An Evaluation of RNA–DNA Ratio as a Measure of Long-Term Growth in Fish Populations

1973 ◽  
Vol 30 (2) ◽  
pp. 195-199 ◽  
Author(s):  
Terry A. Haines
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Environmental Changes ◽  
Age Distribution ◽  
Smallmouth Bass ◽  
Fish Populations ◽  
Population Growth Rates

The value of RNA–DNA ratio as a measure of long-term growth of fish populations under semi-natural conditions and when subjected to environmental manipulations was determined. Populations of carp and smallmouth bass of known age distribution were established in artificial ponds maintained at two fertility levels. After 15 months, population growth rates (as percent increase in weight) and RNA–DNA ratios of muscle tissue from selected fish were measured. Each species exhibited a range of population growth rates. The relation between population growth rate and individual fish RNA–DNA ratio for each species was significant. When reproduction occurred, the relation was not significant unless young-of-the-year fish were excluded from population growth rate calculations. Age of fish was also found to have an important effect on RNA–DNA ratio, with the ratio being higher in younger fish.RNA–DNA ratio can be a reliable indicator of long-term population growth in fish when population age structure is known and recruitment is controlled. The method has potential for use in detecting response to environmental changes before growth rate changes become severe.

scholarly journals Why are population growth rate estimates of past and present hunter–gatherers so different?

2020 ◽  
Vol 376 (1816) ◽  
pp. 20190708 ◽  
Author(s):  
Miikka Tallavaara ◽  
Erlend Kirkeng Jørgensen
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Growth Rates ◽  
Human Population ◽  
Population Growth Rate ◽  
Theme Issue ◽  
Hunter Gatherers ◽  
Population Growth Rates ◽  
Ethnographic Data

Hunter–gatherer population growth rate estimates extracted from archaeological proxies and ethnographic data show remarkable differences, as archaeological estimates are orders of magnitude smaller than ethnographic and historical estimates. This could imply that prehistoric hunter–gatherers were demographically different from recent hunter–gatherers. However, we show that the resolution of archaeological human population proxies is not sufficiently high to detect actual population dynamics and growth rates that can be observed in the historical and ethnographic data. We argue that archaeological and ethnographic population growth rates measure different things; therefore, they are not directly comparable. While ethnographic growth rate estimates of hunter–gatherer populations are directly linked to underlying demographic parameters, archaeological estimates track changes in the long-term mean population size, which reflects changes in the environmental productivity that provide the ultimate constraint for forager population growth. We further argue that because of this constraining effect, hunter–gatherer populations cannot exhibit long-term growth independently of increasing environmental productivity. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.

DETRITUS AS A FACTOR INFLUENCING POPULATION GROWTH RATES OF THREE TENEBRIONID BEETLES IN STORED CORN

1989 ◽  
Vol 24 (4) ◽  
pp. 454-459 ◽  
Author(s):  
Richard T. Arbogast
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Tribolium Castaneum ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Prime Factor ◽  
Fine Dust ◽  
Stored Grain ◽  
Population Growth Rates ◽  
Insect Activity

Experiments showed that changes in population growth rate due to detritus produced by insect activity in stored grain varies with species and is a prime factor determining ecological succession of secondary grain pests. Cynaeus angustus (LeConte), Latheticus oryzae Waterhouse, and Tribolium castaneum (Herbst) were reared on a 1:1 mixture of whole and cracked corn. On this diet, T. castaneum showed the highest rate of population growth and L. oryzae the lowest. Population growth of T. castaneum and L. oryzae was stimulated by adding fine dust (collected from infested corn) or dead moths to the diet, and this effect was much greater in L. oryzae than in T. castaneum. Population growth of C. angustus (as indicated by number of adults) was not affected by supplementation of the diet, but larger larval populations were produced on supplemented corn. The results are related to previously reported observations of succession in stored corn.

scholarly journals Population growth rates: issues and an application

2002 ◽  
Vol 357 (1425) ◽  
pp. 1307-1319 ◽  
Author(s):  
H. Charles J. Godfray ◽  
Mark Rees
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Population Change ◽  
Evolutionarily Stable Strategy ◽  
Model Systems ◽  
Population Growth Rates

