Homologous structures Human Arm Bat Wing Whale Flipper Analogous Structures Similar functions but NOT structurally related Insects are arthropods and birds are vertebrates The wing of a bird and the wing of a butterfly are examples of ID: 927732
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Slide1
Homologous structures
Structures on different organisms are homologous when they have similar base structures but have different functions.
Slide2Homologous structures
Human Arm
Bat Wing
Whale Flipper
Slide3Slide4Analogous Structures
Similar functions but NOT structurally related.
Insects are arthropods and birds are vertebrates.
The wing of a bird and the wing of a butterfly are examples of
analogous structures.
Slide5Slide6Comparative embryology
Slide7Vestigial Structures
A structure in an organism that has lost all or most of its original function
Slide8Transition fossils
Slide9The Panda's Thumb
A classic example of evolution.The giant panda is a bear that adapted to eating bamboo.
Slide10The panda’s opposable thumb
Giant pandas have a thumb pad on the hand
This thumb pad is used by the panda to grasp bamboo shoots
It uses its thumb to hold and manipulate the bamboo while eating
Slide11The Panda has not always had this opposable thumb. Fossil evidence shows that this has evolved over thousands of years.
Slide12Comparing bones.
Slide13Slide14Unrelated species evolve similar traits even though they live in different parts of the world, or at different times in Earth’s history
Slide15Analogous Structures = Convergent Evolution
Slide16Analogous Structures = Convergent Evolution
Slide17Analogous Structures = Convergent Evolution
Slide18Divergent Evolution:
one species gives rise to many species
Slide19Divergent Evolution
One species gives rise to many species in response to the creation of new habitat or other ecological opportunity
Gives rise to homologous structures
Slide20Geographic isolation:
prevents individuals of a species in different populations from mating
Slide21Geographic isolation prevents a mix of genes with the original species.
Example: Kodiak Brown Bears
This group of bears have evolved into a sub-species, that is different form all other grizzly bears.
Slide22An archipelago is a
landform
which consists of a chain or cluster of
islands
.
Slide23Adaptive
radiation:
many species appear to be related to a single ancestral species.
Slide24Slide25Slide26Reproductive Isolation: prevents individuals from reproducing with each other
Prezygotic
isolating mechanisms
: prevent reproduction before fertilization
Postzygotic isolating mechanisms: prevent reproduction after fertilization
Slide27GRADUALISM
L
iving things change very slowly in small, gradual steps:
GRADUALISM
Slide28PUNCTUATED
EQUILIBRIUM
Sometimes species will remain the same for a long period of time and then change very quickly.
This is usually the result of some catastrophic disaster like an earthquake or volcano.
Slide29GALAPAGOS FINCHES
Slide30THE EVOLUTION OF BEAK SHAPE IN GALAPAGOS FINCHES
Darwin first thought about evolution while studying in the Galapagos
13 species of finches in the Galapagos islands
Islands are barriers that separate each group of the species- “Geographic Isolation”
size and shape of the beak has an important consequence for fitness. (What is Fitness?)
Slide31Darwin’s finches
Medium Tree
Finch
Cactus Ground
Finch
Medium Ground
Finch
Warbler
Finch
Slide32Slide33GALAPAGOS FINCHES
Each species has a highly characteristic beak shape. Darwin focused his study on the link between the shape of the beak, the food and the habitat of each species.
This research of his was to result in the theory of evolution and the 14 finches became "stars" in their own right.
Slide34Slide35Slide36Slide37Slide38The Case of the Galapagos Finches
All species of finch derive from the same original species.The observation: despite their strong resemblance, each species of finch has a highly characteristic beak shape.
The evolutionary factors: geographic isolation, ecological environment, food sources, competition.