Biomed Y1 FLS Evolution and Biodiversity Dr Conner 01 November 2024

Introduction to Evolution and Biodiversity

  • Presenter: Sarah Connor

  • Topic: Evolution and biodiversity; relations to biomedical science

  • Learning outcomes: Basic knowledge of biodiversity, natural selection, and human-organism interactions.

The Origin of Life on Earth

History of the Planet

  • Life on Earth began nearly 4 billion years ago.

  • Stanley Miller's experiments (1950s) provided insight into the formation of organic molecules from inorganic compounds in an anaerobic environment.

Formation of Simple Life

  • Inorganic molecules (hydrogen, ammonia, methane) heated in right conditions create organic molecules, including amino acids.

  • RNA and phospholipid-like molecules emerged, leading to protocells (RNA surrounded by a membrane).

Evolution of Life

Prokaryotic Life

  • RNA stability increases; DNA forms, allowing prokaryotes to evolve.

  • Prokaryotes specialized, leading to organisms like cyanobacteria, which produced oxygen.

Eukaryotic Life

  • First eukaryotes evolve around 2.7 billion years ago through symbiotic processes.

  • Evolution of complex cells and multicellular organisms followed.

Expansion of Life on Earth

Extinction Events

  • Extinction events create new niches for species evolution.

  • Pattern of extinctions followed by rapid speciation is noted throughout Earth's history.

Significant Events in Evolution

  • Cambrian Explosion (~500 million years ago):

    • Colonization of land by organisms; led to the proliferation of plants and consumption of carbon dioxide.

    • Resulted in fossil fuel creation from plant death.

  • Supercontinents (e.g., Pangea) played a role in evolution through geographic and environmental shifts.

Major Extinction Events

  • Permian Extinction (~250 million years ago):

    • Uncertain cause (meteor or volcanic activity).

    • Resulted in a drastic loss of species, particularly marine life.

    • New evolutionary opportunities emerged, leading to the evolution of dinosaurs.

  • Cretaceous-Paleogene Extinction (65 million years ago):

    • Caused by an asteroid impact, creating a crater off Mexico.

    • Resulted in massive extinction of species, including dinosaurs, and promoted mammal evolution.

Evolution of Humans

  • Humans evolved approximately 7 million years ago.

  • Key developments: bipedalism, increased brain size, longer gestation.

Hominids

  • Earliest hominids appeared 7-4 million years ago in Africa; possibly bipedal but apelike.

  • Evolved into Australopithecine species (4-2 million years ago), resembling early humans.