Discuss the importance of Charles Darwin contribution to science using examples from a taxonomic group of your choice. Charles Robert Darwin is most well-known for his book ‘On the Origin of Species’ this book contains detailed argument, evidence and ideas on his theory of evolution by natural selection. Despite how much this has influenced today’s research Darwin always wanted more evidence, this was because his theory was controversial at the time. However, it is now a highly regarded concept which is widely accepted in life sciences.
On Darwin’s famous voyage aboard the HMS Beagle around the world he studied and worked on geology, botany, zoology and scientific research. This essay will explore Darwin’s research and contribution to science through insectivorous plants, which is where Darwin believed to be a link. Plants are often seen as immobile and unresponsive but Darwin saw them as ‘active with interesting behaviour’. Charles Darwin actually produced the first well-known book on carnivorous plants (Insectivorous Plants, 1875) and therefore offered the initial study into the topic.
In this book he examines many species and identifies why they must become carnivorous to survive, and individual adaptations to each species. Looking at how the plants reacted to certain stimuli to understand its evolutionary reasoning for their adaptations and surviving environmental conditions. These include heat, nitrogenous fluids and nutrition. Another major modification that these plants have is the ability to move rapidly or faster than other plant types. Darwin contributed in so many ways to this area of botany which this essay will demonstrate.
Darwin enjoyed the peace and quiet of his countryside house in Kent, and to avoid much disagreement with other naturalists he turns his attention to plants. Darwin sketched out how he sees evolution in the tree of life it represents different plants and animals evolving over millions of years. Darwin’s radical theory is that all plants and animals are related. And that a long way back in time animals and plants must share a single common ancestor. Darwin thinks he might be able to find evidence for this shared ancestry in insect eating plants.
The first organism that Darwin studies in Insectivorous Plants is the common sun-dew (Drosera rotundifolia), he states ‘it was evident that Drosera are excellently adapted for the special purpose of catching insects, so the subject seems well worthy of investigation. ’ He was amazed by the sensitivity of the glands and its movements in response to nitrogenous fluids. Also the fact that these plants were able to absorb nutrients through slight digestion which no other plant had shown before, and even closer at the changes that took place in the cells of ‘tentacles’, which Darwin called them.
After many experiments with various food items and other substances including; saliva, urine, cooked meat and numerous chemical solutions, Darwin concluded that food sources containing nitrogen caused the most excitation by the plant. From this we are able to assume that for these plants to survive in areas that they existed (such as nutrient poor bogs) they were not able to achieve a substantial amount of nitrogen through normal botanical methods.
Thanks to Darwin’s tests scientists were able to grasp the idea that these organisms needed other means of gaining nitrogen, so that this contribution may help in the future. Another plant he investigates related to the common sun-dew is the fast and brutal species known as the Venus fly trap (Dionaea muscipula). Darwin tested the plants by putting various pieces of hair and cotton into the plant to see what it responded too. He was looking at the sensitivity of the trap, by looking more closely at the trigger hairs. The mechanism is very quick; it has to be to catch a fly.
But Darwin is curious about the signal between the trigger hairs and the hinge of the trap. He asks ‘could it be possible that the leaves might possess some botanical equivalent to nerves and muscles? ’ Darwin thought that the movement was due to a nervous system and that this could possibly be the link between flora and fauna. To explore this hypothesis he came up with a rather dangerous test to explore if plants had nervous systems like animals. He tried to use many poisons on the plant that would inhibit the fly-traps ‘nervous system’, one being chloroform.
Many had no effect (short of killing a few) to the ‘nervous system’. It is now understood that chloroform vapours depress the central nervous system (Environmental Protection Agency, 2000) and Darwin thought this would have the same effect on these plants. Although Darwin did not make the link between human and plant and attempt to support his common ancestor theory, he did discover that plants did not have nervous systems like humans. This allowed science to continue research into other ideas that may cause movement in the Venus fly trap.
Granting Darwin’s book covers many more species of carnivorous plants it’s shown that he has greatly contributed to the science of these specific organisms. His experiments on the sun-dew and Venus fly trap showed that; the tentacles will only react if desired substances are in contact with the glands, acid is secreted and then the nitrogenous essentials are absorbed after ‘fermenting’. But primarily in the Dionaea muscipulaI he proved that plants are not similar to animal in their movement.
He then went on to discover that certain parts of insectivorous plants will adapt different areas to do diverse tasks. With support of his ‘descent with modification’ (Origin of species, 1858) he predicted that some plants may become too adapted and loose other functions that could create new species- essentially evolution. Darwin understood that many of the plants included in these studies were form nitrogen limited environments and they needed to obtain their nitrogenous substances from captured insects.