Transcript Evolution PPT

Idea of Evolution
 Charles Darwin (1809-1882)
 English naturalist
 Took a trip around the world on a ship called H.M.S.
Beagle
 Mostly fascinated with the Galapagos Islands
 Best known for his theory of evolution by natural
selection
Idea of Evolution
 Galapagos Islands
 Groups of animals vary from island to island
 Ex: tortoises on each island resemble each other but
differ in the shape and function of their shells
 Ex: finches on each island resembled each other but differ
in the shape and function of their beaks
 Darwin believed these unique animals all came from a
common ancestor and they changed/adapted to their
environment
Idea of Evolution
 Evolution
 Development of new types of organisms over time
 Heritable change in the characteristics within a
population from one generation to the next
Ideas of Darwin’s Time
 Scientists thought all species were permanent and
unchanging
 The Earth was believed to only be a few thousand
(not billions) of years old
 Charles Lyell was a English geologist that believed
the Earth’s surface continues to change
 Influenced Darwin
Ideas of Darwin’s Time
 Jean-Baptiste Lamarck
 French biologist that supported the idea that
populations of organisms change over time
 Also believed in biogenesis of simple organisms
 Proposed that individuals acquire traits during lifetime
from behavior and pass them onto offspring
 Called Theory of Acquired Traits
Darwin’s Ideas
 Around the same time Darwin and Wallace formed
theory to explain evolution
 Published book On the Origin of Species in 1858
 Book explained how evolution occurs by means of
natural selection
Descent with Modification
 Idea that every species must have descended by
reproduction from pre-existing species that arrange
over time
 Ex: finch beaks at Galapagos
Natural Selection
 Mechanism from descent
with modification
 1. Overproduction
 More offspring are
produced than survive
to maturity
 2. Genetic variation
 Traits vary within a
species
 Ex: deer fur thickness
is passed on to future
offspring
Natural Selection (cont’d)
 3. Struggle to survive
 Organisms need to
compete with each
other known as
“struggle for existence”
 When an organism is
successful in a new
environment its called
an adaptation
 4. Differential Reproduction
 Organisms best adapted for
an environment will survive
best and reproduce
 Survival of the fittest
 The ability for an
organism to reproduce
and pass on adaptations
The Fossil
Record
 Fossils
 Remains of an organism
that died long ago
 Some are remains of extinct
organisms, meaning the
species is no longer alive
 Superposition
 Idea that strata form in
layers where the layers
closest to the top are the
younger than below
The Fossil Record
 Relative Age
 Age compared to other fossils in order of old to young
 Absolute Age
 Using radiometric dating to get actual number age
The Fossil Record
 Scientists use these relative and
absolute ages to try and make
the history of life on Earth as
precise as possible
 Fossil records are incomplete
history because not all organisms
have left fossils behind
 Fossils can easily be destroyed
during the process
 Finding fossils is rare also
Transitional Species
 We can infer that species have gradually changed based
on the fossil record
 Scientists have hypothesized ancestors and later descendant
species
 Organisms with features that are between hypothesized
ancestors
Biogeography
 Study of locations of organisms around the world
 Darwin used this method when exploring islands and
observed animals variation based on environment
Anatomy and Embryology
 Anatomy: study of the body
 Embryology: study of
development
 Homologous structures
 Anatomical structures that
originated by heredity from a
structure in most common ancestor
 Ex: bones in arms of humans,
penguins, alligator and bat
 Related structure but function may
differ
Anatomy and Embryology
 Analogous Structures
 When structures have
similar function, but did
not develop the same
way
 Ex: wings of bat vs.
bird
 Vestigial Structures
 Organs that no longer
serve a function in an
organism
 Ex: human tail bone,
appendix
Phylogeny
 Relationships among
groups of organisms
 Can make a “tree” of
animals evolved
 Trunk of the tree would
represent species that are
closely related
 Branches represent a
separate population or
lineage
Caribbean Anole
Lizard
 Found in the Caribbean islands of Cuba, Hispaniola, Jamaica,
and Puerto Rico
 Each lizard species body type differs by their habitat
 Ex: stocky body and long legged lizards are best adapted for tree
truck environments, slender bodies and long tails are best adapted
for grassy environments
 Hypothesis #1: An ancestral anole species specialized for living
on twigs originally lived on one island and later migrated to
other islands
OR
 Hypothesis #2: Each twig-dwelling species evolved
independently on each island from distant ancestor anole
species
Evolution in Action
 Biologists tested the hypothesis by comparing DNA
from the various species
 DNA evidence supported hypothesis 2 that each lizard
evolved independently on each island
 Convergent Evolution
 Process by which different species
evolve similar traits
 Ex: sugar glider of Australia and flying
squirrel of North America came from
different ancestors but evolved similar
adaptations to their environment
Divergence & Radiation
 Divergence evolution
 Process by which the descendants of a single ancestor
diversify into species that each fit different parts of the
environment
 Ex: lizards with genes for large toe pads and short legs
ran slowly on the tree trunks and fell easily to predators,
lizards with long legs and small toe pads were able to slip
away and reproduce
Divergence & Radiation
 Adaptive Radiation
 Pattern of variation when a new population in a new
environment undergoes divergent evolution
Artificial Selection
 Process the occurs when human
breeders choose individuals that
will parent the next generation
 Ex: faster greyhounds, smaller tea
cup dogs, high milk yield cows,
high yielding grain per stalk
 Darwin hypothesized
domesticated dogs diverged
from wolves
 DNA evidence indicated
similarities with wolves in East
Asia, supporting Darwin’s
hypothesis and humans selected
domestic dogs from wolf
population 15,000 years ago
Coevolution
 Evolution is on-going and many species may evolve
together
 Coevolution
 When two or more species have evolved adaptations
to each other’s influence
 Predator/Prey Interactions
 Introduction of new species
 Creating antibiotics