Growth Rate Variation and Larval Survival: Inferences from an Individual-Based Size-Dependent Predation Model

We used an individual-based Monte Carlo simulation model to explore how changes in the mean and variance of growth rates of individuals in a larval fish cohort interact with size-dependent predation to affect the number and characteristics of individual survivors. Small changes in initial cohort mean growth rate can change survival over the first 60 d of life 10-to 30-fold. But when variance in growth rate among individuals is high, survival can be substantially higher than expected from the initial mean cohort growth rate. Selection for faster-growing individuals becomes stronger with increasing variance and increasing predation rate. In some cases, > 80% of the survivors may come from the upper 25% of the initial growth rate distribution, and the mean growth rate of the survivors may exceed twice the initial mean growth rate. When individual growth rates change from day to day rather than remaining constant, the contribution of atypical individuals is accentuated even further. Counterintuitively, most of the selection for faster-growing individuals happens only after the majority of mortality has already taken place. These results suggest that interactions between individual variability and selective mortality may have important cohort-level implications for survival in fishes.

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INDIVIDUAL VARIATION OF GROWTH AND FILTRATION RATES OF MUSSELS MYTILUS GALLOPROVINCIALIS LAM

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.31519/conferencearticle_5b1b93b7b86624.98126617 ◽

2017 ◽

Author(s):

Irina Kazankova ◽

Elena Vasechkina ◽

Elena Vasechkina

Keyword(s):

Growth Rate ◽

Individual Variation ◽

Coefficient Of Variation ◽

Individual Variability ◽

Individual Growth ◽

Rate Variation ◽

Sample Mean ◽

Metabolic Costs ◽

Individual Growth Rate ◽

The Mean

Research on individual variation of the filtration and growth rates of mussels was based both on the authors’ field and laboratory experiments and literature data analysis. High individual variability of these characteristics was recorded during the tests. The coefficient of variation grew up as the mean rate diminished. Under low specific growth rate the coefficient of variation (ratio of root-mean-square deviation to the sample mean) could exceed 100 %. Tests revealed the power-law relation of the coefficient of variation from the average for studied characteristics. That relation could be seen in filtration and growth rate charts; it was also true for estimates of production energy and metabolic costs. The exponent varied from -0.36 to -0.77. Individual growth rate variation of mussels was concluded to be an important criterion of the favorability of environmental conditions.

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INDIVIDUAL VARIATION OF GROWTH AND FILTRATION RATES OF MUSSELS MYTILUS GALLOPROVINCIALIS LAM

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.21610/conferencearticle_58b43172e2145 ◽

2017 ◽

Author(s):

Irina Kazankova ◽

Elena Vasechkina ◽

Elena Vasechkina

Keyword(s):

Growth Rate ◽

Individual Variation ◽

Coefficient Of Variation ◽

Individual Variability ◽

Individual Growth ◽

Rate Variation ◽

Sample Mean ◽

Metabolic Costs ◽

Individual Growth Rate ◽

The Mean

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Abstract 180: The Growth Rate of Early DWI Lesions is Highly Variable and Associated with Penumbral Salvage and Clinical Outcomes Following Endovascular Reperfusion

Stroke ◽

10.1161/str.44.suppl_1.a180 ◽

2013 ◽

Vol 44 (suppl_1) ◽

Author(s):

Hayley M Wheeler ◽

Michael Mlynash ◽

Manabu Inoue ◽

Aaryani Tipirneni ◽

John Liggins ◽

...

Keyword(s):

Growth Rate ◽

Acute Stroke ◽

Clinical Outcomes ◽

Endovascular Therapy ◽

Symptom Onset ◽

Growth Rates ◽

Initial Growth ◽

Stroke Patients ◽

Final Volume ◽

Favorable Clinical Response

Background: The degree of variability in the rate of early DWI expansion has not been well characterized. We hypothesized that Target Mismatch patients with slowly expanding DWI lesions have more penumbral salvage and better clinical outcomes following endovascular reperfusion than Target Mismatch patients with rapidly expanding DWI lesions. Methods: This substudy of DEFUSE 2 included all patients with a clearly established time of symptom onset. The initial DWI growth rate was determined from the baseline scan by assuming a volume 0 ml just prior to symptom onset. Target Mismatch patients who achieved reperfusion (>50% reduction in PWI after endovascular therapy), were categorized into tertiles according to their initial DWI growth rates. For each tertile, penumbral salvage (comparison of final volume to the volume of PWI (Tmax > 6 sec)/ DWI mismatch prior to endovascular therapy), favorable clinical response, and good functional outcome (see figure for definitions) were calculated. We also compared the growth rate in patients with the Target mismatch vs. Malignant Profile. Results: 64 patients were eligible for this study. Target mismatch patients (n=44) had initial growth rates (range 0 to 43 ml/hr, median of 3 ml/hr) that were significantly less than the growth rates in Malignant profile (n=7) patients (12 to 92 ml/hr, median 39 ml/hr; p < 0.001). In Target mismatch patients who achieved reperfusion (n=30), slower early DWI growth rates were associated with better clinical outcomes (p<0.05) and a trend toward more penumbral salvage (n=27, p=0.137). Conclusions: The growth rate of early DWI lesions in acute stroke patients is highly variable; Malignant profile patients have higher growth rates than other MRI profiles. Among Target Mismatch patients, a slower rate of DWI growth is associated with a greater degree of penumbral salvage and improved clinical outcomes following endovascular reperfusion.

