Questions tagged [population-biology]
Questions pertaining to populations of organisms.
146
questions
19
votes
2
answers
579
views
Was the recent "conservation hunt" of a black rhino supported by science?
CNN recently covered a sanctioned black rhino hunt in Namibia by Texan Corey Knowlton, who bid US$350,000 for the license. In the story, he claims that the hunt was actually supporting conservation of ...
- 15.2k
15
votes
1
answer
201
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 ...
- 317
11
votes
2
answers
6k
views
Is global life expectancy normally distributed?
I am trying to find out what the world distribution of life expectancy looks like.
- 470
11
votes
1
answer
440
views
What percentage of the fitness variance is explained by the 'n'- most important loci?
Introduction
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 ...
- 68k
10
votes
1
answer
2k
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 ...
- 529
9
votes
1
answer
20k
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 ...
- 5,789
9
votes
1
answer
115
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 ...
- 16.7k
9
votes
1
answer
14k
views
How should species density be calculated for a clumped distribution?
Lets imagine 5 plots of different size are sampled for a target species:
...
- 248
8
votes
3
answers
2k
views
What is called the "area size that an animal usually lives in"?
What is called the "area size that an animal usually lives in" or "needs for a normal life"? Is there any specific term?
- 193
8
votes
1
answer
124
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 ...
- 369
8
votes
1
answer
3k
views
Effect of sex-ratio on the effective population size
As stated on this wikipedia article, the effective population size $N_e$ when the sex ratio differs from $\frac{1}{2}$ is
$$N_e = \frac{4N_mN_f}{N_m+N_f}$$
I understand the biased sex-ratio ...
- 68k
8
votes
3
answers
1k
views
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 ...
- 4,480
8
votes
1
answer
2k
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]
...
- 507
8
votes
2
answers
147
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 ...
- 466
8
votes
2
answers
206
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 ...
- 68k
8
votes
1
answer
186
views
Basic Modelling in Quantitative Genetics
I am pretty bad in thinking quantitative genetics models. I am trying to get some basic understanding of modelling the evolution of a quantitative trait. I am therefore asking for help to analyze a ...
- 68k
8
votes
1
answer
617
views
What sample sizes are ideal for carrying out Bayesian Skyline Plots?
I am interested in creating Bayesian Skyline Plots to look at demographic changes in certain population groups. However, these populations have very little within population variation. Around 5 ...
- 432
7
votes
1
answer
201
views
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 ...
- 171
7
votes
1
answer
1k
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 conclusion?...
- 1,131
7
votes
2
answers
219
views
Within and Between Allelic Class Diversity
I am reading Charlesworth et al. 1997. They talk about diversity within and between allelic classes.
Nucleotide diversities ($π$) at each neutral site were estimated from the mean of $2 \sum z_t (1-...
- 68k
7
votes
1
answer
68
views
Finding population dynamics models for multi-generational species evolution with delays
I am working on a problem from economics, to understand how populations evolve within business organizations. I have found that some of the population dynamics literature is very relevant to my own ...
- 173
7
votes
1
answer
1k
views
Understanding F-statistics in population genetics
I am reading the classic Weir and Cockerham 1984 paper about $F_{ST}$ estimation. At the beginning (first page, right column), they define 3 statistics.
$F$ is the correlation of genes within ...
- 68k
6
votes
2
answers
509
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,
$$...
- 183
6
votes
1
answer
105
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 ...
- 3,832
6
votes
1
answer
134
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 ...
- 2,799
6
votes
1
answer
323
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 ...
- 68k
6
votes
0
answers
205
views
How does the population fitness change 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 ...
- 68k
5
votes
3
answers
2k
views
Initial population when I count backwards?
My question deals with the number of 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$) ...
- 153
5
votes
3
answers
2k
views
Exponential growth equation and bacteria
I'm a microbiologist, but I'm teaching some ecology in my intro-level course, so when we got to population growth, I thought I'd use the example of a microbial population. But, I hit a strange problem ...
- 86
5
votes
1
answer
4k
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 ...
- 68k
5
votes
2
answers
997
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 these? ...
- 199
5
votes
1
answer
812
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 ...
- 68k
5
votes
1
answer
2k
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 ...
- 68k
5
votes
2
answers
819
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 $...
- 68k
5
votes
1
answer
113
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 ...
user22339
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 ...
- 268
5
votes
1
answer
749
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 ...
- 68k
5
votes
3
answers
1k
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 ...
- 698
5
votes
3
answers
216
views
Human Demography - Where can I find this statistic?
In "An Introduction to Genetics" by David J. Merrell, copyright 1975 by W.W. Norton + Co., p. 742, in the Chapter "Genetic Counseling and Eugenics," the author states: "... 50% of the women produce 85%...
- 151
4
votes
2
answers
259
views
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):
...
- 51
4
votes
1
answer
1k
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 ...
- 68k
4
votes
1
answer
777
views
How could one calculate the gene flow between two populations?
Imagine there are two populations X and Y, and for each population you have the genotypes of each individual in that population (e.g. Aa, AA, aa, etc.), but for multiple loci (e.g. AABb).
How could ...
- 3,577
4
votes
1
answer
453
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 ...
- 68k
4
votes
1
answer
139
views
How do susceptible organisms prevent parasites from overcoming resistance?
Bt corn is genetically modified to kill borers, but "regulations require farmers to plant conventional varieties as well, which is intended to stop the borers becoming resistant."
-Source
How do ...
- 1,667
4
votes
2
answers
2k
views
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 ...
- 315
4
votes
1
answer
263
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 ...
- 171
4
votes
1
answer
286
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) ...
- 68k
4
votes
1
answer
73
views
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))...
- 141
4
votes
1
answer
174
views
Expected reproduction rate of a dandelion and/or fern
I am working a basic mathematical/computer simulation of an ecosystem, and I need to know the birth rate of each organism in my simulation. However, I could not find any data for how often a small, ...
- 141
4
votes
2
answers
5k
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, ...
- 317