Transcript NZ Flora - phylodiversity.net

Communities, biogeography, and
selective forces: Flora (including NZ
flora and moa herbivory)
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?
NZ
• Shearing: Sheep grazing
• Sheep (60 m) outnumber people (3m) by 20:1
NZ
NZ herbivorous birds
• NZ lacked native mammals (except 2 bats)
• 50% terrestrial birds eat non reproductive
plant parts
Southern brown kiwi
Paradise shelduck
Weka
Kakapo
NZ quail
NZ pigeon
Kea
North Island
kokako
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)
Moas
• Closest relatives emus, cassowaries, tinamous,
rheas, kiwis
• Snapping: Ostrich feeding
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)
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
Ferns
Gymnosperms
Lots!
Angiosperms
Flora
• Why my these evolve?
– Divaricating
– Heteroblasty
– Colour change
Functions?
• Physiological tolerance of low temperatures,
high wind or high light
• Moa herbivory
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
Evolution of colour changes
Evolution of colour changes
Ferns
Gymnosperms
Angiosperms
Pseudopanax crassifolius
Pseudopanax crassifolius
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
Pseudopanax chathamicus
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
Chatham seedlings
NZ seedlings
litter
Chatham saplings: non thorn
Chatham saplings: thorn
NZ saplings: thorn
NZ saplings: non thorn
29 NZ spp
NZ adults
Chatham adults
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?