Evolution and Environmental Factors in Biology

Evolution

Fixism

Species remain unchanged.

Creationism

Species are divinely created.

Lamarckism

Species change over time. Proposed by Lamarck. Assumptions: environmental conditions vary, creating changes and modifications.

Darwinism

Survival of the fittest drives species change.

Key Concepts in Evolution

Fossils

Remains of organisms that lived on land and are now extinct.

Geographical Distribution

A common ancestor lived on a continent, and upon separation and isolation, species evolved independently.

Homology

Similarity due to a common ancestor.

Embryonic Development

Vertebrate embryos are very similar at early stages due to a common ancestor.

Molecular Genetics

Comparing DNA to determine kinship.

Mutations

Changes in genetic material that can be beneficial, detrimental, or neutral.

Synthetic Theory of Evolution

Principles: The evolutionary unit is the population, not the individual. Individuals within a population have different alleles. Certain phenotypes determined by these alleles influence the ability to leave offspring.

Saltationism

The possibility of intermediate species and fossils that did not exist or changed rapidly.

Gradualism

A species evolves slowly and gradually.

Gradual Adaptation

When a population adapts to a changing environment, natural selection occurs.

Ecology

Levels of Organization

Population

A group of individuals of the same species living in a given area.

Community

The entire set of populations.

Biotope

The place occupied by a community.

Ecosystem

Community + biotope.

Habitat

The ideal place where an organism finds the ideal conditions for living.

Environmental Factors

Conditions that exist where an organism lives and influence it.

Biotic Factors

Factors arising from the presence of other living beings.

Abiotic Factors

Factors that do not depend on the activity of living beings, but their activity can modify them.

Optimal Conditions

Values that allow an organism to thrive.

Limits of Tolerance

For a given environmental factor, the values at which an individual's survival is almost zero and does not leave offspring.

Limiting Factors

Factors that impede the growth of a population.

Abiotic Factors

Air

Influences organisms.

Ground

• Temperature: Low temperatures cause some animals to hibernate. Affects ectotherms (rely on external heat sources) and endotherms (generate their own heat).
• Humidity: The amount of water vapor per unit volume of air.

Soil

• Texture: Sandy soil (coarse, very porous), clay soil (fine particles, less porous), and mixed soil.
• Water: Water-loving plants (require a lot of water) and drought-tolerant plants (require small amounts of water).
• Air: The portion of soil pore space filled with air.
• pH: Salty soils, acid soils, and basic soils.

Water

• Salinity: Fresh water (5g/L of salt), saltwater (33-37g/L), and brackish water (intermediate).
• Light: Euphotic (sufficient light for photosynthesis), oligophotic (twilight zone), and aphotic (total darkness zone).
• Temperature: Influences currents and the amount of oxygen.