In 1859, Darwin published his “Origin of Species”. He was not the first person to propose the idea of biological evolution. The Darwin’s theory is the beginning of a story, but not the end of it. I will discuss two non-mainstream theories of biological evolution
The Lamarckian or Darwinian or Neo-Darwinian theories all have a view: it takes a long a time for new species formed. Contrast with the slow evolution theories, there is total different theory of evolution which claims that the new species do not need a long time, but one generation to form. The first person to propose the idea is the Dutch botanist Hugo De Vries.
“In 1886 De Vries discovered new forms among a display of the evening primrose (Oenothera lamarckiana) growing wild in a meadow. Taking seeds from these, he found that they produced many new varieties in his experimental gardens; he used the term mutations for these suddenly appearing variations. In his two-volume publication The Mutation Theory (1900–1903) he postulated that evolution, especially the origin of species, might occur more frequently with such large-scale changes than via Darwinian gradualism, basically suggesting a form of saltationism.”
Saltationism was the chief evolution theory in the first 30 years of the 20th century, until it was replaced by “Modern Synthesis” or the Neo-Darwinism.Currently, all new species discovered and confirmed without controversies among biologists are consistent with saltationism, there are two major types: polyploidy and bisexual animals become parthenogenesis ones.
Polyploidy chromosome number of people found that many new species, just the old kinds of multiples, such as 2 times 3 times. Polyploidy can be divided into autopolyploid and allopolyploid. Autopolyploid chromosome doubling actions, allopolyploid species are hybrid of two different species. More than half of all land plants species are polyploidy, including wheat, corn, and cotton. It is estimated that up to 85-95% ferns and many other plant species were generated by polyploidy (Grant 1994; White 1978). Speciation via polyploidy is instantaneous, and only takes just one generation. Moreover, the new species are not spatially separated from its ancestors. Speciation through polyploidy occurs less often in animals, but it still exists (Gallardo 1999). Polyploidy animals may occur in a number of insect species including walking sticks, grasshoppers, blackflies, and beetles (Gregory 2005).
Polyploidy was first reported in 1917 (Winge 1917). Neo-Darwinian theorists accept polyploidy speciation in one-generation. Ernst Meyer is one of the important figures of the Neo-Darwin’s theory, his mentioned several times in his books to say polyploidy produce new species instantaneously, without geographic isolation and natural selection (Mayr 1988). He said:
“Speciation, except for polyploidy and some other chromosomal process, is too slow to be observed directly. …… Owing to the slowness of the speciation process, it is not possible to study the same individual or population “just before” and just “after” speciation (Mayr 1988).
2. Generation of Virgin Birth Animals
Another example is more incredible, bisexual animals become parthenogenesis animals.
Parthenogenesis or virgin birth, which has been seen in at least 70 species, including snakes and lizards, is a process in which eggs become embryos without male fertilization, Many annoying insects such as ants, bees, wasps, aphids as well as some fleas and ticks create progeny in this manner. Many of these species are believed to be descended from sexually reproducing ancestors (Schlupp 2005; Simon and Rispe, Claude & Sunnucks, Paul 2002).
A female white spotted bamboo shark at the Belle Isle Aquarium in Detroit surprised zookeepers in July by giving birth to two babies. It was a virgin birth or parthenogenesis as she had not been near a male shark for six years (Mayell 2002). Many of animals generated by virgin birth are self-reproductive, which are different species from their direct sexual ancestors, even they are asexual animals, the biological species concept
does not apply on them. There is no doubt that they are different kind of animals from their parental ones.
3. Fast Speciation
By the Neo-Darwinian theory, speciation should be a very slow process. In fact, new species were constantly discovered, some of them occur within only a few decades. For instance, Fishelson in Eilat in 1975 looked at the morphology of 80 Pterois volitans. None of the specimens had a spotted, feather-like tentacle, although five specimens did have wider tentacles than normal. A follow-up study on the same reefs in Eilat found two new forms of lionfish among the 35 specimens examined. These fish had the eyespot on just a single tentacle. Subsequently, the feather-like tentacle form has been found outside the Red Sea in the Pacific Ocean (Fishelson 2006).
Chauvin R. 1967. The world of an insect. New York: McGraw-Hill. Fishelson L. 2006. Evolution in action-peacock-feather-like supraocular tentacles of the lionfish, – the distribution of a new signal. Environmental Biology of Fishes 75:343-8.
Fishelson L. 2006. Evolution in action-peacock-feather-like supraocular tentacles of the lionfish, pterois volitans – the distribution of a new signal. Environmental Biology of Fishes 75:343-8.
Gregory TR. 2005. The evolution of the genome. Burlington: Elsevier Academic.
Mayell H. 2002. Shark gives “Virgin Birth” in Detroit. National Geographic News. http://tinyurl.com/1xfu
Simon J and Rispe, Claude & Sunnucks, Paul. 2002. Ecology and evolution of sex in aphids. Trends in Ecology & Evolution 17:34-9.
SchluppI. 2005. The evolutionary ecology of gynogenesis. Annu Rev Ecol Evol Syst 36:399-417.