That evolution and Communism are tightly joined ideologically is beyond doubt. Marx was so impressed with the Origin that he wanted to dedicate it to Darwin. The reasons for it are abundantly shown in the paragraph below:
When Marx read the Origin, he enthusiastically declared it to be "a basis in natural science for the class struggle in history". In 1873 he sent a copy of the second edition of Das Kapital to Darwin, who politely acknowledged the gift. "Though our studies have been so different, I believe that we both earnestly desire the extension of knowledge; and this, in the long run, is sure to add to the happiness of mankind." If Darwin had not the least idea of what Marx was up to or what they might have in common, Marx knew precisely what he valued in Darwin. Recommending the Origin to Lasalle, he explained that "despite all deficiencies not only is the death-blow dealt here for the first time to teleology in the natural sciences, but their rational meaning is empirically examined." The other reason for his interest in the Origin emerged in Das Kapital, where he complained of the abstract materialism of most natural science, "a materialism that excludes history and its process." It was his hope that by focusing attention on change and development, the Origin would destroy both the olf-fashioned supernaturalism and the equally old-fashoned materialism.
From: Gertrude Himmelfarb "Darwin and the Darwinian Evolution", page 421.
Another way to put the above is that Marx himself viewed evolution as the basis for scientific materialism.