Parasites, Ecology & the Goldilocks Principle

Would you have ever in your life considered parasites as “tiny, hidden architects” of biodiversity that run a service business for a sustainable global ecology ? The biggest problem for the Earth's natural world is that ever since human beings arrived on the earthly scene, as caretakers of the natural world, they've mucked things up so horribly by introducing parasites where they can & will cause not only the most harm to other living organisms within any and all ecosystems, but where they will cause pain and suffering to other human beings. Let's be totally honest here, as environmental stewards Humans stink at it. There are a number of fascinating studies which have been published recently over the past couple of years which shed light on the positive as opposed to the usual negative aspects of various parasites and their healthy function in the natural world when that world is in a stable balance. I'll simply list a few and you can follow the articles. A parasitologist name Tommy Leung, suggests that parasites don’t just rob and steal; they usually do good as functional players in an ecosystem.

“Parasites are thought of as free-loaders, but many contribute as much as they take,” - “They service the ecosystem. From an ecological perspective, they are more like tiny, hidden architects that are overlooked by most people.”  - “Some parasites do have a negative impact on an ecosystem, especially when they are introduced to a new and unfamiliar environment.” (source)  

Credit: haquintero

The parasite a cricket’s nightmares are made of

"But the very act of forcing crickets to their watery grave actually functions as a kind of fast food delivery service for the fish living in those streams. Cricket do not normally jump into streams and a drowning cricket is usually a rare treat for any fish. But thanks to the hairworm, these fish get to feast regularly on these large insects and it has been calculated that this straight-to-your-stream food delivery service accounts for more than half of the trout population’s energy intake in some watersheds."

Watch this creepy but very kool video below here of what happens when the cricket is forced by it's parasitic hitchhiker to jump into water and drown itself.

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Credit: Tommy Leung

(source) When microbes cause ants to become zombies

"Usually the enemy of an enemy is a friend, but that is of no consequence for a zombified ant. To these fungi the ant is but a stage upon which they play out their lives and conflicts, as they have been doing for millions of years."

Can you imagine the possibilities in dealing a blow to the out of control Argentine Ant Super Colony over-population of California and other areas of the west ? BTW, Mycologist Paul Stamets has brought this up before.

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Photo: Andrew DunnEuropean Mistletoe (Viscum album) attached to a
silver birch (Betula pendula)

"Plant parasites can also affect ecosystem processes. While most people associate mistletoe with Christmas, it is actually a parasitic plant that has special root-like structures called haustoria that burrow into the host tree to suck out water and other nutrients. But for all that it draws from the host, this parasite returns it to the ecosystem in the form of enriched leaf litter."

"A study published in the Proceeding of the Royal Society B shows that when mistletoes are removed from a forest, more than a quarter of the birds species also disappear. The enriched leaf litter allows the forest to support a richer community of insects, which in turn bring in more birds." 

(source)

I previously wrote about Mistletoe on January 3, 2013, but so did many other people. It was the same link above, but it was worth bringing up the subject again as a great reminder.

Mistletoe: Former Demonized Plant Turns Out to be a Great Helper 

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Image: SeaFoods.com

New Zealand Cockle (Austrovenus stutchburyi)

Credit: Tommy Leung

There was a story of a parasitic fluke that infects shellfish helps deposit them on seashores where birds can eat them, and barnacles and limpets and live in the shells – increasing the biodiversity of a shore that would normally have only sand. To the right here in the photo image you can see the Cysts of Curtuteria australis (tagged with fluorescent dye) in the foot of a New Zealand cockle. As more and more parasites accumulate, the presence of those cysts causes the cockle’s foot muscle to degenerate. With a mangled foot, the clam loses its ability to dig and is left stranded on the surface of the mudflat, exposed to hungry shorebirds – just what the parasite Curtuteria australis wanted. The nature of the seashore changes from one covered mostly with mud and sand, to one paved with hard shells. This actually increases the overall level of biodiversity in the area since the shells of the stranded clams provide habitats for other animals like limpets and barncles.

