What observation and facts did Wallace use to support his idea?

Alfred Russel Wallace supported his idea of natural selection through observations of species distribution and variation in different environments, particularly during his travels in the Amazon rainforest and the Malay Archipelago. He noted how species were adapted to their specific habitats, with those in similar environments exhibiting convergent traits despite geographical separation. Additionally, he recognized the role of competition and survival in the struggle for existence, leading to the gradual evolution of species. These observations, alongside the natural variation he documented, formed the basis for his co-discovery of the theory of evolution by natural selection.