Transcript Focus On Life Science - Jefferson School District

6.1 Fossils and Evolution
Fossil Record
• Definition: The fossil record is all the
known fossils and their placements in the
formation of rocks and positions in time.
• Information: The fossil record is evidence
of the evolution of plants and animals, and
their extinction.
6.1 Fossils and Evolution
Fossil record
(cont.)
• Why are there gaps in the fossil record?
– Decay before fossilization
– Geological process destroy fossils
– They are undiscovered
How can fossil and
rock data determine
when an organism
lived?
6.2 Biological Evidence
Homologous Structures
• DEFINITION: Parts of organisms that are
similar in origin and structure are called
homologous structures.
• INFORMATION:
– Are the result of evolution
– Can indicate how closely two or more
species share common ancestors
Homologous Structures
• EXAMPLES: At some point in our pasts,
humans, frogs, bats, birds, and cats all
shared a common ancestor, because the
bones in the upper limbs are homologous.
6.2 Biological Evidence
Homologous Structures (cont.)
The bones in the upper limbs of these
animals are homologous structures.
6.2 Biological Evidence
Analogous Structures
• DEFINTION: Analogous structures
appear similar, but have different
ancestral origins.
• INFORMATION: Result from similar
environmental conditions that produced
similar natural selection outcomes
• EXAMPLE: The wings of birds and
insects.
6.2 Biological Evidence
Vestigial Structures
• DEFINTION: structures that have no
function in their present-day form.
• INFORMATION: Scientists hypothesize
that the structures once functioned in an
ancestor.
Vestigial Structures
• EXAMPLES:
– Pelvic bones in whales
– Wings in ostriches
– Pelvic spurs in boas and phythons
– Eyes in cavefish
– Tail bones in humans
6.2 Biological Evidence
Embryology
• DEFINTION: The science of
the development of embryos
from fertilization to birth is
embryology.
• INFORMATION: The more
closely related species are, the
more features they share during
development.
• EXAMPLES: Fish, reptiles,
birds, and human embryos
6.3 Evolution and Plate Tectonics
Geographic Isolation
• Definition: Geographic isolation occurs
when populations of species are separated
by a physical barrier.
• Information: Leads to closely related
species that appear different.
• Examples:
– Salamanders in California and Oregon
– Squirrels in the Grand Canyon
6.3 Evolution and Plate Tectonics
Convergent Evolution
• Definition: Convergent evolution results
in structural and functional similarities.
• Information: Sometimes distant locations
with similar environmental conditions have
species with similar traits that evolved
independently.
• Examples: Catci and Euphorbia