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Ultrasound Surveillance of Ectatic Abdominal Aortas

Annals of The Royal College of Surgeons of England ◽

10.1308/003588408x301064 ◽

2008 ◽

Vol 90 (6) ◽

pp. 477-482 ◽

Cited By ~ 24

Author(s):

S Devaraj ◽

SR Dodds

Keyword(s):

Growth Rate ◽

Growth Rates ◽

Screening Programme ◽

T Test ◽

Aortic Aneurysms ◽

Aortic Diameter ◽

Ultrasound Screening ◽

The Mean ◽

Clinically Significant

INTRODUCTION Some studies have considered abdominal aortas of 2.6–2.9 cm diameter (ectatic aortas) at age 65 years as being abnormal and have recommended surveillance, whereas others have considered these normal and surveillance unnecessary. It is, therefore, not clear how to manage patients with an initial aortic diameter between 2.6–2.9 cm detected at screening. The aim of this study was to evaluate growth rates of ectatic aortas detected on initial ultrasound screening to determine if any developed into clinically significant abdominal aortic aneurysms (AAAs; > 5.0 cm) and clarify the appropriate surveillance intervals for these patients. PATIENTS AND METHODS Data were obtained from a prospective AAA screening programme which commenced in 1992. The group of patients with initial aortic diameters of 2.6–2.9 cm with a minimum of 1-year follow-up were included in this study (Group 2). This was further divided into two subgroups (Groups 3a and 3b) based on a minimum follow-up interval obtained from outcome analysis. Mean growth rate was calculated as change in aortic diameter with time. The comparison of growth rates in Groups 3a and 3b was performed using the t-test. The number and proportion of AAAs that expanded to ≥ 3.0 cm and ≥ 5.0 cm in diameter were also calculated. RESULTS Out of 999 patients with AAA ≥ 2.6 cm with minimum 1-year follow-up, 358 (36%) were classified as ectatic aortas (2.6–2.9 cm) at initial ultrasound screening with the mean growth rate of 1.69 mm/year (95% CI, 1.56–1.82 mm/year) with a mean follow-up of 5.4 years. Of these 358 ectatic aortas, 314 (88%) expanded into ≥ 3.0 cm, 45 (13%) expanded to ≥ 5.0 cm and only 8 (2%) expanded to ≥ 5.5 cm over a mean follow-up of 5.4 years (range, 1–14 years). No ectatic aortas expanded to ≥ 5.0 cm within the first 4 years of surveillance. Therefore, the minimum follow-up interval was set at 4 years and this threshold was then used for further analysis. The mean growth rate in Group 3a (< 5.0 cm at last scan) was 1.33 mm/year (95% CI, 1.23–1.44 mm/year) with a mean follow-up of 7 years compared to Group 3b (≥ 5.0 cm at last scan) with the mean growth rate of 3.33 mm/year (95% CI 3.05–3.61 mm/year) and a mean follow-up of 8 years. The comparison of mean growth rates between Groups 3a and 3b is statistically significant (t-test; T = 13.00; P < 0.001). CONCLUSIONS One-third of patients undergoing AAA screening will have ectatic aortas (2.6–2.9 cm) and at least 13% of these will expand to a size of ≥ 5.0 cm over a follow-up of 4–14 years. A threshold diameter of 2.6 cm for defining AAAs in a screening programme is recommended and ectatic aortas detected at age 65 years can be re-screened at 4 years after the initial scan. A statistically significant difference was found in the growth rates of ectatic aortas with minimum 4 years follow-up, expanding to ≥ 5.0 cm compared to those less than 5.0 cm at last surveillance scan. Further studies are required to test the hypothesis of whether growth rate over the first 4 years of surveillance will identify those who are most likely to expand to a clinically significant size (> 5.0 cm).

