Term
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Definition
| Evolution of reproductive isolation an ancestral species, resulting in two or more descendant species |
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Term
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Definition
| Proportion of phenotypic variation that can be attributed to genes (varies but is rarely 0 or 1) |
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Term
| What concept does heritability tied to? |
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Definition
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Term
| What concept is almost entirely explained through heritability and the struggle for existence? |
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Definition
| Phenotypic change by natural selection |
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Term
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Definition
| Random changes in the frequencies of two or more alleles or genotypes within a population |
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Term
| What affect does genetic drift have on phenotypes? |
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Definition
| Genetic drift enhances or inhibits the role of natural selection in changing or maintaining phenotypes |
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Term
| What are examples of phenotypic change by natural selection and genetic drift? |
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Definition
- Finches
- Rock Pocket Mice
- Sticklebacks
- Daphnia
- Drosophila
- Corn |
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Term
| What are examples of stabilizing selection? |
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Definition
- Human birth weight
- Blue Tit clutch size |
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Term
| Why does human birth weight display stabilizing selection? |
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Definition
Human infants have lower rates of mortality if they are near the population mean for birth weight than if they are lighter or heavier.
Therefore, the mean only changes a little, if at all. |
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Term
| Why is Blue Tit clutch size an example of stabilizing selection? |
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Definition
| If the clutch size is too little or too large (especially large), it is disadvantageous to both mother and the babies. 12 is found to be optimal clutch size, and is therefore found to be the stabilized mean. |
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Term
| Who observed evolution to occur more rapid than Darwin had proposed? |
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Definition
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Term
| What was considered to be the first 'ecological genetics' work? |
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Definition
| Kettlewell and Ford's study of industrial melanism in moths |
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Term
| What did Darwin argue in regards to heritable phenotypic variation and a struggle? |
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Definition
Heritable phenotypic variation and a struggle...
1. changed species
&
2. could generate new ones |
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Term
| What were Darwin's 'Difficulties on Theory'? |
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Definition
1. On the absense or rarity of transitional varieties
2. On the origin & transitions of organic beings with peculiar habits and structure
3. Organs of extreme perfection & complication
4. Organs of little apparent importance |
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Term
| What does Darwin believe to be the starting point in the evolution of a new species? |
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Definition
| A species with two characters/morphological features doing the same thing (e.g. gills & swim bladder in fish which are both involved in fish respiration) |
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Term
| How does Darwin describe the wing? |
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Definition
| Innovative, as it is just a variant of the mammal arm |
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Term
| Phylogenetic Species Concept |
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Definition
| considering species to be merely populations with distinguishing characteristics |
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Term
| Biological Species Concept |
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Definition
| Cosidering reproductive isolation to be a defining feature of species |
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Term
| What are the two types of genetically-based barriers to gene flow? |
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Definition
1. Prezygotic Barriers
2. Post-zygotic Barriers |
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Term
| Describe prezygotic barriers. |
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Definition
- No hybrids are produced
- Typically (but not always) premating barriers
- Alleles influencing mate recognition or mate choice issues
- Perhaps sperm-egg recognition issues (gametic isolation) |
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Term
| Describe post-zygotic barriers. |
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Definition
- Failure of hybrid zygote to develop properly
- Sterility of hybrid
- 'Ecological Inviability' or 'Behavioural Sterility' (hybrids cannot avoid predators or find food or mates). |
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Term
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Definition
| The occurence of of related organisms in separate geographical areas with no overlap |
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Term
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Definition
| No movement, just the introduction of a barrier that stops gene flow/migration (ie. river, highway, plate tectonics) |
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Term
| Describe Allopatric Speciation by Vicariance |
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Definition
| One species becomes separated into two different regions due to vicariance (such as a river or highway), over time the organisms become more and more different than those on the other side of the barrier. Once the barrier is removed and sympatry is re-established the once-related organisms have now become distinct species. |
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Term
| How is post-glacial climate change an example of allopatric speciation by vicariance? |
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Definition
Species (plants & insects) were pushed south during last ice age and later followed the glaciers North.
Some were left behind however and instead of following the ice North, they followed cool temperatures up moutains and ended up stranded near the top. |
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Term
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Definition
| Organisms whose ranges are closely adjacent but do not overlap |
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Term
| Peripatric Speciation (Founder Effect) |
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Definition
| The principle that the founders of a new population carry only a fraction of the total genetic variation in the source population |
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Term
| What is an example of peripatric speciation? |
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Definition
| Finches flying to Galapagos Islands |
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Term
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Definition
| A measure of the proportion of pairs that mated |
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Term
| What leads to prezygotic biological barriers? |
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Definition
| Reduced gene glow, as evidence by genetic distance |
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Term
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Definition
| Any of several measures of the degree of genetic difference between populations, based on differences in allele frequences |
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