Both Darwin and Wallace independently proposed the theory of evolution by natural selection.

They suggested that organisms best suited to their environment are more likely to survive, reproduce, and pass on their advantageous characteristics to their offspring.

Fossils show that organisms have gradually changed over time, with simpler organisms found in older rocks and more complex ones in more recent rocks.

Comparative anatomy is the study of similarities and differences in the anatomy of different species.

Comparative anatomy provides evidence for evolution, as organisms with similar structures likely evolved from a common ancestor.

Homologous structures are structures that appear different and may perform different functions in different organisms, but have the same underlying structure.

It suggests that all these organisms evolved from a common ancestor, and have adapted these structures for different functions.

Divergent evolution is when closely related species diversify and adapt to new ecological niches, resulting in different sets of adaptive traits and homologous structures.

Divergent evolution often occurs due to migration or loss of habitat.

Cytochrome c and ribosomal RNA are commonly studied molecules in comparative biochemistry because they are highly conserved among species, and slight changes can help identify evolutionary links.

DNA molecules, messenger RNA, and amino acid sequences can also be used to identify evolutionary relationships between organisms.

The DNA molecules may be nuclear, mitochondrial, or from chloroplasts.

DNA sequence data can be compared between species.

Species that are more closely related (have a more recent common ancestor) will have more similar DNA sequences, while those that are distantly related will have fewer similarities.

The hypothesis of neutral evolution states that most variability in a molecule's structure does not affect its function.

Changes that don't affect function, or 'neutral' changes, accumulate at a fairly regular rate as they are not affected by natural selection.

1. Many organisms decompose before they can fossilise
2. The conditions needed for fossils to form are not often present
3. Many fossils have been destroyed
4. Many fossils have not yet been discovered

Comparing amino acid sequences reveals genetic diversity and evolutionary relationships, as amino acid sequences are determined by mRNA and DNA.

By comparing the base sequences of mRNA, which are complementary to DNA, we can assess DNA diversity.

If they are closely related evolutionarily, two species have fewer differences in their proteins' amino acid sequences.