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U4: Topic 1, U4: Topic 2 - Coggle Diagram

- - - - Convergent evolution occurs when organisms that are not closely related independently evolve similar traits because they occupy similar environments or niches
        
        Evidence = Analogous structures (e.g., bird wings and butterfly wings) serve the same function but do not share a recent common ancestor (e.g. the streamlined bodies of sharks (fish) and dolphins (mammals))
    - - Parallel evolution is the independent development of similar traits in distinct but closely related species. It occurs when recently separated lineages experience similar environmental pressures
        
        e.g. Long-necked turtles in Australia and South America independently evolved nearly identical traits for aquatic fish-eating niches.
    - - Divergent evolution occurs when related species evolve from a common ancestor but become increasingly different over time to suit new environments
        
        Evidence = Homologous structures (e.g., the pentadactyl limb in humans, whales, and bats) share a common genetic and anatomical origin but perform different functions (e.g. different species of dogs and wolves descending from a common wolf ancestor)
    - - Co-evolution is a process where two or more species reciprocally influence each other's evolutionary trajectory. The adaptations of one species act as a selection pressure on the other
        
        Mutualistic Example = Birds with long, narrow beaks evolving alongside deep, tubular flowers.
        
        Antagonistic Example = Brood-parasitic cuckoos evolving eggs that mimic the size and color of host bird eggs, while the host birds evolve better detection methods.
  - - - Geographical Isolation: Populations are physically separated by environmental features like mountains, rivers, or vast distances
        
        Temporal Isolation: Populations live in the same area but reproduce at different times (day vs. night, or different seasons)
        
        Spatial (Ecological) Isolation: Populations occupy the same territory but utilize different niches or micro-habitats and thus rarely encounter one another
- - - - Geneticists use these sequences to create molecular clocks, assuming that mutations accumulate at a relatively constant rate. By identifying the number of nucleotide differences and using fossil data to calibrate a timeline, scientists can calculate the rate of mutation (Rate = # base changes ÷ time since last common ancestor). This rate is then applied to species without fossil records to estimate their time of divergence.