What is Symbiosis?

stated clearly presents [Applause] what is symbiosis normally when people talk about symbiosis they're talking about two different types of organisms cooperating to help each other survive for example clownfish hide from predators among the tentacles of sea anemones in return they feed the anemone with their own droppings yum yum the anemone and the clownfish enjoy a symbiotic relationship in biology however symbiosis has a broader definition than simple cooperation it's classically defined as any long term living together of unlike organisms let me say that again symbiosis the long term living together of unlike organisms mutualistic symbiosis or mutualism is when both partners benefit from the relationship like we saw in the clownfish and the anemone when I say that both partners benefit from their relationship what I mean is that both organisms experience a significant increase in evolutionary fitness they both end up being better at surviving and reproducing parasitic symbiosis or parasitism is when one benefits while the other is harmed ticks are a good example of a parasite they drink your blood and then sometimes repay you with Lyme disease total jerks commenced allistic symbiosis or commensalism is when one organism benefits while the other is not dramatically helped or harmed squirrels live in oak trees they sometimes eat bark leaf buds and of course they love to eat acorns they consume the flesh of the oak trees unborn children this is great for the squirrel of course but surely this must be bad for the trees evolutionary fitness right well multiple studies have shown that the relationship between oak trees and squirrels is both extremely complex and extremely ancient apparently stretching back millions of years both organisms are trapped and evolutionary arms race against each other through the ongoing process of descent with modification acted upon by selection oak trees have evolved many tricks to control the behavior and population size of their ancient furry rivals among other things the tree has evolved to produce toxins inside of its seeds squirrels in return have evolved a digestive system that can handle the toxins fairly well but more importantly squirrels have changed their behavior when they find fresh acorns instead of eating them they stash them in shallow hiding places to let rainwater detoxify them over several weeks to several months a single squirrel can make hundreds of stashes all over its territory every single year if the squirrel dies before eating the acorns or simply forgets where some of them were hidden the squirrel has in effect planted brand-new trees often in places far enough from the parent tree that there will be no parent offspring competition for sunlight when the saplings begin to grow this is called seed dispersal and it's actually good for a tree's evolutionary fitness it helps them produce more successful offspring well it's difficult to perfectly calculate evolutionary Fitness there are so many unknown variables involved it appears that right now in the middle of this crazy evolutionary arms race many trees either breakeven or sometimes experience an overall fitness gain when those pesky squirrels move into their branches here we see that there exists a symbiotic continuum from parasite to mutualist symbiotic relationships can and do change dramatically over time even ticks which almost all of us consider to be horrible parasites when they're not carrying diseases sometimes act more like commensal lists than parasites due to their small size they take very little blood from their donors this means that a single tick won't usually cause a noteworthy Fitness decline in its host results from a recent studies show that opossums may actually benefit from tick infestations this is because they snack on ticks and the single opossum may eat over 5,000 ticks per week during tick season now ticks are really small but 5,000 per week that is a noteworthy supplement to the opossums regular diet ticks are sort of like little sack lunches that come directly to you free delivery it might seem silly that biologists invented a word symbiosis to encompass everything from parasites to co-operators but the reason for this is that parasites can evolve to become co-operators and vice versa understanding these evolutionary transitions is fascinating but more importantly this knowledge is now helping us control diseases for example many of the bacteria living in your intestines actually help you digest your food they eat the parts of it that you can't absorb and then excrete the waste waste products that you can absorb yum yum most of the microbes living inside us today either have a mutualistic or a commensal istic relationship with us but some of them started out as parasites in 1991 a bacterial intestinal disease called cholera broke out in South America as you may know cholera causes extreme diarrhea that's why it's so dangerous it makes its host desperate to use the toilet and then spreads to new hosts either through dirty drinking water or through person-to-person contact biologist Pauly wold studied its spread and the evolution of the cholera bacteria in real-time in nations with bad water filtration the bacteria remained deadly year after year this is because natural selection favorite strains of the bacteria that would make people use the toilet more frequently even if it eventually killed them due to dehydration because the bacteria would contaminate more water this way and spread faster to new hosts in countries with good water filtration strains of the bacteria evolved toward commensalism in these environments natural selection favorite microbes that were quote kinder to people because people were then healthy enough to go to school to work and mingle with friends and family this allowed the bacteria to spread slowly and nonviolent through human to human contact the take-home message here is this when there is an outbreak of cholera not only should we immediately treat the sick we should also distribute clean drinking water doing so will guide the bacterial evolution in a direction that's good for the future of the people in the area these fascinating interactions and evolutionary transitions from enemy to friend and sometimes from friend to enemy are all possible because of symbiosis the long term living together of unlike organisms while most people have no trouble understanding how evolution causes animals to adapt to their environment a bear to the cold for example we often forget that a creatures environment also includes the other organisms that share that environment if two species live together and interact long enough the slow process of evolution descent with modification acted upon by selection can cause living things to evolve and adapt to each other I am John Perry and that is symbiosis the long term living together of unlike organisms stated clearly well that is it for this animation but for those of you who are extra curious you probably have some questions after seeing this what did I really mean when I said that there is an evolutionary arms race between trees and squirrels what is an evolutionary arms race what else aside from adding toxins to their seeds our trees doing that allows them to control the behavior of squirrels furthermore what exactly are the toxins that are added to acorns anyways aren't acorns uses food by people in some cultures and finally how on earth do opossums eat up to five thousand ticks per week during ticks season that's over 700 ticks per day that sounds crazy right well don't worry I made a second video called deep dive into what is symbiosis you can watch that on my other channel stated casually there I'm going to show you the literature go over each of these questions and even introduce you to some squirrels that I have been raising some orphaned squirrels for release into the wild a link to that video can be found down in the video description so go check that out also feel free to subscribe like this video support my work on patreon you know the drill so long for now stay curious

Channel: Stated Clearly

Views: 49,500

Rating: 4.9242015 out of 5

Keywords: Symbiosis, Symbiotic continuem, symbiotic continuum, evolution, evolutino of symbiosis, squirrel, evolutionary arms race, arms race, biology, darwin

Id: eChtyqSqUIs

Length: 9min 10sec (550 seconds)

Published: Mon Oct 07 2019