GURPS: Ecosystems and Evolution

[Bruno]

Originally Posted by Vaevictis Asmadi

lwcamp is right about the brain being a hungry organ. The theory about human evolution is that our ancestors couldn't have larger brains until they started eating significant amounts of meat. Meat has denser energy than plants and is also easier to digest, allowing us to have smaller guts and shorter intestines.

There's also the recent evidence of an island-bound goat, now extinct, that adapted to a poor and restricted environment by reducing metabolic rate more and more and more... and one of the primary casualties was its brain, which was reduced to reptilian proportions. They're guessing it actually became virtually ectothermic by the end, before IIRC human sailors showed up and ate it.


EDIT: Good source:
http://www.physorg.com/news177755291.html

Humans settled and ate it. Also they reduced eye size significantly, another complicated organ.

[MagiMaster]

Ok. I'm finally back at my own computer.

Does anyone disagree with my assessment of the relative strength of the various factors, or the inclusion or exclusion of certain factors?

Also, I've been trying to rate the traits within each category on a scale from giant snake at 0 to hummingbird at 10 (meaning some things might be higher or lower than that). Since some of these tables get pretty big, I'll just do one or two at a time for now.

The first one would be from Alien Creation III, locomotion. (I would do II first, but it's really hard to work out good numbers for that one.)

• Immobile - -7
• Slithering - 0
• Swimming - 5
• Digging - 8
• Walking - 5
• Winged Flight - 10
• Floating - -4
• Bouyant Flight - -4
• Climbing - 8
• Solar Sail - -4
• Rocket - 20

(Note to self: Don't forget FP for hunting and what things eat.)

Edit: Another note to self: Don't forget about creatures existing in multiple ecosystems.

Edit again: Actual numbers for consumption per body weight (or just consumption and body weight) are hard to find for real animals. The really low and high end species get noted as being special, but in between no one bothers to write it down if they know at all. Anyway, if anyone runs across any actual numbers, can you let me know?

[MagiMaster]

Hmm... I'm working on the numbers for those tables, and something got me wondering. There are two entries for warm-blooded: warm-blooded and warm-blooded with 2 levels of metabolism control. Which one would need more food on average? I'd guess the one with the metabolism control, but not by much.

Anyway, I've almost got the tables ready, but I'm going to need some help looking them over and making sure they make sense.

Edit: Oh yeah. I'm guessing that a large snake does have the cold-blooded disadvantage, but a hummingbird doesn't have metabolism control.

[Gizensha]

Originally Posted by MagiMaster

Hmm... I'm working on the numbers for those tables, and something got me wondering. There are two entries for warm-blooded: warm-blooded and warm-blooded with 2 levels of metabolism control. Which one would need more food on average? I'd guess the one with the metabolism control, but not by much.

IANAB [Biologist] but, I'd assume that since controling metabolism takes energy (in exchange for better survival if you can keep fed), the one that would need the more food is the one with the metabolism control.

[Flyndaran]

Originally Posted by Gizensha

IANAB [Biologist] but, I'd assume that since controling metabolism takes energy (in exchange for better survival if you can keep fed), the one that would need the more food is the one with the metabolism control.

Being able to lower one's metabolism to suit times of lean would reduce the amount of food needed not increase it.

[Gizensha]

Originally Posted by Flyndaran

Being able to lower one's metabolism to suit times of lean would reduce the amount of food needed not increase it.

...I really should start reading the book text before making comments like that, aheh.

[Luke Bunyip]

Been lurking on this thread, but I thought I should mention three things which may be relivant. I will point out that I am not a fauna expert, and even my knowledge of flora and the vegetation related aspects of ecology are constrained to a couple of geographically specific examples of a few biomes.

Firstly, reproductive strategies and rates. The conditions underwhich a population of a particular organism can reproduce can have dramatic impacts upon it population size. However, if these are very specific or rare, it can be dovetailed with a dormancy strategy. The crustacea which appear within the ephemeral Lake Eyre in Central Australia are an example of this.

The other point relates to food sources. The koala and the panda are both very specific about what sort of food they eat. In Australia some macropods will graze tussock grasses, whilst feral goats will eat the weedy patches of blackberries which grow next to them, as they contain less silicates.

Finally there are the impacts of symbosis. A wallaby which grazes on fungi that occurs in woodlands and forests, and thusly spreads the fungi spores around, can be elimated by colonising carnivores, such as dogs. This could have an impact upon the growth of the trees which rely upon the fungi for nutrient transfer. However the imput of another omnivore, say feral pigs, could possibly reverse this.

