BIOL 2Q04 Lecture Notes - Lecture 11: Cape May Warbler, Blackburnian Warbler, Myrtle Warbler
14 Dec 2016
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BIOL 2Q04 | October 24, 2016
Life History Strategies ad Copetitio Cot’d
Assumptions and Factors
− Assumptions of the competitive exclusion principle
o Competitors have exactly the same resource requirement
▪ Only 1 species can keep resources; 1 out of competition
o Environmental conditions remain constant (rare)
▪ Difficult to define realized niche because conditions are constantly
changing
− A variety of factors affects the outcome of interspecific competition
o Temperature and pH
o Spatial/temporal variations in resource availability
o Competition for limiting resources
▪ I.e. light for plants
o Resource partitioning
▪ When 2 species will share resources in various ways
• I.e. bats and birds – birds during the day, bats during the night;
use of same resources but at different times during the day
Coexistence
− Coexistence can take place due to resource partitioning, location partitioning within the
same habitat
− McArthur with the 5 warbler spp. in New England
o Same size
▪ Overlap in resources
o Same boreal forest
− So why do they live together?
o Myrtle warbler stays at the bottom
o Black-throated green warbler top
o Blackburnian warbler
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find more resources at oneclass.com
o Bay-breasted warbler
o Cape May warbler
▪ Each have a different position in the trees for nesting
o Diet specialization
▪ Cape May will only have the insect outbreak, others will only eat a small
amount in bark, and etc.
Resource Partitioning
− Similar species coexist by partitioning available resources
o Different kinds/sizes of food
o Feed at different times
o Forage in different areas
o Exploit the portion of resources unavailable to others
− Note most populations are NOT at k
o Due to large variability in the environment
Plants Need Water, Light and Nutrients
− How do we study competition?
o Replacement series
▪ Figure 10.15
• Start with 100% of species A (dominant), and 0% of species B
(subordinate), and gradually switches when species B is
introduced, ultimately becoming 100% of species B (dominant)
and 0% of species A (subordinate)
▪ Figure 10-16
• Sum of ryegrass density and clover density produces facilitation
(total yield)
o Facilitation occurs when you have the 2 plants helping
each other
▪ Clover fixes nitrogen in soil, and helps rye to grow
better
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find more resources at oneclass.com
▪ Principle of intercropping in sustainable agriculture
• Helps with preventing pests
Apparent Competition
− Direct or indirect competition
− A single species of predator feeds on 2 prey species
o Predator puts pressure between 2 prey species
▪ Species A feeding on Species B will disappear when predators are present
▪ When predators are gone, species A and species B will go back to being
competitors
− If predation is gone, the 2 species are regulated by purely intraspecific, density-
dependent mechanisms
Recap
− Life is tough!
− Competition can take many forms but always lead to changes in population growth
− And gradually life history traits
− Read chapter on predation
Practice
− Online
Predation
Outline
− What’s predatio ad types
− Functional response
− Numerical response
− Coevolution: how to avoid predation
o Constant movement of species (preys)
− How to hunt
What is Predation?
− Predation is the consumption of one living organism (the prey) by another (the
predator)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
A variety of factors affects the outcome of interspecific competition: temperature and ph, spatial/temporal variations in resource availability, competition for limiting resources. I. e. light for plants: resource partitioning, when 2 species will share resources in various ways. I. e. bats and birds birds during the day, bats during the night; use of same resources but at different times during the day. Coexistence can take place due to resource partitioning, location partitioning within the same habitat. Mcarthur with the 5 warbler spp. in new england: same size, overlap in resources, same boreal forest. Similar species coexist by partitioning available resources: different kinds/sizes of food, feed at different times, forage in different areas, exploit the portion of resources unavailable to others. Note most populations are not at k: due to large variability in the environment. If predation is gone, the 2 species are regulated by purely intraspecific, density- dependent mechanisms. Competition can take many forms but always lead to changes in population growth.
