Download Notes: The Evolution of Living Things

Notes: The Evolution of Living Things
Essential Vocab.:
a. Adaptation - a characteristic that improves an individual’s ability to survive and reproduce in a
particular environment
b. Species - a group of organisms that are closely related and can mate to produce fertile offspring
c. Evolution - the process in which inherited characteristics within a population change over
generations such that new species sometimes arise
d. Fossil - the remains or physical evidence of an organism preserved by geological processes
e. Fossil Record - a historic sequence of life indicated by fossils found in layers of the Earth’s crust
f.
Trait - a genetically determined characteristic
g. Selective breeding - the human practice of breeding animals or plants that have desired
characteristics
h. Natural selection - the process by which organisms that are better adapted to their environment
survive and reproduce more successfully than less well adapted individuals do; a theory to
explain the mechanics of evolution
i.
Generation time - the period of time between the birth of one generation and the birth of the
next generation
j.
Speciation - The formation of a new species as a result of evolution
k. Homologous structures - anatomical features that have similar evolutionary origins and exhibit
similar anatomical patterns
Charles Darwin

In 1831 Darwin signed on the HMS Beagle for a five year voyage around the world

He served as a naturalist – a scientist who studies nature

Darwin made observations that helped him form a theory about how evolution happens

Along the voyage, Darwin collected thousands of plant and animal samples and kept careful
notes of his observation

One interesting place that the ship visited was the Galapagos Islands, 600 miles west of Ecuador

Darwin noticed that the finches of the Galapagos Islands were a little different from the finches
in Ecuador. And the finches on each island differed slightly from each other

The beaks of the finches appeared adapted to the food available on each island

Darwin spent about twenty years researching and studying samples he collected and in 1859
published his famous book On the Origin of Species by means of Natural Selection
Darwin explained that evolution occurs through natural selection. His theory has four parts:
1) Overproduction – each species produce more offspring that will survive to reproduce
2) Variation – individuals within a population have slightly different trait
3) Competition – Individuals within a population compete with each other for limited
resources
4) Adaptation - individuals that are better equipped, or adapted to live in an environment
are more likely to survive to reproduce
Natural Selection - Genetics and Evolution

Today, scientists have found most of the evidence that Darwin lacked

Variations happen as a result of different genes

Changes in genes may happen whenever organisms produce offspring

Some genes make organisms more likely to survive to reproduce

The process called selection happens when only organisms that carry these genes can survive to
reproduce
Speciation – Forming a New Species as a Result of Evolution
1) Isolation- part of the population becomes separated
2) Adaptation- separated populations change & adapt to their environment
3) Division- separated groups become different so that when the barriers removed they can no
longer interbreed