Transcript evolution ppt

Evolution
And the Origin of Species
Question: How did the giraffe get its long neck?
Why are there 9 subspecies of giraffes?
History of Evolutionary Thought
In 1831, Charles Darwin, a 22-year-old naturalist,
accepted a position aboard the ship HMS Beagle that
began a voyage around the world.
Darwin made observations of
animals that inhabited the island
- a study of BIOGEOGRAPHY
- tortoises
- iguanas
- finches
The Voyage of the Beagle
Darwin’s Theory of Evolution by Natural Selection
Finches on the Galápagos
Islands resembled a mainland
finch but there were more types.
Galápagos finch species varied
by nesting site, beak size, and
eating habits.
Darwin proposed that each
bird was descended from the
mainland species.
-
this idea is known as
COMMON DESCENT
Charles Darwin and Alfred Wallace had similar ideas about
how species changed over time….Natural Selection
1. Characteristics
(variations) are inherited
2. More offspring are
produced than can survive
3. Those with the most
favorable characteristics
survive
ADAPTATION
Descent with Modification
Each generation
will have more
individuals with
those traits than
the previous
generation.
Taxonomy is the science of
classifying organisms.
Carolus Linnaeus developed a
binomial system of nomenclature two-part names for each species
GENUS
SPECIES
Homo sapiens
Canis lupus
Giraffa camelopardalis
Giraffe camelopardalis angolensis
(Angolan giraffe)
Giraffe camelopardalis camelopardalis
(Nubian giraffe)
Giraffe camelopardalis reticulata
(Reticulated giraffe)
Masai Giraffe (Giraffa camelopardalis tippelskirchi)
Thornicroft Giraffe
Giraffa camelopardalis thornicrofti
Biogeography
study of the distribution of species and ecosystems in
geographic space and through geological time
A cladogram
shows how
these giraffes
are related.
Why are there so many different subspecies and why in distinct locations?
Are all of these giraffes descended from one common ancestor?
How does natural selection explain the finches on the Galapagos?
The Definition of Evolution
Evolution is the change in allele frequencies, or a
change in the gene pool, of a population.
You don’t need to see
an animal change
physically, you only
need to measure
changes at the DNA
level.
IMPORTANT!!!
1. Individuals do not evolve.
(they either live or die)
*POPULATIONS EVOLVE*
2. Evolution does not have a
direction. Organisms aren’t
“trying” to be anything.
3. Fitness refers to an organism's
ability to survive in their
environment - it doesn’t
necessarily mean “stronger”
These stickleback fish have different
levels of armored scales.
3. Individuals differ in FITNESS (relative fitness)
- fitness measures an organism’s reproductive success
- it does not necessarily mean “stronger”.
A black panther is the melanistic color variant of any
Panthera species. Black panthers in Asia and Africa are
leopards (Panthera pardus) and black panthers in the
Americas are black jaguars (Panthera onca).
Selection Strength
How strong does the environment push for the survival or
elimination of a polymorphism?
Examples: White- Striped Clover & Rock Pocket Mouse
Divergent vs Convergent Evolution
Phenotypes
are similar,
though these
organisms are
not closely
related.
Review Evolution in 3 steps:
The aye-aye survived!??
1. Variation (polymorphisms)
1. Relative fitness
(who survives selection?)
2. Reproduction and inheritance
And the blobfish and naked mole rat??
See “Strange Animals” Boredpanda.com
Evidence of Evolution
1.
2.
3.
4.
5.
The Fossil Record
Anatomy
Embryology
Biogeography
Molecular Biology
FOSSIL EVIDENCE
Fossil Record traces the history of life
Shows transitional fossils ….Archaeopteryx
Hominid Species
EVIDENCE: FOSSIL RECORD
Transitional
species show
links between
ancestors
and modern
organisms.
ANATOMICAL EVIDENCE
Homologous
structures
– similar structures
inherited from a
common ancestor
(ex. Arm bones)
Vestigial Structures
Structures that appear to serve no purpose and are
derived from ancestral populations.
Fossil record indicates
that whales evolved
from land animals.
They retain many of
the features of land
tetrapods, including
vestigial pelvic bones.
In humans ….. The palmaris longus muscle is vestigial
Gill Slit
Embryological
development – all
vertebrates have
the same basic
pattern of
development
BIOGEOGRAPHICAL EVIDENCE
How Plants and Animals are distributed worldwide
Why are these
animals only found
in Australia?
Molecular Genetics
Gene sequences are
similar across animal
groups. The more similar
the genes, the more closely
related the organisms.
Myths of Evolution
1.
2.
3.
4.
Evolution is just a theory
Individuals evolve
Evolution explains the origin of life
Organisms evolve on purpose (or is directional)
What other myths or
questions have you heard
regarding evolution?
18.2 Formation of New Species
Species = individual organisms that
can interbreed and produce fertile
offspring
Liger
Zonkey
Hybrid = cross between two species
= often produce infertile offspring
(mules)
Speciation =
formation of
two species
from one
original species
Allopatric
“Other homeland”
California Salamander Speciation
vs
Sympatric Speciation
“Same homeland”
What type of
speciation is
this?
Adaptive Radiation
One ancestral species
branches into many,
each occupying a
different NICHE
Hawaiian
Honeycreepers
Reproductive Isolation - what prevents interbreeding between species?
Prezygotic Barriers
Temporal Isolation
(breeding at different times)
-
Blocks reproduction
from taking place at all
Habitat Isolation
(living in different places)
Mechanical & Gamete Barriers
(anatomy & egg/sperm problems)
Behavioral Isolation
Damselfly penis
(mating, courtship behaviors)
Post-zygotic barriers
- egg and sperm produce
offspring that don’t survive
or are sterile
Rates of Speciation
Slow change,
small steps
Rapid change,
due to a major
environmental
disruption
Is a hybrid grizzly-polar bear a
“PIZZLY” or a “GROLAR BEAR”