06_Group_Selection (2)

06_Group_Selection (2) - BI SC 002 LECTURE 6GROUP SELECTION...

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BI SC 002 LECTURE 6—GROUP SELECTION Draft: November 9, 2010 Natural selection functions on the individual—the individual’s phenotype is what encounters the environment and it is the individual’s genotype that is passed to the next generation. However, life generally occurs in a population. It is ultimately the population that undergoes a change due to natural selection. Many organisms live in populations . A population is a group of organisms of the same species living in the same area at the same time. By living in a group, certain traits that help the group survive better might be selected. Living as a group, the group might be able to counteract the selective pressure. For example, many birds and mammals produce alarm calls . Alarm calls are vocal calls that alert others in a population to danger. Alarm calls are advantageous to a group—other members in a group are able to escape, increasing their ability to survive and reproduce. However, isn’t natural selection very selfish? Why warn the others? Wouldn’t it increase your survival if you know about the predator and can escape while another that doesn’t know about the predator perishes? In situations with alarm calls, we are not sure if there is a benefit or not. Sometimes the caller benefits—sounding an alarm can produce mayhem and escape can occur. However, other times the caller may draw attention to himself and away from the group. In this case, the caller more often falls prey to non-callers.
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This document was uploaded on 11/29/2011.

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06_Group_Selection (2) - BI SC 002 LECTURE 6GROUP SELECTION...

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