3 Molecular Markers: mtDNA and Allozymes

Question 1

what can we do with nuclear co-dominant markers?
(and NOT with mtDNA)

Answer 1

• inherited from both parents
• therefor it is co-dominant (or dominant)
• we can easily calculate allelic freq. and see if individual is homo- or heterozygote for that allele

Question 2

what is mtDNA characterized by?

Answer 2

• maternal inheritance (all females in a family have the identical mtDNA)
• it is haploid
• not useful for computing HWE
• has a higher mutation rate
• genetic drift acts more quickly on these markers

Question 3

when we have a uniparental inherited marker like mtDNA, we can obtain sequence information about

Answer 3

• haplotype diversity (so the different combinations of allelic variants along a chromosome usually inherithed)
• nucleotide diversity (measure for the degree of polymorphism within a population)
• Estimate rates of substitution
• Estimate divergence times
• Number of divergent sites

Question 4

Co-dominent marker: allozymes

Answer 4

• they are protein alleles that form enzymes
• used to
  (1) Identify aquaculture stocks
  (2) Study the relationship between different species of fishes (so species identification)
  (3) find population structure and signatures of genetic drift

Question 5

cons of Co-dominent marker: allozymes

Answer 5

• low variability: low polymorphic
• frequently under natural selection pressure

–> low statistical power

Question 6

how are allozyme-markers analyzed?

Answer 6

• allozyme electrophoresis
• enables us to identify the genetic variation at the level of enzyme
• co-dominant bec. genetically diff. alleles produce diff. enzymes
• in electrophorese pattern we see 1 or 2 lines
• 1 line: homozygote for that locus
• 2 lines: heterozygote

Question 7

allozymes

Answer 7

Allozymes are variant form of an enzyme that is coded by different alleles at the same locus (opposite of isoenzyme)

Question 8

isozymes

Answer 8

Isozymes are enzymes which perform the same function but are coded by genes located at different loci

Question 9

what are co-dominant markers: allonyms good for?

Answer 9

• to understand gene flow among different populations
• to investigate whether and how intrinsic forces may shape the pop.-structure with larval dispersal