Changes in the heritable attributes of populations of organisms over time. Major mechanisms include drift, natural selection, mutation, and gene flow (migration).

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Why is 2 sexes in an organism so common? [duplicate]

Sorry if this is a super simple question, but why do a lot of species have only 2 sexes? Some species just have 1 sex, but I've never heard of an organism having 3 sexes, for example. 3 sexes seems ...
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1answer
54 views

Why does all life use the same macromolecules in their genetic code?

There is no biochemical constraint of any sort, so why doesn't some other code work? Why is it specifically RNA/DNA?
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28 views

How octopus develops its imitation skill?

I've watched one documentary about a Mimic octopus which they can imitate another animals in several form e.g. a Lion fish, a Sea snake, a Flatfish, etc. My question is how these octopuses can have ...
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How did the double circulatory system evolve from the single circulatory system

I already learned how the mammal circulatory system (double circulatory system) evolved from the reptilian circulatory system. How did natural selection evolve the reptilian circulatory system and the ...
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Is it possible there were multiple origins of life? And, if so, why did the one which became the common ancestor between all organisms prevail?

I have learned that all currently-living organisms come from a common ancestor, which I theoretically understand. However, my professor in a class mentioned that there is a chance that there were ...
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Why do we turn darker in the sun?

I tried the all powerful google to answer this question - but I am not getting the answer I seek. I know we turn darker because the skin produces melanin. The question remains - why darker? I am a ...
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1answer
32 views

why didn't natives of south america evolve darker skin?

I understand that darker skin tone is caused by melanin which helps to protect against the extra UV radiation that comes from more direct sunlight. It evolved in Africa before we migrated away from ...
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26 views

Is our ability to distinguish water as 'completely clear' an evolutionary advantage? [closed]

We perceive a homogeneous mixture of water to be completely clear or see-through. If, for example, you leave that mixture of water open and outside for a week, you will notice that the water is no ...
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29 views

How did the tendency to perform death rituals evolve?

Both elephants and humans perform rituals when deaths occur. However, I do not see any evolutionary benefit of this. The rituals take time, which apparently could be better spent hunting, foraging, ...
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Why didn't humans evolve to reproduce identical twins all the time?

According to the selfish gene theory, it seems like because identical twins sometimes get produced, a mutation to a gene that says, "if you have an identical twin, be fully altruistic towards them" ...
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154 views

What are the theories behind zootoxin evolution?

I've always wondered how toxins secreted or emitted by certain organisms has evolved. Particularly, organisms that produce toxins as a deterrent to predators as opposed to organisms that use it to ...
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1answer
56 views

How did people's liking of ceremonies evolve? [closed]

Habitual group activities are prevalent across many animal species, particularly in mammals, especially in primates. However, I do not see any evolutionary benefit of this. 'Ceremonies' take time, ...
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35 views

Is there a correlation between mutation rate and recombination rate?

I have in mind that homologous recombination (HR) can cause mutations (indels and substitutions). I am wondering if this is true and if it is, then I am wondering whether this effect is really ...
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33 views

Extinction of species with extant descendants

From what I've seen, species such as Homo heidelbergensis which have extant descendants are classified as extinct, which makes sense as far as it goes. However, given that species exhibit a continuum ...
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Endothermy in different species

Birds and mammals are both endothermic, meaning they metabolically generate the heat they need to keep their body within a certain temperature ranger. But birds are closer relatives to reptiles than ...
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226 views

Is our genome decaying (see “Genetic Entropy”), and, if so, is this evidence for our genome being “young”?

In the book Genetic Entropy & the Mystery of the Genome the author says that the genome cannot be old because the genome is "decaying". Decay is a very subjective term, but in this case he means ...
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1answer
38 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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1answer
58 views

Is it “easier” for researchers to detect evolutionary ancestry than distance in the evolutionary tree?

I'm a researcher in another field who has wandered into a problem with applications to biology. I hope to sell my results by making the following statement: Given two species X and Y, it is ...
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1answer
46 views

What was the evolutionary reason for cross lateralization of the brain?

In the human brain the right hemisphere controls the left side of the body and the left hemisphere controls the right side of the body. What led to this development? Why doesn't the left side of the ...
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Why does our body exhibit bilateral symmetry? [duplicate]

Externally, we (humans) look symmetrical. However, internal organs don't show the same patterns of symmetry (heart being on the left side while the liver is on the right side, etc.). It is a bit ...
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0answers
36 views

Did modern alligators and caimans come from prehistoric crocodiles?

I know that crocodilians have been here since the time of the dinosaurs. I also know that crocodiles came first. But alligators have been here for a good 37 million years. Did alligators come from ...
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35 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 ...
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2answers
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Is Mutation Theory still “valid” for complex organisms?

I'm afraid like most people I suffer from having learned "A History of Evolution" in school, rather than cutting to the chase and learning the actual "up to date" version of the subject. (Imagine if ...
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1answer
48 views

How did evolution support sports, fun, entertainment etc [duplicate]

We know that many animals entertain themselves by playing games. But sports actually increases risks of death,or at least accidents. So why did evolution choose it? And why did evolution decide to ...
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4answers
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Why would a plant evolve to produce an addictive chemical?

