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29

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 ...


14

I am not sure I'll answer your question so let me know if I miss your point or if I help! What factors determine weather some species "stick"? Natural selection is nothing but differential fitness (fitness is a measure of both reproductive success and survival) among individuals within a population. Individuals having greater fitness will leave more ...


12

Mathematician/computer programmer's answer here: There is a continuum of different animals — in fact it's pretty fair to say that every animal occupies a different place on this continuum. They're just not uniformly distributed over the continuum; they're clustered around forms that are most likely to survive and reproduce, and the lowest-energy paths ...


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 ...


9

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 ...


8

Nothing happens to them. Organisms exist. They breed with other organisms who are genetically compatible. We humans might try to categorize them according to certain traits, but our labels are just labels, biology isn't governed by them. Over time, we might see that a population used to have one trait, and its descendants no longer have it, they look ...


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 ...


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 ...


6

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 ...


6

Typically when both new and old species still exist it is because evolution pushed the new one into a different habitat or role. As a hypothetical example reef fish vs deep water fish and their relative size. Lets say deep water fish evolved into reef fish, but we still have deep water fish. So there were deep water fish that were a little smaller than ...


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

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 ...


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

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 ...


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 ...


5

More specifically, the lack of observable gradual change between species. Most significant phenotype differences occur over several thousand generations, which means several thousand years on up. While we certainly can create experiments where a controlled form of evolution occurs within a very small time-frame, I'm going to assume that you're not ...


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

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 ...


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

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 ...


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 ...


4

Reeve and Keller in the first chapter of Levels of Selection in Evolution (Princeton Univ. Press,1999) seem to address this question in the second item in the following paragraph. The purpose of this volume is to sample current theoretical and empirical research on (1) how natural selection among lower-level biological units (e.g., organisms) creates ...


4

Could not fit in a comment... This sounds like a very basic question in evolutionary biology that often ask for a very long answer. But I think that you may get the answer you're looking for just if we ask you back how many inbetweeners would you expect to exist between the hammerhead shark and whatever is the closest currently living species of the ...


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

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 ...



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