Creationist talking point #69. And false, like all the others.
Actually, there is virtually no connection between the two, other than that they were contemporaries. They never met. In fact, Marx was an active socialist agitator, who had written and published virtually all of his work, before 1859, when Darwin first published Origin of Species. The only work Marx published after that was Das Capital, which makes no mention of Darwin or evolution. Nor did Darwin's work make any mention of Marx, or his works. So there is no intellectual connection between the two.
Although Marx had never met Darwin, he know that Darwin was one of the most famous scientists of the time, so Marx sent him a copy of Das Capital, and requested permission to dedicate it to him. Darwin declined, and appears never to have read the book.
A source that you might accept, the Institute for Creation Research, has this article posted at their website:
Darwin's Influence on Ruthless Laissez Faire Capitalism. Yes, ICR links Darwin to good ol' capitalism.
From Ol' Darwin to Karl:
Dear Sir:
I thank you for the honour which you have done me by sending me your great work on Capital; & I heartily wish that I was more worthy to receive it, by understanding more of the deep and important subject of political Economy. Though our studies have been so different, I believe that we both earnestly desire the extension of Knowledge, & that this is in the long run sure to add to the happiness of Mankind.
I remain, Dear Sir
Yours faithfully,
Charles Darwin
Letter from Charles Darwin to Karl Marx
October, 1873
Karl on Darwin:
Although it is developed in the crude English style, this is a book which contains the basis of natural history for our views.
Karl Marx on Darwin's Origin of Species
December, 1860