Calculating the Sensitivity of a Salmonid Population Model

1986 ◽  
Vol 43 (4) ◽  
pp. 863-868 ◽  
Author(s):  
Geoffrey T. Evans ◽  
J. Brian Dempson
Keyword(s):  
Life History ◽  
Simple Model ◽  
Computer Simulations ◽  
Population Model ◽  
Theoretical Calculations ◽  
Protection Measures ◽  
Habitat Protection ◽  
Actual Parameter ◽  
Management Actions ◽  
Parameter Values

We present a simple model of salmonid life history, and calculate the sensitivity of its outputs to its parameters. Theoretical calculations are preferred to computer simulations. There are some parameters for which the sign of the sensitivity is independent of the actual parameter values. In an uncertain world, management actions aimed at altering such parameters are safer than other actions. For example, habitat protection measures are more certain to have the desired effect than are changes in fishery regulations.

scholarly journals Selfish Genes, Pleiotropy and the Origin of Recombination

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 2089-2097 ◽  
Author(s):  
Jody Hey
Keyword(s):  
Natural Selection ◽  
Simple Model ◽  
Computer Simulations ◽  
Recombination Rate ◽  
Evolutionary Origin ◽  
Deleterious Mutations ◽  
Beneficial Mutations ◽  
Selfish Genes ◽  
Simple Interaction

Abstract If multiple linked polymorphisms are under natural selection, then conflicts arise and the efficiency of natural selection is hindered relative to the case of no linkage. This simple interaction between linkage and natural selection creates an opportunity for mutations that raise the level of recombination to increase in frequency and have an enhanced chance of fixation. This important finding by S. Otto and N. Barton means that mutations that raise the recombination rate, but are otherwise neutral, will be selectively favored under fairly general circumstances of multilocus selection and linkage. The effect described by Otto and Barton, which was limited to neutral modifiers, can also be extended to include all modifiers of recombination, both beneficial and deleterious. Computer simulations show that beneficial mutations that also increase recombination have an increased chance of fixation. Similarly, deleterious mutations that also decrease recombination have an increased chance of fixation. The results suggest that a simple model of recombination modifiers, including both neutral and pleiotropic modifiers, is a necessary explanation for the evolutionary origin of recombination.

Ontogenetic Niche Shifts

2013 ◽  
Author(s):  
André M. de Roos ◽  
Lennart Persson
Keyword(s):  
Life History ◽  
Extended Model ◽  
Full Model ◽  
Life History Stages ◽  
Ontogenetic Diet Shifts ◽  
Ontogenetic Niche Shifts ◽  
Niche Shifts ◽  
Limited Supply ◽  
Diet Shifts ◽  
Parameter Values

This chapter considers the consequences for community structure of ontogenetic diet shifts that involve the use of different resources in different life history stages, whereby these resources are in limited supply and are hence competed for by all individuals foraging on them. It explores the consequences of ontogenetic diet shifts using stage-structured biomass models that account for two basic resources, a stage-structured consumer population, for which we distinguish between juveniles and adults, and up to two unstructured predator populations. The most extended model is therefore closely related to the model analyzed in Chapter 5, except for the inclusion of an additional basic resource. The equations of the full model are summarized and default parameter values are listed.

DIFFUSION OF A POPULATION OF INTERACTING REPLICATORS IN SEQUENCE SPACE

2002 ◽  
Vol 05 (04) ◽  
pp. 457-461 ◽  
Author(s):  
BÄRBEL M. R. STADLER
Keyword(s):  
Simple Model ◽  
Population Size ◽  
Computer Simulations ◽  
Mutation Rate ◽  
Sequence Space ◽  
Finite Population ◽  
Fitness Landscape ◽  
Diffusion Constant ◽  
Sequence Length

We consider a simple model for catalyzed replication. Computer simulations show that a finite population moves in sequence space by diffusion analogous to the behavior of a quasispecies on a flat fitness landscape. The diffusion constant depends linearly on the per position mutation rate and the ratio of sequence length and population size.

scholarly journals Variance-Based Sensitivity Analysis: Preliminary Results in COAMPS

