Genetics for Animal Health

Question 1

Mendelian inheritance

Answer 1

• parents only pass one allele to offspring
• which allele inherited is random and independent
• doesnt incoorporate environment

Question 2

rg value

Answer 2

= genetic variation between traits

- need to know how genetic traits linked to other diseases

Question 3

Why is genetic diversity within populations important

Answer 3

• population fitness (ability to survive disease threat) is directly related to it heterozygosity (different alleles and genes)
• provies resiliance and helps populations adapt to changing environments (less likely to adapt if same genetics e.g. temp, disease)
• susceptibility differences for diseases (some more resistant than others e.g. piglets resistant to ecoli, as get older less resistant but vary levels)

Question 4

loss of genetic diversity - inbreeding

Answer 4

• increase risk of genetic disease
• increase likelyhood of autosomal recessive dissease
• decrease in heterozygosity (alleles become lost or fixed)
• increased susceptibility to disease and infertility

Question 5

Bottleneck effect - about and examples

Answer 5

• significant reduction in number of individuals within parent population
• enviro impact or change in way animals interact with each other
• certain phenotypes minor in number of individuals are lost
• remaining dont expressed trait = reduce genetic diversity
• e.g. northan elephant seals, 1890s reduced to 30 individuals, all offspring similar genetically, increase risk of disease, breeding increase risk as dominant male breeds the most (up to 100 females)
• e.g. golden hamster which are companion animals all bred from one family of golden hamsters found in syrian desert = significantly reduced diversity
• dogs slective breeding for specific traits

Question 6

Bottle necks - the cheetah

Answer 6

• ice age - 75% mamalian species wiped out
• a bottle neck of cheetahs surviverd = 10,000 to 15,000 individuals remain
• a small population leading to inbreeding and reduced genetic diversity
• compared to other cats
  ~ male cheetahs have impaired sperm quality (<10% of males have good quality ejaculates)
  ~ female cheetahs carry fewer off spring
  ~ offspring have shorter life span
• inbreeding depression in captive breeding rograms though to be a major cause
• wild cheetahs = decline in genetic diversity overtime (captive = no decline diversity/heterozygosity, potentially positive change, more diversity)
• no difference in semen quality/fertility peramiters (sperm motility, testes vol, total spermatozoa ejaculated, strutually normal spermatozoa)
  = management of chetahs in captivity helped control/maintain genetic diversity