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Lecture 1

BIOL 1209 Lecture Notes - Lecture 1: Legume, Understory, Chamaecrista Fasciculata

Biological Sciences
Course Code
BIOL 1209

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BIOL 1209 LECT 1 AND 2
Ecology: study of how organisms interact w each other and the environment
o Why is there diversity?
Population: a collection of organisms of all the same species residing in the same place
and time.
o Abiotic factors: habitat, appropriate climate, oxygen, advantageous traits
o Biotic factors: food, water, reproduction
What do plants need to survive? Sunlight, O2, CO2, water, nitrogen, phosphorus, and
potassium, micronutrients
What do plants compete for? Nutrients, space, pollinators, light
How do multiple species competing for limited resources coexist?
o Competition and Colonization trade off
Resources (food, water, shelter, space, etc.) are finite. When two or more
species require the same resources to survive they compete for them and
the superior competitor can drive the other species extinct or exclude it
from an area. The two-barnacle species in this image compete for space on
the rock. The space that is submerged in seawater most often is better
habitat because it gives the barnacles more time to forage for food and
keeps them from drying out. Balanus is a superior competitor and will
always crowd Chthamalus out of the better low tide habitat. However,
only Chthamalus is tolerant of being exposed to air during high tide.
o Resource Partioning
Reduces competition among the species and allows them to coexist.
Ex: roots of each species take up water and minerals from a different soil
o Increased Defenses Against Herbivores
A plant may develop physical or chemical defenses against herbivores.
The plant strain on the left is resistant to herbivory and the strain on the
right is not. Even if the strain on the right was a better competitor it would
lose some of the benefits of its superior resource acquisition to herbivore
o Positive Interactions with Another Species
Mutualism: mutual beneficial interactions with another species. Think of
Clown fish and the anemones.
Feedback loops: process whereby a change to the system will trigger a certain result.
o Positive: (increase change to system)
Child birth: labor causes pressure on cervixoxytocin releasemore
releaseincreases contractions
Fruit ripening: ripe fruit releases ethylene gasripens unripen fruitmore
ethylene gas
o Negative: (reduces change to system)
Temperature regulation: hotsweatcools, coldshiverheat
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