2014 ◽  
Vol 142 (5) ◽  
pp. 2028-2042 ◽  
Author(s):  
Caren Marzban ◽  
Scott Sandgathe ◽  
James D. Doyle ◽  
Nicholas C. Lederer
Keyword(s):  
Sensitivity Analysis ◽  
Prediction Models ◽  
Theoretical Calculations ◽  
Weather Prediction ◽  
Surface Fluxes ◽  
Cumulus Parameterization ◽  
Convective Precipitation ◽  
Primary Concern ◽  
Total Precipitation ◽  
Parameter Values

Abstract Numerical weather prediction models have a number of parameters whose values are either estimated from empirical data or theoretical calculations. These values are usually then optimized according to some criterion (e.g., minimizing a cost function) in order to obtain superior prediction. To that end, it is useful to know which parameters have an effect on a given forecast quantity, and which do not. Here the authors demonstrate a variance-based sensitivity analysis involving 11 parameters in the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS). Several forecast quantities are examined: 24-h accumulated 1) convective precipitation, 2) stable precipitation, 3) total precipitation, and 4) snow. The analysis is based on 36 days of 24-h forecasts between 1 January and 4 July 2009. Regarding convective precipitation, not surprisingly, the most influential parameter is found to be the fraction of available precipitation in the Kain–Fritsch cumulus parameterization fed back to the grid scale. Stable and total precipitation are most affected by a linear factor that multiplies the surface fluxes; and the parameter that most affects accumulated snow is the microphysics slope intercept parameter for snow. Furthermore, all of the interactions between the parameters are found to be either exceedingly small or have too much variability (across days and/or parameter values) to be of primary concern.

scholarly journals Optimal immunization cocktails can promote induction of broadly neutralizing Abs against highly mutable pathogens

2016 ◽  
Vol 113 (45) ◽  
pp. E7039-E7048 ◽  
Author(s):  
J. Scott Shaffer ◽  
Penny L. Moore ◽  
Mehran Kardar ◽  
Arup K. Chakraborty
Keyword(s):  
Immune System ◽  
Simple Model ◽  
Computer Simulations ◽  
Evolutionary Process ◽  
Affinity Maturation ◽  
Intermediate Level ◽  
Human Immune System ◽  
Human Immune

Strategies to elicit Abs that can neutralize diverse strains of a highly mutable pathogen are likely to result in a potent vaccine. Broadly neutralizing Abs (bnAbs) against HIV have been isolated from patients, proving that the human immune system can evolve them. Using computer simulations and theory, we study immunization with diverse mixtures of variant antigens (Ags). Our results show that particular choices for the number of variant Ags and the mutational distances separating them maximize the probability of inducing bnAbs. The variant Ags represent potentially conflicting selection forces that can frustrate the Darwinian evolutionary process of affinity maturation. An intermediate level of frustration maximizes the chance of evolving bnAbs. A simple model makes vivid the origin of this principle of optimal frustration. Our results, combined with past studies, suggest that an appropriately chosen permutation of immunization with an optimally designed mixture (using the principles that we describe) and sequential immunization with variant Ags that are separated by relatively large mutational distances may best promote the evolution of bnAbs.

scholarly journals A generic population model for the African tick Rhipicephalus appendiculatus

Parasitology ◽  
1997 ◽  
Vol 115 (3) ◽  
pp. 265-279 ◽  
Author(s):  
S. E. RANDOLPH ◽  
D. J. ROGERS
Keyword(s):  
South Africa ◽  
Population Model ◽  
Egg Production ◽  
Population Analysis ◽  
Rhipicephalus Appendiculatus ◽  
Mortality Factors ◽  
Density Dependent ◽  
Tick Abundance ◽  
Annual Range ◽  
Parameter Values

