Carrying Capacity | Population Ecology — Transcript

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1. 0:00have you ever been out on a nice walk
2. 0:02and noticed a cute squirrel eating a
3. 0:04pecan and thought where did he get that
4. 0:07pecan where does he live is he afraid of
5. 0:09heights how big is his family does he
6. 0:11prefer grasshoppers or berries for
7. 0:13dinner how many squirrels live around
8. 0:15here anyway and what if there aren't
9. 0:17enough pecans for all the
10. 0:20squirrels surprisingly ecologists have
11. 0:23the job of asking those questions most
12. 0:25of those questions and the answers
13. 0:27reveal important information about the e
14. 0:30ecosystem and the organisms living in it
15. 0:32today we will be looking at a few
16. 0:34different species and the carrying
17. 0:36capacity of their environment the
18. 0:38carrying capacity of an environment is
19. 0:40the maximum population that environment
20. 0:42can sustain longterm with the resources
21. 0:45available a population is a group of
22. 0:47individuals of the same species who
23. 0:50interact regularly so our squirrels here
24. 0:53on the nature trail are a population the
25. 0:56resources we're talking about are the
26. 0:57things that an organism needs to live
27. 1:00and reproduce these resources vary for
28. 1:03different species but are mostly things
29. 1:05like food Water Shelter in space for our
30. 1:09squirrel friends this nature trail
31. 1:11ecosystem that we're in has a higher
32. 1:14carrying capacity than say a city block
33. 1:17the trail follows this Creek that
34. 1:19provides plenty of water there are even
35. 1:21tons of grasshoppers and seeds like
36. 1:23sunflower seeds for them to eat the
37. 1:25population is strong here so why aren't
38. 1:28there hundreds of squirrels running all
39. 1:30over the
40. 1:31place because even though there are tons
41. 1:34of resources here there are limiting
42. 1:36factors that are keeping the squirrel
43. 1:38population in check we have already
44. 1:40covered a few limiting factors like food
45. 1:44water and shelter not enough of those
46. 1:46and your population will decline but
47. 1:49what about things like space and
48. 1:51predation squirrels aren't territorial
49. 1:53like Bears or lions would be but they do
50. 1:56need space for their nests and they do
51. 1:58not like other squirrel squirrels
52. 2:00getting close to their babies so if
53. 2:02nesting space is limited it could force
54. 2:04some squirrels out of this area
55. 2:06squirrels main predators are birds of
56. 2:08prey animals like red tail hawks Kats
57. 2:12and owls but they can also fall prey to
58. 2:15cats dogs snakes and raccoons especially
59. 2:19when they're young predation limits the
60. 2:21population the more squirrels an
61. 2:22ecosystem has the more Predators it can
62. 2:25sustain in this area there is a family
63. 2:28of kites that I see all the time and I
64. 2:30can hear calling to each other when I'm
65. 2:32out on the
66. 2:35trail I have also seen several Snake
67. 2:38species that would absolutely eat a
68. 2:40young squirrel like this
69. 2:48Copperhead hi little chickies don't poop
70. 2:50on my head the number of squirrels in
71. 2:53this specific area is the population
72. 2:56density it's the number of individuals
73. 2:58divided by the size of of the area the
74. 3:00population density changes when
75. 3:02individuals are born or die move into
76. 3:06the area or leave the area the limiting
77. 3:09factors that we talked about earlier can
78. 3:11be broken down into two types density
79. 3:13dependent factors and density
80. 3:16independent factors things like food
81. 3:19Water Shelter space predation and even
82. 3:22things like disease are density
83. 3:25dependent factors if this area was
84. 3:27impacted by something like a wild fire
85. 3:30and the squirrels flood to escape the
86. 3:32danger that would be a density
87. 3:34independent Factor the fire has nothing
88. 3:37to do with how many squirrels we're here
89. 3:39to begin with but absolutely limits the
90. 3:41amount of squirrels the area can support
91. 3:44after the fire comes through if you're
92. 3:46still here liking this video hit that
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94. 3:50episode what about another example this
95. 3:53is Passion vine it's the host plant to a
96. 3:56species of butterfly called the gulf
97. 3:58frery there is a a population of
98. 4:00butterflies that lives in this
99. 4:02neighborhood because this plant is here
100. 4:05in most seasons the chief limiting
101. 4:07factor to this butterfly population is
102. 4:10the passion vine itself butterflies lay
103. 4:12so many eggs that the population grows
104. 4:15exponentially tons of caterpillars means
105. 4:18tons of butterflies then those
106. 4:20butterflies mate and lay their eggs back
107. 4:22on the same Passion vine once the
108. 4:24population grows to a certain level the
109. 4:27caterpillars can eat almost every leaf
110. 4:29leaving it looking like a skeleton vine
111. 4:32when the leaves run out the caterpillars
112. 4:34no longer have anything to eat and they
113. 4:36will die before they reach their Pupa
114. 4:38phase the vine is a fast growing plant
115. 4:40and will Bud new leaves to support the
116. 4:42Next Generation but this population will
117. 4:45have reached its carrying capacity the
118. 4:47amount of individual caterpillars it can
119. 4:49support with the given resources this
120. 4:51year that same initial growth occurred
121. 4:54and there were lots of caterpillars but
122. 4:56now the leaves are just covered in Holes
123. 4:58the carrying capacity is being greatly
124. 5:01impacted by a predator the Yellow Jacket
125. 5:04once the host plant became covered in
126. 5:06butterfly eggs it attracted the
127. 5:08Predators Yellow Jackets search for
128. 5:10butterfly eggs and caterpillars to
129. 5:12consume and even destroy the protective
130. 5:15crysalis I love these butterflies so I
131. 5:18decided to become a factor in their
132. 5:20environment I've started collecting the
133. 5:22butterfly eggs and Tiny caterpillars and
134. 5:25moved them right next door to this
135. 5:27screened enclosure the caterpillars grow
136. 5:29happily eating the leaves of the passion
137. 5:31vine I place inside for them then go
138. 5:34into their pupa stage and emerge as a
139. 5:36beautiful butterfly all inside here
140. 5:39protected from predators I then released
141. 5:42the butterflies back into the
142. 5:43environment so the cycle can start all
143. 5:46over again take that yellow jackets the
144. 5:49carrying capacity for different
145. 5:51populations of species varies from
146. 5:54ecosystem to ecosystem and even season
147. 5:57to season there's a lot going on even in
148. 5:59your own backyard so go check it out and
149. 6:02if you want to learn more science you
150. 6:04can check out this video next you're
151. 6:07positioning yourself right over my head
152. 6:09and I feel like you're going to poop in
153. 6:11my
154. 6:14mouth