Transcript Evolution: A history and a process

* Evidence for Evolution
*Fossils
*Geographic Distribution
*Similarities in Structure
*Similarities in Development
*Molecular Biology
* The Fossil Record
Fossils= preserved remains or
markings left by organisms that
lived in the past
* Geographic Distribution
*Geographic distribution can be used as a clue for the
evolution of species
* Biogeography is the study of the distribution of plants and
animals throughout the world
Convergent evolution
In evolutionary biology, convergent evolution is the
process whereby organisms not closely related,
independently evolve similar traits as a result of having
to adapt to similar environments or ecological niches.
Example– aardvark and anteater
Divergent evolution
the process of two or more related species becoming
more and more dissimilar. Adaptive radiation
Example Darwin’s Finches
Similarities in Structure
* Homologous structures=
similar structures in species
haring a common ancestor
* Example: mammal
forelimb
* Analogous
Structures: Similar
function with
different structures.
* Example wing of a
bat and wing of a
butterfly.
• Vestigial structures= remnants of structures
that may have served an important function
in an ancestral species, but have no clear
function in some of the modern descendants
– Often smaller in size
* Developmental similarities
*Embryos of closely related species
have similar stages of development
Molecular biology
*Comparison of DNA and Protein sequences between species
*If the two species’ sequences match closely then it is thought
that the two species are related to a common ancestor
*If the two species’ sequences have many differences they
probably do not share common ancestry
* Summary of Natural
Selection
1.
All species produce excess
offspring
* In nature there are limited
resources
* Leads to competition
* Usually only a small percentage
of offspring survive
2.
Variation among the individuals in
a population
* The individuals with the traits
that allow them to survive and
reproduce pass the genes for
the traits to their offspring
Color Variations in Moths in Great Britain
During the Industrial
Revolution through the
mid-20th century, factories
and power plants, which
burned coal, produced
large quantities of soot
and smog. Near
industrialized areas, black
powder covered surfaces,
including the moth habitat.
a. Which color moth would have a better chance of surviving predation
(better camoflage to hide from predators) on this dark surface?
b.How does this help explain the change in the colors of the moth
population shown in the graph?
c. Clean Air Acts were passed by governments of industrialized nations
beginning in the mid-1950s. Use this information to explain why
the color of the moth population shifted again.