Karl Marx (1818-1883) It was with his work Das Capital first published in 1867, that we find a connection, and the contact was initiated by Marx. Marx wrote Darwin, expressing his admiration for Darwin's work and requesting a forward be written by Darwin for the second edition of Das Capital.
Darwin politely declined, pleading an inadequate knowledge of economics. However, he took considerable care not to give offense, because at the time Marx was a respected academic colleague. It was decades later before it became clear to the majority that Marx was a total dweed.
It may be that many Marxists regarded Darwin's ToE to be a God-send (if you'll pardon the expression) because it gave them an excuse to declare God dead scientifically (non-existent), but it's fairly clear to me that Darwin wanted nothing to do with Marx or Marxist economics. Marx did maintain his admiration for Darwin and did send him a copy of his second edition of Das Capital. After his death (Darwin's), the book was found in his library with most of its pages uncut, indicating Darwin did little more than open the book, if even that.
Well, Stalin and his people executed people for advocating Darwin's ideas. Such procedure still didn't improve agricultural production.