The Hidden Wonders of Island Evolution

“When animals that have traits that allow them to survive, over time those traits are amplified. This process happens far faster on islands because there are not many animals on islands initially. Natural selection is constantly happening, it is unnoticeable as it is not something that consciously happens. The phenomenon even happens to humans.”

The Hidden Wonders of Island Evolution

Nature doesn’t stay the same. We all know this, we know that animals change in form over millions of years as they slowly evolve. What we are going to focus on today in this article is evolution on islands, specifically, the Galápagos Islands. When evolution occurs on islands, it is known as island evolution, this will be the main topic in this article.

According to the Oxford Dictionary, evolution is the process by which different kinds of living organism are believed to have developed from earlier forms during the history of the earth. Evolution can happen in 4 main ways, fossil record, comparative anatomy, comparative embryology and from natural selection. The fourth and last one is the one we are going to focus on today. The Oxford Dictionary says Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring (John Simpson). The theory of its action was first fully expounded by Charles Darwin, and it is now regarded as the main process that brings about evolution. Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success. Over time, the characteristics that allowed the animals to survive amplified and causes animals to change due to continued breeding between animals (Osterloff).

Fig1 -ArepresentationofhumanevolutioninaseriesofimagesdepictingapesturningintoHomo Sapiens. (Lynch, Ryan. “ARepresentationofHumanEvolutioninaSeriesofImagesDepictingApes

TurningintoHomoSapiens.” Evolution or Extinction: The Path to Brand Survival Is Fraught with Peril, 26Jan. 2016, www.campaignlive.co.uk/article/evolution-extinction-path-brand-survival-fraught-peril/1380834).

Now that we understand the concept of Natural selection and how it works, lets answer the big question, how and why is natural selection different on islands? Well, island species evolved faster than mainland species. The most extreme effects of isolation will be seen on the smallest, most far-flung islands (Gross). Take the Galápagos Islands, imagine several mocking birds or finches are blown off course during a storm and a handful of turtles are carried in the wrong direction because of the tide, and they end up on the island. There are only several animals of each species there. Natural selection will occur and the strongest or most well adapted will survive, considering that there were not many animals on the island in the first place, the change becomes faster (Helmuth).

An example of this phenomenon on the Galápagos island are the massive turtles that dwell there, they adapted to get bigger so that they could move through the thick bushes that reside on that specific island. On a nearby neighboring island, turtles have adapted to have necks that extend far out from their shell. This is because there is a cactus that live on that island that has its edible portion high up (Helmuth).

Fig 2 - A massive Galápagos Tortoise in the grass.

Klipp, Linda. “Giant Tortoise on Isabela Island.” Galapagos Conservancy, 2020, www.galapagos.org/conservation/our-work/tortoise-restoration/.

The process of natural selection occurring on islands is known as Foster's rule, or the island rule. It, is a biographical rule in evolutionary biology stating that species get larger of smaller in relation to resources available to them. Biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms (“Biological Rules”). What will happen is, over the course of millions of years, creatures will creatures from the mainland will turn into smaller or larger versions of themselves while on an island. (Foster’s Rule). Smaller creatures got bigger on islands when predators weren’t constantly an issue and larger creatures shrank due to their being less food on the island. Predatory pressure wasn’t as present due to the lack of animals, this caused smaller animals to grow. Larger creatures shrunk due to less land and less food.

An example of a mainland animal evolving is the finch. It was discovered by Charles Darwin when he observed that the finches on the Galápagos Islands closely resembled another finch species on the mainland of South America. Darwin theorized that the finches on the island were adapted for the islands climate and conditions. As his research developed he realized that the varied beaks of each finch was a result of the different types of food available on the different islands (Learning Lumen).

Natural selection is responsible for millions of different species around the world. An example of natural selection is the giraffe, giraffes with longer necks have an abundance of food whereas giraffes with shorter necks don’t have access to the bulk of food. This makes them less likely to pass on their genes as they have a higher chance of dying due to starvation. This means that longer necked giraffes have a higher survival rate and are more likely to pass on their genes. There is also randomness within evolution, therefore, the best-adapted animal will not always survive (Osterloff).

In short, natural selection is one of the ways that evolution happens. When animals that have traits that allow them to survive, over time those traits are amplified. This process happens far faster on islands because there are not many animals on islands initially. Natural selection is constantly happening, it is unnoticeable as it is not something that consciously happens. The phenomenon even happens to humans.

Reference List:

Reference List:

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7. Osterloff, Emily. “What Is Natural Selection?” Natural History Museum, www.nhm.ac.uk/discover/what-is-natural-selection.html. “Foster's Rule.” Wikipedia, Wikimedia Foundation, 5 May 2020, en.wikipedia.org/wiki/Foster%27s_rule. Foundation, Wikimedia. “Biological Rules.” Wikipedia, 24 May 2020.

en.wikipedia.org/wiki/Biological_rules. Accessed 27 May 2020.

Gross, Liza. “Islands Spark Accelerated Evolution.” PLOS Biology, Public Library of Science, 12 Sept. 2006, journals.plos.org/plosbiology/article?id=10.1371%2Fjournal.pbio.0040334. Helmuth, Laura. “Evolution World Tour: Galápagos Islands, Ecuador.” Smithsonian.com, Smithsonian Institution, 1 Jan. 2012, www.smithsonianmag.com/arts-culture/evolution-world-tour-galapagos-islands-ecuador5974755/. Learning, Lumen. “Biology for Majors II.” Lumen, Lumen Learning, courses.lumenlearning.com/wm-biology2/chapter/natural-selection/. Oxford Dictionary Oxford University Press. http://www.oed.com/viewdictionaryentry/Entry/7179;jsessionid=61494FA30F662800990 8C800D2210718 (accessed May 22, 2020).

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2. Klipp, Linda. “Giant Tortoise on Isabela Island.” Giant Tortoise Restoration Initiative, Galápagos Conservancy OUR EFFICIENCY, 2020, www.galapagos.org/conservation/our-work/tortoise-restoration/. Lynch, Ryan. “A Representation of Human Evolution in a Series of Images Depicting Apes Turning into Homo Sapiens.” Evolution or Extinction: The Path to Brand Survival Is Fraught with Peril, 26 Jan. 2016, www.campaignlive.co.uk/article/evolution-extinction-path-brand-survival-fraught-peril/1 380834.