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[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.22,0:00:01.46,Default,,0000,0000,0000,,- [Narrator] What we're\Ngoing to do in this video
Dialogue: 0,0:00:01.46,0:00:04.29,Default,,0000,0000,0000,,is talk about different\Npopulation growth strategies
Dialogue: 0,0:00:04.29,0:00:05.41,Default,,0000,0000,0000,,for different species.
Dialogue: 0,0:00:05.41,0:00:06.57,Default,,0000,0000,0000,,And think about if we can come up
Dialogue: 0,0:00:06.57,0:00:08.82,Default,,0000,0000,0000,,with a broad categorization
Dialogue: 0,0:00:08.82,0:00:10.99,Default,,0000,0000,0000,,or if there's a broad\Ncategorization already
Dialogue: 0,0:00:10.99,0:00:12.63,Default,,0000,0000,0000,,out there for us.
Dialogue: 0,0:00:12.63,0:00:15.53,Default,,0000,0000,0000,,So, we see that there are\Nspecies like elephants
Dialogue: 0,0:00:15.53,0:00:17.20,Default,,0000,0000,0000,,that are long lived,
Dialogue: 0,0:00:18.73,0:00:19.82,Default,,0000,0000,0000,,in the wild.
Dialogue: 0,0:00:19.82,0:00:22.80,Default,,0000,0000,0000,,An African elephant can\Nlive roughly as long
Dialogue: 0,0:00:22.80,0:00:26.90,Default,,0000,0000,0000,,as a human being can 50, 60,\N70, in some cases, 80 years.
Dialogue: 0,0:00:26.90,0:00:29.13,Default,,0000,0000,0000,,You also have things like killer whales
Dialogue: 0,0:00:29.13,0:00:30.92,Default,,0000,0000,0000,,that are also long lived.
Dialogue: 0,0:00:30.92,0:00:32.56,Default,,0000,0000,0000,,You have things like human beings that
Dialogue: 0,0:00:32.56,0:00:34.63,Default,,0000,0000,0000,,live a pretty good long time compared
Dialogue: 0,0:00:34.63,0:00:36.50,Default,,0000,0000,0000,,to other things in nature.
Dialogue: 0,0:00:36.50,0:00:39.19,Default,,0000,0000,0000,,You have things like gorillas\Nthat are also reasonably long
Dialogue: 0,0:00:39.19,0:00:41.60,Default,,0000,0000,0000,,lived, live many, many, many decades.
Dialogue: 0,0:00:41.60,0:00:44.12,Default,,0000,0000,0000,,Now there's also other\Npatterns that you see
Dialogue: 0,0:00:44.12,0:00:45.79,Default,,0000,0000,0000,,on these large mammals.
Dialogue: 0,0:00:46.97,0:00:48.42,Default,,0000,0000,0000,,They tend to be large.
Dialogue: 0,0:00:49.29,0:00:50.94,Default,,0000,0000,0000,,Especially, if you think about compared
Dialogue: 0,0:00:50.94,0:00:53.74,Default,,0000,0000,0000,,to very small things\Nin the animal kingdom.
Dialogue: 0,0:00:53.74,0:00:57.33,Default,,0000,0000,0000,,They tend to not have a lot of children
Dialogue: 0,0:00:57.33,0:00:59.76,Default,,0000,0000,0000,,every reproductive event,\NI guess you could say
Dialogue: 0,0:00:59.76,0:01:00.90,Default,,0000,0000,0000,,at every time they give birth.
Dialogue: 0,0:01:00.90,0:01:04.68,Default,,0000,0000,0000,,So few few children,
Dialogue: 0,0:01:05.63,0:01:07.11,Default,,0000,0000,0000,,children
Dialogue: 0,0:01:07.11,0:01:10.81,Default,,0000,0000,0000,,at a time
Dialogue: 0,0:01:10.81,0:01:13.48,Default,,0000,0000,0000,,And it takes them a while to\Ngive birth to those children.
