BLG 144 Lecture Notes - Lecture 8: Apple Maggot, Sympatry, Reproductive Isolation
27 Apr 2018
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Sympatry – populations or species that live in the same geographic region to mate
- Researhers thought sypatri populatios ould’t happe eause gee flo ould still e
possible
- Speciation can happen even though the population is not physically isolated, they might become
isolated by the development of distinct preferences for different sub-habitats /resources
- Eg. Apple maggot flies feed and mate on apply fruits (brought to north America)
Sympatric Speciation
- Each species responds the strongest to its own fruits scent
- Ee though 2 speies are foud sypatrially, they do’t geerally iterreed
- Apple flies and hawthorn flies are diverging and in the process of becoming distinct species
How can polyploidy Lead to Speciation?
- When isolated, a mutation that causes polyploidy can cause speciation, particularly in plants
- Polyploidy – condition of having more than 2 sets of chromosomes
- Tetraploid individuals – genetically isolated from wild-type individuals due to the production of
diploid gametes rather than haploid gametes.
- 2 gametes give a zygote a triploid
- Triploid individuals have a dysfunctional set of chromosomes in the gametes
- Tetraploids ad diploid idiiduals do’t’ ake fertile offsprig he they ate
- Tetraploid and diploid populations are reproductively isolated
- Polyploidy can lead to reproductive isolation
- Mutations can cause doubling in chromosomes number, in the same species, and produce
Autopolyploid individuals
- Allopolyploid individuals are created when parents belong to different species make a new
species in which chromosome number doubles
Autopolyploidy example – tetraploid(4n) maidenhair ferns. The offsprings made diploid gametes and
self fertilized after
- These are genetically isolated from wild type populations, cause tetraploid individuals can breed
with other tetraploids but not with diploids
- New types of these species can make 2 diploid species hybridize ( 2 diploid gametes make a
tetraploid individual)
- Diploid plant species have closely related polyploid species
Allopolyploidy
- When a chromosome doubling happens and the allopolyploid offspring can be fertile and make
a new species
Why Speciation by Polyploidy is common in plants?
1. In plants, somatic cells do mitosis many times and can also do meiosis to make gametes. More
likelihood of tetraploid daughter cells during the multiple rounds (autoploid)
find more resources at oneclass.com
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Document Summary
Sympatry populations or species that live in the same geographic region to mate. Resear(cid:272)hers thought sy(cid:373)patri(cid:272) populatio(cid:374)s (cid:272)ould(cid:374)"t happe(cid:374) (cid:271)e(cid:272)ause ge(cid:374)e flo(cid:449) (cid:449)ould still (cid:271)e possible. Speciation can happen even though the population is not physically isolated, they might become isolated by the development of distinct preferences for different sub-habitats /resources. Apple maggot flies feed and mate on apply fruits (brought to north america) Each species responds the strongest to its own fruits scent. E(cid:448)e(cid:374) though 2 spe(cid:272)ies are fou(cid:374)d sy(cid:373)patri(cid:272)ally, they do(cid:374)"t ge(cid:374)erally i(cid:374)ter(cid:271)reed. Apple flies and hawthorn flies are diverging and in the process of becoming distinct species. When isolated, a mutation that causes polyploidy can cause speciation, particularly in plants. Polyploidy condition of having more than 2 sets of chromosomes. Tetraploid individuals genetically isolated from wild-type individuals due to the production of diploid gametes rather than haploid gametes. Triploid individuals have a dysfunctional set of chromosomes in the gametes.
