Life Sciences 1 Animal Diversity 1 Take Home Assignment 1. Now you have seen both animals and plants, and you know that most Angiosperms require an animal pollinator for reproduction to occur. Below on the left you will see a flower that is pollinated by a bee (a generalist pollinator) which visits a lot of flowers of different species. Below on the right you will see a flower that can only be pollinated by a single species of moth (a specialist pollinator) which only visits this species of plant. List and describe two advantages and disadvantages for plants with generalist or specialist pollinators. Generalist Pollinator Specialist Pollinator Advantages Disadvantages -if a pollinator isn’t compatible, the plant has “back-up” options for self-pollination- a plant may be at an advantage if it attracts several species or types of pollinators, increasing the chance of pollination- greater chance of efficiency for pollination, as the pollinator is compatible for pollination- increased efficiency for the transfer of pollen, as the pollinator focuses on one species of plant instead of different types - reproductive success is limited as pollinator populations vary significantly- the pollinated plant has a lower chance of fertilization as it may receive incompatible pollen- lower chance of pollination opportunities, as the number of potential pollinators is greatly decreased - can only depend on one pollinator at a time, so the plant has a lower chance of fertilization2. Angraecum sesquipedale (a.k.a. Darwin’s Orchid) is a species of Angiosperm found in Madagascar (See the photo on the right above). When Charles Darwin first saw it in 1862, he noticed the very long spur (up to 30 cm) at the end of which the nectar is produced. He was so surprised by this uncommon feature that he wrote in a letter to J. Bateman (the guy who discovered the plant): “Good Heavens! What insect can suck it?” Both Darwin and A.R. Wallace predicted the existence of an insect with a proboscis so long that it was able to get the nectar and successfully pollinate this flowers. In 1867 Wallace said: "That such a moth exists in Madagascar may be safely predicted; and naturalists who visit that island should search for it with as much confidence as astronomers searched for the planet Neptune,--and they will be equally successful!" This prediction was only confirmed in 1903 when scientists discovered Xanthopan morganii, a very large moth from Madagascar with an unusually long proboscis. In 1992, another group of scientists obtained the first evidence (videos and photos) of the moth actually pollinating the flowers of the Darwin’s orquid, supporting the hypothesis of the coevolution between this plants and their specialist pollinators. Exercise: Using all the essential components of evolution via natural selection, explain how the coevolution of this two species was possible, including the characteristics of the initial populations and the selective pressures that lead to the current morphologies of both the moths and the orquids (12 sentences or less). Helpful links: https://www.youtube.com/watch?v=iMz6lApJgu4 https://www.youtube.com/watch?v=sjeSEngKGrg _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Coevolution of the two species (moths and orchids) is possible because of specialist pollination. The moth has a long enough tongue to reach the nectar of the orchid, which is about 30 cm long, and this allows the orchids to increase the efficiency of reproductive success as the moth can be the only pollinator for the orchid. This allows the moth to be the onlyone to receive the orchid’s benefits and this will allow for the moth to keep coming backto receive this benefit. In addition, the orchid benefits from the moth by having the mothtransfer its pollen effectively to other orchids. Since the moth is the only insect to have a long enough tongue to pick up the pollen, the moth will also be the only insect to deliverthe pollen to another orchid, which increases the chance of a successful fertilization. Thisallows for the moth and orchid to depend on each other because of their ability to adapt to one another; the orchid has is nectar inside a “tube” and the moth has a long enough tongueto reach