Dialogue: 0,0:01:13.48,0:01:16.04,Default,,0000,0000,0000,,And then they take care\Nof them for a while.
Dialogue: 0,0:01:16.04,0:01:18.50,Default,,0000,0000,0000,,Now, the other end of the\Nspectrum, you have some
Dialogue: 0,0:01:18.50,0:01:19.91,Default,,0000,0000,0000,,of the things that we have here.
Dialogue: 0,0:01:19.91,0:01:24.31,Default,,0000,0000,0000,,You have amphibians like\Nfrogs, you have insects.
Dialogue: 0,0:01:24.31,0:01:28.17,Default,,0000,0000,0000,,You could imagine small\Nfish, bacteria, mosquitoes
Dialogue: 0,0:01:28.17,0:01:30.21,Default,,0000,0000,0000,,that are more short-lived.
Dialogue: 0,0:01:30.21,0:01:31.09,Default,,0000,0000,0000,,Short
Dialogue: 0,0:01:32.60,0:01:33.43,Default,,0000,0000,0000,,lived.
Dialogue: 0,0:01:34.77,0:01:36.82,Default,,0000,0000,0000,,They tend to be smaller.
Dialogue: 0,0:01:39.08,0:01:42.18,Default,,0000,0000,0000,,And they tend to have a\Nlot of children at a time.
Dialogue: 0,0:01:42.18,0:01:45.85,Default,,0000,0000,0000,,So lots of children
Dialogue: 0,0:01:47.61,0:01:49.89,Default,,0000,0000,0000,,at a time.
Dialogue: 0,0:01:49.89,0:01:53.00,Default,,0000,0000,0000,,Just an example, a frog\Nor what do you see here
Dialogue: 0,0:01:53.00,0:01:56.39,Default,,0000,0000,0000,,is this is a spiders\Ncoming out of an egg sack.
Dialogue: 0,0:01:56.39,0:01:58.43,Default,,0000,0000,0000,,Frogs or spiders,
Dialogue: 0,0:01:58.43,0:02:02.66,Default,,0000,0000,0000,,they can lay in many cases,\Nthousands of eggs at a time.
Dialogue: 0,0:02:02.66,0:02:05.51,Default,,0000,0000,0000,,And they're not really dependent\Non any one of those eggs,
Dialogue: 0,0:02:05.51,0:02:06.87,Default,,0000,0000,0000,,necessarily surviving.
Dialogue: 0,0:02:06.87,0:02:08.99,Default,,0000,0000,0000,,Many of them will be\Nkilled off by predators
Dialogue: 0,0:02:08.99,0:02:12.13,Default,,0000,0000,0000,,but as long as a few survive\Nthen the next generation,
Dialogue: 0,0:02:12.13,0:02:14.11,Default,,0000,0000,0000,,you can imagine, they get to reproduction
Dialogue: 0,0:02:14.11,0:02:16.25,Default,,0000,0000,0000,,and then they'll lay thousands of eggs.
Dialogue: 0,0:02:16.25,0:02:18.07,Default,,0000,0000,0000,,And they're shorter lived.
Dialogue: 0,0:02:18.07,0:02:20.43,Default,,0000,0000,0000,,A frog could live a few years.
Dialogue: 0,0:02:20.43,0:02:23.65,Default,,0000,0000,0000,,Some insects might live\Nanywhere from a few days
Dialogue: 0,0:02:23.65,0:02:25.29,Default,,0000,0000,0000,,to a few years.
Dialogue: 0,0:02:25.29,0:02:27.04,Default,,0000,0000,0000,,You have things like\Nbacteria that can have
Dialogue: 0,0:02:27.04,0:02:29.46,Default,,0000,0000,0000,,an even shorter life span.
Dialogue: 0,0:02:29.46,0:02:32.69,Default,,0000,0000,0000,,So, when biologists or\Necologists look at this, they say
Dialogue: 0,0:02:32.69,0:02:35.92,Default,,0000,0000,0000,,it looks like there is\Na spectrum over here.
