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Questions tagged [population-dynamics]

The scientific study of short- and long-term changes in the size and age composition of populations and the processes driving these changes.

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Does someone know of a website that keeps track of a species population?

I am planning on doing some math on population growth, but I need a reliable website that keeps track of the population growth of some species. Does anyone know of a website that has such information?
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17 views

How should should I run a yeast experiment where I measure population growth?

Soon I will conduct an expirement involving the popoulation growth of yeast. Nonetheless, I am not sure how long should I let my experiment running for, nor do I know at which intervals should I ...
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24 views

Examples of predator populations exterminating prey and dying out

Predator-prey dynamics usually modulates the population size of both prey and predators in a way that no one goes extinct. However,I wonder if there are any real world examples of predators ...
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29 views

Two state exponential growth model

I want to write an expression to model exponential growth of a microbe that scholastically and irreversibly acquires a mutation at a fixed rate that slows growth. I can do it iteratively, but am ...
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Is there any example, where cooperative behaviour of predators induce fear in prey population?

I am basically from math background and doing Ph.D in mathematical biology. So I am not so efficient in biology. But my problem based on cooperative behaviour of animals during hunting which is ...
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1answer
49 views

Is a wild-type strain more “fit” than its mutant strains?

Question's context In the context of a presentation on mathematical models for antibiotic-resistance bacteria research, someone mentioned that wild type strain (WT) are expected to be more fit than ...
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19 views

Sampling of Species counting same member of species twice

As part of the biology class, we performed a sample on the number of red squirrels in a forest a few miles away from the classroom to estimate its population. When we returned to analyse our data, we ...
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183 views

Calculate growth rate of a population by Leslie matrix

We can calculate growth rate of a population by calculate the dominant eigen value of a Leslie matrix. What does this growth rate mean? I think that the growth rate N(t+1)/N(t) is depend on the age ...
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56 views

Genetic disease elimination: Possible?

This is a question having to do with my generation ship story but more specifically, genetics, and even more specifically, genetic disease. Here are the conditions as far as people with or without ...
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2answers
73 views

Spread of a benign virus in a population over time

This is a somewhat difficult (for me) population dynamics question and I wonder if someone with experience in this area could suggest a reasonable approach? My simplifying assumptions: As a gross ...
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1answer
107 views

How to give a biological interpretation to this phase portrait?

Consider the following system and analyze its behavior. $$\begin{array}{rl} \frac{dA}{dt} &= A \left( 2-\frac{A}{5000}-\frac{L}{100} \right)\\ \frac{dL}{dt} &= L \left(-\frac{1}{2}+\frac{...
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1answer
93 views

Mathematical model about the relationship between two animal species

I'd like to relate a mathematical model with two animal species. This is the model: $$ \begin{split} \frac{dN}{dt} & =rN-\frac{rN(N+M)}{k} \\ \frac{dM}{dt} & =r'M-\frac{r'M(N+M)}{k'} \end{...
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Value of r (intrinsic rate of natural increase)

What is the current value of 'r' (instrinsic rate of natural increase) in India? How do we calculate it? My book says that In 1981, the r value for human population in India was 0.0205. But this ...
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1answer
272 views

Do death rate and birth rate become equal at replacement fertility rate?

A population transitions from stage 3 to stage 4 when the fertility rate reaches the population replacement level of 2.1. My question is that if the population replacement level reached, shouldn't ...
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444 views

Human genetic diversity in Africa in comparison with the rest of the world

Background The claim ... Most of the genetic diversity in humans is in Africa ... is quite common. On Biology.SE, it is easy to find posts that make this claim. Consider for example: Do humans ...
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172 views

World population pyramid since 1800 [closed]

I am interested in understanding how the global population pyramid has changed in the last couple of centuries. I have two questions: 1) Has this been calculated? Are there estimates of population ...
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1answer
32 views

