Origins Of ideas About Origins Flashcards
Evidence that shows change has taken place
- Fossil record
- Descent with modification
- Biogeography
- Genetics
- Embryology
What does the evidence for fossils provide us?
A history of past life in earth.
How is this history recorded?
Remains of once-living organisms that escaped decay
What were these fossil remains?
Skeletons, shells, seeds, insects trapped in Amber, dung, DNA
What could have happened over 3.5 billion years ago?
Rare mutations could have resulted in the biological change/ evolution
Why are fossils a significant source of evidence?
It’s shows microevolution (evolution within a species)
Macroevolution (evolution between one group of organisms)
How does fossil evidence show evolution has occurred?
Systematic change through time
Different fossils found in different rock ,ayers with oldest fossils in oldest layers
What method is used to work out age of fossils?
Radiometric dating
What can be seen in the fossil record?
a) increase in complexity over time, simple org appeared first
b) increase in diversity
c) intermediate forms between groups - transitional fossils
What can not be seen in the fossil record?
Unable to show how life started on earth
Earliest fossils were soft bodied, difficult to fossilise
What was the increasing complexity?
The earliest organisms are found in the oldest rocks, giving rise later to more complex organisms, in newer rocks, which evolved
What was the increase in diversity?
The oldest fossil- bearing rocks have less diversity than younger rocks, has enormous diversity
How did younger rocks obtain so. Much diversity?
Descended from common ancestors,which adapted to a variety of environments. After accumalating adaptions,variety of modified descendants were branched out, bio increased from then.
What were the intermediate forms between groups?
What are transitional fossils have mixture of traits, shows that one group given rise to another
E.g Archaeopteryx - mammal like reptilian,
Does evidence from fossils provide conclusive proof of change?
No, biased/ incomplete
Very few individuals become fossils
Hard- bodied organisms often form fossils
Most fossils are aquatic animals
What evidence is there from descent with modification?
Vertebrate -comp external and internal structures, part of a limb has been modified over time to perform a variety of functions
What is a homologous structure?
When pentadactyl limb has same basic plan in all vertebrates
What does animals with homologous structures prove?
These animals are closely related and have evolved from a common ancestor
What is modification of a species?
Species can be traced back through time as they show similarities with fossil species that became extinct…
Newer forms have new traits - modified descendants of earlier species
What is biogeography?
Study of where and why present day and extinct plant and animal species occur.
What was the evidence from biogeography?
Different regions of earth with environmentally similar conditions contained their own distinctive species of animals and plants
- biogeographical reigons
Why does each region have its own distinctive set of organisms?
Over time organisms were able to move freely from place to place with each biogeographical region but not from one region to another , prevented by natural barriers. Organisms must have evolved in their own way in the different regions. Resulted in different species.
What is genetics?
The science of heredity, which includes the study of genes and inheritance of variation and traits of living organisms. Deals with resemblances and differences of related organisms.
What does DNA show us?
Organisms have descended from a common ancestor and how closely organisms are related.
