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Evolution - Comparative anatomy

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camila orozco

on 10 December 2014

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Transcript of Evolution - Comparative anatomy

- Definition
- Explanation
- Vestigial structures
- Homologous structures
- Analogous structures
- History of comparative anatomy
- Examples
- Why is it important today?
- Video
It consists of a comparative study in which the structures of different organisms are analyzed to determine their evolutionary relation, their common ancestor and the changes that the species had during time, called evolution.

Homologous structures
The Homologous structures, are the body parts, which are similar in different species because the species have common descent.
This means they have developed the same structure.
They may or may not perform the same function.
Populations with similar anatomical features are assumed to be relatively closely related evolutionarily, and they are assumed to share a common ancestor. As result, anatomical similarities and differences are important factors in determining and establishing classification of organisms.
Vestigial structures
Are anatomical features that although evolution happens they are still present in an organism. They can be present in different sizes and they can serve for the same function that their ancestors had or they can be present in the organism without a function.
Evolution- Comparative anatomy
By Mariana Valencia & Camila Orozco
Why are they similar? according to comparative anatomy, this organisms had a common ancestor that shares similarities in our genetic code.
Analogous Structures
Why is it important today?
All vertebrates have similar gill slits as embryos.
Gill slit : One of several narrow external openings connecting with the pharynx, characteristic of sharks and related fishes, through which water passes to the exterior, thereby bathing the gills.

Pierre Belon was born in 1517, he was a french naturalist who did research and debates about dolphin embryos as well as the comparisons between the skeletons of birds to the skeletons of humans.
This research led to what is referred to as modern comparative anatomy.
In the same century, Andreas Vesalius was also making some research about anatomy of his own. The young anatomist was investigating and correcting the anatomical knowledge of the Greek physician Galen.
He noticed that many of Galen's observations were not even based on actual humans. Instead, they were based on animals. Up until that point, Galen and his teachings had been the authority on human anatomy.
After this men ideas where corrected and proved. Edward Tyson was credited with determining that marine mammals are, in fact, mammals. Also, he concluded that chimpanzees are more similar to humans than to monkeys because of their arms. This made a tremendous impact in the classification of organisms, and made question a lot of scientists their system of organization.
Some mammals like....
Although they have different functions and externally they look different, these three mammals are closely related, all of them have the same amount of bones and due to this scientist determined by comparative anatomy that they developed from the same ancestor.
Without comparative anatomy, naming and understanding what can be seen in organisms would be impossible.
Neither the descriptive embryology, causal embryology, phylogeny, palaeontology nor systematic could be conducted and the understanding of both biology and evolution of species would be dead.
Comparative anatomy helps to propose homology hypotheses between different organs.
There are some organisms that have an anatomy with the same function but when it comes to development and morphology these structures are very different.
• (Morphology: The shape of bones and physical appearance)
• Definition: The organisms that have similar traits, characteristics, or function but not the same structure and they are not related in their genetic code, they don’t have a common ancestor.
Why they share some traits but not the same structure?
• Usually this happens as a result of convergent evolution which means that these species were raised in the same environment and had similar roles in the ecosystem and due to this they evolve a similar characteristic independently from each other.
• In this image we can see the comparison between a shark, a penguin and a dolphin. Even if they share the same function (swim) for eating, their limb has different names (fin, wing and flipper) and the morphology of the bones are also different.
• These skulls that belong to extinct animals look like if they came from the same ancestor because both have a similar form and both have the large teeth that look like an homology, but when we compare the length of both teeth we notice that they belong to analogy since this characteristic belongs to different ancestors.
One of the skulls, the Thylacosmilus belongs to marsupial mammals (like kangaroos that have a pouch to protect the baby) while the smilodon is a placental mammal ( like humans that complete their development in their mother’s uterus joined by the placenta.)
Bats and birds
They look similar because of their physical appearance and their role in the ecosystem (fly).
Both have wing to fly, but we analyzed them closely, we notice that bat wings are stretched skin in the bones while bird wings are lots of feathers covering the skin of the arm.
Bats and birds are analogous structures because they don’t share the same ancestor.


Education- portal. (s.f.). Recuperado el 21 de noviembre de 2014, de education portal: http://education-portal.com/academy/lesson/analogous-structures-definition-examples-quiz.html#lesson
science.jrank. (s.f.). Recuperado el 26 de Noviembre de 2014, de comparative anatomy: http://science.jrank.org/pages/348/Anatomy-Comparative.html
Encyclopaedia Britannica. (21 de Noviembre de 2014). Obtenido de Comparative Anatomy: http://global.britannica.com/EBchecked/topic/129617/comparative-anatomy
Understanding Evolution. (28 de Noviembre de 2014). Obtenido de Analogies: http://evolution.berkeley.edu/evolibrary/article/0_0_0/similarity_hs_07
animalia. (1 de Diciembre de 2014). Obtenido de animalia: http://animalia-life.com/data_images/dog/dog5.jpg
Wikimedia. (26 de Noviembre de 2014). Obtenido de Wikemedia: http://upload.wikimedia.org/wikimedia/commons/9/9e/Humpback_stellwagen_edit.jpg
b-i.forbesimg. (26 de Noviembre de 2014). Obtenido de b-i.forbesimg: http://b-i.forbesimg.com/parmyolson/files/2013/06/Faces-of-the-Future-1.jpg
(2 de Diciembre de 2014). Obtenido de https://dr282zn36sxxg.cloudfront.net/datastreams/f-d%3Ad37644b4f4b5321ea7d1edd343a49172d079889571d0974d0b5a6f9d%2BIMAGE_THUMB_POSTCARD%2BIMAGE_THUMB_POSTCARD.1
About. (2 de Diciembre de 2014). Obtenido de About.Agnosticism: http://www.atheism.about./library/glossary/evolution/bldef_analogous.htm

Comparing anatomical structures helps determining organisms classification.
Cave fish and salamanders
This two animals have a vestigial structure (the eyes), although they can't see, this is the remain of their common ancestor that had functional eyes.
Anatomy: Study of the structures of living things
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