Properly changing the time scale of a parameter in a growth model

I have a two-population model, where one of the populations is a bacterial culture with its growth described as a logistic growth, with a reported growth rate of $2 \log\hbox{bacteria hour}^{-1}$ and ...
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0answers
57 views

Variance of Stochastic Growth Rate for Average Population Size Over Time

I'm interested in calculating the variance of the stochastic growth rate for the average population size over time, $$\ln \beta = \lim_{t\to\infty}\dfrac{1}{t}\ln V[N(t)]$$ which shows that the ...
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2answers
98 views

References concerning the relative population sizes of predator and prey

In an ecosystem, say there are two species in a predator-prey relationship. What is the most typical ratio of these species' population densities? For instance, it could be that for every fox, there ...
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3answers
1k views

What is the mechanism by which passive immunity works?

My idea is that passive immunity can be used to cure an individual who is infected with a certain disease. For example, for someone infected by clostridium tetani, you would inject them with an ...
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1answer
60 views

How can DNA profiling be used to determine the number of organisms from a specific species that is within a certain area?

Here is the tedious exam question that asks this: question 8(b). https://drive.google.com/drive/folders/0B23NLD5L6099VWJya3dfLVJpbmc The question states: In 2007, the brown bear was a threatened ...
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1answer
2k views

What is full form of r and K in r-selection species and K-selection species?

What is full form/ meaning of 'r' and 'K' in r-selection species and K-selection species? Does this 'r' means "Random" and the 'K' means "constant"?
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60 views

Is the basic reproduction number unique?

Given any epidemic model of an infectious disease, there are various ways of computing a basic reproduction number($R_0$) such as; the next-generation method, survival function, largest eigenvalue of ...
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Example of code with pypgen (python)

I have a VCF file and wish to calculate a few indices of population divergence over a sliding window. I consider using pypgen but the documentation is currently very limited. Can you please give me ...
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1answer
516 views

How can I measure bee and wasp population?

Bees and wasps in our garden disappeared suddenly last year - I asked a question about it at Why our bees might have suddenly disappeared. This year, I see that some bumblebees are active now. I'd ...
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2answers
137 views

Reproduction number of a SIR model with mortality

We know that reproduction number $\mathcal{R}_0$ is $\frac{\alpha}{\beta}$ for the following system, such that if $\mathcal{R}_0>1$, there is an epidemic in the population. Now, assume the system ...
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Is there a name for dominant-intraspecific competition?

Some ecological competition dynamics have particular names (e.g.: scramble competition, contest competition, ...). I wonder if there's such a name for competition dynamics where the interspecific ...
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1answer
67 views

Accurate surveys of urban pigeon and bird populations

I've been working on an assignment to develop mathematical models of urban pigeon populations. (As a disclaimer, this is part of a math course, not a biology course). I already understand the ...
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1answer
125 views

Why are there relatively more predators on the land than in the oceans? [closed]

Our biology teacher told us that among worse conditions one of the reason that intelligent life had actually evolved on land is that there is a more important selective pressure due to the bigger ...
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1answer
95 views

Calculation of Malthusian fertility and mortality from birth and death rates

In a simple Malthusian model, the population $p$ grows according to $p = p_0e^{rt}$, where $r = \beta - \mu$, $\beta$ is the "fertility" parameter and $\mu$ the "mortality" parameter. In the case of $\...
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117 views

Parameters in the competitive Lotka-Volterra model for red and grey squirrels

I am trying to create a simple model of how the population of red and grey squirrels in Scotland will change using the competitive Lotka-Volterra model. I know there are approximately 120 000 red ...
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1answer
407 views

What is a typical value of the selection coefficient s?

