Download Patterns of Evolution PPT

9/20/13


theory that the Earth has been affected in the
past by sudden, short-lived, violent events,
possibly worldwide in scope.
Dinosaurs becoming extinct because of a
meteorite is a good example.


theory which holds that major change is the
cumulative product of slow but continuous
processes.
Evolution of mankind! Very slow and gradual
evolutionary changes from primates to
modern humans.

most species will exhibit little evolutionary
change and then a huge event or a few occurs
to change things. Change in spurts!
Mutations are a good example.
 Demise of dinosaurs and age
of mammals.



independent evolution of similar features in
species of different lineages.
The wing is a classic example of convergent
evolution in action. Flying insects, birds, and
bats have all evolved the capacity of flight
independently. They have "converged" on this
useful trait.
Dinosaur species dominated Earth for over 100
million years. During this time, most mammals
were small mouse-sized nocturnal organisms.
Following the mass extinction of the dinosaurs,
the small mammals rapidly diversified to fill
available habitats and niches. What pattern of
evolution best explains the diversification of
mammals?
A. Catastrophism
B. Convergent evolution
C. Gradualism
D. Punctuated Equilibrium

Forms of natural selection
Disruptive - selection
against phenotypes (physical
appearance) in the middle
and favors both extremes.
Stabilizing – selection against
extreme phenotypes (physical
appearance) and favors the
average.
Directional – favors one
extreme phenotype (physical
appearance) over all others,
causing a directional shift to
one side or another.



Part I – Determine the traits that distinguish
each group.
Part II – Create your own. Follow directions
on your worksheet.
The worksheet will be collected at the end of
class.