Coevolution

Coevolution

• Definition: Reciprocal evolutionary change between interacting species, driven by natural selection. This implies that changes in at least two species reciprocally affect each other's evolution.
• Origin of the Idea: The concept was developed by Darwin in 1862 in his work on the Fertilisation of Orchids.

Results of Coevolution

• Mutualistic Interactions: Each species involved benefits from the interaction.
• Antagonistic Coevolution: Each species decreases the fitness of the other.

Modes of Coevolution

• Pairwise: Involves two species.
• Diffuse: Involves multiple species.

Mutualism

• Evolutionary Methods:
  • From initially neutral interactions.
  • From a relationship where one species benefited and the other was neutral.
  • From an initially parasitic relationship.
  • Even endosymbiosis can be considered a mutualism.

Classic Example: Fig and Wasp

• Each fig species is typically pollinated by only one specific wasp species.
• Benefits:
  • Fig receives necessary reproductive help.
  • Flowers are internal, ensuring a degree of protection.
  • Wasp deposits eggs in the ovary of some flowers, simultaneously pollinating the flowers.
• Outcome: Roughly half of the flowers produce seeds, while the other half produce wasps.
• Reciprocal genetic change: Each player benefits or reacts to the advantages of the other.

Ant-Butterfly Mutualism

• Interaction: Butterfly larvae and pupae secrete sugars that nourish ants.

• Benefit: Ants protect the butterfly larvae and pupae from predators.

• Communication: Communication has evolved to facilitate mutualism.

  Stridulating pupae attract more ants. The data indicates that stridulating pupae attract a higher mean number of attendant ants compared to muted pupae over a period of time.

Other Examples of Mutualism

• Coral: Cnidaria and Dinoflagellata.
• Lichens: Fungi and Green Algae/Cyanobacteria.
• Gut Symbionts: Termites and Protozoa/Bacteria.

Fungus Growing Ants

• Attine ants cultivate basidiomycete fungi as a garden.
• Diffuse evolution exists, involving:
  • Actinomycete bacteria.
  • Escovopsis fungi (parasite).
  • Black yeast.
• The evolutionary history of fungus-growing ants illustrates a complex relationship with their cultivated fungi and other associated microbes.
• The timeline indicates the evolution of different agricultural practices in ants, such as lower agriculture, coral fungus agriculture, yeast agriculture, and higher (