Dialogue: 0,0:02:35.92,0:02:39.41,Default,,0000,0000,0000,,You have these large long-lived animals
Dialogue: 0,0:02:39.41,0:02:41.38,Default,,0000,0000,0000,,that have a few children at a time.
Dialogue: 0,0:02:41.38,0:02:44.90,Default,,0000,0000,0000,,And really the limiting\Nfactor on their population
Dialogue: 0,0:02:44.90,0:02:47.61,Default,,0000,0000,0000,,is how dense their population is.
Dialogue: 0,0:02:47.61,0:02:49.81,Default,,0000,0000,0000,,At some point, these\Nanimals are going to compete
Dialogue: 0,0:02:49.81,0:02:51.72,Default,,0000,0000,0000,,for resources with each other.
Dialogue: 0,0:02:51.72,0:02:53.63,Default,,0000,0000,0000,,And that's true of\Nthings like human beings.
Dialogue: 0,0:02:53.63,0:02:55.72,Default,,0000,0000,0000,,And the other end, you have these things
Dialogue: 0,0:02:55.72,0:03:00.15,Default,,0000,0000,0000,,like spiders or frogs,\Ninstead might be limited
Dialogue: 0,0:03:00.15,0:03:02.62,Default,,0000,0000,0000,,on their reproduction\Nby environmental factors
Dialogue: 0,0:03:02.62,0:03:07.49,Default,,0000,0000,0000,,like how moist or dry it\Nis, how hot or cold it is.
Dialogue: 0,0:03:07.49,0:03:10.97,Default,,0000,0000,0000,,And so generally speaking\Nfolks have attempted
Dialogue: 0,0:03:10.97,0:03:14.10,Default,,0000,0000,0000,,to classify these types of species.
Dialogue: 0,0:03:14.10,0:03:15.78,Default,,0000,0000,0000,,They call them K selected.
Dialogue: 0,0:03:15.78,0:03:18.95,Default,,0000,0000,0000,,I'll talk about where the\NK comes from in a second.
Dialogue: 0,0:03:18.95,0:03:23.63,Default,,0000,0000,0000,,And they talk about these\Ntypes of species as R selected.
Dialogue: 0,0:03:24.53,0:03:26.81,Default,,0000,0000,0000,,And where these letters come from,
Dialogue: 0,0:03:26.81,0:03:29.49,Default,,0000,0000,0000,,is there, there's a general idea that
Dialogue: 0,0:03:29.49,0:03:32.39,Default,,0000,0000,0000,,if we draw a little axis here, time
Dialogue: 0,0:03:32.39,0:03:35.75,Default,,0000,0000,0000,,and then draw up axis here, population
Dialogue: 0,0:03:35.75,0:03:38.65,Default,,0000,0000,0000,,on the vertical axis, most species that
Dialogue: 0,0:03:38.65,0:03:40.79,Default,,0000,0000,0000,,when there's not a lot of\Nthem, and they're not limited
Dialogue: 0,0:03:40.79,0:03:45.61,Default,,0000,0000,0000,,by resources they will grow\Nexponentially like this.
Dialogue: 0,0:03:45.61,0:03:46.96,Default,,0000,0000,0000,,Now, when you go into the math of it,
Dialogue: 0,0:03:46.96,0:03:50.08,Default,,0000,0000,0000,,that rate of growth is usually\Ndenoted by the letter R,
Dialogue: 0,0:03:50.08,0:03:52.55,Default,,0000,0000,0000,,and you could see where this\NR selected is coming from.
Dialogue: 0,0:03:52.55,0:03:56.11,Default,,0000,0000,0000,,And what that R is how\Nlarge it is is determined
Dialogue: 0,0:03:56.11,0:03:59.48,Default,,0000,0000,0000,,by a species biotic potential.
Dialogue: 0,0:03:59.48,0:04:04.07,Default,,0000,0000,0000,,And biotic potential just\Nmeans in a given environment,
Dialogue: 0,0:04:04.07,0:04:05.63,Default,,0000,0000,0000,,how quickly can they reproduce?
