Evolution is a broad term signifying the change over time with inherited modifications. It could be small-scale and large-scale depending upon the gap of changes between each stage. Simply put, a change in the physiological aspects of an organism over time is not to be considered evolution unless it shows modified traits in its following generations. If you see a caterpillar metamorphosising into a butterfly or a tree shedding its leaves during fall, you can not say that they are evolving. Why? Because they are simply undergoing changes in their own life. Simultaneously, if you say that you as a human being have evolved, then it’s the truth you speak! Evolution requires a common ancestor to draw the contrast between the evolving species. Species evolve after their genetic changes undergo a natural selection of the most advantageous traits suitable to be passed on to the next generation.
We are surrounded by many walking examples of evolution. How many examples are you aware of? Yes, Darwin’s finches and fossils are the most popular ones but what about the others? Here are the top 10 evolution examples in real life that will show how some species have evolved over many generations. For the sake of simplicity, I have divided them into physical and biological examples.
2. Homologous Structures
A bird’s wing, a dolphin’s flipper, and a human arm have similar basic bone structures but serve different functions. Such structures are called homologous structures and support the theory of common ancestry between the two species.
3. Vestigial structures
Vestigial structures are the remnants of their ancestral structures that are no longer functional. However, they explain the adaptation in the lineage and hence validate evolution. The human appendix, the wisdom tooth, degraded eyes of blind cave fishes, wings of female cockroaches, wings of flightless birds, hind leg bones in whales, etc are some examples of the vestigial structures supporting evolution.
4. Analogous Structures
As opposed to homologous structures, analogous structures have similar functions but different structures. Their analogy or homoplasty occurs due to environmental limitations rather than a close evolutionary relationship. Wings of birds and butterflies, eyes of vertebrates, and shells of snails and brachiopods (lamp shells) are some examples of analogous structures.
All living organisms reach their adult form after a series of development stages taking place in an order. The study of the anatomy or internal study of these stages is called embryology which also gives potential examples of evolution when compared with other divergent species. By studying and comparing the distinctive structures in the embryos of humans, chickens, fishes, amphibians, and apes, one can easily deduce the similarity in their ancestry. Did you know that humans possess gill slits and tails at their early embryonic stages? Imagine what we could’ve done with them if evolution didn’t happen!
6. Molecular Biology
There are several examples in the molecular structures that implicate the evidence of evolution. The biggest one among all is the universal DNA sequence, the process of gene expression, and the genetic code of proteins that is almost similar in all life forms on earth. This indicates that we all share a common ancestor.
If you are aware of the theories associated with the early formation of our planet, then you must know that following the tectonic plate movement of Pangea, the original species also spread out with the separated continents. Their evolved species groups remained predominant to their respective continents which is evident with the presence of unique flora and fauna found in the Laurasia (presently comprising North America, Alpine-Himalayan mountain ranges) and Gondwana regions (Now, Antarctica, Africa, peninsular India, Australia, South America, and Eurasian regions south of the Alpine-Himalayan chain). Marsupials in Australia, Finches in Galapagos islands, and tropical rainforests of the Amazon basin are diversely populated in their regions, yet remain distantly related to their native ancestors present on the mainland. Their evolution does not come as a surprise since they adapted to live in their isolated habitat.
9. Arctic wildlife
There are certain animals found in the Arctic region that share similar phenotypes despite having no common ancestry. The Arctic Fox and the Rock Ptarmigan both exhibit seasonal camouflage and change their colour from dark to white. This is due to the selective pressure of surviving, reproducing, and evading predators.
The ancestors of Deer mice were found to be dark-coloured due to their habitat preference. After changing their habitat from woods to sandhills, some species of deer mice developed light colouration to survive in their new surrounding. The species that remained in their original habitat, retain their original appearance.
Guppies are tropical fishes with certain phenotypic characteristics occurring due to evolutionary pressure. The variation in colour in male guppy fishes (grey and bright) is the result of natural selection favouring reproduction and survival. Female guppy fishes prefer bright-coloured males for mating, however, their preferences have been observed to change in a predator-infested environment. Male guppies that have evolved to change as per their environment serve as an excellent example of evolution.
Another popular example of natural selection and population genetics is the peppered moth. After the industrial revolution in England, the originally pale-coloured peppered moth species eventually turned to a darker colour in order to blend in with the sooty surrounding caused by air pollution. It was an evolutionary move to avoid getting detected by predators and ensure survival. After the gradual improvement in environmental conditions, light-coloured peppered moths have become common as well. This signifies directional selection (a form of natural selection) in peppered moths.
Farmers often complain about the inefficacy of a specific pesticide that was effective in previous uses. The reason is most likely the development of pesticide resistance by the new generation of pests that evolved over the years. The green peach aphid, two-spotted spider mite, the house fly, and over 500 species of insects have been observed to develop some level of pesticide resistance. This proves their evolutionary traits.
Another example of evolution in insects comes in the form of the present generation of Blue Moon Butterflies. The previous male generation of the Blue Moon butterfly species was being selectively attacked and killed by a certain parasite called Wolbachia. Over the repeated course of stages, only the female population remained to survive. However, after ten generations passed, the male species began to thrive and the balance seem to be restored. This occurred due to the gradual development of immunity in the male Blue Moon Butterflies against the parasite. The strongest males survived and passed on their genes to the next line of males which gradually developed immunity and which further kept passing on the immunity to the next generations. The fittest males survived and through natural selection, thrived in adverse conditions.