Answer:
Fresh water represents only a small part of the water resources of the Earth. the fishes present in these ecosystem have high economical values and are beneficial to mankind. The evolution of these fishes is important because it will allow genetic varieties to arise in these fishes. Hence, these fishes will be able to survive and reproduce. Also, some of these fishes might adapt to live in salty environments in the course of evolution.
Darwin used Multiple lines of evidence to support the theory of evolution by natural selection they are fossil evidence, biographical evidence and anatomical evidence.
Explanation:
The Multiple types of evidences supports the theory of evolution. The homologous structures provides the evidence for common ancestry and the analogous structures describes that similar selective pressures can produce similar adaptions.
Evolution by natural selection is one of the good method in theory of history of science and it is supported by evidence from wide variety of scientific disciplines.
The comparative sequence analysis method is used to examine the relationship between the DNA sequences of different species. This evolutionary relationships are used in the study of diseases like HIV.
The lack of detail and scaling makes the Appalachian trail map useless. An evidence coming from the story is it has a scale of 1:100,000 which compresses the places, the routes, trails of the real world into a mere centimeter in the map.