Dialogue: 0,0:04:05.63,0:04:08.51,Default,,0000,0000,0000,,What percentage of those\Nare able to get to maturity
Dialogue: 0,0:04:08.51,0:04:11.01,Default,,0000,0000,0000,,so that they can reproduce,\Net cetera, et cetera.
Dialogue: 0,0:04:11.01,0:04:13.50,Default,,0000,0000,0000,,And so you could imagine the higher the R,
Dialogue: 0,0:04:13.50,0:04:17.19,Default,,0000,0000,0000,,the faster this\Nexponential growth goes up.
Dialogue: 0,0:04:17.19,0:04:21.04,Default,,0000,0000,0000,,Now, at some point you're going\Nto be resource constrained.
Dialogue: 0,0:04:21.04,0:04:23.86,Default,,0000,0000,0000,,And some there's some carrying capacity.
Dialogue: 0,0:04:23.86,0:04:26.31,Default,,0000,0000,0000,,And so let's say this is\Nthe carrying capacity here,
Dialogue: 0,0:04:26.31,0:04:27.62,Default,,0000,0000,0000,,and let's call that K.
Dialogue: 0,0:04:27.62,0:04:30.78,Default,,0000,0000,0000,,And the reason why we use\NK instead of C is K comes
Dialogue: 0,0:04:30.78,0:04:33.86,Default,,0000,0000,0000,,from a word for capacity in German.
Dialogue: 0,0:04:33.86,0:04:37.30,Default,,0000,0000,0000,,So, at some point you're\Ngonna have so many things
Dialogue: 0,0:04:37.30,0:04:39.10,Default,,0000,0000,0000,,that you're not gonna\Nhave enough resources
Dialogue: 0,0:04:39.10,0:04:39.97,Default,,0000,0000,0000,,to support more.
Dialogue: 0,0:04:39.97,0:04:42.51,Default,,0000,0000,0000,,And so your population would flatten out
Dialogue: 0,0:04:42.51,0:04:44.18,Default,,0000,0000,0000,,something like this.
Dialogue: 0,0:04:44.18,0:04:48.52,Default,,0000,0000,0000,,And so, generally speaking\Nbiologists have categorized
Dialogue: 0,0:04:48.52,0:04:52.64,Default,,0000,0000,0000,,these left categories of\Nspecies as K selected.
Dialogue: 0,0:04:52.64,0:04:55.92,Default,,0000,0000,0000,,The amount that you have,\Nthe amount of population
Dialogue: 0,0:04:55.92,0:04:58.92,Default,,0000,0000,0000,,is going to be determined by\Nthe resources that are there,
Dialogue: 0,0:04:58.92,0:05:01.25,Default,,0000,0000,0000,,the carrying capacity in the environment,
Dialogue: 0,0:05:01.25,0:05:04.43,Default,,0000,0000,0000,,while things like frogs\Nand mosquitoes and bacteria
Dialogue: 0,0:05:04.43,0:05:07.37,Default,,0000,0000,0000,,and spiders, you view more as R selected.
Dialogue: 0,0:05:07.37,0:05:11.45,Default,,0000,0000,0000,,They're gonna grow exponentially\Nat their biotic potential,
Dialogue: 0,0:05:11.45,0:05:14.03,Default,,0000,0000,0000,,but that biotic potential\Nis gonna be determined
Dialogue: 0,0:05:14.03,0:05:16.18,Default,,0000,0000,0000,,by how hot or cold or wet or dry
Dialogue: 0,0:05:16.18,0:05:17.70,Default,,0000,0000,0000,,or other environmental factors.
Dialogue: 0,0:05:17.70,0:05:20.06,Default,,0000,0000,0000,,They're not gonna get\Nto such a high density,
Dialogue: 0,0:05:20.06,0:05:23.04,Default,,0000,0000,0000,,that they're really\Ncompeting with each other.
