• Study of ecology, ecosystems: natural history
• Environmental biology applied to a local (relative) scale (Northern California)

“Structural Levels of Life”

• Compartmentalization of life with regard to the biosphere concept
• Biology — the study of life and living organisms, genetic adaptations and growth, taxonomy, evolution, identification
• Several unifying concepts to biological disciplines: structural levels of life and emergent properties of life
  • Structural levels reflect the complexity;
  • Emergent levels define what a living being is
• Some components of the structural levels do not consist of living things (molecules), but many do

1. Molecule — Non-living
2. Cell — Cumulation of molecules with a living, functioning concept
3. Tissue
4. Organ — Functional structure
5. Organism — Living entity
6. Population — A collective of the same kind of organism, dependent on where it is also specified
7. Community — Groups of populations within a specific area
8. Ecosystem — The community of organisms and the environment and resources which they use; both living and non-living components included
9. Biosphere — Every place on the planet which living things exist; non-living only, and specific to places and areas (environments)

Emergent Properties of Life

• Combined characteristics which define life
• All living things have all of the below components:
  1. Order, organization, and hierarchy;
  2. The ability of reproduction for both cells and offspring;
  3. The ability to grow and develop;
  4. The need to use energy;
  5. The ability to maintain your body/metabolize;
  6. The ability to respond to the environment/environmental stimuli;
  7. The ability to adapt to the environment and genetics;
  8. and the ability to evolve.

Scientific Method

1. Ask a question/make an observation
2. Propose a testable hypothesis
3. Develop a deduction (written as an if… clause)
4. Testing/experimentation/exposure
5. Conclude if the hypothesis has been supported or invalidated based on the tests

• Scientific theories are accepted explanations for a phenomenon that are based on large amounts of evidence obtained from testing vs. conjecture
• Scientific method is practiced through an individual group; scientific process is practiced via the larger scientific community
  • Publishing, peer review, scientific journals; passes through rapid, larger-scale acceptance/rejection

Natural Selection and Speciation

• Living things use energy for metabolism, growth/development, and reproduction (in that order)
  • By using less energy on metabolism, more energy can go into development and reproduction
• Evolution: The change in a population’s genetic makeup (gene pool) through successive generations.  Populations evolve.
  • Microevolution: The small genetic changes that occur in a population.
  • Macroevolution: Long-term, large-scale evolutionary changes that occur in groups of species where new species are formed from ancestral species.
• Selective Pressures
  • Environmental resistance factors
  • Environmental pressures
  • Natural selection pressures: primary force is competition for resources within populations
  • Environmental resistance: physical and biological factors’ effect in preventing species from reproducing at maximum rate
• Natural selection affects the gene pool of the population
  • Adaptation occurs at an individual level
  • Shifting gene pools → biological evolution
  • Differential reproduction: a change in characteristic frequency in the population
    • Biological evolution occurs when the gene pool shifts
• Different forms:
  • Differential reproduction
  • Stabilizing selection
  • Intersexual selection
  • Adaptive radiation
  • Selective breeding
    • Phenotypic plasticity
• Alfred Russell Wallace: distinct differences found on the Malay archipelago: animals on the Western line had Asian ancestry, eastern had Australian ancestry
  • “Wallace Line”
• Major tenets/assumptions of natural selection:
  1. All species have immense reproductive potential unless checked/limited
  2. Natural resources are limited which checks/limits species reproduction
  3. Genetic variation exists in the population
  4. Overpopulation/above capacity limits the number of surviving offspring in each generation
  5. Some individuals with a specific phenotype have a greater fitness in the population than others
  6. Favorable characteristics/phenotypes are more likely to prevail in the population in each generation
• Stephen Jay Gould
• Three outcomes result in intraspecific and interspecific competition:
  • Avoidance via resource partitioning
  • Extinction/death
  • **Physical distance/separation of species
• Niche: a particular role or purpose that a specific population has in its environment at a given, specific period in history
  • Fundamental niche: All possible niches provided no competition from other species exist
  • Realized niche: Conditions under which species actually exist alongside competition
    • Niche compression occurs when competition is introduced (invasive species)
    • Niche expansion occurs during extinction/extirpation
    • Niche shift: A shift in behavior to avoid/reduce competition
  • Both niche types can:
    • Change in different periods of the lifecycle
    • Change between sexes
  • Wide/narrow niches
    • Narrow width niche: Only specialized to do a few things; narrow width of fundamental niches → threatened species
    • Wide width niche: Many possible specializations
• Speciation frequently occurs via various isolating mechanisms:
  • Geological isolation;
  • Ecological isolation;
  • Behavioral isolation;
  • Mechanical isolation;
  • Post-zygotic hybrid inviability, sterility, and breakdowns

Geographic Variation

• Variation that occurs as a result of specific environmental pressures that create variation
  • Clines, where a gradual change occurs in one or more characteristics (Sierra Nevada elevation and blooming rates/times)
  • Ecotypes, where genotype and genetic strains in a population affect survival even in different geography (plants blooming at a specific time always regardless of geography)
  • Geographical reproductive isolation
• Parapatric isolation occurs adjacent to one another without geographic isolation, but without being overlapped; contaminated vs non-contaminated sections of soil
• Polymorphism: the presence/occurrence of different forms in a habitat at the same time