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The natural world. Looking pretty for 3.5b years.

Convergences

Author: Hugh Bollinger/Saturday, January 25, 2014/Categories: natural history, environment, plants

Mountain tops and remote islands are perfect environments to see expressions of  convergent evolution . This fundamental bit of evolution works on unrelated species, on separate continents, but under the same environmental influences---strong isolation, limited competition, and similar climates---to produce lifeforms looking surprisingly alike. Alpine photographs from African and South American mountains show the close appearance of rosette plant forms that evolved from different species.

Habitats in  these so called "sky islands" are typically nutrient poor, frequent temperature extremes, and show high solar radiation. They were originally colonized by a limited number of individual species that survived the conditions to multiply, evolve, and dominate the landscape. Due to their isolation, plants and animals there are often vulnerable to destruction by their slow growth and lack of defenses against fast breeding invaders including goats, rats, and pigs. Even insects like mosquitoes can transmit diseases like avian flu to endemic birds.

  
Ruwenzori Afro-alpine    and      Columbian Altiplano  rosette plants    (credit: Wiki-commons)

Results of convergent evolution are often strikingly odd but also can be very beautiful. In the USA, the best place to see such rarities are on peaks in the Hawaiian Islands. On this volcanic archipelago, the slow process has created some truly beautiful endemic plants found nowhere else. Two outcomes are particularly impressive---the Silverswords of Mount Haleakala on Maui and the tree lobelias on the summits of Oahu's Waianae Range .

 
Silverswords, Maui  (credit: NPS)               Tree Lobelia (Trematolobelia kaalae), Oahu (credit: EOL)

It takes effort to visit these strange landscapes and the beautiful things living there but worth it. Take a book like  Song of the Dodo  to learn more about evolution, convergences, and extinction treats to such wonders.

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