Final answer:
Charles Darwin was the main opponent of Lamarck's claim regarding evolution, countering with the theory of natural selection, yet some of Lamarck's ideas have been revisited with the rise of epigenetics.
Step-by-step explanation:
The leading opponent of Lamarck's claim that evolution has occurred was Charles Darwin. Although Lamarck was one of the first to suggest that species evolve over time, his mechanism, known as the inheritance of acquired characteristics, was incorrect according to Darwin's findings. Darwin's theory of evolution by natural selection did not support the idea that traits developed during an organism's lifetime could be passed down to its offspring. Despite this, Lamarck's work did lay some groundwork for future evolutionary thought, and recent studies in epigenetics have shown that while Lamarck's theory was not completely accurate, the concept of environmental factors influencing genetics is a valid consideration in evolutionary biology.