1) Rassah mentioned the dice example, but the question remains: how probable is beneficial mutation compared to vast amounts of destructive ones. Aren't we talking about something like probability of "private keys collision" for beneficial change to occur? If so, shouldn't we see a lot of garbage mutated species in the fossils and only small percent of those that improved upon predecessor? It's hard to warp my mind around the fact that UV damage and mistakes in replication is the source of positive change.
A destructive mutation usually dies out within one generation. While beneficial mutations experience a exponential growth. Basically that's the definition of any beneficial mutation, one that leads to more breed that manages to breed itself. (More breed only doesn't cut it. A mutation that would lead to 10 Times the newborn would be destructive if this means they all die of starvation)
That's also why there are characteristic that's don't seem beneficial, like the peacocks feathers. But as they lead to more females breeding with the males with big feathers and only the females need to survive in a big number it is "beneficial".
From all beings that ever lived we only find a fraction as fossils. As destructive mutations die out very fast, it's no surprise we don't find them as fossils.
Besides evolution only works in small, barely noticeable changes. A lion with slightly shorter legs would be a destructive mutation, yet we wouldn't notice it as such in a fossil.
Also the highest amount of destructive mutation (the ones from UV / Radiation etc.) that are not mutations in the genetic material that get passed on. And are actually pretty common. They usually lead to something called cancer.
Mutations that get passed on to your offspring are also usually common.
On average, a 20-year-old father passes down about 25 de novo mutations — which arise spontaneously in sperm cells — to his child, the study found. With each year of paternal age, the number of transmitted mutations increases by two. Mothers, in contrast, pass on about 14 de novo mutations through their eggs regardless of their age.
http://sfari.org/news-and-opinion/news/2012/fathers-age-dictates-rate-of-new-mutationsoriginal study:
http://www.ncbi.nlm.nih.gov/pubmed/229141632) TheJoint mentioned about the definition of species and the problem of parents, which is a very good point. Does evolution explain the diversity of species or only adaptation within each one of them? When new mutation occurs, which makes breeding with the old species incompatible, how does that new individual organism procreate then? The explanation I once heard was very complex and a bit "unethical", because it implied that brothers an sisters of this new type must interbreed for a while
That only happens when the species separated for a long time. Many species that are separated by a significant distance could theoretically still breed with each other.
Horse and donkeys are not further away from each other than Human and Chimp, yet they can still breed. Shocking thought isn't it? (
Luckily it doesn't work)
Mutations don't at once form a new type. It's still the same species, but only with a slight difference. It can usually still interbreed with the former while 50% of all offspring get the new mutation. If the 50% have a advantage over the other they will slowly replace them.
If there are separate populations that don't interbreed for a long time. 2 New species can form over a long time, otherwise one is simply replaced.
3) Is mutation really random? Do we see the evidence of this in the fossils? The question of "why pigs didn't evolve wings?" was ironic, but the point remains. Do we see species, that would not be capable of certain behaviours for other reasons, attempt to evolve in that direction and fail as opposed to not even trying.
Yes it it, but if some conditions are met, even seemingly beneficial mutations would die out. Therefore (in some conditions) it sometimes really can only go in one direction. See:
http://en.wikipedia.org/wiki/Muller%27s_ratchet
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