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Stuff you need to know – Week 2

Stuff you need to know – Week 2 - Stuff you...

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Stuff you need to know – Week 2 Sympatric speciation - disruptive selection initiates it - behavioral and/or temporal isolation must overwhelm gene flow- micro habitat differences - polyploidy- pre-zygotic isolation in one generation * o autoploidy- one species new species through chromosome doubling o alloploidy- two similar species give rise to a zygote; reproduces by selfing more likely in plants more germ tissue more likely to be able to self mutation occurs and doubles chromosomes (4N) Hybrids - occurs when two speciated populations come back together and reproduce - viability of hybrid depends on how far apart genetically ( and etc.) the two populations have moved o if to the point of reproductive isolation, no viabile hybrid - when non-reproductively isolated species are reconnected produce hybrids - hybrid zone- overlap of two species that reproduces a hybrid in that geographical area - need to examine fitness of parents species and hybrid to determine what will happen o parents 1&2 fitness > hybrid fitness narrow hybrid zone o hybrid fitness > parents 1&2 in hybrid zone new species arises o parent 1 fitness> hybrid fitness> parent 2 parents 2 becomes extinct Punctuated equilibrium vs gradualism - Punctuated equilibrium o Jumps of evolution o Little gradual change with quick and sudden bursts of speciation o Supported by fossil record - Gradualism o Evolution occurs through a gradual accumulation of change Evolutionary/developmental biology* - also called Evo/Devo o includes molecular genetics, paleontology, evolutionary biology,
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and developmental biology o Homeotic (Hox genes) - control the developmental process of biology - controls modules and axies of structures - more HOX genes, more control and modules to work with Gene duplications, orthologs vs paralogs* - ortholog- part of a gene family - paralog- duplicated Mutations affecting spatial/temporal expression of regulatory genes* Examples of regulatory gene mutations that cause morphological change:* - Gremlin in chicken vs duck feet o BMP4 causes apoptosis of webbed skin between toes o Gremlin gene causes blocks apoptosis in webbed feet o Gemlin gene present = webbed feet - Ubx in arthropod appendages (insects vs others) o UBX protein determines if thoracic segment is a wing or a balancer o UBX is a regulatory protein o What about others?
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