Breeding and Reproduction Flashcards
What is genetics?
The science of heredity
Who determined that traits are passed on to descendants unchanged?
Gregor Mendel
What does basic genetics involve?
Cell division and the law of independent assortment
What is mitosis?
Cell division that results in 2 cells that each have the same number of chromosomes as the parent cell
What is meiosis?
Division of cell material that results in cells with half the number of chromosomes as the parent cell
What is the Principle of Independent Assortment?
Different pairs of alleles are passed to offspring independently of each other
What affects phenotypes and genotypes?
Chromosomes that contain genes and alleles
Does a single gene affect just one trait?
Yes but it can also affect more than one trait
Do several alleles affect several traits?
Usually only affect one trait
What is a phenotype?
Physical characteristics of an animal, including appearance and physiological composition
What is a genotype?
The genetic makeup of an individual for a particular train or group of traits
What is a dominant trait?
An allele or gene variation, that makes the presence of a recessive allele in the phenotype
What is a recessive trait?
An allele that is masked in the phenotype by the presence of a dominant allele
What is homozygous genotype?
A genotype consisting of 2 identical alleles of a gene for a particular trait or characteristic
What is an example of a homozygous individual?
Homozygous dominant (AA) or homozygous recessive (aa)
What is a heterozygous genotype?
A genotype that consists of 2 different alleles for a gene for a particular trait or characteristic (Aa)
How will the phenotype be with a heterozygous genotype?
It will still be the same
What is a mutation?
An alteration of genetic material such that a new variation is produced
What is the only mechanism of mutation that can produce new alleles of a gene?
Mutation
What are some ways a mutation can be caused?
Chemical, biological, environmental and viral means
What is ovulation?
The discharge of an unfertilized egg from the ovary
What is spontaneous ovulation?
Ovulation which occurs independently whether or not the animal has mated
What is induced ovulation?
- Vulvovaginal stimulation is required for the hormones to be released that cause ovulation to take place
- Rabbits, cats, ferrets
What is a zygote?
A cell that is formed when a sperm and egg combine their chromosomes at conception
What is the period in a female mammal from the beginning of one heat period to the next?
The estrous cycle
What is monestrous?
- Animals that have only one breeding season per year
- Basenji, bears, dingos, foxes, wolves
What is polyestrous?
- An animal that has repeated estrous cycles throughout the year
- Dogs, cats, rabbits, mice
What is the gestation period?
The period of time between fertilization (aka creation of the zygote) and birth; or the length of pregnancy
What is parturition?
Giving birth at the end of the gestation period
What is post-partum estrus?
Estrus following parturition, some females can conceive within hours of parturition without having to cycle through their whole cycle again
What factors are determined by species in regards to reproduction?
- Location where and the matter in which the gametes are fertilized (mammals=uterus, birds=eggs)
- Development site of the zygote
- Gestation period
- Ovulation
What is a breeding scheme?
Several different methods that can be used to breed an animal
What foes a breeding scheme typically depend on?
- The animal involved
- Genetic makeup required
- Requirements of research protocol
What is outbreeding, aka random breeding?
Animals that are unrelated that are bred; popular for rodent colonies
What are some advantages to outbreeding?
- Maximum genetic diversity
- It produces the most vigorous offspring
- Often results in larger litters
What is inbreeding?
Produces genetically similar animals by breeding 20 generations successively which results in a colony called a strain
What are some advantages to inbreeding?
- Produces animals that are homozygous at approximately 99%
- Eliminates hereditary differences for experimental purposes
- Also eliminates the rejection of tissue shared between animals
What is hybrid breeding?
Parents from too different inbred strain animals
What is hybrid breeding used for?
To maximize the characteristics of each of the parents, therefor making offspring genetically and phenotypically identical (similar to clones)
What type of breeding would be used to transfer a mutation to another strain?
Hybrid breeding
What is line breeding?
Mating of an offspring to a common ancestor
What is line breeding typically used for?
To isolate an accent a particular desirable trait
Which system do gerbils typically work best for?
Monogamous
What are some advantages of a monogamous breeding mating system?
- Easiest at establishing an inbred system
- Easiest for record keeping
- Maximizes the use of post partum estrus
What are some other names for a polygamous system?
Harem or colony system
Which system do mice adapt best to?
Polygamous
What are some advantages to a polygamous system?
- Largest number of offspring with the least number of breeder animals
- Most economical method
- Maximizes use of the post partum estrus
What are some disadvantages to a polygamous system?
- Difficulty keeping accurate records
- Overcrowding
What animals are used for a separately housed system?
Hamsters and rabbits
What are some advantages of a separately housed system?
- Reduces the number of animals needed
- Promotes accurate records keeping
- Maintains life of non-compatible animals
What are some disadvantages of a separately housed system?
High labor costs
What is intensive breeding?
Leaving the females with the male which results in the maximum number of animals
What are some cons to intensive breeding?
- It exhausts the female’s metabolic reserves
- May contribute to breeding/parturition problems like dystocia
What is non-intensive breeding?
Allows the female to recover completely before her next pregnancy and parturition
What are some necessities for caging with expectant mothers?
The female must be able to build a nest, deliver and nurse the young, and allow for their growth
