Questions pertaining to populations of organisms.

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7
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3answers
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Evolution: One big population vs. many small populations

Let's say I want to evolve a bacterium that is resistant to an antibiotic. I want to do this by growing initially clonal populations of bacteria in presence of this antibiotic for a long time. I have ...
4
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1answer
41 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 ...
3
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0answers
35 views

How many eukaryotes are there on Earth?

I have been reading: William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998. [Full Text] [PDF] ...
5
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0answers
41 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 ...
1
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1answer
71 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? ...
3
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0answers
62 views

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 ...
2
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0answers
47 views

What is the allelic frequency at mutation-selection-drift equilibrium?

mutation-selection equilibrium At mutation-selection equilibrium the expected frequency $f$ of a given locus is $$f ≈ \frac{\mu}{s\cdot h}$$ , where $\mu$ is the mutation rate, $s$ is the selection ...
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0answers
30 views

Effects on Bear Population [closed]

imagine in a given area or an ecosystem ,bear hunting is totally banned, but there is a scarcity of food for the bears. i want know what would be the future of the bear population?. and want to derive ...
1
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1answer
63 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 ...
2
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0answers
100 views

Software to calculate Fst from sequence data

I'm looking for a software to calculate Fst from 3 loci DNA data of individuals from a metapopulation. I don't have any prior on the population structure (have no idea of the number of subpopulations ...
6
votes
1answer
94 views

Can we really 'discover' 85% of mammalian viruses?

This virology [blog] discusses estimates of the number of mammalian viruses and the costs of 'discovering' 85% of them. My question is whether this is not a forlorn hope. The ".632 rule" in ...
2
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1answer
44 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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0answers
43 views

$F_{ST}$ 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 $F_{ST}$: $$V_{Among Pop} = 2 F_{ST}V_G$$ ...
1
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1answer
62 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 ...
1
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1answer
77 views

Coalescent theory - independence of coalescent times

Let $T_i$ be the time to coalesce from $n(t)=i+1$ to $n(t)=i$, where $n(t)$ is the number of sites that have not coalesced yet. In the below example the maximum $n(0)=6$. As I understand it, many ...
3
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1answer
82 views

Inbreeding depression and dominance

From this article, second paragraph of the second page A classic theoretical result is that the mean of a character controlled by a single locus i with two alleles Ai1 and Ai2 is only affected by ...
0
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0answers
46 views

How important is the womb's environment?

- Background - Talking about one phenotypic trait, the total phenotypic variance $V_p$ is decomposed into genetic and environmental variance for this trait, represented by the symbols $V_G$ and $V_E$ ...
0
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1answer
61 views

Defining: Evolutionary (quantitative) Genetics and Population Genetics

How do we define the fields that are Evolutionary (quantitative) genetics and population genetics. What set these two fields apart? Can you try to provide definitions? To my intuitive understanding, ...
1
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1answer
134 views

Heterozygosity and overdominance

Consider $m$ loci with heterozygote advantage (overdominance) such that the fitness of the two homozygotes is $1-\frac{s}{2}$ and the fitness of the heterozygotes is $1+\frac{s}{2}$, where $s>0$. ...
1
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1answer
34 views

Coalescent Theory - Probability for $k$ alleles that of one coalescence event occured $t+1$ generations ago

From this textbook Under the wright-Fisher model of genetic drift and under the assumption that all alleles are neutral, the probability that $k$ alleles had $k$ distinct parent alleles the previous ...
3
votes
2answers
92 views

Heterozygosity under genetic drift

The wright-Fisher model of genetic drift is: $$p_{ij} = \binom{2N}{j}\left(\frac{i}{2N}\right)^j \left(1- \frac{i}{2N}\right)^{2N-j} $$ ,where $\binom{2N}{j}$ is a binomial coefficient. From this ...
3
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1answer
74 views

Book recommendation on selective breeding?

I am looking for a good book that gives a nice overview of the science and technics of selective breeding. I am particularly interested in the use of population genetics to support decision in this ...
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2answers
92 views

Effect on fitness of mutations

What is the distribution/probability density function (PDF) of impacts on fitness of new mutations? I very welcome any partial answer that does not give the whole PDF but just some information ...
1
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1answer
38 views

Dominance/recessivity of new mutations

What is the distribution/probability density function (PDF) of recessivity/dominance of new mutations? I very welcome any partial answer that does not give the whole PDF but just some information ...
1
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1answer
61 views

Additive genetic variance with $n$ loci

The genetic variance of a quantitative trait (the quantitative trait in question is fitness) can be express as the sum of two components, the dominance and additive variance: $$\sigma_D^2 + ...
1
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1answer
97 views

Additive genetic variance with $n$ alleles

The genetic variance of a quantitative trait (the quantitative trait in question is fitness) can be express as the sum of two components, the dominance and additive variance: $$\sigma_D^2 + ...
3
votes
2answers
481 views

Initial population when i count backwards?

My question is dealing with how many ancestors it took to produce me: --> to produce me it took 2 people (my parents) = ($2^1$) people = 2 --> one generation further included = ($2^1 + 2^2$) people ...
4
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1answer
552 views

How do I calculate the change in allele frequency in a haploid population under selection?

