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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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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2answers
42 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 ...
13
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1answer
274 views

What is the percentage of people living in England in 1500 AD whose lineage is still alive?

This sounds a bit random, but it stems from a lecture in statistical genetics which I attended a while ago. We were shown a population lineage graph from which it was clear that most lineages ...
12
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4answers
376 views

When are population dynamics models useful?

When are population dynamics models useful? There seems to have been a lot of research about it, but how does it help? If I need data about how a population will evolve under what conditions, I need ...
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1answer
85 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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0answers
52 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 $p$, ...
3
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0answers
48 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 $F_{ST}$ (...
12
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1answer
7k views

How many mice are on the Earth?

We are 7 billion human beings on the Earth. But how many mice are there? How would you estimate such a number?
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3answers
533 views

Genetic Diversity and Adaptation

I am somewhat new to evolutionary biology, having studied it on my free time as a computer science student. There is one particular thing that has always bothered me for which I have not seen a good ...
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1answer
46 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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0answers
23 views

Monod Kinetics--Growth of E.Coli in a Bioreactor

I am doing a study for a lab class. We are growing E. Coli in a bioreactor. We want to vary the volume of the initial biophase which we add after the substrate has been brought to 37 degrees C. My ...
4
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1answer
187 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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3answers
377 views

Why are the fertility rates of large predators kept low?

Predators at the top of a food chain, like lions, seem to have a relatively low fertility rate, which fits well to the ecosystem and avoids overpredation. But what is the mechanism that keeps the ...
8
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2answers
108 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 ...
0
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0answers
38 views

How many children could Hunter-Gatherer support?

Hunter-Gatherers, to my knowledge, have to cover a fair amount of ground in order to be able to live off the land. This ought to have a placed a limitation on the number of children that they could ...
11
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1answer
164 views

How big should the human population be, as predicted by body mass?

I would guess there is a theory in biology which states that the population size for a given species is inversely proportional to the body mass of individuals in that species. In other words, there ...
6
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1answer
176 views

Is it theoretically possible to restore the Tiger population to 100,000?

The current global Tiger population is roughly 5100 according to Wikipedia. With habitat destruction and poaching continuing and no effective improvement in conservation, most likely the Tiger ...
7
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2answers
330 views

How does Natural Selection shape Genetic Variation?

Background Importance of the additive genetic variance As stated here, the fundamental theorem of Natural Selection (NS) by Fisher says: The rate of increase in the mean fitness of any organism ...
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1answer
97 views

Why did the yeast rise?

Here are the notes I made for an experiment I was doing (I didn't put it here as it is too long) (please ignore the numbers at the end of the pdf file) The graph looks like this: As you see on ...
2
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1answer
77 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 ...
6
votes
1answer
101 views

How can we calculate the minimum sustainable number of the panda population?

I have a degree in Biology so I'm a little embarrassed that I never learned this, but... How do we know 1600 Pandas isn't enough? I know that we have historical numbers (although I couldn't find ...
6
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0answers
65 views

Variance in Fst in the infinite island model

The most famous result in the study of structured populations come from Sewall Wright. He showed that in an island model, where each subpopulation is of size $N$ and the migration rate is $m$, then ...
5
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2answers
106 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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2answers
257 views

Examples of prey predator interactions where density of predator is very low and prey form groups when the predator attacks the prey for food

Examples of prey predator interactions where density of predator is very low (has a threat of extinction) and prey form groups when the predator attacks the prey for food. I have searched this in ...
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2answers
747 views

Is global life expectancy normally distributed?

I am trying to find out what the world distribution of life expectancy looks like.
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1answer
61 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, ...
10
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1answer
222 views

Expected time for a neutral allele to reach a frequency of $p_1$ when starting at frequency $p_0$

Kimura and Ohta (1968) showed that the expected time for a neutral allele to reach fixation (given that it will reach fixation) is $$\bar t(p_0)=-4N\left(\frac{1-p_0}{p_0}\right)\ln(1-p_0),$$ where ...
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1answer
18 views

Where can I find a global life expectancy table?

I've found good information on specific countries and demographics, but I can't seem to find global numbers. I know that the world life expectancy is around 71.0, but I'm trying to get a percentile ...
0
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1answer
88 views

Neanderthal and modern human population sizes

Are there any estimates of both the modern human and Neanderthal population sizes over the last, say, 100 k years? Since "purebread" Neanderthals are extinct, their population has to hit zero; that ...
4
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2answers
85 views

Is it possible for two people to repopulate earth? [closed]

Today I was wondering this question whether it is possible for two people to repopulate Earth. What if everyone else disappeared, except for two people (man & woman)? Can they repopulate? In ...
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1answer
30 views

Genetics of Hybrids

I'm working on this problem, but I'm not sure I've done it correctly. My initial thought was that the answer was $D$, but I don't see anything in the above graph that indicated the Hybrid species is,...
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1answer
42 views

What are the limiting factors of pathogen population size in human populations?

