Friday, November 14, 2008
The Selfish Gene
The Selfish Gene
The Selfish Gene is a book on evolution by Richard Dawkins, published in 1976.
What it essentially states is that... this is a difficult concept to explain and I apologise if I am unable to do justice to the term.
What it means, as far as I understand is that a gene seeks to propagate itself, ensures that it is further replicated through future generations, ensure that it (i.e. a species) lives on.
Survival of the fittest, a quote by Darwin touts that in a competitive situation of limited food and adverse conditions, only the best adaptable will be able to survive and produce offspring to carry on the gene. Thus, only the best will go on living.
So essentially the best gene among a pool of genes- Ie one carried by the alpha male of a troupe of monkeys-the leader of the pack-usually the strongest and healthiest monkey among the group- will be the one being propagated into the next generation. It is indeed so, considering the fact that in certain animal colonies, (case in point-wolves) only the alpha pair have the right to mate and produce progeny.The rest of the wolf pack are childless for they serve as nannies to the alpha pair's cubs. This is nature's selection process.
Okok.. Enough of the preamble... This is actually a post about the intelligence of... I'll give the chance for all to warm up to this thought.... ready? Set? Go!
THE INTELLIGENCE OF PLANTS
Has it sinked in? Or are you shaking your head in disbelief? Hopefully after the rather strainful paragraphs above you still have the will to read on.. keeping my fingers crossed!
(p.s.- I Just handed in my Case write up this afternoon at 5pm.. I slept at 3.30a.m. this morning and woke at 7.30am so pardon me if the quality of this article is off)
(p.p.s- I have never read an article on the same topic so i'll try my best here)
We usually think that plants have no intelligence. Structurally this is true as they don't have a bundle of nerve cells that constitute what we call a brain and technically they are just plain growers reacting to light, water and gravity-(tropisms)
We think that they are the silliest lot in nature... what?... producing fruits only to be eaten by others... They are at the mercy of everything else under the sun- the weather, insects, animals that eat the plant and fruits and leaving nothing behind.
but careful contemplation will reveal that plants apply the concept of the selfish gene and they have the intelligence needed to make sure they are passed on.
Consider the duku (ok, Langsat/ dukong) if you will... and recall the time you absent-mindedly chewed hard enough to break the seed. What follows next is a reflex action of wanting to spit/vomit. The plant wishes that you eat the pulp of the seed but not the seed itself. By being Sour and Bitter it sends the message ---" I AM NOT TO BE EATEN". So you end up eating up the pulp and tossing the seed behind your back.. just what the plant wanted. 'toing!' it lands on a soft spot on the ground and sprouts! (not so if youre living in an apartment la. what happens is your mum comes round and pulls your ears)
The same rule applies to citrus fruits. Then consider this. Ever tasted a green orange? Or a unripe banana? (I will explain the banana story later) They taste sour or in the case of banana what we chinese call "siap-siap"- it leaves a bad sensation on our tongue and mouth.
Again, the plant is trying to say "I AM NOT TO BE EATEN" or perhaps "I AM NOT TO BE EATEN, YET". Before the seed within the fruit is mature, animals (humans ARE animals) are not allowed to consume the fruit. What good to the gene there will be if the unripe seed is strewn around and allowed to rot? A waste of time and resources. Plants spend almost 80-90% of their energy forming flowers and then seeds. A immature seed is a season's toil gone down the drain.
-Bananas used to have seeds. Ask your granddad or grandmum and they will testify not all bananas can be swallowed whole without thinking. Human selection has selected or modified the plants that root sprouting has become the choice method of reproducing instead of seeds. A relief to many that used to chew hard onto the seed and regretted it. Try any jungle bananas- the ones allowed to grow on their own without human intervention and you may still find great big seeds inside, compared to the tiny-weeny seeds we see now.-
So the above illustrates how a plant protects its investment. There are more examples to come. Now. Certain plants "know" that their fruits are going to be eaten. In fact they come prepared for this. Some seeds of certain plants do not germinate unless they past thru the gut of some animals and the acid within the stomach breaks down the waxy coating over the seed allowing the micropyle to absorb water and expand, thus breaking the seed covering and allowing the radicle(root) to burst forth!
An extreme of this example is the the Australian eucalyptus whom seeds only germinate, after a fire. This is a product of generations of survival of the fittest, evolution at its best. Australian bushfires are notorious for the havoc they wreak. And plants living in the outback have thus grown tougher tougher throughout the generations, having roots that withstand fires or thick barks that can stand intense flame. The pinnacle of this form of evolution- being through the (to quote an archaic expression) baptism of fire is the fire-proof seed. The reason is simple. After a fire breaks out the entire landscape is burnt down and there is no competition. There is the added bonus that the ashes of the plants that once stood now become instant fertilizers! These flame-hardy seeds stand to gain the most from a fire. You can imagine them hoping for a blaze to happen soon so that they can sprout and free themselves from the confines of a seed.
