Nuclear and Extranuclear DNA in Insects - Insect Molecular Genetics - page 97

3.19 Transposable Elements are Ubiquitous Agents that
Alter Genomes
Every insect genome probably contains multiple types of transposable elements
(TEs) ( Berg and Howe 1989, Craig et al. 2001 ). An organism may contain active
and inactive TEs, and the inactive TEs are subject to mutation and eventual loss
from the genome. During the process, the sequence of the TE may become
unrecognizable as a TE and be considered junk DNA.
Transposable elements are genetic elements that can move from one chromo-
somal site to another, and they are usually present in multiple copies within a
genome. The ubiquity of TEs in a diverse array of organisms has raised several
interesting questions about their evolutionary impact. New TEs are still invading
and spreading within insect populations, and the role of TEs in insect evolution
and genetic manipulation are discussed further in Chapters 4, 7, 9, and 14.
The diversity of arthropods and their genetic systems has only been hinted at.
In Chapter 4, we will explore additional details of genome organization, devel-
opmental processes, and diversity in insects.
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