Download Review sheet – Chapter 13

Review sheet – Chapter 13
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Understand that evolution is the genetic change in populations over time and is commonly
referred to as “descent with modification”; the idea that living species are all descendents of
ancestral species that have changed over time

Understand that organisms are adapted to their environments and that this is a good fit, but not
perfect

Know that natural selection is the process by which favorable, inherited traits become more
numerous in successive generations of a population

Know that the concept of natural selection was originally proposed by naturalist Charles Darwin

Know the three principles of Darwin’s theory of natural selection: competition (more offspring
produced than environment can support), variation among individuals (which lead to increased
fitness, or survival), and inheritance of traits

Understand that survival of the fittest refers to the pessimistic nature of natural selection in
‘weeding’ out the least fit and retaining the best-adapted individuals to their environment

Understand that evolution can occur in as little as 2 generations (remember, evolution is genetic
change in a population over time!)

Understand that the smallest group of organisms that can evolve is a population (a group of
organisms belonging to 1 species); individuals cannot evolve (by definition!)

Understand that evolution is constant; environmental conditions are constantly changing and
new traits and adaptations are constantly arising

Know the scientific evidence that exists for evolution
o
Fossils – the fossilized remains of organisms can be found throughout the world and
reveal that older, simpler (less evolved) organisms existed before newer, more complex
(more evolved) organisms, and that this ‘succession’ may be viewed in the layers of
sedimentary rock (simpler organisms found in older rock; advanced, more complex
organisms found in newer rock; never all in the same layers)
o
Microevolution – evolution that can be observed in nature over relatively short time
periods; understand that industrial melanism is an example of microevolution and know
how the color morphs of peppered moths changed in England in response to
environmental changes brought about by the Industrial Revolution
o
Artificial selection – the process by which humans have ‘artificially’ modified other
species by selectively breeding for specific (desired) traits; ex. Domesticated animals,
crops
o
Homologous structures – similar characteristics or structures that result from a common
ancestry; ex. The 5 digits of all mammals, be it whales that swim, bats that fly, cats that
hunt and prowl, or humans that type review sheets all day….
o
Vestigial organs or structures – remnants of organs or structures that serve no apparent
function, but once did; e.g., the human appendix, hind limbs in snakes or marine
mammals such as whales (vestigial organs are an example of a homologous structure)
o
Analagous structure – similar structures that result from a common way of life, NOT
from a common ancestry; e.g., the wings of an insect or bird or a flying fish – these
animals are not directly related but they derived them from a common need for wings
(for flight)
o
Darwin’s finches (what we later call adaptive radiation in Chapter 14) – the evolution of
many species from one common ancestor as new lands are exploited

Understand that evolution is a tinkerer, not a master engineer; it uses materials that are already
available, rather than starting from scratch

Understand that mutations and sexual reproduction are the driving forces of evolution, but that
sexual reproduction is usually a quicker means of increasing genetic diversity and variation

Remember that mutation refers to a change in the nucleotide sequence of DNA