Lecture on Natural Selection and Evolution

Introduction

• Evolution is a central theme in understanding life.
• All living things have a common ancestor (LUCA: Last Universal Common Ancestor).

Process of Evolution

• Reproduction leads to new generations slightly different from ancestors.
• Over generations, changes accumulate, resulting in organisms very different from original ancestors.
• Most changes are detrimental or neutral; beneficial changes are rare.
• Organisms with detrimental changes are less likely to reproduce and pass on those genes.
• Beneficial changes increase an organism's chance of survival and reproduction, passing those genes on.

Forces in Evolution

1. Genetic Change
   • Random changes during reproduction.
   • Mutations can be:
     • Beneficial (rare)
     • Neutral (common)
     • Detrimental (common)
2. Natural Selection
   • Non-random selection of advantageous traits.
   • Traits are advantageous based on environmental context.
   • Example: Blood vessel adaptation varies with environmental temperature.

Overview of Natural Selection

• Populations, not individuals, evolve.
• Evolution seen over many organisms and generations.
• No end goal in evolution; it's not a progression to complexity.
• Human traits selected for due to advantages in survival and reproduction.
• Environmental changes can shift what traits are advantageous.
  • Example: Climate change could deselect humans, select other organisms.

Future Topics

• Origin of life on Earth.
• Evidence of life’s presence over time.
• Organization of life into related groups.