Questions tagged [evolution]

Changes in the heritable attributes of populations of organisms over time. The mechanisms of evolution are mutation, migration, drift, and selection.

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2answers
159 views

Comparative evolutionary study: is amino acid or nucleotide comparison more useful?

I am a high school student and am currently learning about evolutionary relationship study in biology. My teacher said that a comparative study of amino acid sequences is more useful than a ...
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230 views

Same 185th million grandfather?

I was watching a lecture by Richard Dawkins earlier today and he mentioned that “Your 185th million grandfather was a fish.” I started wondering about the following question, Is it true that my 185th ...
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170 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-...
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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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645 views

Selection Pressure on Orca Whale Coloration

What is the proposed selection pressure that leads to the distinctive coloration of Orca whales? I can find nothing in the literature.
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How did butterflies evolve to have eyes on their wings?

Some butterflies, such as the UK native Peacock butterfly (Google Image Search) have markings on their wings that look just like eyes, complete with a white fleck to imitate a convex, transparency ...
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Protein in fruits

Why do fruits have such a low protein content (with a few exceptions) ? Don't seeds need protein while growing up? In comparison, the egg of a hen contains lots of protein, used to make a chick.
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Did Carl Linnaeus ever name a species he never saw?

According to this post Carl Linnaeus named more than 13,000 species which is definitely quite impressive. If we consider a 50 years career it makes about 5 species per week! It would feel impressive ...
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704 views

Is abiogenesis possible today?

Life on earth started about 3.5 billion years ago. I would assume abiogenesis happened because the conditions were right. Would the current earth conditions allow for new abiogenesis and completely ...
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438 views

What selective factors drove the evolution of lactose in lactation?

As far as I can determine, lactose, and the monosaccharide galactose have few biological uses outside of mammalian lactation. It not only required enzymes for its production, but enzymes in offspring ...
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472 views

Is there evolution in humans since the first homo sapiens sapiens

Has the human species changed since first defined as homo sapiens sapiens? I'm asking this question partly because I'm wondering how we might evolve next.
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Do mammals and birds have a common warm-blooded ancestor?

Is it homogeneous or did they converge? Did we both evolve from warm-blooded reptiles that are extinct maybe?
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579 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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351 views

Have creatures ever evolved to become less intelligent?

Inspired by https://worldbuilding.stackexchange.com/questions/58533/is-intelligence-the-natural-product-of-evolution , I'm wondering if creatures have ever become less intelligent as a result of ...
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How does natural selection favour large body mass and size (or so it seems)

I was walking through a park this afternoon and observed a few birds having fun flying around and it got me thinking why would natural selection favour birds with flesh at all if it hinders their ...
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How do we call a “burst of evolution”?

I have in mind that evolution is not a constant / continuous process and that there are bursts of evolution. Are there terms to refer to the concepts of fast vs slow evolution rates?
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Evolutionary explanation of the bicuspid on the left and tricuspid on the right

The left heart handles more pressure and logically it would make sens to have a valve with three leafs on the left (If I had got to choose, I'd have put three on both sides). Other than being more ...
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Did spiders respond to light for building webs before artificial light was invented?

I have noticed that during summer, beautiful spider colonies grow wherever a strong light is: I'm wonder whether spiders evolved to seek naturally lighted areas where they build nests (before ...
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293 views

If life began at sea, why organisms are less salty than the sea?

We may take it for granted that a fish, a seaweed, or clams are not too salty to eat, although the sea around them is salty. I know about the existence of a mechanism which prevents their body from ...
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1answer
196 views

How much variation in mutation rate in there in the human genome?

In humans, the average mutation rate is estimated to be around $2.5 \cdot 10^{-8}$ (Nachman and Crowell, 2000). Of course this mutation varies from sequence to sequence. Can you please give some ...
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222 views

Since Darwinian times, has there been any striking/notable effects of evolution on humans?

I understand that evolution is constant process that acts on a population in successive generations. Thus, it is obvious that evolution is happening. However, I'm curious as to the stricking examples ...
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Why are some fungi poisonous?

There are many poisonous fungi in nature. For example Amanita Phalloides. What reasons could a fungus need poison for? Some species, like venomous snakes, use poison to kill other species as prey. ...
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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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485 views

What are some examples of scaling laws in biology?

I've seen that metabolic rate scales logarithmically as function of mass for many animals over an extremely large span of parameters. What other scaling laws exist at the individual level?
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Are evolutionary mutations spontaneous?

