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Evolutionary Biology and Ecology: Key Concepts Explained

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1. Theories of Evolution

Anti-evolutionist Theories

  • Fixism: Defends that species have remained unchanged since their emergence.
  • Creationism: Similar to fixism, but attributes the origin of species to divine creation as described in the Bible.

Evolutionist Theories

  • Lamarckism: The environment creates specific needs; characters are acquired or lost based on use and disuse.
  • Darwinism: Based on diversity between individuals, limited resources, and the process of natural selection.
  • Neodarwinism: Incorporates genetics; natural selection acts on mutations: favorable (remain), unfavorable (disappear), and neutral.

2. Mechanisms of Natural Selection

3. Evidence of Evolution

  • Paleontological: Comparing current species with living fossils.
  • Biogeographical: Comparing species in different geographic areas; the more separated the continents, the greater the differences.
  • Anatomical: Vestigial organs (remnants of ancestral structures), homologous organs (same origin, different functions), and analogous organs.
  • Embryological: Comparing embryos during early developmental stages.
  • Biochemical: Molecular evidence that confirms evolutionary relationships.

4. Speciation

The formation of two distinct species from an original ancestral population.

5. Ecology and Definitions

  • Biotope: The physical space where organisms live.
  • Community: All populations of living beings inhabiting a specific biotope.
  • Population: A group of individuals of the same species living in a specific area.
  • Ecosystem: The unit of study consisting of the biotope and the community.

6. Environmental Factors

  • Biotic Factors: Influences caused by the activity of other living organisms.
  • Abiotic Factors: Physical or chemical environmental factors.
  • Limiting Factor: An environmental factor that restricts population growth.

7. Life in Terrestrial Environments

Humidity and temperature are the main constraints.

  • Homeotherms (Warm-blooded): Can regulate their internal body temperature.
  • Poikilotherms (Cold-blooded): Cannot regulate internal temperature, which fluctuates with the environment.

8. Aquatic Environments

  • Limiting Factors: CO2 and O2 levels (needed for respiration and photosynthesis) and temperature.
  • Salinity: Concentration of salt in rivers and seas.
  • Light: Affects different zones: euphotic, oligophotic, and aphotic.

9. Relationships Between Organisms

  • Competition: Between individuals of the same species.
  • Cooperation: Individuals of the same species helping each other.
  • Predation: Interaction between two different species (predator and prey).
  • Commensalism: One organism benefits while the other is unaffected.
  • Mutualism: Both species coexist and benefit.
  • Symbiosis: A close union where organisms cannot live separated.

10. What Threatens Species?

Habitat: The chemical and physical space, including all environmental conditions, where a species lives.

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