IMHO, there could be utility in defining the 'stamp collection', as opposed to the component 'stamps'.

[Lupo]

I found the data very interesting, but I have to admit that I have no idea on how all this could be useful in a game (or even in worldbuilding).

Sure, designing a believable food web when creating the fauna for an alien world could add some "realism" in a very hard-sf game...
But I fail to see how calculating "total lbs of biomass produced per day" for a given space could impact a game.

[MagiMaster]

@Flyndaran, I agree, but would they need (a little bit) more food on average to be able to do that? I think so, but I have no evidence either way. Do you think camels or bears would qualify for metabolism control?

@Luke, thanks for the info, but I don't know what you mean by stamp collection vs stamps, or what you were trying to point out with the picky eater examples. I know the simple method doesn't single out exactly what eats what, but that's why it's simple. The more complicated method answers that question at the expense of taking more time and effort. Also, for the moment, this is all for a stable ecosystem, not one dealing with invasive species or colonization. (Though I should comment on such things elsewhere.)

@Lupo, I agree that the pounds of biomass per day isn't that interesting by itself, but it's what the whole food chain is based on. Together with some other numbers (which I'm still working on) you can get things like the population in the area, and what eats what and how. Those kind of details are interesting to a world builder. (For example, this can answer the common question of how can such a place support such a big predator.)

Thanks for the interest. Please keep asking questions. I'll post the tables for consumption per day soon. I've got them mostly worked out even though they look a little off in places. I'll have to get yall to help me look over them.

[MagiMaster]

Okay. Here's some numbers to play with. These are still in need of some simplification, so don't bother commenting too much on the fact that there are too many digits in most of these. Anyway, to reiterate, the procedure here is, take the product of all the relavent numbers, multiply that by 1.25* (mass in lbs)^(-1/4). I'll get to autotrophs later, since I think they don't follow the same formula. In the mean time, let me know if any of these numbers seem off to you. Thanks.

Niche

• Decomposer - 0.305
• Scavenger - 0.205
• Omnivore - 0.205
• Gathering Herbivore - 1
• Grazing/Browsing Herbivore - 0.305
• Pouncing Carnivore - 0.115
• Chasing Carnivore - 0.45
• Trapping Carnivore - 0.0675
• Hijacking Carnivore - 0.205
• Filter Feeder - 0.027
• Parasite/Symbiote - 0.0675

Locomotion

• Immobile - 0.26
• Slithering - 0.44
• Swimming - 0.505
• Digging - 0.76
• Walking - 0.505
• Winged Flight - 1
• Floating - 0.34
• Buoyant Flight - 0.34
• Climbing - 0.76
• Solar Sail - 0.34
• Rocket - 3.95

Temperature

• Cold Blooded (w/ disadvantage) - 0.225
• Cold Blooded (w/o disadvantage) - 0.37
• Partial - 0.605
• Warm Blooded - 1
• Warm Blooded (w/ metabolism control +2) - 1.2

Skin

• Soft Skin - 1.15
• Normal Skin - 1.1
• Hide - 0.925
• Thick Hide - 0.795
• Armor Shell - 0.735
• Blubber - 0.54
• Scales - 1.1
• Heavy Scales - 1
• Fur - 0.925
• Thick Fur - 0.735
• Thick Fur over Hide - 0.63
• Spines - 0.855
• Feathers - 1
• Thick Feathers - 0.795
• Feathers over Hide - 0.68
• Light Exoskeleton - 0.925
• Tough Exoskeleton - 0.795
• Heavy Exoskeleton - 0.735

Reproduction

• Spawning/Pollinating - 0.79
• Egg Laying - 0.975
• Live-Bearing - 1.25
• Live-Bearing w/ Pouch - 1.35
• Brood Parasite - 0.925
• Parasitic Young - 0.875
• Cannibalistic Young (parent) - 0.875
• Cannibalistic Young (siblings) - 0.925

Strategy

• Strong K - 0.97
• Medium K - 1
• Median - 1.05
• Medium r - 1.05
• Strong r - 1.1

IQ

• Mindless - 0.66
• Preprogrammed - 0.745
• Low - 1
• High - 1.15
• Presapient - 1.2

Mating

• No bond - 1.05
• Temporary bond - 1
• Permanent bond - 0.985
• Harem - 0.945
• Hive - 0.89

Society

• Solitary - 1.05
• Pair-bonded - 1
• Small Group - 0.97
• Medium Group - 0.945
• Herd - 0.89