Evolution Flashcards
Evolution
Refers to the process by which populations of organisms change over time through variations in traits, leading to the development of new species from common ancestors
Who is Charles Darwin?
Charles Darwin is credited with formulating the theory of natural selection as a mechanism for evolution. His seminal work, “On the Origin of Species” (1859), laid the foundation for evolutionary biology
What is homologous structure?
Structures that are similar in different species because they share a common ancestor.
For example: the forelimbs of humans. whales, and bats have different functions but share a similar bone structure.
What is an Analogous Structure?
Structures that perform similar functions but evolved independently in different lineages (e.g. the wings of birds and insects).
What is the difference between homologous and analogous structures?
Homologous structures share an ancestor but serve a different function. But analogous structures serve a similar function but do not share an ancestor.
Examples of Homologous Structures
Dolphins flipper, a bird’s wing, a cat’s leg, and a human arm.
Human beings have bones such as the humerus, ulna and radius, carpals, metacarpals, and phalanges - these features appear as similar bones in form in the other animals. Bats, whales, and many other animals have very similar homologous structures, demonstrating that these creatures had a common ancestor.
Example: all mammals share the homologous structure of the vertebrate in common. For instance in spite of its height, the giraffe has the very same number of neck bones (7) as a giant whale and a tiny human being)
Human tailbone - homogenous and vestigial
Examples of Analogous Structures
Fins in fish and dolphins; classic example, because these creatures are not closely related, but they both developed fins due to similar environmental demands. Both fish and dolphins have fins that assist in swimming.
More examples: wings in birds and bats; eyes in mammals and octopuses; wings in insects and birds
Vestigial Structures
Remnants of features that served a function in an ancestor but are no longer functional or have reduced function in the current species.
Examples: Human appendix
Human tailbone (both homologous and vestigial). The tailbone is homologous to tails of other vertebrates like monkeys/cats/dogs.
Other animals have a fully developed tails that serve functions, humans and apes don’t.
It is also a vestigial structure because it is a remnant of a structure that was functional in our ancestors. Once human ancestors evolved to walk upright, the tail was no longer needed for balance, and the structure gradually reduced in size and lost it’s original section.
What evidence is there supporting Evolution?
Fossil Records, Comparative Anatomy, Embryology, Biogeography, Molecular Biology, Observations of Natural Selection, Comparative Geneomics
Fossil Records related to Major Lines of Evidence of Evolution
Fossils show a chronological sequence of life forms and transitional species, indicating gradual change over time
Comparative Anatomy related to -Major Lines of Evidence of Evolution
Similar structures in different species (homologous) and unused remnants (vestigial) suggest common ancestry
Biogeography related to - Major Lines of Evidence of Evolution
The distribution of species across the globe, especially on islands, supports evolutionary processes
Molecular Biology related to - Major Lines of Evidence of Evolution
Genetic similarities across species and universal DNA provide evidence of shared ancestry
Embryology related to Major Lines of Evidence of Evolution
Similar early developmental stages in different species hint at a common origin
Observations of Natural Selection related to Major Lines of Evidence of Evolution
Direct observations, like antibiotic resistance, show evolution in action.
