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Let's consider a possible scenario, with a simplified assumption that red hair is a simple Mendelian recessive trait.
Let's say we have a population that is 10% red hair. Everyone with red hair lives on one island, and they only breed among each other. They all have red hair, so we can infer they are all homozygous recessive (rr) for that trait. Everyone ...
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Going through the possible answers
(A) Rates tend to be very high in most populations.
This is a very unclear statement. What does "high" mean? In humans, the average mutation rate per reproduction per nucleotide is of the order of $10^{-8}$ (Rahbari et al., 2016) (hence of the order of 10 - 100 mutations for the whole genome). Whether someone ...
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TL;DR
I'd recommend Population Genetics: A Concise Guide (Gillespie) for an introduction to population/evolutionary genetics (thanks AGS for highlighting this big miss of mine on the first version of my answer).
I'd recommend A Biologist's guide to mathematical modelling in evolution and ecology (Otto and Day) if you want to ensure your knowledge in ...
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I think one of the important things to understand in thinking about this case is that it just hasn't been that long, generationally.
Escobar imported the hippos in the late 1980s. Hippos reach sexual maturity at an average of about 7.5 years old for males and 9.5 years for females, space births about 2 years apart, and live for 40-50 years. Thirty years out,...
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@Remi.b's list is excellent, but it should also include Gillespie's Population Genetics: A Concise Guide.
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Good literature work here and good question +1! In short, your main mistake was that you based your calculations on a single site and not on the whole genome. More info below.
Genome-wide vs sites specific mutation rate
The statistic of $10^8$ generations that you computed is the average rate of fixation of new neutral mutations per site. As considered the ...
14
Plane Crash Analogy
4 people in a plane crash
In a small aeroplane, there are 2 people that wear a blue shirt and 2 people that wear a green shirt. The plane crashes, half of the people died. The 2 survivors are those wearing the green shirt… well, nothing so surprising!
400 people in a plane crash
In a very big aeroplane, there are 200 people that wear ...
14
Frequency-dependent selection is the term you are looking for, I believe. Positive frequency-dependent selection encompasses traits that become more advantageous as they become more common. Negative frequency-dependent selection encompasses traits that become more advantageous as they become rarer.
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In a genome that is 3 billion base pairs, a difference of 0.5% works out to a difference of 15 million bases. When a single base change can change the amino acid sequence of a protein, that can add up to a huge amount of diversity, which is what we see over the nearly 8 billion humans on the planet, and the 99.5% sameness is why we are linked together so ...
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It will be clear with a simple analogy.
You are 50% related to any one of your parent
Let's say you don't have any biology books. You have two friends, Alice and Bob. They each give you a copy of the book Campbell Biology. You now have two Campbell Biology. You have received 50% of your Campbell biology books from Alice and 50% from Bob.
Similarly, you ...
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After reading your question, I had a vague memory that this subject was indirectly touched upon in "On the Origin of Species", so I did some text searches (in this pdf version I found online). From what I can see, Darwin never used the technical term 'variance' (I don't know how old this use of the word is), but 'variability' is often used, both with regard ...
9
Queens do not generally breed with their brothers, but with males from other nests. In the life cycle of bees (and other social Hymenoptera), new queens are born late in the season along with haploid male drones. These all leave the nest and disperse in the landscape to find mates to reproduce with. After mating, all males die and the queens overwinter to ...
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Short answer
The claim is unclear but is essentially misleading and wrong. However, IMO, for lay people, it is a good approximation to just think that mutations are random!
Here, on Understanding evolution is a great source of information on what it means to say that mutations are random
Long answer
What is a mutation?
Mutation is an event causing an ...
8
Genetic drift refers to changes in allele frequencies that are due to random sampling effects, and not selection. If you sample alleles from a finite population (e.g. caused by the fact that only some individuals in the population reproduce each year), the resulting frequencies will deviate from the original frequencies due to random chance. If your sample ...
8
You can use power analysis to work out answers depending on the specifics of your data. The things you need to consider are:
The power of the test. This is the probability that the test will
fail to reject the null hypothesis even if in truth it is false
(Type II error). If the population is not in equilibrium, what is
the probability that the test will ...
8
The reason that an unequal sex ratio affects the effective population size is because offspring are produced by one male and one female parent, and an unequal sex ratio increases the rate at which genetic drift will occur.
