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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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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56 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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37 views

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

I encountered the terms "reduced antipredator defense" and "reduced antipredator vigilance" in this book Can you help me to make sense of these terms?
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31 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, ...
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191 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 ...
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535 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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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 ...
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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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57 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 ...
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28 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 ...
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62 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 ...
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172 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 go ...
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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 ...
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132 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 ...
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33 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, ...
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166 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 ...
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85 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 ...
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75 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 ...
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31 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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29 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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41 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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196 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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96 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 ...
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233 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 ...
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83 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) ...
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85 views

Survival curve in early humans

The survival curve/function describes the probability of a given individual to survive to age $x$. In humans, today's survival function is very much influenced by medicine. This leads me to wonder ...
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71 views

How does the population fitness changes after a change in mutation rate

The mean population fitness as given by mutation load theory depends only on the genome-wide mutation rate ($U$). My question is: how many generations is needed to reach a new mutation load ...
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159 views

What is Environmental Robustness? Is it different from plasticity?

Hansen (2006) in his review uses the concept of environmental robustness independently of the other concepts of robustness (at pages 139 and 140) without defining ...
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154 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 ...
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168 views

Drake's Law. What is the genome-wide mutation rate and what are the estimates?

Drake's rule Drake's rule states that the genome-wide mutation rate is more or less constant across all species — from E.coli to the house sparrow. Data From what I think being Drake's original ...
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95 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 ...
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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 ...
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83 views

Can “human exclusion zones” in national parks for preserving Wolves and Grizzlies be a good idea?

There are National Preserves in the National Parks where some human activities are permitted. But can it make sense to create "exclusion zones" so no human would be permitted in a certain area, not ...
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160 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 = ...
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181 views

Interpretation of graph from evolutionary biology

I am studying evolutionary biology, and been presented with this graph: I am having some difficulties understand its meaning. For a start, why is time measured as a fraction of the population size? ...
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Understanding the meaning of $s$ and $t$ in a population genetics equation

Sewall Wright in this article (1937) at the end of page 313 gives the equation: $$\Delta q = (s+tq)q(1-q) \space\space\space\space\space\space\space\space\space(1)$$ This equation is an ...
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357 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 ...
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How many humans have been in my lineage? Is it almost the same for every human currently living?

If I were to count my father, my grandfather, my great-grandfather, and so on up till, say chimps, or the most common ancestor, or whatever that suits the more accurate answer, how many humans would ...
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48 views

Is there an association between environmental and mutational robustness?

The robustness of a genotype is the ability of this genotype to resist (always produce the same phenotype) to various parameters such as mutations and environment. The ability of a genotype to resist ...
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704 views

Fisher's Geometric Model for Dummies

Fisher's geometric model is still today one of the most important and fundamental model in evolutionary biology but it seems to me that most student in evolutionary biology don't really understand it ...
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268 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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273 views

What does “Mutational Variance” mean?

Background The concept of mutational variance can be found in many articles including this one for example. The mutational variance of a trait number $i$ can be found in the M-matrix in position ...
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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 ...
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Conservation Genetics - Book recommendations

Can you please give me some advice for a book in (evolutionary) conservation genetics that offers an in-depth review of the mathematical formulations used in this field. I read the book Evolutionary ...
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204 views

Start studying mathematical biology from basics

I am really passionate about theoretical and quantitative biology and I would like to build my future career around this topic. I've just got my bachelor's degree in biology (ecology) but scince I've ...
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115 views

What is the outcome of a human population starting with only 2 individuals? [closed]

Starting with a human population N = 2, is there any way the genetic variability seen today could have come about? I don't know that much about meiosis, but isn't there a very limited number of ...
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155 views

Does a top heavy population grow, decline or stabilize?

Imagine a population that has a larger proportion of older individuals than younger ones, what could possible happen to it in the future? I am guessing that if the older individuals reproduce, the ...
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56 views

$F_{ST}$ when considering a multi-allelic locus

Sewall Wright defined the $F_{ST}$ in a metapopulation as being: $$F_{ST} = \frac{\text{Var}(p)}{\bar p (1-\bar p)}$$ , where $p$ is a vector of frequencies of a given allele and $\bar p$ and ...
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$F_{ST}$ and the genetic variance in metapopulations

From this video (21'15''), the speaker gives the following formulae in order to calculate the between and among populations genetic variance from the $F_{ST}$: $$V_{Among Pop} = 2 F_{ST}V_G$$ ...
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187 views

Various Genetic Loads and their Definitions

In population genetics, we talk about several types of genetic loads (also called just loads). I am asking for a exhaustive list and a short definition. Here are for example some genetic loads that ...