Homologous structures under Lamarck I've read that Lamarck's theory doesn't explain homologous structures. But, what about the following hypothetical under Lamarck's theories: * A population develops an adaptation to its environment * Part of the adapted population moves away * The adaptation is passed onto the population's offspring * All offspring of the original population have the adaptation, regardless of whether or not their ancestors moved away Isn't this adaptation a homologous structure?

I agree with you that I can't see why Lamarck's hypothesis could not explain the presence of homologous structures.

The link you offer also claim that Larmarck's hypothesis would fail to explain "Biogeographical diversity patterns". While this expression is a little vague, I would fail to understand why Lamarck's hypothesis would fail to explain patterns of biogeographical diversity.

The phrasing of your scenarios (absence of the term allopatric speciation, usage of the term "develops" instead of "evolves" of just "adapts") suggests that you may take advantage of an intro course to evolutionary biology such as the short and good course by UC Berkeley called Understanding Evolution