It’s usually because there is a selective agent (another animal) which has behavioural preferences. The plant benefits from a resemblance to a model and therefore there’s selection pressure to look more like it. E.g with bee orchids, resemblance to a female bee makes visitation by male bees more likely, meaning those genetics are more likely to spread throughout the population and become a fixed trait.

@thotanist thanks doll learn something new everyday xx

@thotanist but how does the bee orchid actually learn about the shape and color of the bee?

@soupwaylee the orchid has no idea about the bee’s colour or shape! It’s literally just responding to the existence of a selective agent (boy bee). Essentially, imagine an ancestral bee orchid (which has no resemblance to a lady bee) surrounded by lots of horny boy bees. Any genetic mutation/variation which for some reason (shape/colour/scent) increases an individual’s attractiveness to the male bee, will mean that individual’s fitness (likelihood of passing on its genetics) is greater. That slight resemblance will become fixed. Then repeat this process through millions of generations of orchids, eventually the orchid appears to us to be mimicking the bee. If you were an immortal and very committed researcher, and knew exactly what turns bees on, you could probably replicate this by acting as the selective agent, e.g. only gathering pollen from an individual which had some feature a bee would find alluring. Ending up with a bee orchid which had never ‘seen’ a bee

@thotanist Ohh thanks for explaining again, interesting that it's a matter of chance for the orchid to look like the bee, but once it does it will have made total sense

Oh so the flower that has more black and yellow for example is pollinated more so it’s genes are spread more so the next gen of the orchid will have more flowers that are predominantly more black and yellow because the bees like it?

@travis_o in essence - I think they also make a special chemical mix to lure in the particular bee species