alpinus), we reared offspring from multiple families under standardized laboratory conditions and tested to what extent family (i.e. direct genetic and maternal effects) contributes to offspring morphology at hatching (H) and first feeding (FF). To understand the underlying mechanisms behind early life-stage variation in morphology, we examined how craniofacial shape varied according to family, offspring size, egg size and candidate gene expression. Results Craniofacial shape (i.e. the Meckel’s cartilage and hyoid arch) was more variable between families than within families both across and within developmental stages. Differences in craniofacial morphology between developmental stages correlated with offspring size, whilst within developmental stages only shape at FF correlated with offspring size, as well as female mean egg size. Larger offspring and offspring from females with larger eggs consistently had a wider hyoid arch and contracted Meckel’s cartilage in comparison to smaller offspring. Conclusions This study provides evidence for family-level variation in early life-stage trophic morphology, indicating the potential for parental effects to facilitate resource polymorphism.

Toxicity of TFM (Lampricide) to Six Early Life Stages of Rainbow Trout (Salmo gairdneri)

1973 ◽  
Vol 30 (8) ◽  
pp. 1047-1052 ◽  
Author(s):  
L. E. Olson ◽  
L. L. Marking
Keyword(s):  
Rainbow Trout ◽  
Early Life ◽  
Natural Waters ◽  
Life Stage ◽  
Water Hardness ◽  
Salmo Gairdneri ◽  
Life Stages ◽  
Early Life Stages ◽  
Margin Of Safety ◽  
Coexisting Species

The lampricide TFM (3-trifluoromethyl-4-nitrophenol) was tested against the following life stages of rainbow trout (Salmo gairdneri): green eggs, eyed eggs, sac fry, swim-up fry, fry, and fingerlings in four water hardnesses (12, 44, 170, and 320 mg/liter as CaCO3). The eyed-egg stage was one of the most resistant stages tested, and the sac-fry stage was one of the least resistant. Increased water hardness decreases toxicity to all stages. The LC50’s range from 0.532 mg/liter to 40.0 mg/liter depending upon life stage, water hardness, and duration of exposure. The margin of safety for coexisting species exposed to TFM ranges from 3.2 to 4.1 in natural waters. The margin of safety for early life stages of rainbow trout and larval lamprey under controlled laboratory conditions ranges from 4.2 to 12.2. Therefore, all six early life stages of rainbow trout are safe in minimum lampricidal concentrations of TFM.

scholarly journals Cross-Life Stage Effects of Aquatic Larval Density and Terrestrial Moisture on Growth and Corticosterone in the Spotted Salamander

Diversity ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 68 ◽  
Author(s):  
Julie Charbonnier ◽  
Jacquelyn Pearlmutter ◽  
James Vonesh ◽  
Caitlin Gabor ◽  
Zachery Forsburg ◽  
...  
Keyword(s):  
Early Life ◽  
Specific Growth ◽  
Life Stage ◽  
Larval Density ◽  
Life Cycles ◽  
Life Stages ◽  
Early Life Stages ◽  
Release Rates ◽  
Specific Growth Rates ◽  
Corticosterone Release

For organisms with complex life cycles, conditions experienced during early life stages may constrain later growth and survival. Conversely, compensatory mechanisms may attenuate negative effects from early life stages. We used the spotted salamander, Ambystoma maculatum, to test how aquatic larval density and terrestrial moisture influence juvenile growth, food intake, evaporative water loss and water reuptake rates, and corticosterone levels. We conducted an outdoor mesocosm experiment to manipulate larval density and transferred metamorphosed salamanders into low and high terrestrial moisture treatments in laboratory terrariums. After the larval stage, high-density salamanders were significantly smaller and had higher corticosterone release rates than those from low-density treatments. Salamanders in the low terrestrial moisture treatment consumed fewer roaches, had lower mass-specific growth rates, higher water reuptake, and higher corticosterone release rates than salamanders in high terrestrial moisture treatments. Across moisture treatments, smaller salamanders had higher mass-specific growth rates than larger salamanders. Our results suggest that salamanders can partially compensate for competition in the larval aquatic habitat with increased growth as juveniles, but this response is dependent on terrestrial habitat quality. Thus, the persistence of early life stage effects can be an important, yet context-dependent, component of amphibian life cycles.

scholarly journals Meta-analysis reveals taxon- and life stage-dependent effects of ocean acidification on marine calcifier feeding performance

2016 ◽  
Author(s):  
Jeff C. Clements
Keyword(s):  
Ocean Acidification ◽  
Early Life ◽  
Meta Analysis ◽  
Life Stage ◽  
Early Life Stage ◽  
Effect Sizes ◽  
Larval Feeding ◽  
Ecosystem Structure ◽  
Early Life Stages ◽  
Feeding Performance

