Island Gigantism

“Reptiles and amphibians are sometimes thought of as primitive, dull and dim witted. In fact, of course, they can be lethally fast, spectacularly beautiful, surprisingly affectionate and very sophisticated” - David Attenborough. Amphibians have survived on earth for 300 million years longer than humanity and have gone through some unusual evolutionary changes over their period of settlement. Over 8000 known species of amphibians exist and they comprise frogs, toads, salamanders, newts and caecilians. Although morphologically similar to the class of reptiles, amphibians have adaptations which allow them to survive in land and water. In order to survive, amphibians are dependent on pristine freshwater habitats as they are vulnerable to habitat degradation. An ecological indicator is an organism which provides relevant data about an ecosystem and the impacts of human activity on it. Amphibians are considered ecological indicators as they have complex reproductive requirements and porous...

1) The Indian (Malabar) giant squirrel tops the list due to its distinct colouration and size. It is a prodigious multi-coloured species of tree squirrel which is endemic to India. Found in forested areas, this species is a herbivore and has adopted an arboreal way of living. Among squirrel species, the Indian giant squirrel is one of the largest squirrels with a length of 25-50 cm and a weight of around 1.5-2 kg. Additionally, it is a diurnal species and is very easy to spot. Being the state animal of Maharashtra, you should plan on spotting this magnificent creature. 2) The black giant squirrel is another species of squirrel found in India and the rest of South-East Asia. It is one of the largest squirrels in the world and can be identified with its black fur and light face. Found in rainforests, it is an arboreal species and feeds on herbivorous food sources. 30% of the black giant squirrel’s population has been lost in the last 10 years and this is attributed to human activity like...

  A keystone species is an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.  Keystone species have low functional redundancy. This means that if the species were to disappear from the ecosystem, no other species would be able to fill its ecological niche. The ecosystem would be forced to radically change, allowing new and possibly invasive species to populate the habitat. Any organism, from plants to fungi, may be a keystone species; they are not always the largest or most abundant species in an ecosystem. However, almost all examples of keystone species are animals that have a huge influence on food webs. The way these animals influence food webs varies from habitat to habitat.  Their consumption of plants helps control the physical and biological aspects of an ecosystem. In African savannas such as the Serengeti plains in Tanzania, elephants are a keystone species. E...

The productive west coast of North America holds one of the greatest spectacles known to nature. During fall, dormant water bodies pulsate with millions of migrating Pacific salmon and the events that follow create the ‘salmon run.’ Mature Pacific salmon migrate from the Pacific Ocean to rivers to spawn and their annual arrival is of immense importance to Grizzly bears, Bald eagles, wolves, local fisherman, etc. Each year, these salmon provide a bountiful supply of fresh food to other creatures, therefore it is regarded as a keystone species. Pacific salmon are born in freshwater and as they mature, they undergo physiological changes so that they can adapt to saltwater conditions. During these changes, they spend time in the brackish waters of river estuaries and once they are 15 to 20 centimetres long, they swim out to sea. The salmon spend around 4 years at sea, where they grow strength and mass to prepare for their strenuous migration back to freshwater systems, to spawn. Salmon are...

Island gigantism is a biological phenomenon in which animals living on an island grow much larger in size than their mainland relatives in the absence of predators. The phenomenon is  corroborated by Foster’s rule, which explains how an organism’s size differs in relation to its surrounding environment and resources . Miscellaneous islands shelter organisms which have been subject to this phenomenon and they are continually studied to provide concrete evidence for evolution. New Zealand is a renowned example of island gigantism and has intrigued scientists for a long time. Although the phenomenon has existed for millennia, widespread expansion of humanity and introduction of invasive species (predators) onto fragile islands have led to the extinction of various giant organisms.  In 1964, J.Bristol Foster introduced the concept of island gigantism in the published paper ‘Evolution of Mammals on Island.’ This was done based on a survey which involved the comparison of 116 islan...