Dialogue: 0,0:05:23.04,0:05:26.12,Default,,0000,0000,0000,,Now, as you can imagine\Nwith most categorizations,
Dialogue: 0,0:05:26.12,0:05:29.42,Default,,0000,0000,0000,,nature is not that clean\Nthat things are always going
Dialogue: 0,0:05:29.42,0:05:31.18,Default,,0000,0000,0000,,to be on the left side, or always gonna
Dialogue: 0,0:05:31.18,0:05:32.37,Default,,0000,0000,0000,,be on the right side.
Dialogue: 0,0:05:32.37,0:05:35.10,Default,,0000,0000,0000,,For example, things like\Nturtles, lay a lot of eggs
Dialogue: 0,0:05:35.10,0:05:37.74,Default,,0000,0000,0000,,but they live a very long time.
Dialogue: 0,0:05:37.74,0:05:41.21,Default,,0000,0000,0000,,It's also worth noting that\Nthere's no value judgment
Dialogue: 0,0:05:41.21,0:05:43.86,Default,,0000,0000,0000,,that one strategy is\Nbetter than the other.
Dialogue: 0,0:05:43.86,0:05:45.23,Default,,0000,0000,0000,,They've both been successful.
Dialogue: 0,0:05:45.23,0:05:47.12,Default,,0000,0000,0000,,The fact that these species exist today,
Dialogue: 0,0:05:47.12,0:05:49.21,Default,,0000,0000,0000,,show that they have worked well.
Dialogue: 0,0:05:49.21,0:05:52.03,Default,,0000,0000,0000,,It is worth noting that\Ninvasive species tend
Dialogue: 0,0:05:52.03,0:05:53.81,Default,,0000,0000,0000,,to be more R selected.
Dialogue: 0,0:05:53.81,0:05:55.54,Default,,0000,0000,0000,,They will just grow and grow and grow,
Dialogue: 0,0:05:55.54,0:05:58.43,Default,,0000,0000,0000,,and gonna be limited by the\Nenvironment and not as much
Dialogue: 0,0:05:58.43,0:05:59.73,Default,,0000,0000,0000,,by each other.
Dialogue: 0,0:05:59.73,0:06:02.57,Default,,0000,0000,0000,,While K selected species\Nare often the ones
Dialogue: 0,0:06:02.57,0:06:06.27,Default,,0000,0000,0000,,that are most effected\Nby invasive species.
Dialogue: 0,0:06:06.27,0:06:08.60,Default,,0000,0000,0000,,Now, the last thing I wanna highlight is,
Dialogue: 0,0:06:08.60,0:06:12.11,Default,,0000,0000,0000,,what we just talked about as\Npopulation growth strategies.
Dialogue: 0,0:06:12.11,0:06:16.15,Default,,0000,0000,0000,,And that can sometimes be\Nconfused with niche strategies
Dialogue: 0,0:06:16.15,0:06:18.53,Default,,0000,0000,0000,,where are there certain\Nspecies that are generalists,
Dialogue: 0,0:06:18.53,0:06:20.31,Default,,0000,0000,0000,,that can occupy many different niches
Dialogue: 0,0:06:20.31,0:06:23.54,Default,,0000,0000,0000,,while there's certain species\Nthat are more specialists.
Dialogue: 0,0:06:23.54,0:06:26.06,Default,,0000,0000,0000,,Here, we're just talking\Nabout generally speaking,
Dialogue: 0,0:06:26.06,0:06:28.75,Default,,0000,0000,0000,,how do species tend to grow in population?
Dialogue: 0,0:06:28.75,0:06:31.01,Default,,0000,0000,0000,,While when we talk about niche strategies,
Dialogue: 0,0:06:31.01,0:06:34.16,Default,,0000,0000,0000,,we're gonna talk about the\Ntypes of niches they feel
Dialogue: 0,0:06:34.16,0:06:36.45,Default,,0000,0000,0000,,in order to get their resources.
Dialogue: 0,0:06:36.45,0:06:39.35,Default,,0000,0000,0000,,And we'll talk more about\Nall of that in future videos.