Questions tagged [population-biology]
Questions pertaining to populations of organisms.
146
questions
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 = ($2^1 + 2^2$) ...
- 697
2
votes
1
answer
198
views
Impact of Natural Selection on Population Size [closed]
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 ...
- 9,122
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 ...
- 9,122
1
vote
1
answer
892
views
How do you convert mtDNA sequences in FASTA to FSTAT format?
I've got control region sequence data from a population of shark and I'm looking to convert this from FASTA to FSTAT in order to calculated the effective population size of females. The software I ...
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 ...
- 5,324
1
vote
1
answer
109
views
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 ...
- 5,324
0
votes
1
answer
91
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 ...
- 5,324
2
votes
2
answers
180
views
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 ...
- 191
0
votes
1
answer
61
views
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 ...
CommunityBot
- 1
1
vote
1
answer
204
views
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 ...
- 12.2k
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
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
2
votes
4
answers
19k
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 ...
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,
$$...
- 191
0
votes
0
answers
22
views
The evolution equations under different year classes of a age-structured model?
This sounds a bit complicated but I want to grab more feelings on age-structured problems. Less than 2 days to the exam so I appreciate any help.
So suppose we only get 3 year classes in a school at ...
- 111
1
vote
0
answers
16
views
Evolution equations of a 2-gender age-structure model?
This sounds a bit complicated but I want to grab more feelings on age-structured problems. Less than 2 days to the exam so I appreciate any help.
So suppose we get 4 age classes in a population census ...
- 111
2
votes
1
answer
111
views
Will Fst (inbreeding coefficient) always be a value close or at 0 in asexual populations?
FST is the average inbreeding coefficient of a total population. The equation is:
$F_{ST} = \frac{Var(S)}{Var(T)} $
$Var(S)$ = variance in the frequency of the allele between different subpopulations, ...
CommunityBot
- 1
0
votes
1
answer
147
views
Is it possible to determine the initial population given the final one?
It is possible to determine the initial population of, say, bacteria given a measure at a later time?
Let's say I use the logistic growth model
$$\dot N (t) = rN(t)\left(1 - \frac{N(t)}{K}\right)$$
...
3
votes
2
answers
66
views
Techniques to find out which species are endangered
Most countries have a list of endangered species and international organisations too issue such lists of vulnerable and endangered species.
What mathematical or statistical models are those estimates ...
- 425
-1
votes
1
answer
90
views
How many giant kelp are there per square meter?
In a high-density giant kelp (Macrocystis pyrifera) bed how many "holdfasts" or roots would there be per square meter of seafloor on average?
- 425
3
votes
1
answer
190
views
Coalescent theory - independence of coalescent times
Let $T_i$ be the time to coalesce from $n(t)=i+1$ to $n(t)=i$, where $n(t)$ is the number of sites that have not coalesced yet. In the below example the maximum $n(0)=6$.
As I understand it, many ...
- 2,799
2
votes
1
answer
82
views
What are the long term consequences of settling an isolated territory with an extremely limited gene pool?
I remember reading about a discredited theory - I'm afraid that, despite some frantic Googling, I've been unable to track down a link - which stated that Australia was first settled by a woman, ...
- 2,351
2
votes
1
answer
152
views
$F_{ST}$ when considering a multi-allelic locus
Sewall Wright defined the $F_{ST}$ in a metapopulation as being:
$$F_{ST} = \frac{\text{Var}(p)}{\bar p (1-\bar p)}$$
, where $p$ is a vector of frequencies of a given allele and $\bar p$ and $\text{...
- 9,122
2
votes
0
answers
52
views
Range for which the Verhulst-Pearl model is a good approximate
The Verhulst-Pearl model describes the growth of a population using the differential equation,
$$\frac{dN}{dt}=rN \left(\frac{K-N}{K} \right)$$
where N is the population (no. of organisms), r, the ...
0
votes
0
answers
111
views
How can we calculate the constants of the SIR model?
I am not a biologist by profession, but I am attempting to implement a simple SIR model from the following paper. The paper assumes the following constants are known:
rc = growth rate of ...
- 209
2
votes
2
answers
147
views
What proportion of the people who lived 1000 years ago have genetic descendants alive today?
For context, I've been wondering about this for a paper I'm writing (in philosophy). Really, I want to figure out the chances that someone alive today will end up still having descendants 1000 years ...
- 141
2
votes
0
answers
71
views
Is a nightly curfew an effective intervention strategy for limiting the spread of an infectious disease? [closed]
The governing bodies of several geographic areas hit by disease outbreaks will sometimes impose a nightly curfew on their citizens, restricting or limiting the ability of their citizens from going ...
- 244
0
votes
1
answer
40
views
Calculating Rate of Growth without a Population [closed]
Lets say that by studying individuals of a rare species, you have determined that species gestation period, age of sexual maturity, average time between pregnancies, maximum lifespan, and average ...
- 5,324
2
votes
2
answers
142
views
How to model species interactions on population size dynamic?
Here are two classical discrete time models of population size dynamic. The exponential growth model
$$N_{t+1} = r\cdot N_t \qquad\qquad(1)$$
and the logistic growth model
$$N_{t+1} = r\cdot N_t \...
- 35.2k
-1
votes
2
answers
224
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 ...
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:
$$p_i(t+1) = g_i(p(t))...
CommunityBot
- 1
1
vote
1
answer
81
views
Growth rate oscillation in the a population of non-interacting bacteria
I have come across this theoretical paper claiming that if you start a batch culture from a single E. coli cell, the exponential growth rate of the population defined as $$k = \frac1N \frac{dN}{dt}$$
...
- 136
1
vote
1
answer
34
views
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 ...
CommunityBot
- 1
0
votes
1
answer
51
views
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 ...
- 476
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, ...
- 88
2
votes
1
answer
161
views
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-...
- 68k
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 ...
CommunityBot
- 1
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 ...
- 1,198
3
votes
0
answers
94
views
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 ...
- 81
2
votes
0
answers
34
views
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 ...
- 569
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 ...
- 16.7k
1
vote
0
answers
701
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 ...
- 11
-2
votes
1
answer
338
views
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. ...
- 141
3
votes
1
answer
288
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}{...
CommunityBot
- 1
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 ...
- 44k
1
vote
1
answer
795
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 ...
- 16.7k
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%...
- 10.3k
1
vote
0
answers
32
views
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?
- 11
1
vote
2
answers
110
views
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 ...
- 3,346
2
votes
1
answer
205
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{...
- 5,324