Charles Darwin explored locations in S. hemisphere and made observations on plants, animals and fossils; he hypothesised that new species form from a common ancestor and developed the theory of evolution by natural selection. He proposed the following:-
Natural variations occur within species
Characteristics of offspring that do not survive are removed from the popln.
Organisms that survive and reproduce adapt to environment
Variations are passed on to offspring and become more common

Charles Darwin and Alfred Wallace published articles with similar findings. Lamrack suggested that evolution occurs when the enviro. acts on an organism and causes it to change. Darwin suggested that only the fittest (most suited to enviro.) can survive.

Example of evolution is seen in Darwin’s Galapagos Island finches; he hypothesised that they evolved from a common ancestor

Fossil record: provide evidence for evolution; Darwin noted how modern armadillos resemble fossils

Comparative anatomy: modern horses can be traced back through fossil record 60 million year ago ancestors. The forelimbs of unrelated vertebrates show how they developed from common ancestor.

Comparative embryology: embryos of some vertebrates have structures that may be remnants of evolutionary past.

Biogeographical evidence suggest common ancestor. There are 2 distinct birds found in the east and west coasts of Australia. They were once found throughout Australia but were geographically separated and evolved into different species.