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Evolution
The scientific theory according to which populations change gradually through a process of natural selection.
5,264 Questions
How Has the evolution of the eye give an example of evolution in general?
The eye is a good example because there are living animals with eyes that represent each step in it's evolution. Human eyes also show how evolution can produce "bad" results; the retina is essentially "inside-out" - the nerves are on top and there is a blind-spot where the optic nerve leaves the eye.
How is speciation and reproductive isolation related?
Reproductive isolation is a type of speciation. Reproductive isolation is when a species divides forming two subspecies, due to different mating periods.
What is it called when one species evolves into another while the ancestor is still present?
Speciation. In almost all cases, the ancestor species of an organism are still in existence during the early stages of the population growth of the new one.
That's one of the ways we end up with "cousins" in the evolutionary tree of life. Difference species diverge from the same species at some point and the original species will either continue for quite a long time or will further speciate creating more branches.
Why should you discourage the cutting tree?
Pros
Timber
Firewood
Carving
Fixing
Nice Decoration
Creating
Cons
Are you going to use all that wood?
How many trees are you going to cut?
Are you going to use all the resources it provides?
How large/small is the tree?
Do you do it often?
Are you doing this for the benefit of someone/something?
Check through these then cut the tree(Christmas Trees don't count) if you think that the majority goes to Pros, go ahead and do it; If the majority goes to cons I wouldn't.
What were Charles Darwin's observations that were the foundation for the theory of evolution?
The individuals of a specie demonstrate variations. On average more offspring get produced than are needed for replacement of the parents but populations do remain more or less stable in nature. So there must be competition for survival/ The best adapted variants survive and reproduce. Thus evolution occurs by means of natural selection acting on this individual variation so resulting in the survival of the fittest
Why has evolution not produced a wheel?
Probably for the same reason it has not produced a high powered hunting rifle for lions. Think of the ease of hunting gazelles if lions came equipped with hunting rifles. Some things are outside the realm of physics, chemistry and biology. The mechanics of biological wheels does not fit with evolved muscles and sinews.
Which step in the evolution of life is the most complex and probably occured last?
Answer 1
We used to think intelligence represented by brain growth and complexity. Recently it has been found, in the cephlons of early trilobites, that complex brains reached back into the Cambrian.
So, I am now at a loss to tell you what step was most complex and probably last.
Answer 2
Most evolutionary biologists will agree that the most complex evolutionary "step" was the emergence of multi-cellular lifeforms.
I say "step", because like all evolutionary developments, it wasn't exactly a leap, but more of an incremental development, taking place over many millions or even billions of generations. It took Earth life approx. 3 billion years to go from single celled replicators to true multicellular organisms, although colony organisms - temporary conglomerations of many single celled organisms - evolved after only about a billion years.
It is, according to many researchers, entirely possible that Earth-like planets could exist on which true multicellular life would never evolve.
Of course it is impossible to gauge probabilities, since we do not have a complete understanding of the processes involved just yet, and we have no basis for comparison: our sampling space consists of one example, and one example only: Earth.
Can the world heal itself if the humans die out?
One would think so. Imagine how much of the ecosystem humans impact by, just for instance, cutting down the rain forest or just expanding their living areas. Aside from all other human impacts on the environment just freeing up space again for all the diverse organisms of the world, other than humans, would go a long way toward healing, in the sense I think you mean, the world.
What are specific examples of variation within a species?
Human species, as in the variation in height.
How long is the origin of species book?
About 400 pages. You need to read it anyway, then you truly get the basics of evolutionary theory.
What evidence is used to put together evolutionary history for the animal kingdom?
The evolutionary history of the animal kingdom is largely hypothetical and is mainly based on studying the structural homology of different creatures. Once this is done, any animals that appear to be rather similar are put into the same evolutionary thread. However, this is a rather inaccurate method, as shown by various changes and modifications made to standing theories (such as the evolution of the horse) over the years.
In addition to comparative morphology, these days phylogenetic trees are mainly based on genetic assays in comparative genomics. Comparative genomics assays yield much more accurate trees than those based on morphology alone, due to phenomena like convergent evolution. Of course trees generated by these means remain fluid, as more accurate data becomes available every month. Also, evolution is per definition a stochastic phenomenon, meaning that even though trees based on genomics are vastly more accurate than trees based on morphology alone, their accuracy is not absolute.
No, b) a common ancestor.
What is the difference between cladistic and traditional taxonomy?
Traditional taxonomists used physiological makers of the organism and some even assigned numerical value to these markers. This lead to confusion as organisms can be very closely related in an evolutionary and family sense and look nothing alike, Also analogous traits were confusing here.
Cladists use only evolutionary relationships that can be shown to be on the branching tree of evolution and that have empirical support, such as genetic analysis. This can lead to a bit of ridiculousness as birds to a strict cladist are just dinosaurs!
yes exactly
What is an example of an exaptation?
Exaptation. The shift in the purpose of a trait during its evolutionary history. Recent findings on feathers rather well support feathers as exaptions. They originally evolved, so we think, as insulation and then later they became useful for flight.
What big mistake did Darwin make when he formulated his evolutionary theory?
His mechanism of heritability was wrong.
Did Charles Darwin have evidence to prove evolution?
No, of course not. Evidence does not prove evolution - it validates the theory.
Evidence which Darwin had included limited fossils, and observed apparent speciation in birds.