We present a simulation population model for the African tick Rhipicephalus appendiculatus, based on previous analyses of the mortality factors most closely correlated with observed population changes at 11 sites in equatorial and South Africa. The model incorporates temperature-dependent rates of egg production and development, climate-driven density-independent mortality rates, particularly during the adult-larval stage, and density-dependent regulation of both nymphs and adults. Diapause is also included for tick populations in southern Africa. The model successfully describes both the seasonality and annual range of variation in numbers of each tick stage observed at each of 4 test sites in Uganda, Burundi and South Africa. Sensitivity analysis showed that the final version of the model is robust to 4-fold variation in most parameter values (that were per force based on informed guesses), but is more sensitive to the regression coefficients determining density-dependent interstadial mortality (that were derived from analysis of field data). The model is able to predict the seasonality of ticks from a site in Kenya where a full prior population analysis was not possible because only adults and nymphs had been counted. The model is potentially applicable to other species of ticks, both tropical and temperate, to predict tick abundance and seasonality as risk factors for tick-borne diseases.

scholarly journals First direct evidence of reproductive behaviour of the white grouper, Epinephelus aeneus (Geoffroy Saint-Hilaire, 1817)

2019 ◽  
Vol 20 (2) ◽  
pp. 326
Author(s):  
ELENA DESIDERÀ ◽  
LUANA MAGNANI ◽  
AUGUSTO NAVONE ◽  
PAOLO GUIDETTI ◽  
CARLOTTA MAZZOLDI
Keyword(s):  
Direct Observation ◽  
Marine Protected Area ◽  
First Record ◽  
Reproductive Behaviour ◽  
Western Mediterranean ◽  
The Body ◽  
Protection Measures ◽  
Management Actions ◽  
Western Mediterranean Sea ◽  
Colour Patterns

This study describes the first ever reported direct observation of a pair spawning event and the reproductive liveries of the white grouper, Epinephelus aeneus. Spawning took place on a rocky bank located in the Marine Protected Area (MPA) of Tavolara-Punta Coda Cavallo (NE Sardinia, Italy), in the Western Mediterranean Sea. In the evening of August 4th, 2018, the spawning of two large-sized individuals (~90 cm total length), displaying distinct colour patterns, was observed using SCUBA diving. This direct observation is the first record of E. aeneus male reproductive livery, characterized by a darker coloration on the head, the dorsal part of the body and the caudal fin. In addition, information on the environmental conditions in which reproduction occurred was collected. At the study site, relatively high seawater temperatures were recorded at the time of the E. aeneus spawning (24 °C at 24.7 m), as well as over the 2018 summer months (July-September), even in deep waters (>35 m), compared to previous summers. The spawning event occurred in a coralligenous-dominated seascape where fishing is prohibited, while diving activities are allowed. The site hosts abundant populations of ecologically and commercially valuable fish species (e.g., groupers, sparid fishes), with significant proportions of large-sized individuals (i.e. reproducers). Further studies are needed to advance our knowledge of the white grouper, with a particular emphasis on reproduction and the importance of implementing effective protection measures. Prioritizing management actions at key reproductive sites, such as rocky banks, is essential for ensuring the protection and/or recovery of over-exploited species. 

scholarly journals Bio-Ecological Features Update on Eleven Rare Cartilaginous Fish in the Central-Western Mediterranean Sea as a Contribution for Their Conservation

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 871
Author(s):  
Antonello Mulas ◽  
Andrea Bellodi ◽  
Pierluigi Carbonara ◽  
Alessandro Cau ◽  
Martina Francesca Marongiu ◽  
...  
Keyword(s):  
Life History ◽  
Mediterranean Sea ◽  
Stomach Content Analysis ◽  
Western Mediterranean ◽  
Reproductive Period ◽  
Cartilaginous Fish ◽  
Management Actions ◽  
Western Mediterranean Sea ◽  
Ecological Features ◽  
Key Species

Cartilaginous fish are commonly recognized as key species in marine ecosystems for their fundamental ecological role as top predators. Nevertheless, effective management plans for cartilaginous fish are still missing, due to the lack of knowledge on their abundance, distribution or even life-history. In this regard, this paper aims at providing new information on the life-history traits, such as age, maturity, reproductive period, in addition to diet characteristics of eleven rare cartilaginous fish inhabiting the Central-Western Mediterranean Sea belonging to the orders Chimaeriformes (Chimaera monstrosa), Hexanchiformes (Heptranchias perlo and Hexanchus griseus), Myliobatiformes (Aetomylaeus bovinus and Myliobatis aquila), Rajiformes (Dipturus nidarosiensis and Leucoraja circularis), Squaliformes (Centrophorus uyato, Dalatias licha and Oxynotus centrina) and Torpediniformes (Tetronarce nobiliana), useful for their assessment and for future management actions. Particularly, the present paper provides for the first time the age estimation of D. nidarosienis and L. circularis which were both found capable of becoming older than ten years. In addition, the present study updates the sizes of first maturity of C. uyato and D. licha, which appeared to be capable of reproducing earlier than what was previously hypothesized, representing very valuable information for a better understanding of these rare species populations status and, eventually, their conservation. On the basis of the stomach content analysis, it was possible to identify five different predator groups.

