Island evolution

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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour
Development of tameness
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Falkland Islands fox, Dusycion australis,
Falkland Islands
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Blue-footed booby, Sula nebouxii, Galapagos
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Tamar wallaby, Macropus eugenii, Kangaroo Island
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(No Transcript)
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House mice, Mus musculus, feeding on Tristan
albatross, Diomedea dabbenena, Gough Island
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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour
Development of tameness Relaxation in
territoriality
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House mouse, Mus domesticus, Isle of May and UK
mainland
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Gray Hurst 1998
House mouse, Mus domesticus, Isle of May and UK
mainland
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Resource hypothesis
Defence hypothesis
Competition release
Predation release
Mild climate
Abundant resources
Increased survival of "have-nots"
Increased territorial defence costs

• Relaxation in territoriality
• smaller territories
• increased overlap
• tolerance towards subordinates
• reduced aggressiveness
• abandonment of territorial defence

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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour Life history
Reduced fecundity
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Resource predictability hypothesis milder
climate, reduced seasonality favours a reduction
in clutch size
Energy reallocation hypothesis predation
relaxation, density compensation select for
investment in fewer,higher quality young
reduced clutch size higher quality young
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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour Life history
Reduced fecundity Changes in reproductive strategy
Dioecy
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Monoecious
Dioecious
Hermaphrodite
male
male
female
female
male
female
Tag alder, Alnus serrulata
Holly, Ilex aquifolium
Lily, Lilium
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worldwide
Hawaii
monoecious 5-6
monoecious 7.6
dioecious 6-7
dioecious 14.7
hermaphrodite 85
hermaphrodite 62.4
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avoiding inbreeding depression
sex allocation theory
dioecy
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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour Life history
Reduced fecundity Changes in reproductive strategy
Dioecy Loss of flower attractiveness
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Sun orchid, Thelymitra longifolia, New Zealand
Psychopsis papilio, South America
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Bellflower, Campanula punctata, Izu Islands
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Honshu
Bombus diversus
Oshima
Toshima
Niijima
Kozu
Miyake
Bombus ardens
Mikura
0
100 km
Hachijo
Lasioglossum
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30
Honshu
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Oshima
Niijima
Toshima
Corolla width (mm)
Kozu
Hachijo
Miyake
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0
1
2
3
4
5
6
Pollinator width (mm)
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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour Life history
Reduced fecundity Changes in reproductive strategy
Dioecy Loss of flower attractiveness Anemophily
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Rhetinodendron berteroi, Juan Fernandez Islands
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Plocama pendula, Canary Islands
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Windy conditions allow wind pollination
Inbreeding avoidance
Anemophily
Lack or paucity of animal pollinators
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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour Life history
Reduced fecundity Changes in reproductive strategy
Dioecy Loss of flower attractiveness Anemophily Un
usual pollinators
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88
Bumble bee, Bombus canariensis, Canary Islands
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Mauritius ornate day gecko, Phelsuma ornata, Ile
aux Aigrettes, Mauritius
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30
80
Aeonium holochrysum, Canary Islands
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Madeira wall lizard, Teira dugesii, Madeira
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Lilford's wall lizard, Podarcis lilfordi,
Balearic Islands
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Island evolution
Evolutionary forces on islands Evolutionary
trends on islands
Morphology Behaviour Life history
Reduced fecundity Changes in reproductive
strategy Unusual dispersal agents
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Podarcis lilfordi, Balearic Islands
Podarcis pityusensis, Balearic Islands
Gallotia atlantica, Fuerteventura
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Robust skink, Cyclodina alani, New Zealand
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Aldabra giant tortoise, Dipsochelys dussumierri,
Ile aux Aigrettes (Mauritius)
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Ile-aux Aigrettes ebony, Diospyros egrettarum,
Ile aux Egrettes, Mauritius