1. A group of organisms that can interbreed and produce fertile offspring
Species
A group of organisms that can interbreed and produce fertile offspring
Common gene pool
Have similar physiological/morphological characteristics
Are genetically distinct from other species
Have common phylogeny (family tree)
Challenges:
What about two populations that could potentially interbreed, but do not because they are living in different niches or are separated by a long distance?
How should we classify populations that do not interbreed because they reproduce asexually?
What about infertile individuals? Does the fact that a couple cannot have a child exclude them from the species? What about in vitro fertilization?

2. Challenges to species definition
Hybrids
Two separate species produce offspring  not fertile
Due to different number of chromosomes
Not considered distinct species – cannot create future generations
Horse: 64 (32)
Donkey: 62 (31)
Lion: 38 (19)
Tiger: 38 (19)
Genetic barrier
Horse: 64 (32)
Zebra: (16-23)

3. Reproductive Isolation
Group of species separated from rest
Geographic Isolation:
Bodies of water, mountains, continent moving, forests
Separate species  only able to reproduce with its population  traits may start to vary
Behavioral isolation:
Migration patterns change – change nesting times
Courtship patterns change – changing whose attracted to whom

4. Communities
Ecosystems
Group of populations living and interacting with each other in an area
Interactions of biotic and abiotic factors
Abiotic measurements allows for predictions on type of species living in that ecosystem
Feeding relationships, symbiotic relationships, protection, parasitic
Studied via random sampling or systematic sampling

5. Autotrophs
Make own organic molecules from inorganic molecules
Producers

6. Heterotrophs
Must obtain organic molecules from other organisms
Consumers
Consumers ingest energy rich C-compounds, proteins, lipids to grow, repair, operate
Saprotrophs
Detritivores
Live in/on non-living organic matter
Eat non-living organic matter
Breakdown nutrients via external digestion
Breakdown nutrients via internal digestion
humus

7. Saprotrophs Role
Nutrient Cycling
Finite amount of nutrients – must be recycled
Role = breakdown waste material
Secrete enzymes into dead tissue
Break down complex molecules into simpler energy-rich compounds
Saprotrophs/organisms absorb products
Create rich soil that is needed to sustain life

8. Sustainability