What was first appearance or function?
2006/05/15 Galarraga Aiestaran, Ana - Elhuyar Zientzia
The cactus are perfectly adapted to the desert environment. They are willing to absorb, physiologically and anatomically, the little water that surrounds them and to maintain what is achieved. For example, to avoid water loss from perspiration, most species lack leaves and perform photosynthesis in the stem. The stem also serves to store water, so it is usually thick.
The researchers wanted to know how these adaptations have been emerging throughout evolution and have tried to answer the question of what was first the change of aspect or the development of a water saving strategy.
To answer the question, botanists at the University of Yale have focused on the cactus of the genus Pereskia. For botanists, this genus is the most primitive. It is divided into two branches, one of which does not resemble the rest of cactus, although it has similar functions. For example, its leaves are conditioned to store water and perform photosynthesis, in an unusual way in other cactus.
Analyzing the peculiarities of the species of the genus Pereskia, the botanists have concluded that the cactus were adapted to the water shortage first physiologically and then developed the anatomical characteristics that allow them to save and store water.
In the image, Pereskia godsefiana (Paul Brunelle/ Evolution and phylogeny of cactus).
