Moss sperm are motile and capable of swimming short distances to fertilize an egg. However, it was unknown until recently how sperm make their way from male to female gametophytes that may be separated by a distance of several centimeters or more. Animals are responsible for pollinating many flowering plants. Did animal-mediated fertilization originate with flowering plants, or was this mode of sperm dispersal likely in place before the origin of flowering plants? Explain.

Video transcript

Welcome back. Here's our next question. If plants and insects both existed for the 1st 300 million years after plants first evolved, why was pollination by insects not common in that period as it is today? So we're looking at the explanation of why even though there were plants and there were insects living side by side for 300 million years after plants first evolved, we weren't seeing insect pollination in that whole time. So what is the explanation for that? Let's look through our answer choices, choice a says. Because insects at that time would not have been able to use Nectar as food. Well nectar is just essentially a solution of sugars and there's no reason why insects would not have been able to use sugars for food. So Choice A. Is not our explanation, Choice B. Says because insects were flightless at the time. No, that's not correct. There were insects that flew all during that time. So that's not an explanation for lack of insect pollination. Choice C says. Because plants were dominated by non flowering plants at that time and this is correct. Insect pollination depends on flowers producing nectar to attract the insects that carry the pollen, and for that 1st 300 million years plants were dominated by non flowering plants, mainly ferns, cycads and conifers, ferns are non seeded plants they reproduce with spores and therefore they don't require pollination. Meanwhile, cycads and conifers use wind pollination. Their pollen is designed to be uh light, small, easily carried by wind to other plants. And so since you didn't have flowering plants you didn't have insect pollination uh flowering plants or angiosperms developed around 100 50 million years ago and co evolved to with various insects to attract insects with their flowers to come get nectar as a food source and spread pollen just to be thorough. We look at Choice D. Which says because nectars did not have a sweet taste at the time. Well, that's not our explanation for why there was no insect pollination. It was that you didn't have flowering plants, you didn't have flowers and therefore you didn't have nectar. So Choice D. Is not the right explanation. So why was pollination by insects not common in the 1st 300 million years of plants being around choice c. Because plants were dominated by non flowering plants at that time? See you in the next video?