I've been kicking this thought around for 2 years now and I don't know if it has any merit but I'm going to throw it out here.  When trying to adapt new plants to your land and saving seeds there are various recommendations out there.  Save the healthiest, strongest, tallest, etc.  Might there be another way?  Take my ying yang beans plants as an example.  For the past few years I've been planting these bean plants out.  Some sprout and others don't.  Nature's round 1 elimination of unfit plants has happened.  The growing season now continues on with the ones that made it past the sprouting stage.  They have to adapt to heat, lack of water ( because I try to not water things if I can get away with it ), competition, weeds, bugs, etc.  At the end of the growing season the plants that had a good experience or were a good fit for the land have the most beans on them.  Wouldn't the statistics work out in favor of these adapted plants?  If the adapted plants had a greater number of saved seeds they would over time come to dominate I would think.  So with this in mind I haven't worried much about savings unfit plants' seeds.  Nature I would think will do the work for me and eliminate this plant in the next go around.  What do you think about this?  I realize if you're trying to create a new line with a certain trait that this is just not going to work.  But maybe this would give hope to people who are confused about saving seeds and worry about messing up. 

I've tried saving seeds the same way... kinda like applying darwinism to seeds.  From observation only, I've decided to just harvest seeds wherever and whenever I can... call me a lazy permies gardener.  Sometimes they grow, sometimes they don't.  I also am getting closer to more chaos in the garden and not planting in rows anymore... just throw 'em out there, cover 'em with straw and what grows, grows.

I agree!  Nature seems to constantly surprise me with its resilience.  It is kind of Darwin haha.  I think it's more laziness on my part that seemed to just keep working.  I started thinking like this after reading the One Straw Revolution book and just being completely shocked at how skilled/unskilled Fukuoka was with letting nature do its thing. 

"Survival of the fittest"  on a micro scale.

I'm not sure if this would be actually "adapting" the plants themselves or just finding occasional genetic variations that fit. I think any actual genetic changes to the plants caused by your environment would take many generations.

I save seed from random plants/fruits/pods, I never really try that hard to select the biggest or best necessarily because this might just be an effect of the fertility of that specific spot in the garden, sunlight or water variation.
As long as the seed is mature and fully formed, I think it has as much potential as the seed from a larger plant. 

One of the things I saved from last year was tomato seed.
This Spring I split up the 30 or so plants I grew over Winter and planted them a few different areas of the yard.

What is interesting is that one section of plants have been sickly and small and are already dying out, and one of the other tomato areas is exactly the opposite- giant, leafy, dark green and covered with tomatoes. 
These plants were all from the same fruits and grew up together- but their final planting location determined how well they would do.

I guess my point was that "survival of the fittest" can depend on more factors than how healthy the ancestor plants were.

Of course there is the possibility that out of many plants you might get some genetic "sports" or variations that just happen to fit your location better than its peers- it is just kind of hard to determine given all the other varying conditions that effect the general health of plants.

i collect most of my seed from plants that are growing semi wild. mostly from seed i just tossed into the forest and clearings. out of hundreds of seeds maybe a dozen will grow. and out of those 1 or 2 will be supremely healthy and vigorous. so those are what i use both in the garden the next year and toss more seed out into the wild for seed stock later on.

i have quite a few greens and veggies that just grow wild now with no help at all, no water, no fertilizer, and sometimes they outproduce the gardens plants if they get that perfect spot.

to go with the thread topic i have noticed seed stock adapt more to my conditions. the first few years with some wild greens there was not that many, now in the spring/early summer they are EVERYWHERE. and are slightly different from the way they were when i first started.

What NATURE wants from plants is not necessarily the same as what PEOPLE want from the same plants.

Leave a species that humans have selected over many centuries to produce a desirable crop to it's own breeding devices and the plants that don't waste energy producing the desired human product may well out compete the rest.

So left to nature your peas and beans may get smaller because perhaps nature favours a slightly smaller size than you want.