Homologous Structures vs. Analogous
Structures
Homologous Structures
Homologous structures have similar anatomy
but not necessarily the same function.
Example: upper limbs of humans, bats, whales
and cats
They are a result of similar origins.
Homologous structures
Analogous Structures
Analogous structures appear similar and have
similar functions.
Example: birds wings and insects wings.
They are a result of different ancestral origins.
Analogous structures
The birds wing and the insect wing have similar functions and shapes but
different origins.
Convergent Evolution
(the cause of analogous structures)
• The independent evolution of species with
similar traits (analogous structures) that do
not have recent common ancestors.
• They appear similar, but are from different
branches of the evolutionary tree.
• They have evolved geographically isolated
from each other, but because their
environments are similar they have functional
and structural similarities.
These two animals are not closely related although they
look a lot alike.
Thylacine
A recently extinct animal from Australia, Tasmania, and
New Guinea.
It received the common names of Tasmanian Tiger or
Tasmanian Wolf because it looked like a wolf or a tiger.
• The Thylacine was a marsupial, and not closely related to
tigers or wolves.
• It did not share a recent ancestor with the wolves and
tigers for which it was named, but in the process of
becoming the top predator down under it evolved into a
similar looking animal.
Thylacine
Commonly known as either the Tasmanian Tiger or the Tasmanian Wolf