Examples of Homology
Homology refers to two things that have an
equivalent role or relationship. Homology is important in comparative biology
since it makes it possible to determine if two different animals or plants
share a common ancestor. Essentially, homology in this context means that there
are two species that have related parts that do similar things, but that are
not exactly the same.
Homology In the
Animal Kingdom
Following are some examples of homology:
·
The arm of a human, the wing of a bird
or a bat, the leg of a dog and the flipper of a dolphin or whale are homologous
structures. They are different and have a different purpose, but they are
similar and share common traits. They are considered homologous structures
because they have a similar underlying anatomy.
·
The forelimbs of a frog, a bird, a
rabbit and a lizard look very different because they have evolved differently
to account for the specific lifestyles of each animal. However, they share a
common ancestor and a common set of bones (the radius, ulna and humerus). The
shared bones date back to a prehistoric fish that emerged onto land, eventually
becoming an extinct transitional animal from which they evolved. These
different structures are also homologous to the arms of people, the wings of
the bat, and the other animal parts described above.
·
The pelvis of a dog, of a cat and of a
human and of a snake are homologous structures.
·
The tailbone of a human being and the
tail of a monkey are examples of homology. The tailbone is actually called the
tailbone because of this shared lineage. Because a human doesn’t actually have
a tail but the tailbone is the last vestige or remains of where a tail would
be, it is referred to as “vestigial.”
·
The leaves of a pitcher plant, a Venus
fly trap, a cactus and a poinsettia are all examples of homology. They are
homologous structures because, although they have different shapes and
different functions today, they all share a common ancestor.
·
The mouthparts and the antennae of
different insects such as the grasshopper, the honeybee, the butterfly and the
mosquito are used for different purposes. The grasshopper, for example,
primarily bites and chews while the honeybee bites and the butterfly sucks
pollen. Although different today, these different parts are examples of
homology because they share the same basic structure which was just modified or
enlarged as needed for the particular species.
·
Non-identical chromosomes in DNA that
can pair with each other and that are believed to share common ancestry are
also examples of homology. They can also indicate that there is a common or
shared function in the chromosomes.
Homologous structures can be traced back to the last common ancestor
that the animal’s shared. For example, if the wing of a bat and the forearm of
a person are examples of homology, this means that the anatomical structure of
the forearm and of the wing were both present in the last common ancestor along
the evolutionary chain that was shared by the bird and bat.
Now you have lots of examples of homology and you have a better
understanding of how homology works in the field of comparative biology.
·
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