Download HMH 10.5 notes - Deer Creek High School

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 2005. 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
Evolution unites all fields of biology.
• 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.
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.