Islands – an endless source of biodiversity

We are talking more and more about biodiversity: we know it has to be protected, it represents a priority of the European Union’s policies and we are aware that the changes it suffers, be it on a local or global scale, carry with them serious effects for the entire planet. But what exactly is biodiversity – and how can we celebrate it?

What is biodiversity?

When we discuss biodiversity, we essentially refer to the variations of life on Earth. Nevertheless, for practical reasons, we need a more complex approach of this notion.

Thus, we can speak of a diversity of ecosystems – their variability across the world, and by ecosystems we mean a community of organisms and environments, with both biotic and abiotic components; a diversity of species, the entire array of plant and animal species and, finally, a genetic biodiversity, all the genetic characteristics of a species.

Photo 20140319193514May the 22nd was proclaimed the International Day of Biological Biodiversity through a decision taken by the General Assembly of the UN on December 20th 2000, when the date of adoption for the Convention on Biological Biodiversity was adopted – 22nd of May. For 2014, the theme was Island biodiversity, because islands represent a treasure-trove for scientists working in the field of biodiversity: each one is a unique ecosystem due to its isolation, which determined the apparition and evolution of endemic plant and animal species

Why are islands so important?

Probably the most important example of the importance and biological uniqueness of islands comes from the research of Charles Darwin in Galapagos. Among other, he observed the local populations of finches (Geospizinae) and noticed elements that later would form the pillars of his theory of evolution by natural selection. All finches looked similar, except for their beaks, which were either short and narrow, or long and wide, rounded, and so on. Darwin came up with the hypothesis all these birds evolved from a common ancestor who migrated on the islands, and the differences in beaks appeared as an adaptation to different diets.

Finches

Therefore, islands provide a favorable environment for the development and evolution of unique species because of their isolation from continents. An island species tends to become narrowly adapted in order to occupy a small ecological niche in order to survive, due to the fact that resources are limited on an island. Thus, creatures end up possessing specific characteristics and adaptations, such as gigantism, dwarfism, particular defense mechanisms, the loss of flight (for birds), etc.

Islands, seen as hotspots of biodiversity, harbor a greater concentration o endemic species than continents. For example, more than 98% of all species found in Hawaii are endemic to this region. In Mauritius, around 50% of plants, mammals, birds, reptiles and amphibians are endemic. Cuba has 18 endemic mammal species whereas Guatemala and Honduras, both located on the mainland, only have 3.

Because they are isolated and have limited surface and resources, islands are also very vulnerable. Among the 724 extinctions recorded over the last 400 years, around half affected island-dwelling species. Among the changes that impacted on our relation with the environment during the last decades, islands face new threats to their fragile environment: pollution, invasive species, habitat destruction, over-exploitation of resources and species and finally, climate change. These alterations harm not only biodiversity, but also the local economies, since inhabitants of islands belonging to developing nations depend more than us on natural resources.

For more information on island biodiversity, visit the website of the Convention on Biodiversity.

Biodiversity

Pictures taken from: 1, 2, 3.

Sources of information: 1, 2, 3, 4, 5.

Article written by Magda Baidan and translated by Mihail Mitoșeriu.

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