Download File - Tabb Life Science

The Evolution of Living Things
Change Over Time
Essential Vocabulary
Adaptation - a characteristic that improves an individual’s
ability to survive and reproduce in a particular environment
Species - a group of organisms that are closely related and
can mate to produce fertile offspring
Evolution - the process in which inherited characteristics
within a population change over generations such that new
species sometimes arise
Fossil - the remains or physical evidence of an organism
preserved by geological processes
Essential Vocabulary
Fossil Record - a historic sequence of life indicated by
fossils found in layers of the Earth’s crust
Trait - a genetically determined characteristic
Selective breeding - the human practice of breeding animals
or plants that have desired characteristics
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
Essential Vocabulary
Generation time - the period of time between the birth of one
generation and the birth of the next generation
Speciation - The formation of a new species as a result of
evolution
Homologous structures - anatomical features that have
similar evolutionary origins and exhibit similar anatomical
patterns
The Five Year Adventure
Charles Darwin
HMS Beagle
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
Charles Darwin
 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 hypothesized that the island finches
were descended from South American
finches and may have been blown from
South America by a storm. Over many
generations, the finches adapted to different
ways of life on the islands.
Darwin’s route
Galapagos Island Organisms
On the Origin of Species by
Means of Natural Selection
 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
Overproduction
What factors limit the number of young that survive?
Variation- difference in traits
What controls these differences?
Competition
for food, water, space, sunlight
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
Adaptations
Speciation
formation of new species as a result of evolution
3 Stages
1. Isolation / separation - 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
Selective Breeding
Tennessee Walker
straight profile,
long powerful
neck, sloping
shoulders and
broad chest, short
back, strong
sloping
hindquarters, legs
fine, long tail
carried high
Natural Selection
Process
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an individual inherits a gene for a helpful trait
that individual will likely survive & reproduce
helpful trait is passed to offspring
those without the trait died & did not reproduce
nature “selected” organisms best adapted to
their environment & they survived to pass their
genes on next generation