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Author Topic:   The Koala, Lamark and Epigenetics
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


(3)
Message 34 of 43 (775067)
12-26-2015 5:47 PM


Clear up some things
Hi, LamarkNewAge.
Welcome to EvC!
I want to clear up a few things.
LNA writes:
The late Farrell Till said that the koala has a very narrow diet; infact some are so specialized that they not only can't eat anything but eucalyptus leaves but they also cannot eat from eucalyptus trees outside their local eucalyptus woods (or something like that).
What the hell would Farrell Till know about koalas?
I'm not a marsupial biologist, but Farrell Till wasn't any kind of biologist, so I'm fairly comfortable suggesting that Farrell Till is most likely wrong about how specialized a koala's diet is.
LNA writes:
A random mutation (or series of mutations) that lead to such a narrow diet that by coincidence only enables digestion of a single type of plant just doesn't seems to fit what must go on in nature (so my thinking goes anyway).
Keep in mind that the word "eucalyptus" refers to a group of several hundred species, most of which are found in Australia. In fact, eucalyptus is one of the most abundant and widespread types of food in Australian forests. So, specializing on it seems like a reasonable way for an herbivore to make a relatively easy living in Australia.
Another thing to remember is that the claim that koalas cannot digest other foods is probably wrong. More likely, they simply have a preference for eucalyptus; or they have only been trained to eat eucalyptus, and since eucalyptus is everywhere, they've never had to look for something else. Over time, the close association selects for specialized adaptations.
LNA writes:
Selection for an animal going blind happens when the animal species will live in a (nearly or)100% dark environment. It takes a lot of molecular energy for eyes to (be able to) see so selection can and does lead to that gene-for-seeing getting turned off in increasingly large numbers of the species over time.
The same sort of process works for digestion. If you're only eating one thing, why would you maintain a diversified digestive system? It would be like a factory choosing to specialize in producing cars, but still performing regular upkeep in the machinery for tooling airplane parts.
LNA writes:
have been thinking of using the example of a human breeding foxes so that by the 26th generation, all in a breed we able to respond to the "sit" command when none could at first. But Darwinian theory supporters will just say the genetic information "was there to start with" or some DNA change (or some "standard theory" change) can be explained.
In every population, there is variation in virtually every trait. In the famous Russian fox-breeding program, they selected the foxes that had the 'tamest' temperament in each generation, and bred them to make the next generation. So, each generation, genes associated with docile and sociable traits became more and more pervasive, while genes associated with wild and aggressive traits became less and leas pervasive. It isn't surprising that, 26 generations later, they had foxes that were highly compliant and responsive to social cues from humans.
LNA writes:
I was amazed when a friend told me that she worked for an organization that actually trained Octopi to disarm bombs.
I'm calling bullshit on this one, too. I have always had a bit of a soft spot for octopus, and I am generally very credulous when it comes to stories about their cognitive abilities. But, nobody has trained octopus to disarm bombs. I have heard some people propose to train them to locate bombs, but I doubt that they have even done that.
LNA writes:
With evidence coming in that learning can be an acquired characteristic...
My PhD and postdoctoral research has involved studies into the learning abilities of arthropods. When you say "learning can be an acquired characteristic," what do you mean? Most animals have the ability to learn, and learning is a way to acquire new behaviors, but I have never seen any evidence that learned behaviors can be passed on without teaching, so I'm not sure what learning has to do with Lamarckian evolution

-Blue Jay, Ph.D.*
*Yeah, it's real
Darwin loves you.

Replies to this message:
 Message 35 by LamarkNewAge, posted 12-26-2015 8:26 PM Blue Jay has replied

  
Blue Jay
Member (Idle past 2697 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 36 of 43 (775075)
12-26-2015 11:25 PM
Reply to: Message 35 by LamarkNewAge
12-26-2015 8:26 PM


Re: Fear of something (like a serpent) among species
H, LamarkNewAge.
LNA writes:
a random mutation that turns on the fear gene if the senses detect a serpent?
(if so then selective breeding, by a geneticist qualified to detect the mutation in the gene code, will pass the trait to offspring OR slow "natural-selection" will kill off those without the mutation - especially/only if serpents are part of the environment, and those with the beneficial mutation will eventually predominate)
Here is a concept paper about the genetics of fear in domesticated animals.
Here is a good review paper about modern views on behavioral genetics (I should be able to get a PDF once I get back to my work computer). It's considerably more sophisticated than the simplistic idea of a "fear gene."
In a nutshell, behavioral syndromes are general patterns of behavior, such as "aggressive" or "docile," which influence how an organism responds to a wide range of stimuli (e.g., foraging, territoriality, and predator avoidance). They are driven by whole suites of genes. An animal has genes that give it sensory receptors to respond to specific sensory stimuli (e.g., the scent or sight of a snake), and other genes that govern how it decides to respond to those stimuli (e.g., hide, run away, bluff, fight).

-Blue Jay, Ph.D.*
*Yeah, it's real
Darwin loves you.

This message is a reply to:
 Message 35 by LamarkNewAge, posted 12-26-2015 8:26 PM LamarkNewAge has replied

Replies to this message:
 Message 37 by LamarkNewAge, posted 12-27-2015 6:56 PM Blue Jay has not replied

  
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