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Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.32,0:00:02.97,Default,,0000,0000,0000,,A food web is the network of feeding interactions
Dialogue: 0,0:00:02.99,0:00:05.04,Default,,0000,0000,0000,,among species in an ecosystem.
Dialogue: 0,0:00:05.20,0:00:07.06,Default,,0000,0000,0000,,When you think about feeding interactions,
Dialogue: 0,0:00:07.20,0:00:09.68,Default,,0000,0000,0000,,predators and prey are the first thing \Nthat spring to mind,
Dialogue: 0,0:00:09.72,0:00:12.55,Default,,0000,0000,0000,,like a cheetah chasing, \Nkilling and eating an antelope.
Dialogue: 0,0:00:12.90,0:00:16.01,Default,,0000,0000,0000,,But in fact, there are lots of ways \Nthat matter and energy
Dialogue: 0,0:00:16.04,0:00:18.72,Default,,0000,0000,0000,,get transferred from one \Norganism to another:
Dialogue: 0,0:00:19.06,0:00:20.100,Default,,0000,0000,0000,,a calf consuming milk from its mother,
Dialogue: 0,0:00:21.28,0:00:23.24,Default,,0000,0000,0000,,a vulture feeding on a dead fox,
Dialogue: 0,0:00:23.45,0:00:27.46,Default,,0000,0000,0000,,a parasatoid wasp larva living inside \Nand feeding on a caterpillar,
Dialogue: 0,0:00:27.72,0:00:30.77,Default,,0000,0000,0000,,a honey bee gathering nectar \Nand pollen from a sunflower,
Dialogue: 0,0:00:31.03,0:00:34.06,Default,,0000,0000,0000,,and a katydid taking \Nsmall bites of willow leaves.
Dialogue: 0,0:00:34.26,0:00:38.54,Default,,0000,0000,0000,,There are many ways that the existence \Nof one creature depends on another.
Dialogue: 0,0:00:39.27,0:00:44.12,Default,,0000,0000,0000,,A food chain is one way of representing \Nfeeding relationships among several species
Dialogue: 0,0:00:44.28,0:00:48.53,Default,,0000,0000,0000,,with predators eating herbivores that eat \Nplants that draw energy from the sun.
Dialogue: 0,0:00:48.73,0:00:52.52,Default,,0000,0000,0000,,An example is a hawk \Nthat eats a rabbit that eats grass.
Dialogue: 0,0:00:52.67,0:00:57.79,Default,,0000,0000,0000,,That's a good start, but it doesn't really \Nlet you understand the whole complex ecosystem.
Dialogue: 0,0:00:58.36,0:01:02.99,Default,,0000,0000,0000,,To do that we collect data \Non the myriad species that co-occur in a habitat
Dialogue: 0,0:01:03.02,0:01:06.01,Default,,0000,0000,0000,,and then figure out who they eat and who eats them.
Dialogue: 0,0:01:06.30,0:01:11.100,Default,,0000,0000,0000,,Each species is usually in many different food chains \Nand those chains weave together to form a network.
Dialogue: 0,0:01:12.25,0:01:14.90,Default,,0000,0000,0000,,That ecological network is called a food web.
Dialogue: 0,0:01:15.86,0:01:19.45,Default,,0000,0000,0000,,Here's an example of an aquatic food web \Nfrom Little Rock Lake, Wisconsin,
Dialogue: 0,0:01:19.47,0:01:25.71,Default,,0000,0000,0000,,that includes fishes, aquatic insects, \Nzooplankton, algae, plants, and parasites.
Dialogue: 0,0:01:25.94,0:01:30.98,Default,,0000,0000,0000,,The spheres represent different species \Nand the links show the interactions between the species.
Dialogue: 0,0:01:31.20,0:01:36.57,Default,,0000,0000,0000,,There are 92 tacks in this food web \Nwith almost a thousand feeding interactions.
