One more pass.

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• One more pass.
• 1. Examples of Mendelian genetics rare in nature.
• 2. The power of meiotic recombination in animals
  that reproduce sexually.
• Meiosis and maternally and paternally derived
  chromosomes.
• Combinations of maternally and paternally
  chromosomes.
• Independent assortment of chromosomes.
• Two classes of chromosomes (m p)
• If a hypothetical organism has 2 pairs of
  chromosomes
• (Im and Ip and 2m and 2p).
• Each gamete gets one chromosome I and one
  chromosome 2
• Therefore, there are 2n ( 4 combinations,
  where n haploid number of chromosomes.

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Example of multiple alleles
Sequencing of cystic fibrosis locus in cystic
fibrosis patients CFTR gene 30,000 alleles (Loss
of function mutations)
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Mutations entire sets of chromosomes

• Polyploidy
• 1. Plants
• Relatively common
• Frequency (survey samples)
• 43 of 12,000 species of dicots
• 58 of gt 5,000 species of monocots

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Nicotiana
Allodiploid problem
Fertile autotetraploid
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No!
gain
No!
loss
Figure 10.01 Terminologies used for different
polyploids
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2. Polyploidy in animals -- RARE
Aspidocelis neotesselata 3n species

• sexlineata
• 2n paternal progenitor

A. tesselata 2n maternal progenitor
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Does this matter?
B
A
C
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A. tesselata
F1 hybrid
A marmorata
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A. tesselata (female parent) 7 fissioned 3
intact
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Karyotypic divergence

• Two closely related species of muntjacs (barking
  deer)
• SE Asia and Indonesia

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Change in chomosome numberTranslocation

• Via centromere fusion

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Measuring genetic variation

• 1. DNA sequencing
• 2. Electrophoresis (allozymes)
• A. Proteins (e.g., phosphoglucomutase)
• 18 killifishes (Fundulus zebrinus)

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• 2. Electrophoresis
• B. DNA fragments (Restriction fragment length
  polymorphisms)
• C-C chemokine receptor 32 (CCR5)
• Coreceptor of HIV

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Calculating allele frequencies

• E.g. delta 32
• 1. Biparental species
• E.g., Pakistan 34 individuals
• 32 /
• 2 /?32
• 68 alleles
• Freq. 64 2 / 68 0.97
• Freq. ?32 2 / 68 0.03

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• 2. Uniparental species
• Aspidoscelis neotesselata (triploid tesselated
  whiptail lizard)

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A. neotesselata genetic variation at MPI locus
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• 34 loci assessed for protein phenotypes
• Only one locus (mannose-6-phosphate isomerase)
  revealed variation
• Sample of 17 individuals
• ABC (N 9) BBC (N 5) ACC (N 3)
• Sample of 51 alleles
• Frequency of allele A 9 3 / 51 0.24
• Frequency of allele B 9 10 / 51 0.37
• Frequency of allele C 9 5 6 / 51 0.39

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Amount of genetic variation in populations

• Can be determined from heterozygosity
• Biparental species
• A. sexlineata 7
• Uniparental species
• A. tesselata 56
• A. neosselata 74

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Mutations Chromosomal rearrangementsInversions
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Drosophila pseudoobscura 12 inversions
chromosome 3