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Domestication as a Model of Speciation 50 years long experiment, run in the Institute of Cytology and Genetics Biology. Summer School 2007 Novosibirsk Marina Voloshina Phys-Math School, Novosibirsk State University, 2007 http://www.slideshare.net/outdoors
This is an educational lecture for students – an overview of an experiment conducted by scientists of Novosibirsk Institute of Cytology and Genetics and its evolutionary implications
In 1959 a group of Siberian scientists, headed by academician Dmitry K. Belyaev , the Director of the Institute of Cytology and Genetics in Novosibirsk, started a large-scale experiment on fox domestication.
It lasts ~ 50 years by now
Institute of Cytology and Genetics, Novosibirsk, Academgorodok
These was in line with one of well-known and mysterious facts about domestication: a striking parallelism in the morphological changes
In a wide range of mammals – herbivores and predators, large and small – domestication seems to lead to strictly coincident forms
all except sheep changes in reproductive cycle dogs, cats, pigs, sheep, goats, cattle floppy ears dogs, cats, sheep shortened tails, fewer vertebrae dogs, pigs rolled tails sheep, poodles, donkeys, horses, pigs, goats, mice, guinea pigs wavy or curly hair all piebald coat color all appearance of dwarf and giant forms Domesticated species Character
What distinguishes the domesticated foxes of the wild ones?
The first is the behavior
Behavior is strictly determined by hormones – and hormone level changed significantly too
The reproductive cycle regulated by hormones is very conservative in wild animals. Domestication shifted time of the normal breeding season and even made some animals capable for twice a year reproduc tion . (normally once)
4. More surprising were the morphological changes
The new morphological characters that are absent in wild animals but are quite common in dogs:
a loss of pigment in the coat color – “Star” mark on the forehead and piebald coat
The answer of Belyaev was that the key is the selection for behavior .
He considered the genetic transformations of behavior to be the main factor entraining other genetic events.
Many of the genes determining behavior may be regulator y , engaged in stabilizing an organism’s early development, or ontogenesis .
Ontogenesi s is an extremely delicate process. In principle, even slight shifts in the sequence of events could throw it into chaos. Thus the genes that orchestrate those events and keep them on track have a powerful role to play.
The recent results from molecular study of genomes come in line with this view on speciation
They revealed that most of general changes in organism’s structure are result of changes in gene regulation , their spatial and temporal pattern of expression , rather than direct changes in their DNA sequence
Regulatory evolution at the yellow gene underlies the wing pigmenation of Drosophilidae Staining for yellow protein D.melanogaster D. biarmipes D. guttifera Wings
Humans and dogs – convergent evolution? http://email.eva.mpg.de/~tomas/pdf/Hare_Tomasello05.pdf
Implications of Domestication Mechanisms for H uman C ognitive E volution
This recent comparative work suggests that human-like social intelligence could initially have evolved, not as an adaptation,
but rather as a by-product of selection on social-emotional systems –
perhaps supported primarily by limbic and endocrine systems rather than the neocortex
Links Wikipedia article http ://en.wikipedia.org/wiki/Tame_Silver_Fox Lyudmila Trut. Early Canid Domestication: The Farm-Fox Experiment http://www.americanscientist.org/my_amsci/restricted.aspx?act=pdf&id=3038739723681 Website of the Cornell University on the collaboration work with the Institute of Cytology and Genetics, Novosibirsk http ://cbsu.tc.cornell.edu/ccgr/behaviour/Index.htm What Can Dogs And Silver Foxes Tell Us About Each Other? http ://cbsu.tc.cornell.edu/ccgr/behaviour/04_Recent_Publications/FoxChapter.pdf B.Hare and Michael Tomasello. Human-like social scills in dogs? http://email.eva.mpg.de/~tomas/pdf/Hare_Tomasello05.pdf
Copyright notice This is an educational presentation, based on works of D.K. Belyaev and L.N.Trut of the Institute of Cytology and Genetics. You can use it in education with the links to original works. Any commercial use is prohibited. You have no right to place it on any website or portal for download. Marina Voloshina http :// www.slideshare.net / outdoors http:// biologii.net