Questions tagged [population-biology]

Questions pertaining to populations of organisms.

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Can SARS-COV2 strain competition be modelled by inter-species lotka volterra equations?

Currently studying infectious diseases epidemiology and never studied ecology. But I was wondering if the interspecies Lotka Volterra equations could model and explain strain dominance. r = could be ...
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2 answers
83 views

Population numbers in the presence of restricted resources

I wonder if the following simple system is considered in population dynamics, under which name, and in which textbooks. Consider a population $X$ (also indicating its number of individuals) with a ...
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4 votes
2 answers
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Which approach is the common one in the literature for determining the bacterial growth rate?

I have the following data, which is OD600 (the second component) vs. time (the first component): ...
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6 votes
1 answer
94 views

Viruses in human history

How much do we know about ancient viruses and the viral evolution throughout the human history? To my knowledge the HIV history has been rather well documented for about hundred years back (e.g., see ...
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Ancestral inference from demographic data

The question is inspired by this one, in the History community: We consider a population, whereas the data we have the number of migrants arriving every year, as well as the initial and the current ...
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6 votes
2 answers
495 views

Understanding expected mean number of breeding seasons

I've recently come across an equation for the expected mean number of breeding seasons after the first breeding season, as a function of the annual survival rate (S) and the probability of breeding, $$...
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The evolution equations under different year classes of a age-structured model?

This sounds a bit complicated but I want to grab more feelings on age-structured problems. Less than 2 days to the exam so I appreciate any help. So suppose we only get 3 year classes in a school at ...
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Evolution equations of a 2-gender age-structure model?

This sounds a bit complicated but I want to grab more feelings on age-structured problems. Less than 2 days to the exam so I appreciate any help. So suppose we get 4 age classes in a population census ...
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2 votes
1 answer
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Will Fst (inbreeding coefficient) always be a value close or at 0 in asexual populations?

FST is the average inbreeding coefficient of a total population. The equation is: $F_{ST} = \frac{Var(S)}{Var(T)} $ $Var(S)$ = variance in the frequency of the allele between different subpopulations, ...
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Is it possible to determine the initial population given the final one?

It is possible to determine the initial population of, say, bacteria given a measure at a later time? Let's say I use the logistic growth model $$\dot N (t) = rN(t)\left(1 - \frac{N(t)}{K}\right)$$ ...
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How many giant kelp are there per square meter?

In a high-density giant kelp (Macrocystis pyrifera) bed how many "holdfasts" or roots would there be per square meter of seafloor on average?
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3 votes
2 answers
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Techniques to find out which species are endangered

Most countries have a list of endangered species and international organisations too issue such lists of vulnerable and endangered species. What mathematical or statistical models are those estimates ...
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1 answer
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What are the long term consequences of settling an isolated territory with an extremely limited gene pool?

I remember reading about a discredited theory - I'm afraid that, despite some frantic Googling, I've been unable to track down a link - which stated that Australia was first settled by a woman, ...
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2 votes
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Range for which the Verhulst-Pearl model is a good approximate

The Verhulst-Pearl model describes the growth of a population using the differential equation, $$\frac{dN}{dt}=rN \left(\frac{K-N}{K} \right)$$ where N is the population (no. of organisms), r, the ...
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What happens to male turkeys?

My family and I have almost never seen a wild male turkey though we have seen countless female turkeys. Is the male to female sex ratio of turkeys at birth extremely low? If not, what happens to the ...
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Is a nightly curfew an effective intervention strategy for limiting the spread of an infectious disease? [closed]

The governing bodies of several geographic areas hit by disease outbreaks will sometimes impose a nightly curfew on their citizens, restricting or limiting the ability of their citizens from going ...
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How can we calculate the constants of the SIR model?

I am not a biologist by profession, but I am attempting to implement a simple SIR model from the following paper. The paper assumes the following constants are known: rc = growth rate of ...
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Calculating Rate of Growth without a Population [closed]

Lets say that by studying individuals of a rare species, you have determined that species gestation period, age of sexual maturity, average time between pregnancies, maximum lifespan, and average ...
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2 answers
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How to model species interactions on population size dynamic?

Here are two classical discrete time models of population size dynamic. The exponential growth model $$N_{t+1} = r\cdot N_t \qquad\qquad(1)$$ and the logistic growth model $$N_{t+1} = r\cdot N_t \...
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Growth rate oscillation in the a population of non-interacting bacteria

I have come across this theoretical paper claiming that if you start a batch culture from a single E. coli cell, the exponential growth rate of the population defined as $$k = \frac1N \frac{dN}{dt}$$ ...
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2 votes
2 answers
121 views

What proportion of the people who lived 1000 years ago have genetic descendants alive today?

