chapter 16: human intervention in evolution
TRANSCRIPT
![Page 1: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/1.jpg)
Human intervention in evolution
Chapter 16
![Page 2: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/2.jpg)
Phenotypic level:• Selective breeding• Reproductive technologies– Artificial insemination (in animals)– Artificial pollination (in plants)– Embryo transfer– Sex selection through sperm sorting
Genotypic level:• Transgenic organisms
![Page 3: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/3.jpg)
Selective breeding• Selective breeding is the deliberate selection by a
breeder of individual plants or animals to provide the genetic material for the next generation
• Artificial selection occurs when breeders favour particular inherited features in their livestock and use selective breeding to enhance those features
• Unlike natural selection, the traits selected in this type of breeding may not be positively selected in the wild
• Loss of genetic variability
![Page 4: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/4.jpg)
Reproductive technologies• Artificial insemination (AI)• Sex selection through sperm sorting• Multiple ovulation and embryo transfer• Oestrus synchronisation
![Page 5: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/5.jpg)
Artificial insemination• AI involves collecting semen from a selected
stud animal and then introducing this semen by artificial means into the reproductive tract of females of the same species
• Freezing of semen was introduced in 1949 this means one prize stud animal can:– Fertilise many more
females than naturally– Fertilise females located
far far away– Fertilise females long
after it‘s dead
![Page 6: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/6.jpg)
Embryo transfer in livestock (MOET)• Allows high quality ewes to makes a much greater
contribution to the future generations• Multiple ovulation: female receives injections of
FSH that stimulate her to super-ovulate (produce multiple eggs)
• Embryo transfer: embryos at day 6/7 are inserted into surrogate mother
• Embryos can be frozen
![Page 7: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/7.jpg)
Sex selectinon through sperm sorting
• Treat semen to seperate X & Y chromosomes• Sperm cells are labelled with fluorescent dye– X chromosomes larger so fluorescent more brightly
Manipulating breeding cycles• Oestrus (part of sex cycle when female is ready to mate)• Oestrus synchronisation results in sexually mature females being in oestrus for a very specific
timeframe• Less time wasted• Higher fertilisation rates and birth rates
• Progestrone (stops production of Oestrogen)• Feeding diety supplement• Implants under skin• Sponges inserted into vagina• CIDRs (controlled internal drug releasing devices inserted into vagina
![Page 8: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/8.jpg)
Artificial pollination in plants• Process involves:
– Removal of unripe stamens from the plant to be fertilised– Protection of the stigma of the selected female plant from stray
pollen– Collection of pollen to be used in artifical pollination– Transfer of donor pollen onto the stigma of female parent
• AP is used to create new plant species (wheat-rye hybrid) see p. 628
![Page 9: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/9.jpg)
Cloning
• Creating genetically identical copies of an organism
• There are two ways:– Embryo splitting– Nuclear transfer
![Page 10: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/10.jpg)
Transfering genes between species• Any organisms with „foreign“ DNA is a transgenic organism
(TGO)• This introduction and incorporation of external DNA can result
in permanent genetic changes– Prokaryotic cells (bacteria): Transformed– Eukaryotic cells : Transfected
• Techniques for gene transfer:– Micro-injection of the DNA of a gene into a cell– Transfer using a virus (retrovirus or adenovirus)– Use of an electric pulse– Use of ballistics (gene gun)– Cloned transgenic mammals (Polly) (case studies p. 638)
![Page 11: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/11.jpg)
Gene therapy
• See chapter 4• Faulty allele in an organism is replace by the
normally functioning allele of the gene• Directly targets genotype• Gene therapy is still in its first stage with
clinical trials occuring in various institues (p. 639)
• Read blue box on p. 640
![Page 12: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/12.jpg)
Stem cells: a new approach
• Stem cells are undifferentiated (precursor cells) that have the ability to differentiate into many different and specialised cell types
• Totipotent: give rise to all cell types• Pluripotent: give rise to most cell types• Mulitpotent: give rise to certain cell types
• Two different stem cell types:– Embryonic stem cells (obtained from blastocyst)– Adult stem cells (Somatic stem cells) (bone marrow, skin etc)
![Page 13: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/13.jpg)
Stem cells: therapeutic cloning
• Nuclear transfer technique
• Ethical issues– Australia: use of excess embryos allowed
![Page 14: Chapter 16: Human intervention in evolution](https://reader036.vdocument.in/reader036/viewer/2022062418/5560e4b7d8b42aa65e8b4f13/html5/thumbnails/14.jpg)
Technology in human reproduction
• Stopping conception• Overcoming infertility– Donor insemination– IVF (in vitro ferilisation) BIOTECH p. 648
– Donatino of eggs– Surogacy– Gamete intrafallopian transfer (GIFT)– Intracytoplamis sperm injection