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Adaptation and Speciation
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- 1Human Resource Avaliability 6Extinct huminoid species H. floresiensis on island Flores, Indonesia
Short in stature - assume limited in resources
Result of increased competition on the island
Limits to overwhelm any new opportunities
Islnd dwarfing
Island gigantism = no longer limited by predators - 2Convergence of Traits 3Samoana Usually thin-shelled pigmented mantle
S. strigata and S. ganymedes - thick shells and non-pigments mantles
Phylogeny - thick shells and non-pigments mantles re-evolved in Samoana - 3Allopatric Selection 51. Original population
2. Physical barrier
3. Reproductive isolation
4. New range equilibrium
Eg Partula snails split by allopatric sections of rainforest (canopy, rainforest plant and bushes) - 4Chirality 6Sinistral and dextral snails cona't easily mate
Chirality determined by single gene locus
Single gene - reproductive isolation = speciation
Chirality maternally inherited
Dextral snails have sinistrally coiled shell if genotype of mother
= shell coil does not prevent gene flow in species - 5Asexual Reproduction 4Sexual reproduction - removed deleterious homologus recessive mutations
Asexual reproduction - exponential increase in population size because each produce two daughter offspring
2 forms of flatworm Schmidtea mediterranea
Why asexuality persists in some species and not in others - 6Evolutionary Constraints of Adaptation and Speciation 4Pleiotropy - one gene may effect >1 trait
Trade-offs - trait > 1 purpose
OWLS
Time-frame - sufficient time to reach optimum
Past history - starting point of adaptation - 7Sympatric Selection 61. Original population
2. Reproductive isolation in ABSENCE of physical brrier
3. New range equilibrium
Eg Cichlids in Lake Victoria
Mate with wrong type due to murky waters
Species form in clear water - 8Adaptation Definition 1Variation within species being differently adapted to environment
- 9Parapatric Selection 41. Original population
2. Movement into adjacent territory
3. Reproductive isolation occurs
4. New range equilibrium develops - 10Hawaiian Happy Face Spider 3Theridian grallator
Predators hone in on a particular morph
Rare morphs gain advantage - 11Negative Frequency Dependence 3Morph becomes less rare
Lose advantage
Stable equilibrium can resulty - 12Positive Frequency Dependence 1Elimination of rare morph
- 13Fishers Sex Theorem 3Equal number of males and females
Rare sex has advantage and has more offspring than common sex
Sex ratio is restored in 1st generation by frequency dependent selection - 14Hamiltons' Work 5Frequency ratio doesn't apply when individuals are closely related to one another
Co-op and sharing as a group = uses resources more efficiently
Eg Anelosimus spiders co-operate
Each spider grows bigger for each unit of food
Closely related = don't gain same advantage to producing a rarer sex - 15Unusual Species Process 5Anolis lizards
Currently parapatric distribution
Similar ecological niches
Hybridise when in sympathry
Speciation in allopatry followed by range expansion most likely explanation - 16Micro Allopatric/Sympatric Speciation 5Last 100yrs
Rhagoletis pomonella flies
Originally fed on hawthorn
Divergent feeds on apples after introduction to N. America - 17Thresholds not Frequency 11Colour vision in New World primates
Number not frequency dependent
Males always DICHROMATIC
Females either DICHROMATIC or TRICHROMATIC
Females have extra allele as one on each X chromo
Allele is S OPSIN on chromo 7
M and L opsin allels at same locus on X chromo
M and L = tri
Benefits groups as some can see berries and others predators
Collected and genetically types faeces - 18Density Dependent 1Growth rates in shrimp Penaeus japanicus
- 19Fast Adaptation 5Ab in bacteria
Pesticide resistance in insects
Eg Colorado potato beetle
Pesticide removal = selection favour non-resistant type
DEET resistant mosquito - 20Not all Polymorphisms are Adaptive 4Leg length and abdomen colour in Hawaiian Happy Face spider
Cannot evolve independently
Factor constrains evolution of given trait - 21Mimicry Batesian 1Hoverflies mimic stinging wasp
- 22Mimicry Mullerian 2Unpalatable butterflies mimic other non-palatable butterflies
Mimics influenced by both density and frequency dependent selection - 23Supergenes 2Collection of genes physically close in proximity
Unlikely to be split during recombination - 24Adaptive Radiation 5Rapid diversification and speciation to occupy different ecological niches
Eg Cichlid fish in African lakes
Anolis lizard in Antilles
Theredid spiders in Hawaii
Model systems for adaptation and speciation - 25Speciation Definition 1Process in which new species arise
- 26Speciation and Gene Flow 4New species isolated from each other
No longer exchange genes
PREZYGOTIC BARRIERS - eg mating calls incompatible
POSTZYGOTIC BARRIERS - failure of the embryo to develop
eg in leopard frogs
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- Degree Evolutionary Biology of Animals Fichas sobre Adaptation and Speciation, creado por katy.lynock el 22/05/2013.
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- katy.lynock
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