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Patterns of metamorphic age and length in marine fishes, from individuals to taxa

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f00-019 ◽

2000 ◽

Vol 57 (4) ◽

pp. 856-869 ◽

Cited By ~ 23

Author(s):

Hugues P Benoît ◽

Pierre Pepin ◽

Joseph A Brown

Keyword(s):

Growth Rate ◽

Population Level ◽

Individual Variability ◽

Marine Fishes ◽

Exponential Relationship ◽

Factors Affecting ◽

The Mean ◽

Time Required ◽

Increasing Temperature ◽

Dominant Influence

We present a summary of variability in age and length at metamorphosis for marine fishes. Data from the literature were partitioned into taxonomic, population, and individual levels of resolution to examine the factors affecting the timing of metamorphosis. Temperature appears to be a dominant influence on timing, likely due to its effect on growth rate. Interspecifically, length at metamorphosis correlated poorly with that at hatching but was significantly related to temperature. This pattern was inconsistent for population-level comparisons. Metamorphic age decreased exponentially with increasing temperature in interspecific and population-level comparisons but did not covary with length for either level of resolution. This suggests that age at metamorphosis largely reflects the time required to grow to a given metamorphic length. Within populations, the correlation between metamorphic age and length increases with growth rate, a reflection of variance in age and length. A strong exponential relationship between mean metamorphic age and length and their associated variability (SD) exists, with a slope greater than unity in both cases (i.e., variability increases relative to the mean). With these relationships, we can infer the manner in which individual variability in metamorphic traits is generated throughout ontogeny. These results are considered in light of recruitment variability in marine fishes.

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Individual growth pattern and variability in Serranus scriba: a Bayesian analysis

ICES Journal of Marine Science ◽

10.1093/icesjms/fsp265 ◽

2009 ◽

Vol 67 (3) ◽

pp. 502-512 ◽

Cited By ~ 26

Author(s):

Josep Alós ◽

Miquel Palmer ◽

Salvador Balle ◽

Antoni Maria Grau ◽

Beatriz Morales-Nin

Keyword(s):

Growth Rate ◽

Bayesian Analysis ◽

Growth Pattern ◽

Growth Curves ◽

Individual Variability ◽

Growth Patterns ◽

Individual Growth ◽

Individual Level ◽

Population Dynamics Models ◽

Dynamics Models

Abstract Alós, J., Palmer, M., Balle, S., Grau, A. M., and Morales-Nin, B. 2010. Individual growth pattern and variability in Serranus scriba: a Bayesian analysis. – ICES Journal of Marine Science, 67: 502–512. Variability in growth patterns at an individual level in Serranus scriba is described using a Bayesian approach for a generalized von Bertalanffy growth model that accommodates one change in growth rate at a specific point during the lifespan. The approach enables individual growth curves to be inferred, even in a species with a relatively short lifespan and no commercial value, i.e. limited sample sizes available, but potentially endangered by recreational fishing. The change in growth rate may be the result of differing allocation of energy between reproductive and somatic activities at different ages. Overall, the approach presented provides adequate input for future implementation of population dynamics models that take into account individual variability, e.g. individual-based models, even for species for which limited data are available.

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Selection for plasmid post–segregational killing depends on multiple infection: evidence for the selection of more virulent parasites through parasite–level competition

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2004.2921 ◽

2005 ◽

Vol 272 (1561) ◽

pp. 403-410 ◽

Cited By ~ 26

Author(s):

T. F. Cooper ◽

J. A. Heinemann

Keyword(s):

Growth Rate ◽

Growth Rates ◽

Multiple Infection ◽

Virulence Determinant ◽

New Hosts ◽

Parasite Reproduction ◽

Selection For ◽

The Cost ◽

Selection Of

Is the virulence of parasites an outcome of optimized infection? Virulence has often been considered an inevitable consequence of parasite reproduction when the cost incurred by the parasite in reducing the fitness of its current host is offset by increased infection of new hosts. More recent models have focused on how competition occurring between parasites during co–infection might effect selection of virulence. For example, if co–infection was common, parasites with higher intrinsic growth rates might be selected, even at the expense of being optimally adapted to infect new hosts. If growth rate is positively correlated with virulence, then competition would select increased virulence. We tested these models using a plasmid–encoded virulence determinant. The virulence determinant did not contribute to the plasmid's reproduction within or between hosts. Despite this, virulent plasmids were more successful than avirulent derivatives during selection in an environment allowing within–host competition. To explain these findings we propose and test a model in which virulent parasites are selected by reducing the reproduction of competitors.

