Biology Reference
In-Depth Information
Table 13.1: (Continued)
Table 13.1: Molecular Methods that Can be Used to Evaluate Insects in Ecological Studies.
Technique
Technique
Level of discrimination
Level of discrimination
Selected references
Selected references
Advantages (
+
) and disadvantages (-)
Advantages (
+
) and disadvantages (-)
l
Type of data obtained
(gene frequencies or
base-pair changes)
Type of data obtained
(gene frequencies or
base-pair changes)
l
l
Gene frequency data
−
Sensitive to DNA concentration,
no genetic information on PCR
products, can yield nonreproducible
products, markers are dominant and
heterozygotes may be difficult to
identify, Incorrect scoring can occur if
two different fragments comigrate
Edwards and
Hoy 1993,
MacPherson
et al. 1993,
Landry et al.
1993
RFLPs
Differences in single
nucleotides detected by
sequences recognized
by restriction
endonucleases in
nuclear and mtDNA
+
mt DNA most often analyzed,
standard probes are available
Aquadro et al.
1992, Dowling
et al. 1990,
Tegelstrom
1992, White and
Densmore 1992
−
Requires large amounts of DNA;
Usually requires radiolabeled probes,
l
Gene frequency and
changes in base pairs
Single locus or several loci only analyzed,
Relatively expensive and technically
demanding
PCR-RFLPs
Differences in single
nucleotide sequences
in nuclear and mtDNA
recognized by the
specific restriction
enzyme used
+
Requires only a small amount of
DNA, can be visualized with EtBr, less
expensive and more sensitive than
standard RFLPs
Karl and Avise 1993
l
Gene frequency data
−
Specific primers required, two
separate procedures are required,
making it more time consuming and
expensive than allele-specific PCR
Protein
electrophoresis
Detect changes in
charged amino acids
+
Inexpensive, many protocols available,
produces codominant Mendelian
characters of enzymes important in
physiology
May 1992, Pasteur
et al. 1988,
Murphy et al.
1990
l
Gene-frequency data
−
Less sensitive than DNA tests, number
of tests that can be performed may
be limited in small insects, proteins
subject to environmental influences
Sequencing PCR-
amplified DNA
Differences in single
nucleotides of nuclear
and mtDNA including
coding and noncoding
regions
+
Relatively small amounts of DNA
needed, high resolution possible,
some universal PCR primers available
Hoelzel and Green
1992
l
Gene frequency and
changes in base pairs
−
Time-consuming and expensive,
relatively small portion of genome
can be sampled, technically more
demanding than other methods, not
often used when large numbers of
insects must be screened due to cost
