Adaptation/Evolution
What is adaptation
An adaptation is a trait or characteristic that helps an organism survive and reproduce in its environment.
Convergent evolution
occurs when unrelated species develop similar traits because they live in similar environments. Ex: Bats, birds
Homologous structures
similar structures, different functions
Andreas Vesalius (Comparative Anatomy)
Compared structural features between humans and other animals and recognized that there were many similarities.
Charles Lyell (Uniformitarianism)
Processes that shape the geological Earth are slow and gradual and still taking place today. He recognized that the Earth must be much older than what current people were thinking (6000 years old)
Structural adaptation
affects a specific part or feature of the organisms body. Ex: camouflage, mimicry
Coevolution
occurs when two species evolve in response to each other’s changes.
Analogous structures
Different structure, same function
Nicholas Steno (Paleontology)
Law of superposition, fossils on the bottom are older than those found at the top.
Thomas Malthus (Population Growth Theory)
Human populations outgrow their available resources leading to death from disease, starvation, etc
Essentially, more are born than can survive.
Behavioral adaptation
affects the way an organism acts Ex: migration, playing dead, nest building
Fossils
any ancient remains, impressions, traces of an organism
Vestigial structures
Structures that are still present but no longer useful
George Louis Leclerc (Comte de Buffon)
Tried to explain that similar species are located in different places around the world by saying that they migrated and then changed based on the organic materials available.
Stabilizing selection
The environment favors the average phenotype.
Ex: average birth weight has higher chance of survival
Physiological adaptation
an internal response to an external stimulus
Ex: hibernation, shivering, producing venom, bee stinger
Fossil formation
rare and only occurs in low oxygenated areas
Evidence from embryology
Evidence from the pre birth stage of an organism's development, indicates a common ancestor
George Cuvier (Catastrophism)
Recognized that the Earth could go through massive changes (volcanic eruptions, earthquakes, etc) causing massive extinction events.
Directional selection
The environment favours individuals with extreme variations of a trait.
Ex: Hummingbirds migrate to a new area with different flowers; those with longer beaks are now more fit (favoured). These will live to pass on the trait of long beaks furthering the selective advantage of having a long beak.
Divergent evolution
occurs when one species splits into different species that become more different over time. (Common ancestor > Elephants + Mammoths)
Biogeography
Scientific study of the geographic distribution of organisms based on both living species and fossils
Evidence from DNA
Comparing dna sequences of different species allowing to see how closely related two species are
Jean Baptiste Lamarck (Use and Disuse)
If you use an organ/structure it will grow bigger/stronger and this change is heritable. (Disproved)
Disruptive Selection
Opposite extremes are selected for
Ex. flowers of two different sizes may result in high fitness of two different beak lengths (long and short) in hummingbirds