My question is whether mutations which lead to evolution occur by any environmental force or it occur spontaneously? I have read in genetics that x-rays, ultraviolet rays and chemical mutagens are the ...
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Evolution theory - roses spikes - being more bulgy doesn't give you advantage

I've seen spike, huge spike. And I thought that development of such spikes could be contrary to the evolution theory. Being „little more” spiky doesn’t give you any advantage... So those individuals ...
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1answer
322 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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$F_{ST}$ 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 $F_{ST}$: $$V_{Among Pop} = 2 F_{ST}V_G$$ $$V_{...
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668 views

Fecundity per woman in early humans

The average fecundity per woman varies a lot from country to country. I call average fecundity per woman the average number of born children per woman. In Homo sapiens, what was the average fecundity ...
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Are all mammals capable of sneezing?

I only know dogs and humans sneeze... so do other mammals sneeze as well? Is it possibly an evolutionarily-determined immunological trigger?
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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 ...
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121 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 ...
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110 views

Interbreedability between current humans and his ancestors

I want to know the first point of time in the past when genomes have diverged so far from modern human genomes so that they both (human and ancestors) are not interbreeadable anymore and can be seen ...
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Were there any terrestrial species in the ancestry of all crustaceans?

To the exception of woodlice, Crustaceans live in aquatic (marine or freshwater) environments. Crustaceans are arthropods which is an immensely diverse taxon. Many arthropods live in terrestrial ...
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264 views

Does modern theory of evolution include modification of physical environment?

Does any branch of modern evolution theories include aspects of evolving organisms modifying the physical environment? An example from the evolution of life could be early stage introduction of ...
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722 views

Why does the gc content deviate from 50% in prokaryotes

I have read quite some articles but I can't figure out the main reason for gc content deviation in prokaryotes. In eukaryotes I can understand it, because the genome isn't composed at random, like ...
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1answer
269 views

Evolutionary Cell Structuring

I'm a total novice when it comes to biology, and I'm really just looking for an answer to a question that has been posed to me by people who deny evolution fervently. Evolution dictates that we've ...
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1answer
450 views

Has any flying creature evolved into a sea creature?

I am talking about a creature that has evolved true flight. Has any such creature evolved into a sea creature, that permanently dwells on water (like fully aquatic fish) and doesn't come out? ...
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1answer
366 views

Evolution of plants and chloroplasts?

I am considering the evolution of plants, specifically considering the chloroplast. I am getting slightly confused and cannot seem to find the information I need to build a coherent picture in my head....
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Plants without bacteria? is it theoretically possible?

I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But ...
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3answers
301 views

Have humans finished evolving?

I thought that massive changes among organisms are over long periods of time. This is caused by, to my knowledge: Evolutionary pressure Natural/artificial selection Mutations Genetic drift Will ...
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1answer
199 views

Pen and paper game to explain the theory of evolution [closed]

Sometimes when explaining the theory of evolution one sees a glazed-over look on the persons face. To this person the theory seems completely incomprehensible no matter which avenue one takes to ...
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Was the evolution of humans inevitable? [closed]

Suppose we wind time back to the instance when life emerged on Earth and let evolution start over again, will human beings or any other kind of self-conscious animals evolve ultimately, inevitably? ...
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414 views

Definitions of robustness and canalization

The concepts of robustness and canalization are fashionable today in the biology literature. However, I am not sure of their definitions and I am not sure either that all authors actually use the same ...
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994 views

Is the fixation rate always equal to the mutation rate for neutral alleles?

Background A classical result of population genetic is that the rate of fixation of netreual alleles is the mutation rate $\mu$. The reason is that each generation $PN_e\mu$ mutations enter the ...
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1answer
184 views

Evolution from Mating types to different sexes

Imagine a lineage of multicellular organisms that had mating types and evolved their mating types into sexes. What are the possible mechanisms that might have brought this lineage to evolve sexes from ...
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117 views

Is there a word for the assumption that a sufficiently complex and refined organ must be the result of natural selection on a large time scale?

Is there a term for the valid assumption that a sufficiently complex and refined organ must be the result of natural selection on a large time scale? Example: A biologist exists in a world where ...
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Why don't most animals have “heads” in the middle of their bodies? [closed]

For example, humans. It would seem like, to me, if our brains and eyes, ears, etc. were situated in our stomach area they would be more protected from harm and more central than up at the top in and ...
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Why can we control our breath rate but not our heart rate? [closed]

Even though we cannot survive for more than few minutes if we stop breathing or if our heart stops, why is it so that our heart beat is controlled involuntarily while breathing can be voluntarily ...
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1answer
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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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