10.5 Evolutionary Biology Today KEY CONCEPT New technology is furthering our understanding of evolution.

10.5 Evolutionary Biology Today Fossils provide a record of evolution. Paleontology is the study of fossils or extinct organisms. Fig. This skeleton of Basilosaurus isis was found in a desert in Egypt in It lived 40 million years ago and has characteristics of both land and marine animals.

10.5 Evolutionary Biology Today Paleontology provides evidence to support evolution. There are many transitional fossils that have characteristics of both land mammals and whales. These are a few examples:

10.5 Evolutionary Biology Today Molecular and genetic evidence support fossil and anatomical evidence. 5. Two closely-related organisms will have similar DNA sequences.

10.5 Evolutionary Biology Today Pseudogenes are sequences providing evidence of evolution. –no longer function –carried along with functional DNA –can be clues to a common ancestor

10.5 Evolutionary Biology Today Homeobox genes indicate a very distant common ancestor. –control the development of specific structures –found in many organisms –A hox gene is an example of a homeobox gene Protein comparisons (amino acid sequencing), or molecular fingerprinting reveals similarities among cell types of different organisms. Fig. The eye spots of this marine worm have light sensitive cells with a molecular fingerprint similar to that of a vertebrate eye

10.5 Evolutionary Biology Today Homeobox vs. Hox Every Hox gene is a homeobox gene, but not every homeobox gene is a Hox gene. The homeobox genes have diversified so much through evolutionary history that there are now distinct classes of them. The most famous is definitely the family of Hox genes. This is also where the terms come from. When scientists first discovered the homeobox domain, they found it because they were studying animals that had mutated Hox genes. These mutants often had body parts in the wrong place, and were described as “homeotic mutants”. When they identified the genes causing the mutations, they discovered that they all shared a common motif, so they named it the homeobox. This is one of the most incredible discoveries in biology, as they quickly realised that the homeobox is found in genes from humans, flies, jellyfish, daffodils, yeast, and so on. But the actual genes they had discovered were a distinct group of homeobox genes, which we now call the Hox genes. They definitely are homeobox genes, and they regulate other genes.

10.5 Evolutionary Biology Today Scientist from any fields contribute to the understanding of evolution. The basic principles of evolution are used in many scientific fields like medicine, geology, geography, chemistry and ecology. Evolution unites all fields of biology. Fig. Baleen whales, such as this humpback whale, have evolved a highly specialized adaptation for catching microscopic food. Molecular techniques have allowed scientists to discover the whale's relationship with hoofed animals.