AbstractWhile ocean acidification is considered among the greatest threats to marine ecosystems, its effects on the feeding performance of marine calcifiers remain uncertain. I conducted a meta-analysis of effect sizes (LnRR) assessing the impacts of acidification on the feeding ability of three groups of marine calcifiers - molluscs, arthropods, and echinoderms. Results suggested taxon-dependent effects of acidification on calcifier feeding performance, with depressed feeding observed for molluscs, echinoderms, and when all taxa were considered. However, ocean acidification had no effect on feeding performance in marine arthropods and larval feeding performance appeared more vulnerable than that of juveniles and adults. Feeding performance was not related to acclimation time nor pCO2 level. This study suggests that the feeding performance of molluscs and early life-stage echinoderms may be depressed in a more acidic ocean, but that arthropod feeding performance is unlikely to suffer. Such changes in feeding performance could contribute to slower growth and development in the early life stages of these organisms and could potentially contribute to changes in community and ecosystem structure where these organisms coexist. Finally, feeding performance could, at least in part, moderate the degree to which molluscs and echinoderms can use food to overcome acidification effects early in life.

scholarly journals Stable Isotope Analysis of Juvenile White Sharks Inside a Nursery Area Reveals Foraging in Demersal-Inshore Habitats and Trophic Overlap With Sympatric Sharks

2021 ◽  
Vol 8 ◽  
Author(s):  
Emiliano García-Rodríguez ◽  
Sharon Z. Herzka ◽  
Oscar Sosa-Nishizaki ◽  
Christopher G. Lowe ◽  
John B. O’Sullivan
Keyword(s):  
Stable Isotope ◽  
Early Life ◽  
Trophic Ecology ◽  
Trophic Position ◽  
Life Stage ◽  
Isotope Ratios ◽  
Nursery Area ◽  
Isotopic Niche ◽  
Life Stages ◽  
Early Life Stages

Knowledge about top predators’ trophic ecology is crucial for defining their role in ecosystems, understanding habitat preferences, characterizing life stage-specific feeding habits, and evaluating their interaction with fisheries. In the northeastern Pacific, white sharks (Carcharodon carcharias) occupy coastal habitats during the early life stages, including Bahía Sebastián Vizcaíno (BSV) in Mexico, which is a known nursery area. Although BSV presumably provides high prey abundance, the trophic ecology of immature white sharks is poorly understood. Carbon and nitrogen bulk stable isotope analyses (SIA) were used to explore the trophic relationship of early life stages with their potential prey and to infer dietary overlap with sympatric sharks, while SIA of amino acids were used to estimate trophic position. Muscle samples from young white sharks and inshore demersal prey commonly found in their stomach contents were sampled. Demersal prey and literature-derived isotope ratios for pelagic and offshore species were incorporated into mixing models with a Bayesian framework to estimate their contribution to white shark tissues. Nearshore demersal prey had the highest contribution for all life stages (between 35 and 47%), consistent with previous reports based on gut content analysis. The contribution of pelagic (between 26 and 37%) and offshore (between 14 and 32%) prey was smaller and suggests potential periodic changes in foraging grounds and the presence of a maternal-derived isotopic signature. A high contribution of demersal prey indicates a high level of interaction with local fisheries that target those species and catch white sharks incidentally and is consistent with immature shark movement patterns. Isotope ratios of two sympatric sharks, smooth hammerhead Sphyrna zygaena and copper sharks Carcharhinus brachyurus, were used to estimate the overlap in isotopic niche space. Immature white sharks had the smallest isotopic niche, while the highest was for copper sharks. Overlap was greatest between white sharks and hammerheads (∼45%), while overlap with copper sharks was limited (<20%), suggesting less potential for competition. Trophic position estimates were similar to those previously reported for the species. These results highlight the importance of coastal demersal prey heavily targeted by local fisheries for the diet of young white sharks and support the importance of BSV as a nursery habitat.

scholarly journals Optimal reproductive phenology under size-dependent cannibalism

2019 ◽  
Author(s):  
Nao Takashina ◽  
Øyvind Fiksen
Keyword(s):  
Environmental Conditions ◽  
Early Life ◽  
Life Stage ◽  
Larval Growth ◽  
Reproductive Phenology ◽  
Life Stages ◽  
Breeding Phenology ◽  
Early Life Stages ◽  
Size Dependent ◽  
Game Theoretic

AbstractIntra-cohort cannibalism is an example of a size-mediated priority effect. If early life stages cannibalize slightly smaller individuals, then parents face a trade-off between breeding at the best time for larval growth or development and predation risk from offspring born earlier. This game-theoretic situation among parents may drive adaptive reproductive phenology towards earlier breeding. However, it is not straightforward to quantify how cannibalism affects seasonal egg fitness or to distinguish emergent breeding phenology from alternative adaptive drivers. Here, we devise an age-structured game-theoretic mathematical model to find evolutionary stable breeding phenologies. We predict how size-dependent cannibalism acting on eggs, larvae, or both change emergent breeding phenology, and find that breeding under inter-cohort cannibalism occurs earlier than the optimal match to environmental conditions. We show that emergent breeding phenology patterns at the level of the population are sensitive to the ontogeny of cannibalism, i.e. which life stage is subject to cannibalism. This suggests that the nature of cannibalism among early life stages is a potential driver of the diversity of reproductive phenologies seen across taxa, and may be a contributing factor in situations where breeding occurs earlier than expected from environmental conditions.

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