I understand that one limiting factor in non-human animal populations is that increased pathogen populations decrease animal populations from killing them, which decreases the density of the animals, ...
6
votes
1answer
178 views

Effects of selection on effective population size

Background The effective population size ($N_e$) is a central concept of evolutionary biology and is influenced by several parameters. For example: sex ratio bias affects $N_e$ $\left(N_e = \frac{...
3
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1answer
558 views

Why do genetic drift generates negative linkage disequilibrium?

The very first sentence of the abstract of this article is: "In finite populations subject to selection, genetic drift generates negative linkage disequilibrium, on average, even if selection acts ...
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1answer
73 views

History: Do evolutionary and ecological processes occur at the same timescales?

Classically, it was thought that evolutionary processes occurred at a much slower pace than demographic/ecological processes. Nobody, ever thought about incorporating both processes into the same ...
2
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1answer
202 views

Why does the number of mutations per individuals follow a Poisson distribution?

I was reading this review. On page 11, left column, first paragraph, one can read: [..] there is a Poisson distribution of the equilibrium number of mutations per individual, if fitness effects ...
4
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1answer
119 views

Forward versus backward numerical simulations in population genetics

My question is closely related to this post. There are a number of existing platforms to perform numerical individual-based simulation in populations genetics. An almost exhaustive list of such ...
2
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1answer
79 views

Better population models than the logistic equation [closed]

For modelling the population of a single species in a region, the logistic equation is used $$ \frac{dN}{dt} =kN\Big(1-\frac{N}{K}\Big) $$ where $N$ is the number of organisms, $K$ is the carrying ...
4
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0answers
32 views

How to calculate the number of sterile insects that must be released in SIT?

The sterile insect technique (SIT) is used to control insect pests through overwhelming the population in sterile males. The increase in sterile males released into an environment causes the increase ...
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0answers
33 views

Analytical Methods for Estimating Probability of Fixation

The probability of fixation $P$ of an allele is an very important measure and there exists several solutions to estimate this probability. Each method has its own assumptions and it is often hard to ...
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0answers
59 views

What is the probability of fixation for a mutant under fluctuating selection?

Here is an answer which explain how one can model the frequency of an allele that is under fluctuating selection (selection that varies through time). Not, thinking about fluctuating selection, there ...
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2answers
8k views

How many organisms have ever lived on Earth?

I've looked for some information on this, but couldn't find anything useful. Has there been any noteworthy attempt to estimate the sum amount of individuals of all species that have ever lived on ...
4
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1answer
151 views

Fixation rate at neutral loci

It is a classical result that the expected time for a neutral mutation to occur and to get fixed is $2 N \mu \frac{1}{2N} = \mu$, where $N$ is the population size and $\mu$ is the neutral mutation ...
4
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1answer
161 views

Chaos theory and population cycles of odd periodicity

I have just begun to read about Chaos theory and have come across the statement that "Period three implies chaos." My question: Does any odd period imply chaos or only 3? If so, how can populations ...
5
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2answers
177 views

Premise of life cycle synchronization between predator and prey

While reading about the predator satiation hypothesis of the periodical cicadas' 13/17 year life cycles, I started wondering about its premise. By the way, I understand the math behind the prime ...
9
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4answers
1k views

What prevents predator overpopulation?

I've often heard that a population, human or otherwise, will continue to grow as long as there is food available (assuming nothing else is killing them off). It makes sense: if you have food you can ...
8
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0answers
103 views

How to define “Quasifixation” in continuous approximation of finite population?

Background Many models including the famous very first models derived by Sir Ronald Fisher in his early career, assume infinite population size. In an infinite population, an allele can rise in ...
3
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1answer
87 views

Mutation Rate in Multicellular Eukaryotes

I always hear people saying that the mutation rate is around $10^{-6}$ or $10^{-7}$. I don't even know if this number is the mutation rate of genes or of a single nucleotides and I actually (almost) ...
4
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480 views

Mutation-Selection-Drift Equilibrium

mutation-selection-drift equilibrium is one of the most important concept of population genetics. I could easily find the calculations for mutation-secltion equilibrium and for mutation-drift ...
4
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1answer
166 views

How to calculate the effective population size ($N_e$) with overlapping generations?

From this Source: If generations are overlapping, then the effective population size $N_e$ does not equal the population size $N$. I know mathematical formulations in order to find the effective ...