Unit 2: Artificial Selection and Domestication Flashcards
What is the red queen hypothesis
- describes the competitve nature of adaptation
- coevolution
- hosts continually change to stay one step ahead of their pathogens
the difference between natural and artificial selection can be [–]
hard to define
methicillin is a type of
- penicillin (beta lactams)
- toxins derived from molds
natural selection in terms of toxins
development of resistance to an environmental toxin
artificial selection in terms of toxins
deliberate exposure of staph aureus to the toxin
artifical selection
the identification by humans of desirable traits in plants and animals, and the steps taken to enhance and perpetuate those traits in future generations
natural selection
the process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Continuous competition also occurs [–]
within species
antibiotic resistance is which type of selection
- directional
- mutant shifts toward the goal of being antibiotic resistant
Domestication syndrome was described by Darwin an includes
a suite of commonly recognized traits
domestication syndrome
the characteristic collection of phenotypic traits associated with the genetic change to a domesticated form of an organism from a wild progenitor form
dog traits demonstrate variability consistent with
artificial selection and domestication syndrome
Dmitri Belyaev fox domestication
- wild animals kept in cages
- started breeding foxes
- got to point of true breeding domesticated foxes
- started seeing white patches
- floppy ears
What are specific markers of fox domestication?
- two different phenotypic changes in an Ss heterozygote: the star depigmentation and a floopy right ear
- homozygote for the star mutation (SS)
- Phenotypica similarity between brown mottling in fox and dog
Using selective breeding, Belyaev’s experiement generated
foxes with clear hallmarks of domestication
HPA Axis and Domestication
- the CRH tells the pituitary to release ACTH
- this causes cortisol to be released
- domestication = decreased cortisol release
- foxes with less cortisol = less threat posture
What are the domesticated foxes dog-like similarities?
- coat depigmentation
- curly tail
- tail carriage
- floppy ears, wider face
- long jaw
- skull elongation
domestication changes [–] as well as [–]
behavior and morphology
domesticated foxes are referred to as the
behavioral elite
Domestication syndrome and the neural crest cell hypothesis
shorter snouts and smaller teeth
the neural crest hypothesis referes to
- certain stages of development and may explain many of the changes found in domestication syndrome
- a few key mutations in developmental genes (pleitropy) would have a profound impact on many traits observed in domesticatied animals
Cell migration from the neural crest during the neural crest hypothesis results in
- weakened ear cartilages: floppy ears
- shortened snout
- reduced brain size
- odontoblasts: reduced tooth size
- melanocytes: pigment changes
- sympathetic ganglia
- adrenals
- cartilages of tail (shortening, curling, etc.)
According to the neural crest hypotheis, the significant features of domestication may be [–]
“unselected by-products”
Selection for Tameness results in
reduced neural crest input (mild neurocristopathy)
what are the unselected by-products of reduced neural creast input
- white patches (melanocytes)
- floppy ears (chondrocytes)
- Reduced muzzles & jaws (osteoblasts)
- reduced teeth (odontoblasts)
- reduced forebrain size (potential indirect side-effect)
what are the selected traits for reduced neural crest inputs
- reduction in adrenals & sympathetic ganglia
- reduced stress
- reduced fear of humans
- learning: “humans OK”
