Download Chapter 13 Review Adaptation: an inherited trait that helps an

Chapter 13 Review
Adaptation: an inherited trait that helps an organism survive
Evolution: the process of how organisms acquire adaptations over time. (Change in a species over time)
Diversity: a variety (5- 50 million living species)
*scientists hypothesize that all life forms evolved from a common ancestor and new species branch off
from earlier species (bacteria?)
Cladogram (branching tree): a tree-like diagram that displays evolutionary relationships among living
species and their ancestors
Evidence of Evolution
1. Comparative anatomy (homologous structures, embryo development among vertebrates)
2. DNA
3. Fossils
Comparative anatomy: the study of anatomical similarities and differences among species (arms, legs,
head, hands, etc.
Homologous structures: body structures that have a common origin bt do not necessarily perform the
same function
Vertebrates: animals with a backbone
Fossils: remnant or trace of an organism from the past, such as a skeleton or leaf imprint, embedded
and preserved in earth’s crust
Finches led to Charles Darwin’s Theory of Evolution: beaks adapted for types of food they ate. They all
had a common ancestor that they evolved from
Natural selection: The process by which organisms with favorable adaptations survive and reproduce at
a higher rate than organisms with less favorable adaptations.
Artificial Selections: breeders select the desired traits to produce changes in a species over a few
generations
Darwin concluded that:
1.
2.
3.
4.
Organisms change over time
All organisms are descended from common ancestors by a process of branching
Evolution is gradual, taking place over a long time
The mechanism of evolution is natural selection
Process of Natural Selection
1. Populations over-produce (weak die, strong survive and reproduce)
2. Individuals in population vary
3. Favorable adaptation are selected
4. Favorable adaptation accumulate
Random mutations in genes produce variations of traits in a population
Alleles: different forms of a gene (can cause mutations- helpful, harmful, or have no effect)
Rr, RR, rr, RW, rw
Mutations occur randomly in genes and produce variations
Genetic variation: the variety of alleles in a population
Genetic variation is necessary for natural selection and ensures that a population has a better chance of
survival should the environment change
NO VARIATION => NO EVOLUTION OCCURS
MORE VARIATIONS => BETTER CHANCE OF SURVIVAL IF ENVIRONMENT CHANGES
Isolation: occurs when populations become divided by an event (floods, volcanic, eruptions,
mountain/canyon formation, earthquakes, new river forming)
New species evolve due to:
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

Isolation
Adaptation
Species formation (when isolated populations become so different that they can no longer
interbreed)
Extinction: occurs when the environment change and the adaptations of a species are no longer
sufficient for its survival. (Main cause is loss of habitat caused by human destruction)
Moth Population