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Biology 191 Lect. 5
Biology 191 Lect. 5 - Biology 191 Lecture 5, Exam 1 Study
| Question | Answer |
|---|---|
| _______ as bridge between microevolution and macroevolution | speciation |
| microevolution | evolution within population |
| macroevolution | evolutionary change above species level, differential speciation, mass extinction |
| speciation | process by which one genetically cohesive population splits into two or more reproductively isonlated populations |
| Biological species concept | Ernst Mayr - defines species as "groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups" |
| limitations of Biological species concept | cannot be directly applied to <br /> - asexual organisms <br /> - fossils <br /> - organisms about which little is known regarding their reproduction |
| Difference between: Morphological, paleontological and phylogenetic species concept | Morphological - species is defined on basis of being sufficiently morphologically (anatomically distinct from others) <br /> - Paleontological - focused on morphologically discreet species known only from fossil record<br /> - Phylogenetic - common ancest |
| Stages in speciation process: be able to recognize correct sequence | 1. single reproductively-cohesive pop.<br />2. Barier to gene flow splits pop into 2 or + isolated pop<br />3. populations grad. diverge<br/>4. reproductive isolating mechanisms evolve<br />5. members incapable of interbreeding<br />6. separate species |
| Geography of speciation: allopatric versus parapatric versus sympatric speciation | allopatric - most common, lease controversial, geographic separation of populations (vicariance, dispersal and colonization)<br />parapatric- evolution of reproductive isolation between adjacent pop. <br />sympatric - speciation within single locality |
| Allopatric speciation through vicariance: how and examples | - emergence of geographic barrier that divides previously continuous population <br /> - evolution of reproductive isolating mechanisms between populations that are geographically separate (ex: formation of grand canyon w squirrels, Panama isthus) |
| Allopatric speciation through dispersal and colonization: how and examples | rare dispersl event results in colonization of isolated habitat (i.e. offshore islands) ex (galapagos finches, hawaiian drosophila) |
| Secondary contact, reinforcement | <br />reinforcement- if reproductive isolating mechanisms not complete, secondary contact may result (and cause hybridization/possible reunification of gene pool) BUT if hybrid have lower fitness, leads to reinforcement (selection for assortive mating) |
| reproductive character displacement | species in sympatry show greater differences in mating-stage isolating mechanisms than same species in allopatry (see images) |
| Parapatric speciation: how and examples | species along side, occours in absence of obvious geographic barrier, may occur when sharp environ. discontinuity developes (ex. plants grow in mine tailings flower at different times than plants growing in surrounding pastures in wales) |
| Sympatric speciation: | speciation without geographic separation. Fairly common in plants |
| speciation- allopolyploidy | duplication of combination of chromosomes from different species |
| speciation - autopolyploidy | duplication of chromosome set of single species |
| haploid | one set of chromosomes |
| Apple maggot fly as example of sympatric speciation in animals | hawthorne -> apple, affinity for host plant in which they developed (leads to breading only with flies only on that fruit) |
| Prezygotic reproductive isolating mechanisms: know definition and recognize examples | - before fertilization<br /><br />- mechanisms that impede mating between species or hinder fertilization of ova if members of different species do mate |
| Postzygotic reproductive isolating mechanisms: know definition and recognize examples | - After fertilization <br /><br /> - Mechanisms that act to reduce the viability or fertility of hybrids |
| Haldane’s rule (of speciation): what is it and what is evidence for it | In hybrids produced by interpopulation or interspecies crosses, the heterogametic sex is more likely to be inviable or infertile<br /> In mamals and most insects males XY, but in birds, butterflies and moths, female ZW (heterogametic), = sterile/inviable |
Created by:
analeah
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