Why Sex Matters
Bacteria usually reproduce asexually, which produces two
identical copies of the parent cell.
Why don’t humans or other animals also use this form of
reproduction? The answer: genetic
reproduction allows populations of organisms to be different from one
another. Why would this be
adaptive? Because when
ecosystems change, a population made up of non-identical members has a
considerably greater chance to adapt and respond to change in a positive
way. By the way, even bacteria have a
sex-like mode in which they occasionally fuse and exchange DNA.
Sexual reproduction has another importance.
Members of the
population must have sex in order to create offspring.
Obviously, this means that for populations to survive, individuals
must live long enough to reproduce. As
you will see in the What We Know section, this is the main requirement of
When humans interfere…
Why do we call this unit "Population
…Because our world isn’t just a collection of independent groups of
populations. It’s a fragile, global network of interaction.
In nature, removing a block could be equivalent to the extinction of a species. When this happens, every member of the complex ecosystem involved is in danger, and most of the time, this includes humans as well.
Species Diversity - Who Cares?
Why does it matter if species go extinct? Who should care if the number of species on earth decreases? Several answers come to mind. Practical applications in medicine and agriculture often result from discovering unique properties of species, and the more species there are the greater the potential for finding useful genes. These genes can be inserted into existing organisms to produce medicine, disease resistance properties, growth enhancement, and other desirable things.
Human activity is creating massive extinctions. Only a few areas on earth support highly diverse species. Nearly one half of the earth's plant species and over 1/3 of the vertebrate species are found in only 25 local areas. To learn more about these diversity "hot spots," click here.