Speciation and Adaptive Radiation

Speciation

Allopatric Speciation

• Occurs when a population is geographically isolated from the rest of the species
• Can be due to physical barriers (e.g. mountains, rivers) or dispersal limitations
• Over time, the isolated population may evolve into a new species

Adaptive Radiation

• A process of rapid speciation in a group of organisms that colonize a new area
• Often occurs when a single species invades a new region with few or no competitors
• Examples: Hawaiian honeycreepers, Galapagos finches

Sympatric Speciation

• Occurs when a new species emerges from a single population within the same geographic area
• Can be driven by ecological or behavioral differences
• Examples: Apple maggot fly, sockeye salmon

Species Concept

• A species is a group of interbreeding organisms that are reproductively isolated from other groups
• Different species concepts exist, including:
  • Biological Species Concept (BSC): emphasizes reproductive isolation
  • Morphological Species Concept (MSC): emphasizes physical differences
  • Ecological Species Concept (ESC): emphasizes ecological differences

Hybridization

• The process of interbreeding between two different species
• Can result in fertile or sterile offspring
• Can be a source of genetic variation and adaptation

Charles Darwin and Galapagos Island

• Darwin's visit to the Galapagos Islands in 1835 influenced his development of the theory of evolution
• He observed the unique characteristics of Galapagos finches and tortoises, which led him to question the fixity of species
• The Galapagos finches are a classic example of adaptive radiation, with 14 distinct species evolving from a single ancestral species

Speciation

Allopatric Speciation

• Geographical isolation leads to speciation, caused by physical barriers or dispersal limitations
• Isolated population evolves into a new species over time

Adaptive Radiation

• Rapid speciation occurs when a group of organisms colonize a new area with few competitors
• Examples: Hawaiian honeycreepers, Galapagos finches, and Darwin's finches

Sympatric Speciation

• New species emerge from a single population within the same geographic area
• Driven by ecological or behavioral differences
• Examples: Apple maggot fly, sockeye salmon

Species Concept

• A species is a group of interbreeding organisms reproductively isolated from other groups
• Different species concepts exist:
  • Biological Species Concept (BSC): reproductive isolation
  • Morphological Species Concept (MSC): physical differences
  • Ecological Species Concept (ESC): ecological differences

Hybridization

• Interbreeding between different species, resulting in fertile or sterile offspring
• Source of genetic variation and adaptation

Charles Darwin and Galapagos Island

• Darwin's 1835 visit to the Galapagos Islands influenced his theory of evolution
• Galapagos finches and tortoises showcased unique characteristics, questioning species fixity
• Galapagos finches exemplify adaptive radiation, with 14 species evolving from a single ancestor