Examples Flashcards
Example of Divergent, Directional and stabilising selection
E.G Spadefoot toads
* 2 morphs 1) omnivore 2) carnivore -> separate feeding niches
Divergent S = mark recapture experiment showed less survival of intermediate morphs
Directional S = Carnivores shown to do better than omnivores
Stabilising S = Intermediate morphs selected for when other species are present and dominant
Example of heterozygote advantage
Sickle cell anaemia, heterozygote for gene means you are immune to malaria whereas homozygote Is detrimental
Frequency dependant selection
PFDS - Mullerian mimicry
NFDS - Batesian mimicry
NFDS - (Gigord et al 2001) -Negative frequency-dependent selection maintains a dramatic flower color polymorphism in the rewardless orchid ( purple selected for as bees perceive it as “novel” and are attracted to it)
Example of a steep + shallow CLINE
Steep CLINE = cryptic + conspicuous morphs of rock pocket mice, reasonable gene flow but high predation selection (wrong morph in wrong area = dead)
Shallow CLINE = Alpha
Primary Hybrid zone
Directed reading - ring species Linn et al
Secondary hybrid zone
- Postglacial recolonization in European hedgehogs,
Example of reinforcement , RCD and magic trait/ direct system
E.G. Pied flycatchers (+ collared) - normally live in allopatry, when in sympatry males (P) change their plumage to make It different to C’s (female preference for plumage also changes) - the gene that is adaptive is linked to mating preference
EXAMPLE OF
1) Reinforcement
2) Reproductive character displacement
3) Magic trait / direct system
Example of peripatric speciation + founder effect speciation
E.G. Paradise Kingfishers (New Guinea)
- small periphery population split off and colonised islands
- each different island has own species which are morphologically different
Example of habitat isolation , hybrid inviability , sexual isolation and cryptic isolation
E.G. Timema Cristinae ( stick insect)
- 2 different ecomorphs , specialised to 2 different host plants (demonstrate a level of reproductive isolation)
- hybrids inviable as camouflage ineffective
Example of sympatric speciation
E.G Howea palm
- thatch + curly palm
- 1 island , 6 hybrids ever found
- differing soil preference + phenology
Example of ecological character displacement
Inter species
E.G. Brook + ninespine stickleback
- when ninespines present, brooks show evidence of benthic living (stronger jaws + wider bodies)
Sexual selection vs Natural selection
E.G. Marine Iguanas of Galapagos
- male size is sexually selected for
- increase in size shown to have negative effect on male fitness (harder to maintain larger body in extreme conditions)
Examples of sexual selection being affected by : Food resources, predation , parasitism,
FR: Red crossbills - (10 ecotypes + minimal gene flow) females select based of feeding efficiency + strategies
Predation: Guppys, red spots attrative to females but increase predation
Parasitism: Common Yellow throat , females select for melanin based black marks (which are linked to immunity) , parasites can affect production of these black marks
Example of mutation accumulation
E.G. Huntingtons disease - caused by a dominant allele expressed at 30+ years old
Example of Antagonistic pleiotropy
E.G. gene that causes overproduction of sex hormones can cause cancer later on