Most pollinator networks for which we have data are “nested.” Draw and describe what a nested plant-pollinator network looks like. What may be the reason for nestedness to evolve?

Question

This is a question from TED ED's video (link: https://youtu.be/Y5uRVv7GGQM)

Video: How Bees Help Plants Have Sex

Pause Times: 1:25: Number of Plant Species vs. Pollinator Species 1:51: Evolution of Bees from Wasps 2:00: Pollinator Networks 2:20: Specialists 2:30: Generalists 3:00: Nested Network 3:45: Modular Network

Please help me create an 8th-grade level simple chart/graph/drawing/etc with the computer about Pollinator's Network (nested) and then answer the other questions. [The other questions being the reason for nestedness to evolve, and a short description of whatever you drew].

Thank you so much!

Answer 1

Hi Eagle E.,

So you've watched the video, I would presume. Let's start with the basics: what is nestedness? I find this easiest to think about as a conceptual model, with pollinateds (plants) on a bottom layer, and pollinators (bees or whatever) on a top layer. Just one representative of each species! Then the pollination linkages are a network of lines, like spiderwebs, from the top to the bottom layer, or alternatively you might think of them from the bottom to the top layer. If a bottom-layer element "generalist" has lots of connections upwards in various directions, you might think of that as resembling a very crude sort of "nest": if you dropped something into it, it might tend to be funneled and trapped downwards to the bottom-layer element. --> Among the things which might look as if they are being so funneled and trapped, are the specialist-down connections <-- The crucial idea!! (behind "nested" network). Note that there is no "trapping" causation implied by this designation, it's just a geometrical organizational concept. BUT there are plenty of consequences of having networks with varying amounts of specialist/generalist diversity, including successively larger concepts such as hub species, modules, resilience to removal of species, and so on.

-- Cheers, --Mr. d.