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Incubation temperature and clutch effects on initial body sizes and growth rates in green iguana hatchlings (Iguana iguana)

Animal Biology ◽

10.1163/15707563-00002535 ◽

2017 ◽

Vol 67 (3-4) ◽

pp. 239-249 ◽

Cited By ~ 2

Author(s):

Yuleimis T. Martínez-Caballero ◽

Brian C. Bock ◽

Isabel Pérez ◽

Ángela M. Ortega-León ◽

Vivian P. Páez

Keyword(s):

Growth Rate ◽

Body Size ◽

Growth Rates ◽

Egg Size ◽

Incubation Temperature ◽

Size Variation ◽

Early Growth ◽

Rate Variation ◽

Body Sizes ◽

Green Iguanas

Large initial body size and rapid early growth rate are important in many species, both because predation rates decline as individuals grow and because females that attain a larger adult body size are more fecund. To identify possible factors contributing to size and growth rate variation in hatchling green iguanas, we artificially incubated six clutches at three constant temperatures to test for effects of incubation temperature and/or clutch effects on initial size and growth rate. Higher incubation temperatures resulted in significantly shorter incubation periods but did not influence initial body size. There were significant differences among clutches in egg size, and also in initial hatchling body size, even after correcting for differences in egg size among clutches. A subset of hatchlings from each nest was reared in semi-natural conditions for four months, with individuals from the high incubation temperature condition exhibiting the slowest longer-term growth rates. No clutch effects were detected in the growth rate analyses. The observed variation in early growth rate of juvenile iguanas seems to be selectively important and this variation may be due in part to the conditions the eggs experience during incubation, but clutch effects in this study were limited to egg size and initial hatchling body size variation, but were not found for subsequent growth rates.

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Estimation of Recent Growth of Field-Caught Postlarval American Lobsters, Homarus americanus, from RNA:DNA Ratios

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f94-030 ◽

1994 ◽

Vol 51 (2) ◽

pp. 286-294 ◽

Cited By ~ 23

Author(s):

Marie Antonette R. Juinio ◽

J. Stanley Cobb

Keyword(s):

Growth Rates ◽

Food Limitation ◽

Homarus Americanus ◽

Zooplankton Biomass ◽

Individual Growth ◽

Prolonged Duration ◽

The Mean ◽

Temperature And Growth ◽

Relationship Of ◽

The Relationship

We developed a growth model for the postlarvae of the American lobster, Homarus americanus, using the relationship of RNA:DNA ratios, temperature, and growth rates during postmolt through early pre-molt of laboratory-reared postlarval lobsters. The model was used to estimate individual growth rates of 385 postlarval lobsters in molt stages C and D0, collected at two sites in Block Island Sound over three years, 1988–90. The mean growth rates of postlarvae collected in June 1989 and 1990 (0.57 ± 0.19 and 0.54 ± 0.18 mg protein∙d−1) were significantly higher than those collected in July (0.39 ± 0.17 and 0.43 ± 0.18 mg protein∙d−1). Changes in sea surface temperatures of zooplankton biomass did not account for the seasonal difference in growth rates, nor was there correlation between the biweekly mean growth rates and postlarval densities. The incidence of poorly nourished postlarval lobsters (individuals with growth rates < 0.22 mg protein∙d−1) was less than 10% of the total samples in each year. We found no evidence that food limitation, resulting in starvation or prolonged duration of the postlarval instar, was a significant factor contributing to the observed interannual variability of postlarval densities.

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Estimating larval fish growth under size-dependent mortality: a numerical analysis of bias

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f07-031 ◽

2007 ◽

Vol 64 (3) ◽

pp. 554-562 ◽

Cited By ~ 9

Author(s):

Tian Tian ◽

Øyvind Fiksen ◽

Arild Folkvord

Keyword(s):

Growth Rate ◽

Longitudinal Data ◽

Growth Rates ◽

Mortality Rates ◽

Growth Patterns ◽

Cross Sectional ◽

Larval Phase ◽

Size Dependent ◽

Recruitment Success ◽

Dependent Mortality

The early larval phase is characterized by high growth and mortality rates. Estimates of growth from both population (cross-sectional) and individual (longitudinal) data may be biased when mortality is size-dependent. Here, we use a simple individual-based model to assess the range of bias in estimates of growth under various size-dependent patterns of growth and mortality rates. A series of simulations indicate that size distribution of individuals in the population may contribute significantly to bias in growth estimates, but that typical size-dependent growth patterns have minor effects. Growth rate estimates from longitudinal data (otolith readings) are closer to true values than estimates from cross-sectional data (population growth rates). The latter may produce bias in growth estimation of about 0.03 day–1 (in instantaneous, specific growth rate) or >40% difference in some situations. Four potential patterns of size-dependent mortality are tested and analyzed for their impact on growth estimates. The bias is shown to yield large differences in estimated cohort survival rates. High autocorrelation and variance in growth rates tend to increase growth estimates and bias, as well as recruitment success. We also found that autocorrelated growth patterns, reflecting environmental variance structure, had strong impact on recruitment success of a cohort.

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