chapter 19 homologous and analogous structures. need to know the difference between homologous and...
TRANSCRIPT
Need to Know
• The difference between homologous and analogous structures and how this relates to evolution.
• Convergent evolution
Concept 19.3: Evolution is supported by an overwhelming amount of scientific evidence
• New discoveries continue to fill the gaps identified by Darwin in The Origin of Species
• There are four types of data that document the pattern of evolution
– Direct observations– Homology– The fossil record– Biogeography
Homology
• Evolution is a process of descent with modification.
• Homology is similarity resulting from common ancestry.
Example of homology
Example of homology
Video clip
• Homologous structures are anatomical resemblances that represent variations on a structural theme present in a common ancestor.
Example of homologous structures
Humerus
Carpals
Radius
Human
Ulna
Metacarpals
Phalanges
Whale Cat Bat
Human embryo Chick embryo (LM)
Pharyngealarches
Post-analtail
Example of homologous structures
• Vestigial structures are remnants of features that served important functions in the organism’s ancestors.
• Vestigial Structure example
• Vestigial Structure example
Example of Convergent Evolution
The wings are analogous.
Shark (Chondrichthyes) Dolphin (mammal)
Example of Convergent Evolution
The fins and streamlined shape are analogous.
Example of Convergent Evolution
AUSTRALIA
NORTHAMERICASugar
glider
Flyingsquirrel
The side flaps of skin are analogous.