Nitrate slider sensitivity

Here we report bugs in the beta.
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wapcaplet
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Joined: Thu Dec 08, 2016 9:52 pm

Nitrate slider sensitivity

Post by wapcaplet » Mon Feb 05, 2018 2:12 am

I've been tinkering with evolution using the nitrates slider to try and force nitrocyte development. There appears to be a hard threshold, near 0.2, above which cells don't need nitrocytes at all. At 0.2 or below, they cannot reproduce without a strong nitrocyte presence in the genome.

Here's an example substrate:

https://www.dropbox.com/s/q3s7gmc72o4ae ... trate?dl=0

These are some 100% evolved "Floaters II" organisms that have evolved nitrocytes, living in the "Floaters III" challenge substrate with 0.203 nitrates. They do well at nitrate level 0.203 or more. But at <= 2.00, they all die very quickly.

There may be ways to keep them alive, with higher salinity. But I wonder why the thereshold would be so sharp?

I hope longer evolution at 0.201+ might eventually give them an edge that lets them live in 0.2 or below. I did succeed with evolving a winner to "Harsh Conditions II" (nitrate swimmer) in this way, so it can be done with time...
JustYourAverageHuman
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Re: Nitrate slider sensitivity

Post by JustYourAverageHuman » Mon Feb 05, 2018 3:44 am

Yep I noticed this too. Cells require greater than 20% nitrates to split, so 0.201 or greater. Each of the daughter cells get half the nitrates. The only things affected by the nitrates setting are the max nitrates a cell will receive from the environment and the speed that it receives those nitrates. Therefore the only advantage an organism with nitrocyte has over one without at 0.201 nitrates is speed of reproduction. The organism with the nitrocyte can reproduce every ~0.5 hours, while the one with no nitrocyte, even if at max food will take several hours to get enough nitrates. Therefore, the optimal environment for evolving nitro swimmers is one with abundant food and nitrates set to 0.201. Evolution will take place much slower or not at all when food is scarce enough for the lack of abundant nitrates to not affect successful reproduction.
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wapcaplet
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Re: Nitrate slider sensitivity

Post by wapcaplet » Mon Feb 05, 2018 3:48 am

In addition to the sharp ledge at 0.2 nitrates, above that is mostly a plateau. Between 0.201 and 1.00, there is not a very noticeable difference.

Here's a "Slippery Slope II" substrate with an organism that has not evolved nitrocytes:

https://www.dropbox.com/s/uzhdxqzks50s6 ... trate?dl=0
https://www.dropbox.com/s/mmeb50ehm30j1 ... trate?dl=0

I don't see a dramatic difference in cell count.
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wapcaplet
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Re: Nitrate slider sensitivity

Post by wapcaplet » Mon Feb 05, 2018 3:59 am

JustYourAverageHuman wrote:The only advantage an organism with nitrocyte has over one without at 0.201 nitrates is speed of reproduction. The organism with the nitrocyte can reproduce every ~0.5 hours, while the one with no nitrocyte, even if at max food will take several hours to get enough nitrates.
I did not think of that. And it needs to be a pretty big advantage, to be worth the energy cost of the extra cell. Sometimes, a temporary nitrocyte is enough--a nitrocyte egg can get a simple swimmer through a few reproductions before it runs out. A permanent nitrocyte can be hard to come by through evolution.
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