It seems kind of anti-productive in terms of survival for a plant to produce an addictive chemical as that plant will constantly be sought after by animals that ingest it. In this instance, I'm ...
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76 views

Evolution of protein and protein efficiency

Suppose we have a bacterial protein that performs a function and let's say we can measure the efficiency of the protein. Let's say we have two species, species A and B, both of which have this ...
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81 views

What are the evidence that all life today descended from a common ancestor (LUCA), and which organisms (if any) challenge the concept?

If I understand correctly, the concept of the LUCA (last universal common ancestor) is based on the hypothesis that archaea and bacteria share common ancestry. In the realm of mathematics, the same ...
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143 views

Why are lions the only social cats?

We know that almost all cats are solitary. How did the Lions (Panthera leo) end up social animals? Do we have an explanatory evolutionary path describing how the Lions became social while the rest of ...
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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 ...
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1answer
63 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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2answers
98 views

Driving force for speciation for millions of species today

I would like to know if speciation really occurs (trans-speciation). Have we had enough time for millions of species? A creationist argument is that the slow changes in traits in organisms, taking ...
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1answer
103 views

Why is the pituitary gland located in the brain?

Why is the pituitary gland located in the brain in humans, instead of elsewhere in the body? Why would this be an evolutionary beneficial adaptation?
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1answer
69 views

Is there a schema for how human behavior is genetically determined?

It seem one can distinguish three different kinds of genetic determinism of common patterns of human behavior: behavior that is directly wired into our nervous system, e.g. face-related mirror ...
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1answer
39 views

What is variation in Speciation

I read a lot about speciation. To my knowledge, A species is often defined as a group of individuals that actually or potentially interbreed in nature and produce fertile offspring. Speciation is a ...
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Why are sight and sound prerequisites for intelligence?

Edward O. Wilson, in The Diversity of Life wrote (emphasis mine): Ninety-nine percent of the animals find their way by chemical trails. […] Animals are masters of this chemical channel, ...
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There aren't any animals like hornets that hunt large prey (like a rabbit, or even up to a deer), right? Why not?

There aren't any eusocial animals (hives of wasps, ants, termites, etc) that hunt large prey, are there? I'm thinking prey in the size range of, say, a rabbit, or even a deer. I can't see a rabbit ...
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Why are there no complex hermaphrodite land animals? [closed]

The title says it all. I know that 'complex' is a pretty ambiguous term to use, but I can't think of a more scientific term/definition for my meaning. I can't think of any large (larger then a small ...
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What form of reproduction did the first land animals use?

What form of reproduction did the first animals on land use*? Were they hermaphrodites, or did they have male and female sexes? [Is there a proper term for sexual separation in a species?] Were any ...
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75 views

Why is there a seeming dichotomy between mobility and photosynthesis?

At least among more complex organisms, I cannot think of any examples of highly mobile species (like animals) that also incorporate photosynthesis. Perhaps there are examples that I'm unaware of, but ...
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Wolbachia - cytoplasmic incompatibility

I read that cytoplasmic incompatibility in Wolbachia occurs when wolbachia-infected male insects mate with wolbachia-free female insects and produce non-viable offspring. By contrast, ...
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What chordata evolve first limb

I try to search when and what specie develop first bone limb. I also want to know when second pair develop. And first pair was front or back one? And why it stop only at 2 pairs. Are there any fish ...
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why do marine organisms orient with their bellies facing downwards?

why do marine organisms orient with their bellies facing downwards (like most creatures) given that they have relatively fewer constraints on their orientations than land or air organisms?
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Name/Examples of Traits whose benefit is non-obvious and/or which evolve despite apparent mal-adaptivness?

I'm a graduate student in cognitive science doing work on people's explanations and learning, particularly having to do with natural selection. Often, students misunderstand natural selection as a ...
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42 views

Saline solution for animals

A popular "well-known fact" is that all creatures on Earth consist mostly of water (i.e. H2O). Indeed, a liquid called "normal saline solution" is just a solution of 0.9% sodium chloride in distilled ...
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Why does bacillus thuringiensis produce bt toxin?

Background : B.thuringiensis produces an inactive crystalline toxin during sporulation which when ingested by an insect, gets activated and causes pore formation in gut , subsequently leading to death ...
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1answer
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Where do most mutations come from, mitosis or meiosis?

According to this (old) paper there are 10 times more mutations during meiosis than during mitosis. One reason for that is that recombination often causes replication error and therefore mutations. ...
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Understanding F-statistics in population genetics

I am reading a classical Weir and Cockerham 1984 paper about Fst estimation. At the beginning (first page, right column), they define 3 statistics. $F$ is the correlation of genes within individuals ...
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1answer
133 views

Are there any theories why such an imbalance in chirality of molluscs?

Most gastropods exhibit sinistral (right hand) winding of their shells. But very few species are anti sinistral. Have there been any theories as to why such a great difference?
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Evolution of the Redundancy of the Genetic Code

In short Looking at the genetic code, it appears that most redundancy is on the third letter rather than on the first or the second letter of the codon. Why has it evolved this way? Longer version ...
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What fraction of sites are expected to be polymorphic?

Question Consider a very long (eventually infinite) DNA sequence of neutral sites. Consider a panmictic population of constant size $N$ with a per site mutation rate of $\mu$ where all individuals ...