Current issues in population dynamics are discussed in the context of The Royal Society Discussion Meeting 'Population growth rate: determining factors and role in population regulation'. In particular, different views on the centrality of population growth rates to the study of population dynamics and the role of experiments and theory are explored. Major themes emerging include the role of modern statistical techniques in bringing together experimental and theoretical studies, the importance of long-term experimentation and the need for ecology to have model systems, and the value of population growth rate as a means of understanding and predicting population change. The last point is illustrated by the application of a recently introduced technique, integral projection modelling, to study the population growth rate of a monocarpic perennial plant, its elasticities to different life-history components and the evolution of an evolutionarily stable strategy size at flowering.

Maximum Likelihood Estimation of Population Growth Rates Based on the Coalescent

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 429-434 ◽  
Author(s):  
Mary K Kuhner ◽  
Jon Yamato ◽  
Joseph Felsenstein
Keyword(s):  
Growth Rate ◽  
Maximum Likelihood ◽  
Maximum Likelihood Estimation ◽  
Population Growth ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Likelihood Estimation ◽  
Effective Population ◽  
Population Growth Rates ◽  
Neutral Mutation Rate

Abstract We describe a method for co-estimating 4Neμ (four times the product of effective population size and neutral mutation rate) and population growth rate from sequence samples using Metropolis-Hastings sampling. Population growth (or decline) is assumed to be exponential. The estimates of growth rate are biased upwards, especially when 4Neμ is low; there is also a slight upwards bias in the estimate of 4Neμ itself due to correlation between the parameters. This bias cannot be attributed solely to Metropolis-Hastings sampling but appears to be an inherent property of the estimator and is expected to appear in any approach which estimates growth rate from genealogy structure. Sampling additional unlinked loci is much more effective in reducing the bias than increasing the number or length of sequences from the same locus.

scholarly journals Devil in the details: growth, productivity, and extinction risk of a data-sparse devil ray

2016 ◽  
Author(s):  
Sebastián A. Pardo ◽  
Holly K. Kindsvater ◽  
Elizabeth Cuevas-Zimbrón ◽  
Oscar Sosa-Nishizaki ◽  
Juan Carlos Pérez-Jiménez ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Extinction Risk ◽  
Somatic Growth ◽  
Small Scale ◽  
Fishing Mortality ◽  
Population Growth Rates ◽  
Size At Age

Devil rays (Mobulaspp.) face rapidly intensifying fishing pressure to meet the ongoing international trade and demand for their gill plates. This has been exacerbated by trade regulation of manta ray gill plates following their 2014 CITES listing. Furthermore, the paucity of information on growth, mortality, and fishing effort for devil rays make quantifying population growth rates and extinction risk challenging. Here, we use a published size-at-age dataset for a large-bodied devil ray species, the Spinetail Devil Ray (Mobula japanica), to estimate somatic growth rates, age at maturity, maximum age and natural and fishing mortality. From these estimates, we go on to calculate a plausible distribution of the maximum intrinsic population growth rate (rmax) and place the productivity of this large devil ray in context by comparing it to 95 other chondrichthyan species. We find evidence that larger devil rays have low somatic growth rate, low annual reproductive output, and low maximum population growth rates, suggesting they have low productivity. Devil ray maximum intrinsic population growth ratermaxis very similar to that of manta rays, indicating devil rays can potentially be driven to local extinction at low levels of fishing mortality. We show that fishing rates of a small-scale artisanal Mexican fishery were up to three times greater than the natural mortality rate, and twice as high as our estimate ofrmax, and therefore unsustainable. Our approach can be applied to assess the limits of fishing and extinction risk of any species with indeterminate growth, even with sparse size-at-age data.

