Tag Info

Hot answers tagged

27

Very intresting question. The problem is that animal intelligence is hard to measure not only for scientists, but probably also for the potential mate. Paradoxically, that is why selection for intelligence, if it occurred, may be very strong. One has to be smart in order to recognise smart behaviour, so preference and preferred feature are strongly ...


11

He formulated his theory after travelling the world aboard the Beagle, here's the route! He found the Galapagos Islands particularly inspiring, 'The natural history of this archipelago is very remarkable: it seems to be a little world within itself.' This is a more detailed account of his relationship with the Galapagos islands, and there is also a ...


8

To get a non-circular answer to why humans and other mammals have only two sexes, it's helpful to take a look at our evolutionary history. While mammals possess several adaptations to a terrestrial life cycle, including internal fertilization and gestation, which require substantial anatomic specialization between males and females, these are all secondary ...


8

I just wanted to add that although we are pretty confident that domestication of wolves created domestic dogs in pretty short order. In addition to the fact that they can still interbreed and the taxonomical resemblence of dogs to wolves and finally the genome sequence, probably the most awesome evidence is the domestication of the silver fox. Russian ...


7

The idea that we only love our family according to biology is not true, but its also not clear what people mean by the word 'love'. There are many ways to interpret that word! Hope this doesn't totally suck any romantic ideas out of you, but metaphysical concepts of love and romantic ideas of love are not always relevant when you talk about biology. A ...


7

According to Serpell, 1995 (http://books.google.co.uk/books?id=I8HU_3ycrrEC, page 8), wolf bones in association with human bones have been found from as early as the middle pleistocene (126,000–781,000 years ago). I think we're talking about more than a few centuries here :) It's still relatively little in comparison to naturally selected evolution, but ...


5

Its pretty much impossible to predict what will happen in the evolution of species. Evolution is a parallel search with millions (or in the case of humans 8+ billion) of threads. Our adaptive capacities have never been fully understood and will always surprise us I think. Of course that doesn't stop people from trying! The prediction you mention is ...


5

Very little is known about the structure of fitness landscapes. H.A. Orr (2005; also Whitlock et al., 1995; Kryazhimskiy et al., 2009) explains that most experimental results do not actually attempt to measure the fitness landscape, but instead report just the average fitness versus time and average number of acquired adaptations versus time. This can't be ...


5

Well first of all I don't know if natural selection favors larger animals - most of the living things in the world are single celled. Still there are advantages to being larger. I don't know if I can list them all! In no particular order: 1) Living things that are large are more metabolically efficient. The amount of food required goes as a 3/4 power ...


5

Galápagos islands are one of few islands with a unique fauna and flora. This can only happen when the distance to other land is great enough, and when the island exists long enough that flora and fauna could grow (volcano islands are sterile for a long time). Now Galápagos is even more unique because it is comprised of several islands that are distant ...


5

A commonly used empirical example of species selection (a.k.a clade selection, lineage selection) is pelagic larvae in sessile ocean species. See Maliska et al (2013) for a recent paper discussing this in Tunicata and Jablonski & Hunt (2006) for larval modes in gastropods. The idea is to some extent really intuitive - pelagic larvae means higher ...


5

Do you know about BioPython? Here, on another website, someone already asked this question and a pretty nice answer was provided by Brad Chapman. He gives already written functions to perform this kind of analysis (I personally haven't tried the codes). In Perl there is Bio::Align::DNAStatistics. You might adapt it to Python. This might be useful as well. ...


5

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!


5

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". s*y is what ...


4

I know nothing about biology however I did watch an amazing PBS documentary on cuttlefish that I think is fairly relevent. From http://www.pbs.org/wgbh/nova/nature/kings-of-camouflage.html NARRATOR: During mating, males outnumber the females, sometimes 10 to one. And they're all looking for the chance to pass on their genes. While a female lays eggs ...


4

How about EWS-FLI1 and other oncofusion proteins? One could argue that cancer progression is as close to viewing "evolution in real time" (as you say) as possible.


