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.

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.

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.

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.

scholarly journals Trophic interactions and population growth rates: describing patterns and identifying mechanisms

2002 ◽  
Vol 357 (1425) ◽  
pp. 1259-1271 ◽  
Author(s):  
Peter J. Hudson ◽  
Andy P. Dobson ◽  
Isabella M. Cattadori ◽  
David Newborn ◽  
Dan T. Haydon ◽  
...  
Keyword(s):  
Growth Rate ◽  
Time Series ◽  
Population Dynamics ◽  
Population Growth ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Empirical Studies ◽  
Population Level ◽  
Model Framework ◽  
Negative Growth

While the concept of population growth rate has been of central importance in the development of the theory of population dynamics, few empirical studies consider the intrinsic growth rate in detail, let alone how it may vary within and between populations of the same species. In an attempt to link theory with data we take two approaches. First, we address the question 'what growth rate patterns does theory predict we should see in time–series?' The models make a number of predictions, which in general are supported by a comparative study between time–series of harvesting data from 352 red grouse populations. Variations in growth rate between grouse populations were associated with factors that reflected the quality and availability of the main food plant of the grouse. However, while these results support predictions from theory, they provide no clear insight into the mechanisms influencing reductions in population growth rate and regulation. In the second part of the paper, we consider the results of experiments, first at the individual level and then at the population level, to identify the important mechanisms influencing changes in individual productivity and population growth rate. The parasitic nematode Trichostrongylus tenuis is found to have an important influence on productivity, and when incorporated into models with their patterns of distribution between individuals has a destabilizing effect and generates negative growth rates. The hypothesis that negative growth rates at the population level were caused by parasites was demonstrated by a replicated population level experiment. With a sound and tested model framework we then explore the interaction with other natural enemies and show that in general they tend to stabilize variations in growth rate. Interestingly, the models show selective predators that remove heavily infected individuals can release the grouse from parasite–induced regulation and allow equilibrium populations to rise. By contrast, a tick–borne virus that killed chicks simply leads to a reduction in the equilibrium. When humans take grouse they do not appear to stabilize populations and this may be because many of the infective stages are available for infection before harvesting commences. In our opinion, an understanding of growth rates and population dynamics is best achieved through a mechanistic approach that includes a sound experimental approach with the development of models. Models can be tested further to explore how the community of predators and others interact with their prey.

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’.

Effects of harvest and climate on population dynamics of northern bobwhites in south Florida

2011 ◽  
Vol 38 (5) ◽  
pp. 396 ◽  
Author(s):  
Virginie Rolland ◽  
Jeffrey A. Hostetler ◽  
Tommy C. Hines ◽  
Fred A. Johnson ◽  
H. Franklin Percival ◽  
...  
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Population Growth Rate ◽  
Population Decline ◽  
South Florida ◽  
Winter Survival ◽  
Demographic Parameters ◽  
Population Growth Rates ◽  
Annual Changes

Context Hunting-related (hereafter harvest) mortality is assumed to be compensatory in many exploited species. However, when harvest mortality is additive, hunting can lead to population declines, especially on public land where hunting pressure can be intense. Recent studies indicate that excessive hunting may have contributed to the decline of a northern bobwhite (Colinus virginianus) population in south Florida. Aims This study aimed to estimate population growth rates to determine potential and actual contribution of vital rates to annual changes in population growth rates, and to evaluate the role of harvest and climatic variables on bobwhite population decline. Methods We used demographic parameters estimated from a six-year study to parameterise population matrix models and conduct prospective and retrospective perturbation analyses. Key results The stochastic population growth rate (λS = 0.144) was proportionally more sensitive to adult winter survival and survival of fledglings, nests and broods from first nesting attempts; the same variables were primarily responsible for annual changes in population growth rate. Demographic parameters associated with second nesting attempts made virtually no contribution to population growth rate. All harvest scenarios consistently revealed a substantial impact of harvest on bobwhite population dynamics. If the lowest harvest level recorded in the study period (i.e. 0.08 birds harvested per day per km2 in 2008) was applied, λS would increase by 32.1%. Winter temperatures and precipitation negatively affected winter survival, and precipitation acted synergistically with harvest in affecting winter survival. Conclusions Our results suggest that reduction in winter survival due to overharvest has been an important cause of the decline in our study population, but that climatic factors might have also played a role. Thus, for management actions to be effective, assessing the contribution of primary (e.g. harvesting) but also secondary factors (e.g. climate) to population decline may be necessary. Implications Reducing hunting pressure would be necessary for the recovery of the bobwhite population at our study site. In addition, an adaptive harvest management strategy that considers weather conditions in setting harvest quota would help reverse the population decline further.