Relationship between body size and population growth rate in two opportunistic polychaetes

2002 ◽  
Vol 82 (3) ◽  
pp. 403-408 ◽  
Author(s):  
D. Prevedelli ◽  
R. Simonini
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Sex Ratio ◽  
Population Growth ◽  
Growth Rates ◽  
Life Histories ◽  
Population Growth Rate ◽  
Population Growth Rates ◽  
The Relationship ◽  
Dinophilus Gyrociliatus

The relationship between body size and population growth rate λ has been studied in two species of opportunistic polychaetes, Dinophilus gyrociliatus and Ophryotrocha labronica, which colonize harbour environments. These species exhibit a semi-continuous iteroparous reproductive strategy, are phylogenetically closely-related but differ in body size and in some aspects of their sexuality. Ophryotrocha labronica is about 4 mm in body length, displays only slight sexual dimorphism and its sex ratio is biased towards the female sex in the ratio 2:1. Dinophilus gyrociliatus is about 1 mm in length, the males are extremely small and the sex ratio is strongly biased (3:1) in favour of the females. In spite of the considerable differences in all traits of their life histories and in many demographic parameters, the growth rates of the two populations are very similar. The analyses carried out have shown that the rapid attainment of sexual maturity of D. gyrociliatus gives it an advantage that offsets the greater fecundity of O. labronica. It is very likely that the reproductive peculiarities of D. gyrociliatus help to raise the population growth rates. The ‘saving’ on the male sex achieved both by the shift of the sex ratio in favour of the females and by the reduction in the males' body size would appear to enable D. gyrociliatus to grow at the same rate as O. labronica, a larger and more fecund species.

Estimating Population Growth Rate from an Age Distribution of Natural Deaths

1987 ◽  
Vol 51 (4) ◽  
pp. 941 ◽  
Author(s):  
John Van Sickle ◽  
C. A. M. Attwell ◽  
G. Colin Craig
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Population Growth Rate ◽  
Age Distribution

scholarly journals A POPULATION OF LYCHNOPHORA ERICOIDES MART. (ARNICA) (ASTERACEAE) IS PRONE TO EXTINCTION IN A SAVANNA OF CENTRAL BRAZIL

2017 ◽  
Vol 74 (3) ◽  
pp. 281-297 ◽  
Author(s):  
S. Ribeiro-Silva ◽  
M. B. Medeiros ◽  
V. V. F. Lima ◽  
A. B. Giroldo ◽  
S. E. de Noronha ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Plant Species ◽  
Population Growth Rate ◽  
Forest Products ◽  
Life Stages ◽  
Transition Matrices ◽  
Population Growth Rates ◽  
Central Brazil ◽  
Non Timber Forest Products

Lychnophora ericoides Mart. (Asteraceae), popularly known as arnica, is a plant species subjected to non-timber forest products extraction. Evidence is mounting that some local populations are on the brink of extinction. However, demographic studies of Lychnophora ericoides are rare. Therefore, as a step towards conservation, a remnant population of Lychnophora ericoides located in an area of the Cerrado (Brazilian Savanna) in Central Brazil was evaluated from 2010 through 2014. Disturbances such as wildfires and harvesting of Lychnophora ericoides were randomly distributed throughout the study period in this area. Four annual transition matrices (A1, A2, A3 and A4) were constructed, based on life stages. The main results of studies of population dynamics for this species are as follows: 1) population growth rates (λ) with 95% confidence intervals indicated a declining population in all periods from 2010 to 2014; 2) stochastic population growth rate considering the four matrices was < 1 with value λ = 0.358 and CI95% = (0.354–0.362); 3) survival with permanence at the same stage of reproductive adult individuals (46–80%) contributed most to population growth rate, based on elasticity analysis; 4) the population is much less likely to have increases in density, compared with reduction, for all intervals from 2010 to 2014, based on transient indices; 5) the low value of λ in the high-mortality year was caused by lower stasis of individuals in the seedling or sapling and juvenile life stages, as well as fecundity in the 2011–2012 and 2012–2013 intervals, as shown by a life table response experiment; and 6) 100% of the population will probably be extinct within 15 years. There is evidence that the main cause for local extinction of Lychnophora ericoides could be the effects of frequent wildfires. Based on these results, it is suggested that the time has come for significant conservation efforts to rescue this population, including monitoring, protection and education as the first steps towards protection of this vulnerable plant species.

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