Download Evidence of evolution guided notes Answer Sheet

Adaptations & Evidence for Evolution:
Darwin proposed that over long periods of time, natural selection produces organisms that look different from
their ancestors. Darwin’s theory that all living things share an ancestor is known as descent with modification.
Many different scientific discoveries and types of evidence have supported Darwin’s theory of evolution by
natural selection.
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1. Fossil Evidence: Fossils are the remains or traces of organisms that once lived. Fossils show us that life
went from simple to complex, moved from sea to land, and existed over 3 billions years ago.
Many found in sedimentary rock, which is formed
from layers of slowly deposited sediments.
There are two ways to date fossils:
A. Relative Dating: dating based on the observation
that Fossils in the bottom= oldest, top = youngest
B. Absolute Dating: using radioactive isotopes to
determine the exact age of a fossil.
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2. Comparative Anatomy: comparing anatomical (body or structural) features between organisms,
looking for evolutionary relationships
Homologous structures: have similar structure but different function. Organisms with similar bone
structures may have evolved from a common ancestor.
For example, the wing of a bat, the
flipper of a whale, and a human arm are
homologous structures because they
have a very similar structure but
perform different functions!
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Vestigial structures: have NO function in present day organism,
but was probably useful in its ancestor. Examples include the
human appendix and the leg bones of a whale. These structures
provide further evidence of changing structure and function.
3. Comparative Biochemistry: comparing DNA sequences between 2 different species
Can use a DNA fingerprint!
4. Comparative Embryology: looking for similarities during the early stages of embryo development
_______ ________ _______ _______
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Examples of Evolution
 Evolution of the Horse
The ancient ancestor of the horse was the size of a fox. It had
four toes on its front feet. As time passed, some of the toes
disappeared and the horse grew bigger. The modern horse is
one-toed.
 Evolution of the Elephant
The ancestor of the present day elephant was about the size of a
pig and no tusks. Over time, the size of the elephant’s body and
head increased tremendously. The early trunk was much
shorter than the trunk of today’s elephant.
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Structural Adaptations: Form and Function
1. Feeding Adaptations
Characteristic
Giraffe’s long neck
Finches beaks
Hummingbird beak
Used…
To reach tall branches
Fitted for specific foods
Fits deep down into flowers
2. Adaptations to ensure successful reproduction
Characteristic
Lion Mane
Songs, calls
Bright colors
Large canines (teeth)
Used to attract mate
Sign of health, power
Insects, bird: specific calls for specific species
Birds, flowers (attract pollinators), mammals
Sign of strength, protection
3. Adaptation to life on land
Organism
Frog
Vascular plants
Mammals
Fish  Reptiles
Characteristic
Evolved lungs as it moves onto land as an adult
Roots, stems, vascular tissue to transport H2O
Fur
Fins  Feet