Random mutations are the least potent source of change in evolutionary mechanisms. So much so that some experts don't even consider them as one.
Reinforcement of already existing traits through variation between individuals under environmental preasure is the main mechanism. (i.e. when food sources are high, individuals with longest reach are the fittest).
You seriously believe in Lamarck? Like, I don't know, I'm not a native speaker, maybe I'm missing something.
How many fucking times do we have to repeat this: TRAITS ACQUIRED DURING LIFETIME ARE NON-INHERITABLE
If you lose your fingers in an industrial accident, your children aren't going to be born fingerless, are they?
Giraffes don't have long necks because one little giraffe long, long ago tried really, really hard to grow a longer neck, but because giraffes who had been born with longer necks could compete better than those without, and pass on their genes. And they got those necks due to mutations.
Environmental pressure selects for benefitial mutations, while the mutations themselves are random. That's literally the mechanism of evolution through natural selection.
Neither am I a native speaker so I worded my joke poorly. I elaborated in another comment but let me point out that in epigenetics, traits gained during lifetime are inherited, but within the range of what mutations "allow".
But not by Darwin. The modern evolution theory is a synthesis of Darwin and Mendel. I should have elaborated but the joke was that Darwin didn't have mutations in his theory yet and when you stick to Darwin Claus, there ain't no mutations
To be fair to him, this type of variations could also be due to epigenetics, although he obviously has a rather fuzzy understanding of what he's talking about.