For context, I've been wondering about this for a paper I'm writing (in philosophy). Really, I want to figure out the chances that someone alive today will end up still having descendants 1000 years ...
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Repopullation after a mass extinction [duplicate]

Is it possible to restart the whole human species with less than 10 individual. let say that the whole human species was wipe out of the surface of the earth by a catastrophe only 8 different couple ...
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1 answer
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What determines the duration of larval stage?

Why do insects have very long pre reproductive periods and very short reproductive periods? Is there a common characteristic that can indicate the duration of these stages or offer an explanation for ...
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4 votes
1 answer
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How to check if a population density obeys replicator dynamics

Say we have a probability vector or population density $p = (p_1,...,p_n)$ with $p_i \geq 0$ and $\sum_i p_i =1$. Also assume we know the functions $g=(g_1,...,g_n)$ such that: $$p_i(t+1) = g_i(p(t))...
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2 votes
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Linkage between chromosomal loci and the Hardy-Weinberg principle

Referring to the Hardy-Weinberg principle, which is always stated with respect to a particular locus on the chromosome, if we observe that two different loci are either always together in Hardy-...
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3 votes
0 answers
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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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2 votes
0 answers
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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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2 votes
1 answer
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Impact of Natural Selection on Population Size

I have conducted a lab with my IB Biology 11 class, regarding changes in allele frequencies within generations overseeing the natural selection of an advantageous phenotype. We were looking to ...
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1 vote
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549 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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3 votes
2 answers
4k views

Can predator-prey relationship be an example of negative feedback?

Predators eat their prey, prey population decreases. This results in the predator population to decrease, so less prey are consumed which causes the prey population to increase. Therefore, if the ...
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Why hasn't evolution gotten rid of the appendix yet?

A figure I have recently stumbled upon suggests that about 7% of the world population will, or have, had appendicitis in their lifetime. Cutting out the appendix was impossible until very recently. ...
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7 votes
1 answer
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How is (Insect) population control through male sterilization effective

This is no doubt a simple question. I was reading about Sterile Insect Technique where sterile males out-compete non-sterile ones to mate with females and thus reduce the population. My question ...
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How does one calculate Rx/a in population genetics?

The ratio of sex-linked to autosome mutation frequencies (R) is Rx/a =(2/3)(2+ α)/(1+ α) for X-linked genes and Ry/a = 2 α /(1+ α) for Y-linked genes. How does one calculate Rx/a, in order to find α?
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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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3 votes
1 answer
236 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{A}{...
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2 votes
1 answer
157 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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2 votes
1 answer
3k views

What does 'per capita births and deaths' mean?

My book says, If in a pond there are 20 lotus plants last year and through reproduction 8 new plants are added, taking the current population to 28, we calculate the birth rate as 8/20 = 0.4 ...
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2 votes
4 answers
18k views

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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3 votes
2 answers
153 views

Have there ever been as many mammals as there are now?

I apologize for the weird question, but based on a Google search it looks like this topic hasn't been discussed before. I'm hoping that enough information about population biology is stored in the ...
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1 vote
1 answer
732 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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Could there be latent infections in the human population that we don't know of?

Herpes simplex 1 virus and toxoplasmosis are common infections that that many of use have (65% and 10% of americans, respectively). Both of these are chronic, latent infections that can occasionally ...
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2 votes
0 answers
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Population-biology, migration-patterns, & ethology of the Big Five (elephants, rhinos, lions, leopards, & buffalo) in S. Africa's winter months?

I know that animals are unpredictable, but I also know that there are seasons in which the wildlife are more active. Now, August in South Africa is still their winter season, which is emerging into ...
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8 votes
2 answers
139 views

Is it mostly true that predators or parasites traverse wider spatial areas than their prey or hosts?

Does it tend to be true that as you go up the food chain, the species tend to cover wider areas? I am basically asking whether a population's prey varies spatially more than a population's predators ...
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4 votes
2 answers
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Is there a reliable estimate of the number of cells on Earth?

A quick Google search didn't turn up any reliable sources. An awkward Cosmoquest thread gives a rough estimate of 10^25 to 10^32, but this is just a bad extrapolation of the number of cells in a human ...
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0 votes
1 answer
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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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5 votes
1 answer
1k 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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1 vote
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How many animals inhabit the United States?

How many animals inhabit the United States and its waters? Not the number of species, but the number of individual animals. And since animals are diverse, maybe we can limit the estimate to just ...
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0 votes
1 answer
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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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3 votes
1 answer
106 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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2 votes
2 answers
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What are the migratory patterns of Orcas in the Pacific Northwest? Do they pass by Vancouver in the Fall?

What are the migratory patterns of Orcas in the Pacific Northwest? Do the pass by Vancouver in the Fall? I know you can never predict the sightings of a wild creature, but I was wondering what the ...
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