darwin’s idea descent with modification descendants spread into different habitats new habitats...
TRANSCRIPT
Darwin’s Idea
Descent with modification Descendants spread into different habitats New habitats necessitated adaptation This accounts for diversity of life
Natural Selection Individuals inherit characteristics well-suited to
their environment Those individuals leave more offspring than others Those offspring are more likely to have well-suited
characteristics Problem: Blending theory of Inheritance
Fossil Record
Most fossils found in sedimentary rock
Due to aquatic preservation, fossils remain largely intact and fossilize in layers
Rock forms in layers, or strata
Often sand or silt is deposited on top of existing layer, compacting it into rock
Fossil Record is formed due to the layering Older rock is “lower” than younger rocks Charles Lyell- Uniformitarianism
Helps put the puzzle of life together Fossils help show what organisms have as similarities or
dissimilarities due to…..
Geographic Distribution
Another way to understand the similarities Is to see how they are spread out around the globe
Some animals in South American tropics share similarities with African desert animals rather than African tropical animals
Australia is home to more marsupial animals than anywhere else in the world, and had relatively few placental animals.
Mammals-Marsupials
Structural Similarities
Skeletal structures are very similar in parts of different animals.
Human, Feline, Whale, and Bat limbs are similar
Homologous structures
structures that indicate common ancestry
Analogous Structure-
they serve the same function in different species but they
evolved independently rather than from the same
embryological material
ex. Bat Wing- moth wing
Vestigial structures
structures that have a major function in one organism, but less in another
Blind Mole Rat
???Vestigial structure
Developmental Similarities
Developing embryos of different organisms appear similar during maturation.
Organisms start differentiating at different times, with more closely related organisms differentiating later in the process.
Distinctive differences occur later in the process
Molecular Biology
In the era of DNA, why don’t we just use the ultimate similarity of life and compare DNA sequences to see how closely organisms resemble one another? The closer the DNA sequences, the closer
related The less the sequences match, the further
relationship