Download The Puzzle of Life`s Diversity

The Puzzle of Life’s Diversity
Charles Darwin


sailed around the world on the H. M. S.
Beagle in 1831.
Evolution: how modern organisms have
descended from ancient organisms
Darwin’s Observations

Patterns of Diversity: plants and animals well suited
to their environments


Fossils: preserved remains of ancient organisms.


Why 2 similar ecosystems contain different animals
Why species disappeared & relation to living species
The Galápagos Islands: the characteristics of many
animals and plants varied noticeable among the
different islands
Important Scientists: Hutton & Lyell

the Earth is many millions of years old

the processes that changed Earth in the past
are the same processes that operate in the
present
Important Scientists: Malthus

unchecked human population growth would
lead to insufficient living space and food

Forces Against Growth



War
Famine
Disease
Lamarck’s Evolution Hypothesis



Through selective use or disuse of organs,
organisms acquired or lost certain traits
Traits could then be passed on to offspring.
Led to change in a species.


Ideas are flawed; traits are inherited and behavior
has no effect heritable characteristics.
But organisms are adapted to their environment.
Darwin
Darwin



Completed 25 years of research
Published On the Origin of Species
Proposed Natural Selection

mechanism for evolution
Evolution By Natural Selection


Struggle for existence: member of each
species compete regularly for food, living
space, and other necessities
Survival of the Fittest


better suited  survive and reproduce more
not well suited  die or leave few offspring
Fitness: ability to survive & reproduce


Successful adaptations allow organisms to
become better able to survive and reproduce.
Natural Selection


changes in a population’s inherited characteristics
increase a species’ fitness
Evidence of Evolution

Fossils: observe changes over time

Geographic Distribution: Similar species
descended with modifications from a
common ancestor

Similar embryo development
Embryo Development
Evidence of Evolution


Homologous Structures: structures that have different
mature forms but develop from the same embryonic
tissue
vestigial organs: reduced organs are traces of
homologous structures
 miniature legs/tails
 appendix