genetic diversity

Question 1

discovery of isozymes

Answer 1

1960s discovery of protein isozymes ( alternative forms of the same enzymes ) range of studies showed a whole new level of unsuspected variability

Question 2

single nucleotide polymorphisms (SNPs)

Answer 2

• occur normally throughout a persons DNA once every 300 nucleotides on average, so there are roughly 10 million SNPs in the human genome
• when SNPs occur within a gene or in a regulatory region near a gene, they may affect gene function
• SNPs can be used to estimate relatedness

Question 3

how frequent is a mutation?

Answer 3

• DNA is remarkably stable
• rare when considering a per-locus or per-nucleotide level
• but from a genome-side perspective, mutations are common. the genome of most species consits of billions of base pairs
• average rate of mutation in nuclear DNA is estimated at 10^-9 per nucelotide (per meiosis), but this increases to 0.1-10 in eukaryotic genome
• most mutations have no phenotypic effect, but most mutations with phenotypic ffects tend to reduce fitness

Question 4

how do we estimate genetic variation?

Answer 4

•gene diversity (polymorphism)
- occurance of 2 or more alleles at one locus, in
a population
• heterozygosity
- a diploid organism is heterozygous at a gene
when its cells contain two different alleles of
a gene

Question 5

founder effect example

Answer 5

• ellis-van creveld syndrom typically occurs in 1 in 60,000 to 200,000 newborns
• old order amish population of lancaster country
• over the last 40 years of the 20th century, 61 babies with the genetic disorder were born to 23 amish families
• founding population, a few dozen individuals from a anbaptist sect in Germany who migrates to pennsylvania during the early 1700s, carried the gene

Question 6

bottleneck example 1

Answer 6

• 1755 typhoon left 30 survivors
• current population > 1600
• achromatopsia (colour blindness) in 5% of the population
• god isoahpahu fell in love with several local women
• pedigree analysis revelaed that the chief in 1775, Mwahuele was a carrier

Question 7

bottleneck example 2

Answer 7

• northern elephant seal, overhunting resulted in population reduction to 30 individuals in 1980s
• currently >30000 individuals
• male dominance ( males mate with as many as 100 females )
• reduction in genetic diversity persists, with increased susceptibility to disease

Question 8

irish potato famine

Answer 8

(population with low genetic diversity are more vunerable to changing environments)

• kack of genetic variation in irish potatos contributed to the famine
• in 1800s, the irish solved their problem by feeding a growing population by planting potatoes of the ‘lumper’ variety
• poatoes can be propogated vegetatively, thus lumpers were clones, genetically identical to one another
• genetically identical lumpers were susceptible to phytophthora infestans, an oomycete (water mold) that causes potato blight, which affected the crops in 1840s

Question 9

rate of evolution

Answer 9

depends on:

• population size
• generation times
• amount of genetic variation underlyying phenotypic variation
• rate of environmental change

Question 10

red squirrel popultions

Answer 10

• 325 population in canada
• warmer, earlier springs and more food availiablity
• breeding at right time is essential
• strong selection
• high levels of genetic variation for parturition in population
• breeding adavnaced 18 days over 10 years ( 6 days per generation )
• genetic (microevolution among generations) and phenotypic change (within generation)

Question 11

exploitation of populations : change in allele frequencies

Answer 11

• icelandic stock of atlantic cod is distributed around icelandic continental shelf
• analysis of pantophysin locus ( Pan1 ), along with tracking devices revealed that costal cod are more likely to have AA genotype, and deep-migrating animals tend to have BB genotypes. AB animals detected in both groups
• cod with different genotypes also have different phenotypes
• during the period of intence fishing at the end of the last century, frequencies of Pan1 changed, with the frequency of BB decling from 26% since 1930s to 5% in 1990s. the frequency of AA increased to 50% in same period

Question 12

in situ conservation ( protect genetic diveristy )

Answer 12

• habitat protection

- habitat restoration

Question 13

ex situ conservation ( protect genetic diveristy )

Answer 13

• captive breeding
• genome libaries
• cyro-conservation of cells/tissues
• sperm/ooctye banks
• seed banks
• embryo banks

Question 14

pocillopora damicornis

Answer 14

brooding
internal fertilisation and embryogenesis
release larvae ready for settlement

Question 15

goniastrea australensis

Answer 15

broadcast spawning
release eggs and sperm in mass-spawning events
larvae reside as plankton for several weeks

Question 16

captive breeding programs

Answer 16

• provide demographic/genetic support for wild populations
• sources of new populations in the wild
• prevent extinction where survival in the wild is not possible

Question 17

reintroduction of stocks via selective breeding programmes

Answer 17

• restoring marine habitats may involve or reintroducing animals or plants
• choosing the source of individuals to be reintroduced may require matching genotypes with local ones so they are closely related, while mainting a high level of genetic diversity
• need genetic analysis of populations in the area to identify source populations