Evidence for Evolution - Anatomy, Embryology and Biogeography Flashcards
What is comparative anatomy?
The study of the similarities and differences in the structure of organisms.
How do similar anatomical features in animals provide evidence for evolution?
More similarities - more recent separation from common ancestor
What is a homologous structure?
A structure that is similar in shape, corresponding in origin from a common ancestor, dissimilar in function
Provide an example of a homologous structure.
The pentadactyl limb of all vertebrates share the same basic bone plan. Bird wings, lizard forearm and whale flipper are homologous, they share a common evolutionary origin.
Describe the basic bone plan of the pentadactyl limb.
Arms contain a humerus, radius, ulna, carpals and phalanges.
Legs contain a femur, tibia, fibula, tarsals and phalanges
What are analogous structures?
Structures that have similar functions, but are completely different in structure and composition. Result of convergent evolution. The features started off different, evolved to be similar as they were selected for a similar function.
Provide some examples of analogous structures.
Wings of birds and insects
Eyes of insects, octopuses and vertebrates
Spines of echidna and hedgehog.
How do analogous structures provide evidence for evolution?
They provide evidence for the evolution of structures to serve a common purpose in a common environment. (Convergent evolution)
What are vestigial structures?
Evolutionary remnants of body parts that no longer serve a purpose in the population. They provide evidence of common ancestry.
Provide examples of vestigial structures
The presence of the coccyx (reduced tail) in humans, the pelvic bones in snakes and whales.
What is phylogeny?
Studying the degree of evolutionary relatedness of animals
What is comparative embryology?
The comparison of the developmental stages of different species. These similarities can be used to infer relationships between organisms.
How does comparative embryology serve as evidence for evolution?
Similarities in embryos of different organisms suggests common ancestry/ relatedness.
Describe an example of comparative embryology.
The embryos of amphibians, fish, birds and mammals all show the presence of pharyngeal slits, tails, and distinct muscles. This can be explained by a common ancestor., that was probably aquatic.
What is biogeography?
The study of the geographical distribution of organisms.
How does biogeography serve as evidence of evolution?
Since isolation is a criteria for speciation, then the new species should resemble the species they shared a habitat with. They will be more similar to organisms they lived close to, or shared a common area.
What did Darwin notice on the Galapagos islands that influenced his theory about evolution and biogeography?
Darwin noticed that animals and plants on the islands had a closer resemblance to organisms on the South American mainland than animals much further away.
Provide an example of biogeography serving as evidence for evolution.
Support macroevolution with flightless birds. The present day distribution of these birds suggests they shared a common ancestor on Gondwana, then the different species evolved as the continent separated.
Describe the current distribution of flightless birds.
Emus - Aus, Ostriches - South Africa, Kiwis - NZ, rheas - South America. No flightless birds in Northern continents, part of Laurasia, separate from Gondwana.
What is adaptive radiation?
The migration of organisms into new environments because they have traits that allow them to exploit resources in the new environment and survive in new niches.
