Topic 5.4

5.4.1: The Tree of Life and Evolution

Placing your mouse pointer on the Tree of Life for plants and animals below for a brief discussion on evolution.

Tree of Life

5.4.2: Evidence of Evolution

How does the fossil record shown below provide evidence for evolution? provided by the fossil record, selective breeding of domesticated animals and homologous structures.

Evidence of Evolution

5.4.3 & 5.4.4: Offspring and a Struggle for Survival

Populations tend to produce more offspring than the environment can support. The consequence of this potential overproduction of offspring is the struggle for survival. Which of the populations below will lead to a greater struggle for survival?

Offspring overproduction and survival

Where are the Galapagos Islands?

Charles Darwin travelled to the Galapagos Islands aboard the HMS Beagle in 1831. Some of the scientific evidence he gathered during the Beagle expedition was used in his book "The Origin of Species". Specifically, his investigation about the finches of the Galapagos Islands.

Map of the Galapagos Islands

5.4.5 & 5.4.6: How sexual reproduction promotes variation in a species?

The figure below illustrates that the members of a species (e.g., Galapagos finches) show variation (in beak depth). Explain how sexual reproduction promotes variation in a species.

Place mouse pointer on the figure to view explanation for variation in beak depth.

Beak variation in finches

5.4.7: How does natural selection lead to evolution?

The first set of graphs demonstrated how drought and the availability of seeds between 1973 and 1978 affected the size of the G.fortis finch population. The second set of graphs show how the beak size evolved (i.e., increased in depth) over that time. Can you explain how natural selection lead to the evolution in beak depth?

Offspring overproduction and survival
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How natural selection leads to evolution explained
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