What is Homology, and is Convergent Evolution somehow different?

Dear Readers,

From Darwin's theory of natural selection to Lamarckian inheritance, evolutional theories have been created since the time of Greek philosophers. While the history of how evolution came to be so accepted is important this post will focus on the overwhelming amount of scientific evidence that supports it, specifically Homology and Convergent Evolution.

Homology, in simple terms, describes the similarities among different organisms. Per a book called Biology a Global Approach, as descendants of a specific ancestral organism face different environmental conditions they can have characteristics that are similar, yet function in very different ways. This similarity is known as homology when it comes from a common ancestor. While not visible to the naked eye, genetic code is a homologous characteristic shared by all species from its LUCA (Last Universal Common Ancestor). In the coming days, I will be focusing more on homologous characteristics that evolved recently and are shared within a similar group of organisms, typically of the same phyla/ subphyla. Within the scientific community, the representation of homology is done through an evolutionary tree or phylogenetic tree.

On the other side of the coin, there is Convergent Evolution. This outlines distantly related organisms that somehow resemble each other due to similar adaptations within similar environments. Convergent Evolution is said to be analogous, being features that share a similar function, however not due to a common ancestor.

These concepts can be found everywhere within the Plantae, Metazoa, and Fungi kingdoms.

Until next time,

Sol

Comments

Gymnosperms, Angiosperms, and the life cycle of all Plants

Hello everyone, Today I decided to think about the difference between Gymnosperms and Angiosperms. While Gymnosperms do have four phylum and Angiosperms one, Phylum Anthophyta/ Flowering plants compose around 250,000 known species while Gymnosperms altogether equate to around 806 known species. The major difference between Gymnosperms and Angiosperms is that one has seeds not enclosed in chambers while the other has its seeds develop inside chambers (within flowers). With the numbers above and the inclusion of nonvascular and seedless plants, we can approximate that nearly 90% of living plant species are angiosperms. Now let's talk about the life cycle of all plants. Plants go through a process called alternation of generations between gametophytes and sporophytes. While this does not occur in charophytes (there is always an exception to the rule in biology) this type of reproductive cycle came from green algae. Basically, the process goes as such: The gametophyte produces haplo...

Flatfish and Sharks

Dear Readers, This post will talk about whether several flatfish observed illustrate convergent evolution or homologous evolution. We will also discuss the difference between sharks and 'ordinary fish' and how they are easily distinguished from one another. Flat Fish Those visible in the large monumental hall were The European Plaice/ Pleuronectes platessa and Sole/ Solea solea. European Plaice and Solea Solea Both flatfish come from the same order being Pleuronectiformes. They are both found in similar habitats like the Mediterranean and enjoy burrowing themselves in the sandy or muddy seabed. Since they come from the same order we can hypothesize that both the Common Sole and European Plaice have a common ancestor. Common Stingray with leopard shark directly above Unlike the two flatfish, Dasyatis pastinaca (Common Stingray) shares the same phylum with the flatfish, however not much else. Diverging into the class Chondrichthyes. Much like the flatfish they can be fou...

West African Lungfish

Dear Fellow Readers, This post talks about the African lungfish, specifically its classification within the Chordata phylum and its characteristics that demonstrate vestigiality. African Lungfish/ Protopterus annectens Phylum: Chordata Order: Dipnoi Family: Lepidosirenidae Genus: Protopterus Per the name, the African Lungfish is distributed throughout Africa. Being an obligate air breather they are seen in basins and rivers. As of today, there are only seven known species of lungfish, being found in Africa, South America, and Australia. Being abundant since the Triassic geologic period they are thought to be over 250 million years old (phylogenetically speaking). While they do retain marginal teeth and an ossified braincase it has been significantly reduced in size due to vestigiality. This is also visible in something called the cosmine which has been lost in post-Devonian (between ~419-358 million years ago) lungfishes. While called Lungfish they are actually able to live on lan...

From The Classroom To The Real World

Search This Blog