Date post: | 26-Dec-2015 |
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Month Day Topic
Nov. 8 Individuals to populations
10 Holiday!
13 Populations to communities
15 Community patterns
17 Ecosystems
20 Film-1st showing
22 Film-2nd showing
24 Holiday!
27 Ecosystem services
What controls where a population lives?
• It has to get there– Evolution– Dispersal
• Its ecological niche
Key concept in ecology: the niche
• Fundamental niche– Abiotic conditions that the species can live
within
Key concept in ecology: the niche
• Fundamental niche– Abiotic conditions that the species can live
within
• Realized niche– Biotic interactions that reduce or enhance
the fundamental niche
Barnacle story
Balanus’ fundamental niche: upper, middle and lower zone
Balanus’ realized niche: middle zone, limited from upper by competition, lower by predation
A community is:
Populations of different species that live
together in a given area at a given time.
Communities are...
• Defined by abiotic factors– Populations in a community have similar
fundamental niches
Communities are...
• Defined by abiotic factors– Populations in a community have similar
fundamental niches
• Defined by biotic interactions– Some are weak– Some are strong
Types of community interactions
POP. 2
Harm No effect Benefit
Harm Competition Amensalism Predation or Parasitism
POP. 1 No effect Amensalism Commensalism
Benefit Predation or Parasitism
Commensalism Mutualism
Types of community interactions
POP. 2
Harm No effect Benefit
Harm Competition Amensalism Predation or Parasitism
POP. 1 No effect Amensalism Commensalism
Benefit Predation or Parasitism
Commensalism Mutualism
Types of community interactions
POP. 2
Harm No effect Benefit
Harm Competition Amensalism Predation or Parasitism
POP. 1 No effect Amensalism Commensalism
Benefit Predation or Parasitism
Commensalism Mutualism
• Organisms compete for limited resources
• Can be:– Intraspecific– Interspecific
Keys to competition(-/-)
Competition can:
• Restrict species ranges
• Reduce species abundances
• Cause the local extinction or competitive exclusion of species from an area
Predator-prey interactions(+/-)
• Predators are generally larger than their prey (but many exceptions...)
Predator-prey interactions(+/-)
• Predators are generally larger than their prey (but many exceptions...)
• Predators live outside of the body of their prey
Predator-prey interactions(+/-)
• Predators are generally larger than their prey (but many exceptions...)
• Predators live outside of the body of their prey
• Predators generally kill their prey
Predator-prey interactions
• Dynamics of predator and prey populations may be:
• Loosely coupled– predator “switches” when prey is scarce
• Tightly coupled– predator starves when prey is scarce
Predator-prey interactions change over time
• An evolutionary “arms race”
• Mimicry
• Plant defenses against herbivores
Host-parasite interactions(+/-)
• Parasites are generally smaller than their hosts
• Parasites live inside or on the body of their host
• Parasites generally kill their hosts more slowly than predators
Communities are...
• Defined by abiotic factors– Populations in a community have similar
fundamental niches
• Defined by biotic interactions– Weak and strong interactions determine a
population’s realized niche
• Dynamic– Vary in time and in space
Communities vary in time
Ecological succession:
a sequence of change in the species composition of a community
Succession
1. Primary– establishment of communities on new
sites that previously had no organisms
2. Secondary– re-establishment of communities
following disturbance
Terrestrial biome
• A major community type that differs from other types in the structure of its dominant vegetation.
Terrestrial biome
• A major community type that differs from other types in the structure of its dominant vegetation.
• Primarily controlled by climate.– Relationship between rainfall and
temperature
• The vegetation of a biome has a similar appearance wherever on Earth that biome is found.
• In many cases, this is due to convergent evolution.
Biomes
-found near the equator
-temperature varies little from approximately 23°C
-Over 2 m of rainfall
Tropical Rain Forest