I am trying to gain an understanding of the real world effects of natural selection from the equations, especially comparing it with drift. However I have been unable to find any examples which give ...
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208 views

Parasite - host equations

The Lotka–Volterra equations describe how predator–prey interactions affect population growth. Do these equations describe parasite-host interactions? If not, how would they change by adding these ...
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38 views

Variance of frequency in expanding populations

I'm trying to understand the variance in frequency of some strain after some time as passed in a growing population. The idea is to then plug this in kolmorov foward equations and get the classic ...
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2answers
240 views

Modeling population growth - Variance

I've been studing population growth models, but there's something I can not find that's fustrating. That's a formula for the variance in population growth. I know that other models can be aplied, but ...
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3answers
150 views

Can we use differential equations for population that is discrete?

Population dynamics is often modeled using ODE. For example one common model is logistic growth model: $$\frac{dx}{dt} = k.x.\left(1-\frac{x}{C}\right)$$ where x is population size, k is rate ...
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2answers
89 views

Interspecies competition and pathogen

Following my answer to this question, a debate ensued on whether the loss in population of one species (namely red squirrels) due to its lesser resistance to a pathogen brought by a competing species (...
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201 views

Why our bees might have suddenly disappeared

We have a large garden in Bedfordshire, UK, next to woods and to arable fields currently planted with intensively farmed rape. We usually have many bees in the garden. Earlier this year, things were ...
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1answer
156 views

What happened to the gypsy moth epidemics in the Northeast US?

I remember that back in the 1980s, 1980-1984, gypsy moths were a veritable plague in the Northeast United States. They were literally everywhere. Sidewalks were covered with their squashed bodies (of ...
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2answers
149 views

doubt with a multiple choice question [closed]

Permanent decrease in population would occur due to- A) Migration B) Natality C) Emigration D) Mortality E) Territoriality . It's obvious that C) & D) options are possible . But I'm confused ...
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1answer
126 views

How much do urban pigeons move around cities?

Do they tend to live their lives in one area of the city or do they move around? For example, do pigeons born on London's Trafalgar Square live their whole lives centered around Trafalgar Square or ...
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1answer
161 views

Guide to learning about Population biology / ecology / dynamics for a non-Biologist

I'm an applied mathematician who works in the field of feedback control systems but has been becoming interested in looking at population biology (e.g. Lotka-Volterra, Mathusian growth,etc.) from a ...
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190 views

Population size and genetic drift - What are the evidences?

Wright-Fisher model From the Wright-Fisher model of genetic drift, the random sampling of allele from one generation to the next is taken from a binomial distribution with parameters $2N$ and $p$, ...
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97 views

Is $F_{ST}$ a probability and a correlation coefficient?

$F_{ST}$ is one of the most famous and most important statistics of all of evolutionary biology. Yet, many people misunderstand it or misuse the classical results from the literature on $F_{ST}$ (...
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1answer
1k views

Population dynamics ODE with Allee Effects

From reading about Allee effects, it appears that there is a modification of the one-dimensional logistic equation to account for an allee effect given by: $$\frac{dN(t)}{dt} = rN\left(1-\frac{N}{K} \...
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2answers
167 views

Would a colony with only one male and female collapse?

This is a thought experiment: If we form a population with only a single founder pair, can this population survive? What would happen? Would this inbreeding cause the population to go extinct? Could ...
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2answers
180 views

Stochastic parameters in population growth equations

I'm more of a mathematician than a biologist, so I had a question about an application of the population growth equation to real-life models, and thus would like to ask biologists for their insights. ...
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1answer
331 views

Basic reproduction number in epidemiology

The basic reproduction number $R_0$ of diseases depends on the population size (or the number of susceptible individuals). The commonly reported $R_0$ is based on what population size (when they do ...
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1answer
80 views

What do “reduced antipredator defense” and “reduced antipredator vigilance” mean?

The book BIOMAT 2010 (International Symposium on Mathematical and Computational Biology, edited by Rubem P. Mondaini) mentions the terms reduced antipredator defense and reduced antipredator vigilance....
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253 views

How to determine the relationship of competition or cooperation?

I am currently studying the interaction of Twitter memes (two or many), such as competition and cooperation. Is there any model or method in biology that can identify the types of the relationship, ...