scholarly journals Integrating physiological data with the conservation and management of fishes: a meta-analytical review using the threatened green sturgeon (Acipenser medirostris)

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Essie M Rodgers ◽  
Jamilynn B Poletto ◽  
Daniel F Gomez Isaza ◽  
Joel P Van Eenennaam ◽  
Richard E Connon ◽  
...  
Keyword(s):  
Life History ◽  
Elevated Temperatures ◽  
Swimming Performance ◽  
Yolk Sac ◽  
Physiological Data ◽  
Future Research ◽  
Green Sturgeon ◽  
Acipenser Medirostris ◽  
Life History Stages ◽  
Management Actions

Abstract Reversing global declines in the abundance and diversity of fishes is dependent on science-based conservation solutions. A wealth of data exist on the ecophysiological constraints of many fishes, but much of this information is underutilized in recovery plans due to a lack of synthesis. Here, we used the imperiled green sturgeon (Acipenser medirostris) as an example of how a quantitative synthesis of physiological data can inform conservation plans, identify knowledge gaps and direct future research actions. We reviewed and extracted metadata from peer-reviewed papers on green sturgeon. A total of 105 publications were identified, spanning multiple disciplines, with the primary focus being conservation physiology (23.8%). A meta-analytical approach was chosen to summarize the mean effects of prominent stressors (elevated temperatures, salinity, low food availability and contaminants) on several physiological traits (growth, thermal tolerance, swimming performance and heat shock protein expression). All examined stressors significantly impaired green sturgeon growth, and additional stressor-specific costs were documented. These findings were then used to suggest several management actions, such as mitigating salt intrusion in nursery habitats and maintaining water temperatures within optimal ranges during peak spawning periods. Key data gaps were also identified; research efforts have been biased towards juvenile (38.1%) and adult (35.2%) life-history stages, and less data are available for early life-history stages (embryonic, 11.4%; yolk-sac larvae, 12.4%; and post yolk-sac larvae, 16.2%). Similarly, most data were collected from single-stressor studies (91.4%) and there is an urgent need to understand interactions among stressors as anthropogenic change is multi-variate and dynamic. Collectively, these findings provide an example of how meta-analytic reviews are a powerful tool to inform management actions, with the end goal of maximizing conservation gains from research efforts.

Hydrogeology of brook trout (Salvelinusfontinalis) spawning and incubation habitats: implications for forestry and land use development

1996 ◽  
Vol 26 (5) ◽  
pp. 767-772 ◽  
Author(s):  
R. Allen Curry ◽  
Kevin J. Devito
Keyword(s):  
Land Use ◽  
Groundwater Flow ◽  
Brook Trout ◽  
Buffer Zone ◽  
Nearshore Zone ◽  
Recharge Area ◽  
Protection Measures ◽  
Habitat Protection ◽  
Land Use Development

We demonstrated that nearshore spawning and incubation habitats of brook trout (Salvelinusfontinalis) are manifestations of lenses of coarse overburden materials underlying the nearshore zone. Lenses directed and accelerated groundwater flow into the habitats. They were <17 m wide, >1 m thick, and could be restricted to the nearshore zone or extend at least 20 m into the terrestrial catchment. Recharge areas necessary to sustain discharge in the habitats were estimated to encompass 3–10 ha, or 1–97%, of the associated terrestrial catchment. A 90-m buffer zone adjacent to the shoreline protected only 9–55% of the required recharge area. A hydrological approach to defining habitat protection measures is suggested.

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