scholarly journals Role of carbon allocation efficiency in the temperature dependence of autotroph growth rates

2018 ◽  
Vol 115 (31) ◽  
pp. E7361-E7368 ◽  
Author(s):  
Bernardo García-Carreras ◽  
Sofía Sal ◽  
Daniel Padfield ◽  
Dimitrios-Georgios Kontopoulos ◽  
Elvire Bestion ◽  
...  
Keyword(s):  
Growth Rate ◽  
Temperature Dependence ◽  
Growth Rates ◽  
Carbon Allocation ◽  
Thermal Sensitivity ◽  
Potential Growth ◽  
Allocation Efficiency ◽  
Population Growth Rates ◽  
Performance Curves

Relating the temperature dependence of photosynthetic biomass production to underlying metabolic rates in autotrophs is crucial for predicting the effects of climatic temperature fluctuations on the carbon balance of ecosystems. We present a mathematical model that links thermal performance curves (TPCs) of photosynthesis, respiration, and carbon allocation efficiency to the exponential growth rate of a population of photosynthetic autotroph cells. Using experiments with the green alga, Chlorella vulgaris, we apply the model to show that the temperature dependence of carbon allocation efficiency is key to understanding responses of growth rates to warming at both ecological and longer-term evolutionary timescales. Finally, we assemble a dataset of multiple terrestrial and aquatic autotroph species to show that the effects of temperature-dependent carbon allocation efficiency on potential growth rate TPCs are expected to be consistent across taxa. In particular, both the thermal sensitivity and the optimal temperature of growth rates are expected to change significantly due to temperature dependence of carbon allocation efficiency alone. Our study provides a foundation for understanding how the temperature dependence of carbon allocation determines how population growth rates respond to temperature.

Life history and environmental influences on population dynamics in sockeye salmon

2014 ◽  
Vol 71 (8) ◽  
pp. 1198-1208 ◽  
Author(s):  
Douglas C. Braun ◽  
John D. Reynolds
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Population Growth ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Sockeye Salmon ◽  
Life History Traits ◽  
Relative Importance ◽  
Population Growth Rates ◽  
Habitat Variables

Understanding linkages among life history traits, the environment, and population dynamics is a central goal in ecology. We compared 15 populations of sockeye salmon (Oncorhynchus nerka) to test general hypotheses for the relative importance of life history traits and environmental conditions in explaining variation in population dynamics. We used life history traits and habitat variables as covariates in mixed-effect Ricker models to evaluate the support for correlates of maximum population growth rates, density dependence, and variability in dynamics among populations. We found dramatic differences in the dynamics of populations that spawn in a small geographical area. These differences among populations were related to variation in habitats but not life history traits. Populations that spawned in deep water had higher and less variable population growth rates, and populations inhabiting streams with larger gravels experienced stronger negative density dependence. These results demonstrate, in these populations, the relative importance of environmental conditions and life histories in explaining population dynamics, which is rarely possible for multiple populations of the same species. Furthermore, they suggest that local habitat variables are important for the assessment of population status, especially when multiple populations with different dynamics are managed as aggregates.

Sign in / Sign up

Export Citation Format

Share Document