From this book For simplicity, let us consider a haploid organism and assume that the frequencies of alleles $A_1$ and $A_2$ are given by $x$ and $y=1-x$, respectively. We also assume that the ...
4
votes
1answer
120 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 ...
5
votes
2answers
70 views

Linkage disequilibrium with multiple alleles and loci

Linkage disequilibrium $\left(D\right)$ for two bi-allelic loci is defined as: $$D=X_{11}X_{22} - X_{12}X_{21}$$ where $X_{11},\ X_{12},\ X_{21},\ X_{22}$ are the frequencies of the haplotypes ...
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1answer
71 views

Why will world population keep growing if all women have only 2.1 children

Why is it that, even if we were going to immediately agree that every women will not have more than 2.1 children on average, the world population would continue to grow for another 60 years? I've ...
4
votes
1answer
204 views

Why does the slope of parent-offspring regression equals the heritability in the narrow sense?

Background ---- Notations and assumptions ---- let $W_{ij}$ be the fitness associated to the genotype $AiAj$. $x$ is the frequency of the allele $A1$ in the population. The frequency of the allele ...
2
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1answer
197 views

Why do genetic drift generates negative linkage disequilibrium?

The very first sentence of the abstract of this article are: "In finite populations subject to selection, genetic drift generates negative linkage disequilibrium, on average, even if selection ...
6
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1answer
190 views

What percentage of the (additive or not) genetic variance is explained by the 'n'- most important loci?

Standard models in population genetics look up at the evolution of few loci which impact fitness. The variance in fitness is determined by the genetic variance and the environmental variance (and the ...
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1answer
113 views

Definition of “Regime of selection”

How would you define Regime of selection (or Selection regime)? In addition to a accurate definition, a developped example ...
2
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0answers
31 views

How has the use and subsequent ban of DDT affected insect populations?

Living in Australia there were less ticks for example during the use of DDT, now there are more ticks prevalent here. I am wondering if any insect species have declined permanently as the result of ...
6
votes
1answer
92 views

Is there a website that shows population sizes?

I'm looking for a website that shows the population sizes of a species (doesn't matter which) as a function of time at a geographic coordinate. Is there a government website or other free database ...
3
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1answer
58 views

Does a large effective population size result in faster decay of linkage disequilibrium (LD)?

I am thinking about an invasive species that was introduced into North America just a few (<20) generations ago. Using microsatellite genotypes (105 loci), I have identified almost no significant ...
1
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1answer
121 views

Population genetics and the fitness probability distribution. Why is the arithmetic mean all we need?

When recording change in allele frequency in diploid, bi-allelic, infinite and panmixic population we usually use this kind of equation: $\delta_p = \frac{p * q *( p (w11 - w12) + q * (w12 - ...
1
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1answer
639 views

How many honeybees are there, and how has the number changed across time?

How would you begin to estimate the world population of the European Honeybee (Apis mellifera)? Would recent colony collapse disorder show up as a blip? How about the spread of A. mellifera from ...
3
votes
1answer
64 views

To what extent is immature eggs in insects (beetles) a good approximation for maximum fecundity?

To what extent is the number of immature eggs from dissected, newly emerged individuals a reasonable approximation for maximum/potential fecundity in insects (more specifically beetles)? I know that ...
1
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1answer
99 views

Hardy-Weinberg applied to three alleles and stimation of allele frequencies

I have this equation: Corresponds to HW in equilibria with three alleles: $(p+q+r)^2=1$ Expanding the square results: $p^2+2pq+r^2+2pr+q^2+2qr = 1$ I need to separate homozygous and ...
6
votes
1answer
189 views

What is the minimum population size that Hardy-Weinberg calculations can be applied to?

I'm trying to find out if a particular allele is in Hardy-Weinberg disequilibrium, but the data is poor. What's the minimum population number that you can use to get any sort of respectable ...
5
votes
3answers
280 views

What is the inbreeding coefficient for the female offspring of a sib-mating in a haplodiploid system?

The inbreeding coefficient of a sibling mating for a diploid organism is 0.25 (each allele has a 25% of being identical by descent in the offspring). In haplodiploid organisms, males result from ...
11
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1answer
106 views

Vaccination and population dynamics of an epidemic

I'm trying to figure out how should a vaccination model be built to correlate with population density, and I'm having problems to understand meanings of the results I receive when I apply theory on ...
3
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2answers
667 views

Does finite rate of increase depend on mortality of individuals in a population?

As written in my lecture handouts, there two main factors in the Geometric Growth Model of populations: $R_{0}$ is the expected lifetime reproductive output. This way, for unicellulars, for example, ...
3
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1answer
69 views

What's in a Name: Statistical Genetics

The novice often performs population calculations using what is referred to as Mendelian Genetics. Soon after the publication of Mendel's results; Hardy and Weinberg presented their results after the ...
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1answer
770 views

How does population stability evolve?

The number of individuals constituting a population is called population size. Over time population size does not remain constant, it fluctuates to different extent over generations because of ...
5
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2answers
144 views

Difference between biological control and introducing species for conservation?

I have a biology assignment and we have to explain various methods and strategies for conservation, two of which are: Biological control Introduced Species What is the difference between ...