Parasitism as a determinant of community structure on intertidal flats

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Credit: Alvesgaspar/Wikipedia

Grassopper of Acrididae family: Anacridium aegyptium

"Scientists have known for some time that P. locustae infections in individual locusts leads to less swarming in locusts around them. What was not known was how it happened."

"The researchers are still puzzled as to why P. locustae would "want" to cause less swarming, as doing so would seem to lead to more difficulty in spreading from one of the insects to another." (No Kidding, why ????)

Team uncovers how microsporidian parasites prevent locust swarm behavior

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Credit: Vittorio Baglione

A carrion Crow brood parasitized by a great spotted Cuckoo

"Most everyone knows that cuckoo birds are the ultimate free-loaders. Mothers lay their eggs in the nests of birds of different species, leaving them to raise their young for them. What many may not realize however, is that different kinds of cuckoo birds behave differently when they hatch. Some famously push all the other eggs out of the nest, leaving themselves as the sole survivor and beneficiary. Other's however, don't do that, instead, they leave the other chicks alone and share in food the mother brings, acting as an adopted sibling, of sorts. At first glance it would appear that the host birds gain no benefit from this arrangement, but upon closer inspection, that assumption has been proved wrong."

"The researchers in Spain were studying the relationship between cuckoos and host carrion crows. In so doing, they were surprised to find that survival rates for crow chicks in nests shared by a cuckoo, were actually higher than for cuckoo-less nests. Looking even closer they discovered that the cuckoos had a survival mechanism that crows did not—they gave off a stink when threatened that caused predators such as feral cats to stay away. The stink, the researchers found, was caused by a chemical mix of repulsive compounds that included indoles, acids, sulfur and phenols. Taken together it proved too much for cats and birds of prey which typically find chicks in a nest easy pickings when the mother is away gathering food."

Study shows some cuckoo birds may actually help their hosts 

The major sad thing here is that in most of the television documentaries (where the majority of people get their science education) which reference the Cuckoo or Cow Bird as a parasite that robs and steals from others, we almost never see this side of the story. 

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Wasp parasitizing Gypsy Moth
Carepiller

So once again, how does it go ? Parasitism is bad. Parasitism is evil. Parasites wage war against innocent hosts. This is normal human  mindset. But what if parasites can actually do good ? If they are only suppose to be doing harm to the host, why do some biologists find that there are “positive benefits” which seem to be maintaining their hosts ? Ignorance has caused us to create an imbalance in nature by means of our horrible science-based agricultural practices which destroys both beneficial parasitic insects along with the bad. Our mind's naturally have a tendency to classify what we consider bizarre phenomena out in nature into moral categories: good kitty, bad doggie, so forth & so on. We do that with parasites all the time because we know how often some of them annoy, harm or kill us. I certainly don't want to suggest from these above articles that there is anything good about Mosquitos, Ticks, Fleas, Leeches, Roundworms or Malaria. But who knows how even these things behave when in a balanced system ? The majority of us have no clue as to what such a system would be like. I have found over the years that many things considered by humans to be plagues, cause famines and/or Pestilences are most often times the results of human ignorance, environmental sloppiness, lack of hygiene, etc. 

"Survival of the Fittest"