Dialogue: 0,0:01:37.19,0:01:40.100,Default,,0000,0000,0000,,This image places species in the food web \Nbased on their trophic level.
Dialogue: 0,0:01:41.29,0:01:43.41,Default,,0000,0000,0000,,Trophic is just another word for feeding,Trophic is just another word for feeding,
Dialogue: 0,0:01:43.45,0:01:48.12,Default,,0000,0000,0000,,and trophic level is a measure of how many times \Nenergy and matter are transformed
Dialogue: 0,0:01:48.15,0:01:49.36,Default,,0000,0000,0000,,as they work their way up
Dialogue: 0,0:01:49.67,0:01:52.22,Default,,0000,0000,0000,,from species to species up the food web.
Dialogue: 0,0:01:52.56,0:01:56.21,Default,,0000,0000,0000,,Or organisms such as plankton and algae \Nthat generate energy from sunlight
Dialogue: 0,0:01:56.24,0:02:00.25,Default,,0000,0000,0000,,have a trophic level of one, and they show up at the bottom of food web.
Dialogue: 0,0:02:00.66,0:02:02.66,Default,,0000,0000,0000,,The species that feed on these, like zooplankton
Dialogue: 0,0:02:02.69,0:02:05.25,Default,,0000,0000,0000,,and aquatic insects, show up in the middle.
Dialogue: 0,0:02:06.05,0:02:09.54,Default,,0000,0000,0000,,Predatory fishes and their parasites \Nshow up on the top.
Dialogue: 0,0:02:10.42,0:02:14.88,Default,,0000,0000,0000,,You can use food webs to learn many different things about ecosystems.
Dialogue: 0,0:02:15.18,0:02:18.80,Default,,0000,0000,0000,,For example, we can use food webs from different places
Dialogue: 0,0:02:19.09,0:02:21.55,Default,,0000,0000,0000,,to understand whether a desert food web,
Dialogue: 0,0:02:21.83,0:02:23.08,Default,,0000,0000,0000,,a marine food web
Dialogue: 0,0:02:23.17,0:02:25.15,Default,,0000,0000,0000,,and a tropical forest food web
Dialogue: 0,0:02:25.23,0:02:27.54,Default,,0000,0000,0000,,are organized in similar or different ways.
Dialogue: 0,0:02:27.91,0:02:31.72,Default,,0000,0000,0000,,Our best science suggests that they have \Nfundamentally similar organization,
Dialogue: 0,0:02:31.74,0:02:34.04,Default,,0000,0000,0000,,no matter what the habitat that is examined.
Dialogue: 0,0:02:34.52,0:02:37.16,Default,,0000,0000,0000,,Even food webs from hundreds of millions of years ago
Dialogue: 0,0:02:37.23,0:02:39.78,Default,,0000,0000,0000,,appear to be structured like modern webs.
Dialogue: 0,0:02:40.10,0:02:44.62,Default,,0000,0000,0000,,The species may be very different \Nbut their fundamental relationships are not.
Dialogue: 0,0:02:45.12,0:02:49.72,Default,,0000,0000,0000,,We can even use food webs to understand \Nhow humans fit into and impact ecosystems
Dialogue: 0,0:02:49.74,0:02:54.82,Default,,0000,0000,0000,,through their roles as hunters, \Ngatherers, fishers, herders and farmers.
Dialogue: 0,0:02:55.12,0:02:58.95,Default,,0000,0000,0000,,We can compare the feeding roles of humans to other species and their food webs
Dialogue: 0,0:02:59.13,0:03:03.100,Default,,0000,0000,0000,,and learn lessons that help us to understand \Necological resilience and sustainability.
Dialogue: 0,0:03:04.17,0:03:06.90,Default,,0000,0000,0000,,Developing the science of ecological networks such as food webs
Dialogue: 0,0:03:06.92,0:03:10.66,Default,,0000,0000,0000,,is some of the research \Nwe do here at the Santa Fe Institute.