4

That ratio is essentially, as WYSIWYG pointed out, called GC-content. In actuality, GC-content is reported as $(G+C)/(A+C+G+T)$, converted to percent; i.e., what percent of the genome is G or C. There is vast variation in GC-content, both amongst species and within a given species' own genome. For example, in humans the first intron and exon are generally ...


4

Short answer Yes that would work in the condition that the trait you select for (size) is heritable. Long answer The kind of selection you would apply is called truncated selection because you fix a limit in size (depends on your filter) under which individuals do not survive and above which individuals survive and reproduce equally. The response to ...


3

Yes that ratio varies and is generally referred to as GC-content which is expressed as percentage. Earlier, people used GC-content as one of the identifiers for a group of organisms. Though there have been quite a few studies on the evolution and variation of GC-content, there is still no clear explanation for why certain organisms have a certain level of ...


3

My question was why does evolution take place at the same rate with the same results to every member of the species all around the world? It doesn't. Evolution acts on populations, not individuals. I will never evolve, you will never evolve, but humans are evolving, and sure, certain pockets evolve at different rates. Here's a long but ...


3

Why does evolution (namely the evolution of primates into humans) take place both uniformly and universally on the earth? Short answer: it doesn't. All human beings descended from the same group of Homo sapiens. There has been some genetic deviation since, but not enough to call it a "species". Evolution happens, but at very long time scales and not at ...


3

I want to point out that Darwin did not notice about the finches as everybody thinks until the captain of the Beagle (Robert Fitz Roy) pointed that to him. Also it was after a lifetime of collecting evidences not only from his voyages but from experiments in his own house and contributions from colleagues that he developed his theories, many years after his ...


3

You're not wrong, per se, but in practice they refer to two different concepts. I honestly think the Wikipedia article does a good job, in particular this sentence: In summary, while natural selection results from the struggle to survive, sexual selection emerges from the struggle to reproduce. It also cites Darwin: The sexual struggle is of two ...


3

Evolution, in the Darwinian sense, can be broadly described as the interaction of three processes: inheritance, mutation and selection. Of those three processes, mutation is the one that produces novel innovation, by occasionally producing new alleles that did not exist in the parent population. It is, however, a blind innovator — the novel genotypes ...


3

I don't believe you can produce a general function for this. It will depend on the exact gene and organism you are considering. From a molecular point of view, the vast majority of recessive mutations result from a change producing either a non-functional protein product or a truncated product that is cleaned up by the cell. We can reasonably assume that ...


3

To a good first approximation $\overline{\Delta f} = 0$. Where $\overline{\Delta f}$ is the mean change in fitness down to any point or indel mutation. The reasons for this are as follows: In the genome of higher organisms, most of the genome is non-functional ("junk") so most mutations will not have any effect regardless of the change made. A substantial ...


2

From the following free review: Here we review some of the successful strategies in creating protein diversity and the more recent progress in directed protein evolution in a wide range of scientific disciplines and its impacts in chemical, pharmaceutical, and agricultural sciences. Quoting three examples, but the article has much more: ...


2

Great question! A lot of things affect how quickly a population or species can adapt to a new environment, including population size, mutation rate, generation time, standing genetic diversity, and selective pressure. The diversity of life encompasses practically all combinations of those variables. A bacterial population might very well contain enough ...


2

Many dog breeds went through genetic bottlenecks about 200 years ago. Many of today's breeds either did not exist a couple to few hundred years ago or looked rather different than the breed looks today. It doesn't take long to change the characteristics when selective breeding occurs. One may need to consider the co-evolution of Homo sapiens and Canis ...


2

@emanuele you seem to be asking why there are only 2 sexes for animals, in contrast to fungi which can have many sexes or maybe bacteria which have mobile sex - the ability to donate genetic information can be acquired or lost. Some animals - worms and fish for instance are hemaphrodites - they can accept sperm or donate them to produce offspring. Fungi ...



Only top voted, non community-wiki answers of a minimum length are eligible