Does everything evolve at the same rate?

I realise a broad-brush definition of environment would cover all factors affecting species, but as it is usually spelt out here, it leaves an impression that it just covers physical pressures--cold, heat, food supply,possibly radiation, etc. But wouldn`t a far greater effect on species come from bacterial and parasite attacks. Wouldn`t these drive a tendency to mutate more than physical pressures? Not merely causing symbioses, but weeding out the less responsive mutations?

The meaning of the term 'environment' depends on the context it is used in. When used in the context of evolution, usually it means everything that affects the succesful procreation of a creature. So you have to take into account not only temperature, radiation, etc., but also the presence of predators, whether those predators move slower or faster than our creature, whether or not possible sexual partners find our creature attractive, whether or not it is strong enough to survive a flooding of its habitat, whether or not it is smart enough to go and find a softer nut instead of exhausting itself on an uncrackable one, whether or not it is camouflaged well enough not to be picked off of a tree, whether or not ...The list is endless.You could even take it a step further and say that the creature itself is part of the environment. For that, you have to look at it not from the viewpoint of the creature, but from the viewpoint of the genes. In the end, it's the genes that "want" to be copied. It's their sole "aim".

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"Ignorance more frequently begets confidence than does knowledge: it is those who know little, not those who know much, who so positively assert that this or that problem will never be solved by science." - Charles Darwin.

Thanks, Para. What I was inferring was that the greatest environmental pressure for natural selection would come from bacterial or parasitic assault. If a sub-species could cope better, the likelihood would be that they would proliferate a lot better than similar forms with lesser resistance.

I’ve looked around and noticed that few creationists are posting here. Their arguments have failed and the 2 persons in this forum are new, junior members.tdcanam: Why are there no elephants with wings and lighter bone structures?First. We are looking at organism and observe what they have encountered during their evolution. What mutations (by chance) they have gained or not. Some animals adapted to this niche and others to that niche. So presupposing that animals would look like anything you could think of for evolution to be true is completely false. Heavy animals like elephants have been walking the ground for millions of years. So for them developing limbs that would be adapted to flight would not be a benefit if they are supposed to use all four legs to lift their heavy weight. One group of meat-eating and two-legged dinosaurs (dromaeosaurids) on the other hand turned small and climped trees. They had conditions for evolving wings.tdcanam: Right now there should be an animal halfway between it's origional species and a new species.We have that. But many of them also died out. Look and testudines. There are many forms of waterliving to semi-aquatic up to those completely terrestrial. There are lizards lacking legs or have very tiny ones. Passerine birds is another good example with many intermediates. In Crustacea there are intermediates with respect to for example number of walking legs and number of pleopods.