What’s instructive about many of these stories is that many of these research teams start with an assumption that parasites are bad. They are at war with the host, using the host’s resources for their own good. The evidence gathered above suggests the opposite; they might really be beneficial after all. Another organism we often demonize & insert into the “bad” category are Viruses. After all,  they do invade a host cell, hijack and use its replication machinery to make copies of themselves. Why, then, do only a small fraction of viruses cause disease ? What are the others out there doing ? Interestingly, many of them kill bacteria; that could be a good thing, couldn't it ?  Maybe we should take a fresh look at what we consider the creepy icky things of our natural World. In biology there are many pushes and pulls. But these pushes and pulls are not necessarily good or bad; they are simply opposite forces that maintain any ecosystem's homeostasis. Maybe by learning how nature really operates in a complete context, we can come to some conclusions of how to better deal with what has come to be termed invasive. These so-called invasive plants, insects, animals, birds, fish, etc are only a problem of ecosystem imbalance which resulted from some historical stupid decision made by humans which  created the problem in the first place. Nature had zero to do with it. Such findings by these researchers, do lend themselves to new ways of thinking about our natural world's parasites as designed mechanisms originally intended for health of the entire global ecosystem, a few of which have subsequently gone bad. For readers who cannot accept that, the story is a lesson about not trusting metaphors as reliable guides to understanding our natural world. You know many of these metaphors, some good and instructive, but some of these are horrible like "Survival of the Fittest". Okay, everybody for the most part completely understands how the best & healthiest seeds out perform sickly seeds and so forth. But people like Prof Suzanne Simard have revealed how bad and outdated that metaphor is from her research about "Mother Trees" in a forested Ecosystem where all the biological components have been observed working together to help each other survive as opposed to selfish competing individuals. This goes a long way in explaining the inept reforestation practices where the chaparral plant community is viewed as an enemy as opposed to an ally which actually insures a forest's natural rebuilding program. The reality is, this terrible religious metaphor has actually hindered our understanding as opposed to educating mankind by instilling respect for the natural world. A little over a decade ago, there was a great article I have never forgotten which puts things into perspective. It was called, Natural Enemies: Metaphor or Misconception ? ( in other words, is that a reality, or just another  metaphor ?), by Matthew K. Chew and Manfred D. Laubichler in the July 4, 2003 issue of Sciencemag.org , an online journal which discussed the usefulness and dangers of metaphors in the language of science. You know, like, "Survival of the Fittest" ? Please click and read the link below, but here are the two concluding paragraphs which I'll post here:

"What troubles us is that biology's metaphorical abstractions all too easily become concrete objects and substitute for specific, describable processes. Maximal diversity becomes evolution's telos instead of its tendency. Biogeographical frontiers become prescriptive and enforceable, rather than descriptive and conceptual. Seasonal “disturbances” such as floods interrupt normal ecological processes, instead of exemplifying them. Biological “productivity” and “diversity” become not only measurable, but virtuous."

Matt Chew's & Manfred Laubichler's essay provides many excellent metaphor examples like; ecology speaks of predator and prey, but these suggest one is good and the other evil. Hence we have Wolf versus Elk, Mountain Lion versus Big Horn Sheep, etc. You may also remember that metaphors have been used for describing the signalling and machinery that are used in cell biology, as well as being used to explain what goes on within DNA such as “coding” and "development". But for me personally, I find that bad metaphors associated with parasites have hindered us from viewing them in a way that helps us to better understand their roles in the Natural World. In conclusion, Chew & Laubichler warned: 

"Perhaps we cannot avoid metaphors altogether in scientific language. But scientists must be aware of the potential problems inherent in invoking the familiar as a convenient way for describing their ideas. At the very least, we should be concerned about what the frequent use of “natural enemies” (and the notable absence of “natural allies,” describing an equally familiar set of ecological interactions) reveals about the ways in which we interpret nature through metaphorical lenses, especially in the current historical situation."

(source: "Natural Enemies--Metaphor or Misconception ?")

BTW, Matthew Chew has an updated version from 2011 called, The Rise and Fall of Biotic Nativeness: a Historical Perspective 

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So what really is this Goldilocks Principle ?

Well, we've all heard of the classic fairytale 'Goldilocks and the Three Bears' which tells us the story of a young fair golden haired Girl who wanders into a strange house in the woods. She finds one bowl of porridge too hot, another too cold and the third just right. Many Scientists sometimes apply the tale to a planet's ability to sustain life as we know it. In our own star system for example, Venus is too hot and Mars is too cold, but Earth is just right. But there's far more  here on the Earth itself which is loaded with the Goldilocks Principles. Hence even the subject of parasites. These ideas  haven't always been very popular, because it smacks of fine-tuning and the Earth being special and unique among other known planets and so forth. Broadly speaking, the Goldilocks Principle applies to any situation where only a particular range of conditions is acceptable or agreeable for a healthy ecosystem. The Earth's ability to perfectly recycle and maintain itself is now seriously being called into question. Here was an interesting read from just last week on this very subject: 

Goldilocks principle: Earth's continued habitability due to geologic cycles that act as climate control 

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 So Parasites, Ecology & the Goldilocks Principle ?

File under: "Religion & other Metaphysics"