"...the smaller number of males still contributes half of the genes in the next generation..."
In other words, assuming the male ...
8
They often do. You hear a lot about all of the times invasive species succeed in invading a new habitat, because there is a surviving population around for researchers to observe. There are lots of cases where new species are introduced to an environment in a single event but fail to survive. Rabbits and foxes were repeatedly introduced to Australia, only ...
7
Here is my full derivation to the book example you gave, hopefully it'll help you clear up what went wrong:
You need to remember that after there is selection acting on the population, you no longer have a total of 1 after selection. Think of selection as "killing" individuals, which means the total is now 1 minus what has been "selected out". sy is what is ...
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I personally like the Primer on Population Biology by Wilson and Bossert. For a book that is almost 45 years old, it holds up pretty well. One of the best things about this book is that they provide examples and then walk through the solutions step by step. Once in a while it gets a bit too mathematical for this Biologist, but overall, I find it readable and ...
7
Not relatively short, but I'm going to repeat a recommendation I just made in another thread. Population Genetics and Microevolutionary Theory by Alan Templeton covers many of the topics listed above, and is heavy on the self-learning of various population structure statistics, with examples. It is an introductory textbook with for people with some ...
7
Speciation in sexually-reproducing organisms can be identified as the inability to produce viable offspring. In other words, when two suspected sub-species are not able to produce viable offspring, they can be considered to be two species. In this case it is not so much determined at the molecular level, but at the organismal level.
This mating procedure ...
7
As you probably know, there exists many different species concepts (or definitions of species). Often, you see a separation into at least six different categories of species concepts, which are then often subcategorized futher (and they can also overlap to some extent), namely:
Biological species concept
Phylogenetic/cladistic species concept
Evolutionary ...
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No, not necessarily!
The terms might be confusing I agree. The most common allele (the wild type allele) might be a mutant of one other type of allele (one mutant allele) present in the population.
The reason we call the least common alleles the mutant alleles is that beneficial mutations are rare compared to neutral or deleterious mutations. If at a given ...
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Though broad, here I provide a summary in graphical way.
Mitosis:
.
MEIOSIS: 2 successive steps : Meiosis-1 and meiosis-2
Meiosis-1
Meiosis-2
So lets see what happens with cells given at question.
1. Cell with genotype Aa
(monohybrid or one-point cross-experiments; that means we are looking to gene-pair at 1 loci; not looking to any other genes):
...
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You are right. Inbreeding strongly increases overall homozygosity which subjects inbred individuals to diseases caused by rare recessive alleles. In non-inbred individuals the chance is quite low to receive those because many deleterious variants (and in fact, most segregating alleles we can observe) are recessive. Most often, but depending on the dominance ...
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Here is a tree based on mitochondrial DNA variations in human populations.
van Oven M, Kayser M. Hum Mutat. 2009 Feb;30(2):E386-94.
Updated comprehensive phylogenetic tree of global human mitochondrial DNA variation.
Looking at genetic distance between populations via mitochondria DNA, all nonafricans are descended from a founder in one mtDNA group (L3). ...
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There are some references on this: Castelblanco-Martinez, 2021 is a recent one. There doesn't seem to be much doubt at least that hippopotami are thriving as an invasive species.
I didn't see anything on the genetics, but I will give in to the temptation to speculate even if perhaps I shouldn't. There are some advantages that are likely working against the ...
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Your calculations are the following. Assuming non-overlapping generations, the number of ancestors you have in the last $t$ generation is given by:
$$\sum_{i=1}^t 2^t$$
This sounds correct. But there are some very strong assumptions:
Generations are non-overlapping. A more realistic model would need to consider $t$ as a continuous variable a give a ...
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Well, I think I found the very simple mistake I made…
Looking again in my equations, I realize that (for some reason) $cor = 2 \cdot \frac{\sigma_A^2}{\sigma}$
And looking at this website, I see that the slope of the parent-offspring regression is $\frac{h_N^2}{2} = slope$
Here was my mistake!
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The topic you describe is very interesting and known as "species selection." Some traits exist that not only affect the reproductive success of individuals, but also affect the diversification rate of the entire species, either through affecting the extinction rate, the speciation rate, or both.
To give you an example, I'll summarize this paper by Goldberg ...
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