Starting to believe that plants are smart and may have a brain or two tucked somewhere?
I hope to convince you even further.
Sometimes there are plants that depend solely on an animal for its pollination.
You would think "oh the poor poor plant, having only a sole pollinator... its entire species depends on a single animal... it's like having its life controlled forever"
But in reality it is the plant which controls the animal. It enslaves it with sugary nectar or delicate fruits. The animal is entirely reliant on that plant having adapted mouth parts uniquely suited to draw nectar from a unique flower, while the plant may have a host of pollinators to show off with.
An example of a superbly unique evolutionary relationship
The Angrecum Orchid in Madagascar.
A simple demonstration of the relationship between forest plants and animals comes from the night-blooming Angrecum orchid. The yellow-flowered beauty has a nectary at least 8 inches long -- meaning that its pollinator needs a snake-like tongue to reach the delicious, high-sugar nectar inside.
No less a naturalist than Charles Darwin, who saw the Angrecum in Madagascar in the 1860s, correctly predicted that a moth with a 22-centimeter tongue must exist in the forest. Fifty years later, the moth was found -- with a rolled-up tongue that snoots out like a Hong-Kong New Year's party favor.
For the explanation of symbiotic evolution refer the link below
Now... For the grand story... accelerated evolution- hard to imagine without the plant having a brain!
What is this?
Yup this is a Passion fruit. Recently being imported to Malaysia and planted here. This fruit has an unique taste like no other. If you want a sample ask one from me the next time I come back from Muar. I passed quite a few to a few friends and one to a midwife that allowed me to conduct a delivery. To my horror she said:
"Apa ni? ada jampi ke?"
Oh well.. I hoped she liked it!
The passion fruit comes from the...teng teng teng teng... the passion vine! No prizes for guessing it right! I have one of them at home and it is currently sprouting ten passion fruits!!! Hohoho...
Back to the story....
There is a strain of wild passion vines in the forests of...uh... I can't remember... south america maybe? that has the unfortunate luck of being favored by a particular species of caterpillar and gets eaten all the time. So the poor plant starts to think... of the available options...
1) have toxic stem and leaves! that should keep the moth away!
But the plant thought that wouldn't work. The caterpillar would soon grow resistant to the toxin. (Meerkats and Scorpions have this arms race in that the scorpion tries ever so hard to produce a new poison that the meerkat isn't resistant from. But the meerkat gets sick once, twice and if it doesn't die passes the immunity on to its progeny. So here's a super resilient baby meerkat. The scorpion doesn't concede defeat and rebrews its venom so that it is more toxic or works faster ... and the race goes on until today where same species of scorpions from different regions in africa have different toxic cocktails within their tails... evidence that they are adapting, changing the venom to counter the meerkat's immunity.) (Kinda like how the arms race between Russia and the US during WWII works)
So what do you think the plant do that doesn't involve cooking up cauldrons of toxins?
It starts to look like this!
Nope, that isn't a bud about to grow. In fact it serves no purpose but to trick the moth/butterfly into thinking that this plant has already been visited by many moths before and if she lays her egg on this plant... her baby caterpillars will have to compete with dozens and dozens of other caterpillars that will definitely hatch sooner than hers... so off she goes in search of a less tasty plant to lay her eggs on. Brilliant, isn't it?
I may not be a good story teller so here goes
"Interesting associations have developed between plants and insects like that of the Heliconid butterflies and passion flower vines of the genus Passiflora. Passion flower vines contain cyanide-based compounds for protection against predators. However, Heliconid caterpillars have adapted to these compounds and are able to eat the vine's leaves. Therefore, Heliconid butterflies lay their eggs directly on the passion flower vine, so the larvae will have easy access to their food source. Passion flowers have counter-adapted to the behavior by developing mechanisms to discourage Heliconid butterflies from laying eggs on their leaves. Some Passiflora have evolved structures (actually nectaries) that create housing and produce excess nectar for ants. In return, the ants attack anything, including butterfly eggs, that intrudes on their host. One- upping their predators, some Passiflora have structures that mimic the eggs of Heliconid butterflies. Since a Heliconid butterfly will not lay its eggs on leaves that already have (or appear to have) these eggs, she will move on to another plant. In this manner, Passiflora deter Heliconid butterflies without devoting any resources to the production of nectar for a guard of ants, a technique of protection adopted by many other plants as their primary means of defense."
So there you go! I hope I did justice to the subject... There are plenty of examples out there that I have no idea off... this is just a limited selection of "plant cleverness" that I know off. I hope my short article successfully piqued your interest in finding out more about the weird and wonderful world of nature that we are losing fast... please do your part to preserve this lovely story so that we can show them to our children!