Communities, biogeography, and selective forces: Flora (including NZ flora and moa herbivory)
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Transcript of Communities, biogeography, and selective forces: Flora (including NZ flora and moa herbivory)
![Page 1: Communities, biogeography, and selective forces: Flora (including NZ flora and moa herbivory)](https://reader036.fdocuments.us/reader036/viewer/2022081603/56649f145503460f94c29197/html5/thumbnails/1.jpg)
Communities, biogeography, and selective forces: Flora (including NZ
flora and moa herbivory)
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Questions
• Discussions: – Maria P: posting paper and questions for this
week– Jose Luis: will be picking a paper to post for next
week
• Any questions?
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NZ
• Shearing: Sheep grazing• Sheep (60 m) outnumber people (3m) by 20:1
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NZ
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NZ herbivorous birds
• NZ lacked native mammals (except 2 bats)• 50% terrestrial birds eat non reproductive
plant parts
North Island kokako
Weka
NZ pigeon
Kakapo
KeaNZ quail
Paradise shelduck Southern brown kiwi
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Moas
• Largest herbivores in scrub and forest up to 1800 m– Ratites: ~10 species in 6 genera of moas (20-200 kg)– Tallest stood ~ 2.5-3 m (giant moa)– Hunted to extinction in 15th century (along with 50% of
endemic birds, 40% of all birds)
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Moas
• Closest relatives emus, cassowaries, tinamous, rheas, kiwis
• Snapping: Ostrich feeding
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Moas: coprolites and gizzards
• Many twigs of shrubs and trees• Despite large size, they were feeding on small
herbs (<30 cm) and many rare species• Probably strongly shaped vegetation structure
(e.g., reduced niches of broad leaved woody species)
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Flora
• High endemism and numerous trees (215 spp)– Many trees are short statured– Divaricating (wire plants): 10% of all woody plants
(overall common on islands: e.g., Madagascar, Hawaii, New Caledonian)
• Thin spreading branches
– Heteroblasty: 200 tree species• Changing leaf morphology with age
– Colour change with age
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FernsGymnosperms
Angiosperms
Lots!
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Flora
• Why my these evolve?– Divaricating– Heteroblasty– Colour change
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Functions?
• Physiological tolerance of low temperatures, high wind or high light
• Moa herbivory
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Evidence
• Cafeteria style feeding trials with emus and ostriches: Divaricating habit suffered 30-70% less herbivory
• Most divaricating, poisonous and deciduous species are short
• Small stature, deciduousness and divaricating, teeth increase with latitude
• Reversions to homoblasty found in Chatham Islands lacking moas
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Evolution of colour changes
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Evolution of colour changes
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FernsGymnosperms
Angiosperms
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Pseudopanax crassifolius
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Pseudopanax crassifolius
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Pseudopanax crassifolius
• Seedling leaves: dull and mottled brown due to anthocyanin production– Produced in plants <10 cm tall
• Juvenile leaves: long, linear, toothed with light areas near teeth– Produced in plants <3 m tall
• Adult leaves: oblong of more typical size and shape– Produced in plants >3 m tall
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Pseudopanax chathamicus
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Questions
• Could moa herbivory be a selective pressure leading to colour changes seen in P. crassifolius?– Compared spectral reflectance of different stages
to leaf litter– Compared spectral reflectance to a closely related
species (P. chathamicus) from nearby Chatham Islands (800 km from NZ) lacking moas with a flora derived from NZ
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NZ seedlings
Chatham seedlings
litter
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NZ saplings: thorn
Chatham saplings: thorn
NZ saplings: non thorn
Chatham saplings: non thorn
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NZ adults
Chatham adults
29 NZ spp
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Questions
• Could moa herbivory be a selective pressure leading to colour changes seen in P. crassifolius?– Compared spectral reflectance of different stages
to leaf litter– Compared spectral reflectance to a closely related
species (P. chathamicus) from nearby Chatham Island (700 km) lacking moas
– What do we think?