Download File - Hanna Biology

The Puzzle of Life's Diversity
__________________________ is the process by which modern organisms have descended from ancient organisms.
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A scientific ___________________is a testable explanation of phenomena that have occurred in the natural world. It can’t
be proven right, only supported. It can be proven wrong.
Voyage of the Beagle In 1831, Darwin set sail from England aboard the H.M.S. Beagle for a voyage around the world. During his
travels, Darwin made numerous observations and collected evidence that led him to propose a hypothesis about the way life
changes over time. That hypothesis has become the theory of evolution (aka theory of natural selection).
Darwin's Observations - Darwin made many observations:
 He observed many plants and animals were ___________________________________________________ they inhabited.
 He was impressed by the ways in which organisms survived and produced offspring.
 Darwin was puzzled by where different species lived and did not live.
Living Organisms and Fossils
 Darwin collected the preserved remains of ancient organisms, called ______________________. Some of those fossils
resembled organisms that were still alive. Others looked completely unlike any creature he had ever seen.
The Galápagos Islands - Darwin observed that the Galápagos Islands were close together but had very different climates.
The Journey Home - Darwin wondered if animals living on different islands had once been members of the same species. These
separate species would have evolved from an original South American ancestor species.
Darwin Presents His Case
Inherited Variation and Artificial Selection
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Due to genes _________________________ in the process of meiosis (formation of gametes), all organisms will inherit
_______________________________. That is why no two organisms (except for identical twins) look exactly alike.
However, when humans interfere, they can decide which individuals to breed. They will choose to breed the individuals
with the desired characteristics.
_______________________________ is the selection by humans for breeding of useful traits from the natural variation
among different organisms. Results in “breeds” (ex. Dog breeds)
Evolution by Natural Selection - Darwin compared processes in nature to artificial selection. By doing so, he developed a scientific
hypothesis to explain how evolution occurs.
Struggle for Existence - Darwin realized that high birth rates and a shortage of life's basic needs would force organisms to
___________________________________________________.
Survival of the Fittest
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The ability of an individual to survive and reproduce in its specific environment is___________________________.
Darwin proposed that ________________________________________________ of adaptations. An
_______________________________________is any inherited characteristic that increases an organism's chance of
survival.
Because of its similarities to artificial selection, Darwin referred to the ___________________________________________
___________________________________. In natural selection, the traits being selected contribute to an organism's
fitness (_________________________________________________) in its environment.
Evolution by Natural Selection
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The organisms that survive long enough to reproduce because of certain traits then pass on those traits that helped them
survive. These changes increase a species' fitness in its environment. Over time, natural selection results in _____________
in the inherited characteristics of a population. This process is known as __________________________________.
Descent with Modification
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Natural selection produces organisms that have different structures, establish different niches, or occupy different habitats.
Each living species has descended, with changes, from other species over time. Darwin referred to this principle as
___________________________________________.
Evidence of Evolution
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Darwin argued that living things have been evolving on Earth for millions of years. Evidence for evolution include: _______
_____________________________________________________________________________________________________
The Fossil Record
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Darwin saw fossils as a record of the history of life on Earth. By comparing fossils from older rock layers with fossils from
younger layers, scientists could document that _____________________________________________________ over time.
Geographical Distribution
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Similar, ___________________________________ develop similar characteristics
due to having to cope with similar environmental pressures. The existence of similar
but unrelated species was a puzzle to Darwin. Later, he realized that similar animals in
different locations were the product of different lines of evolutionary descent. Here,
the beaver and the capybara are similar species that inhabit similar environments of North America and South America. The
South American coypu also shares many characteristics with the North American muskrat.
Homologous Body Structures
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Structures that have different mature forms but develop from the same embryonic tissues are
called ________________________________________. Not all homologous structures serve
important functions. The limbs of these four modern vertebrates are homologous structures.
They provide evidence of a common ancestor whose bones may have resembled those of the
ancient fish shown here. Notice that the same colors are used to show related structures.
Homologous structures are one type of evidence for the evolution of living things.
Homologous structures are one type of evidence for the _____________________________________________________.
There are organs in many animals that have no use and are so reduced in size that they are just vestiges, or traces, of
homologous organs in other species. These organs are called ______________________________________________.
Homologous Structures
Physical Characteristics – Found in
related species
May not appear similar at first, but
they are closely related.
Analogous Structures
Physical Features – Serve the
same function
Do not indicate a shared
common ancestor, but they
evolved independently.
Ex. Wings on insects, bats, and
birds.
Vestigial Organs
Often Homologous structures in
other organisms.
Some organisms have structures
or organs that seem to serve no
useful function.
Ex. Forelimbs in humans, cats, &
Ex. Wisdom Teeth, Human
whale.
Tailbone (coccyx), or Wings on
flightless birds.
Similarities in Embryology - The early stages, or embryos, of many animals with _________________________ are very similar. The
same groups of embryonic cells develop in the same order and in similar patterns to produce the tissues and organs of all
vertebrates.
Glue this side
into notebook
EVOLUTION and NATURAL SELECTION