Download Macroevolution

LEQ: What is
Macroevolution?
Evolution on a grand scale, encompassing the origin of new
taxonomic groups, evolutionary trends, adaptive radiation, and
mass extinction.
Evolutionary Novelties
 Complex structures evolve in increments from simpler
versions – having the same basic function
 Natural selection acts on structures in such as way as
to improve it in the context of its current use
 For example – the eye evolved from a cluster of light
sensitive cells. From the very beginning these cells
enable the organism to gather information about its
environment. With each successive change organisms
were able to gather more and more useful information
about their environment
Evolutionary Novelties –
Evolution of the Eye
 http://www.pbs.org/wgbh/evolution/library/01/1/quicktim
e/l_011_01.html
 http://learn.genetics.utah.edu/content/selection/eye/
Evolutionary Novelties
 Name two other examples from your book….
 Evolution of feathers – dinosaurs to birds
 http://www.youtube.com/watch?v=zVEjVIo-jro
 Flippers of penguins
EVO - DEVO
 http://www.youtube.com/watch?v=14yxfot5sq8
 http://www.youtube.com/watch?v=kG6nDDSE_4k
Evolutionary Trends do not Imply
Evolution is Goal Directed
 Trends in evolution have been identified:
 Horse – fossil record shows evolution of horse moving from 3
toes to one; small size to large; browsers to grazers
 Human – fossil record shows human evolution moving from
smaller skull to larger; simple brain to more complex
 REGARDLESS OF TRENDS - Evolution is the result of
interactions between organisms and their current
environments
 If the environment changes, the current evolutionary trend
may cease or even reverse itself
 Blind Cave Fish – cannot see – flesh grows over the eyes