Evolution In Nz
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Evolution In Nz

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Powerpoint presentation on NZ endemic species and their evolution in isolation with resultant special features.

Powerpoint presentation on NZ endemic species and their evolution in isolation with resultant special features.

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Evolution In Nz Presentation Transcript

  • 1. Evolution in NZ
    • Geological Time Scale
    • Some useful information.
    • Significant Geological Events
    • Biological Factors that have shaped NZ’s Flora and Fauna.
  • 2. Known as K/T boundary 206 Jurassic 144 Cretaceous Mesozoic 65 Paleocene 57 Eocene 35 Oligocene 23 Miocene 5 Pliocene Tertiary 0.01 1.8 Recent Pleistocene Quaternary Cenozoic Age (millions of years) Periods Epochs Eras
  • 3. The Key Factors that have shaped NZ’s Biota are:
    • Isolation – NZ has been isolated from other land masses for 65 million years.
    • Lack of terrestrial mammals – many of the niches occupied by mammals in other parts of the world have been filled by a diversity of birds, insects and reptiles. Lack of mammalian predators has allowed species to develop in a way that has ill suited them to the influx of humans and their mammal associates.
    • Size – NZ has a relatively small landmass that at times has been considerably smaller.
  • 4. There are two basic processes which explain why a species occurs in a specific area :
    • Dispersal – a species can move itself to eg NZ on currents, winds, by floating, flying, on rafts of vegetation.
    • Vicariance -The earth itself can move the species by continental drift. Species that were present in Gondwanaland when NZ drifted away from Australia 80 ma are vicariant groups.
  • 5. New Zealand’s flora and fauna (biota) are a mixture of vicariant and dispersed types.
  • 6. Organisms present during the Cretaceous (vicariant groups)
    • Dinosaurs
    • Ratites
    • Wrens
    • Tuatara
    • Frogs (Leiopelma)
    • Like being on Noah’s Ark! They will drift with NZ. They are the “Gumboot Gang”
    • Peripatus
    • Giant Land Snails
    • Skinks
    • Geckos
    • Beeches
    • Kauris
    • Podocarps
  • 7. Significant Events in NZ’s Geological History These specific occurrences have made NZ the unique place it is.
  • 8. Gondwana breaks up.
    • During the Jurassic Period, Gondwana begins to break apart.
    • NZ is connected to Australia and Antarctic portions (fully for the first time) and terrestrial plants and animals from Gondwana colonise NZ.
  • 9. The K/T boundary Mass Extinctions
    • K/T boundary (Cretaceous/Tertiary) was 65 ma.
    • An estimated 85% of all living species at the time are wiped out by a mass extinction event – probably a massive asteroid strike.
    • This was the end of the Age of Dinosaurs and the rise of the mammals ( adaptive radiation into all the empty niches)
  • 10. Losing Australia in the Paleocene!
    • 60 ma the Tasman Sea is fully open and NZ has geographical isolation from Australia.
    • However there are probably not many mammals aboard when NZ starts its journey away from Australia*.
    • Founder Effect.
    • *See list of organisms on slide 6
  • 11. Drowning in the Oligocene
    • 35 ma, NZ was reduced to islands separated by waterways.
    • 18% of today’s land mass remained.
    • Habitat was severely depleted, the temperature was lowered.
    • Reduction in genetic diversity had a large effect on NZ fauna
    • The bottleneck effect
  • 12. Making Mountains in the Miocene
    • Miocene is 23 – 5 ma
    • In the mid-Miocene, the Kaikoura Orogeny(mountain building) thrust up the Southern Alps, and NZ’s other mountains.
    • Geographic Isolation
  • 13. Freezing in the Pleistocene.
    • Ice Ages occurred from 1.8 ma to 14,000 years BP.
    • Cyclical cooling with glaciers advancing; sea levels dropping and land bridges being created with offshore islands.
    • Every 5000 years the interglacial phase caused warmer conditions; glaciers retreating; sea levels rising.
  • 14. What now?
    • We are in an interglacial at present.
    • We also seem to be in the middle of the sixth of the great mass extinctions that have occurred approximately every 100 million years since the Cambrian Period. It takes another 5 – 10 million years for species diversity to recover from these mass extinction events.
  • 15. Biological Factors that have shaped NZ’s Flora and Fauna.
  • 16. Flowers and Pollination
    • We have no indigenous long-tongued bee species (social bees)
    • Most flowers rely on unspecialised agents for pollination so have generalised flowers not adapted to one specific pollinator.
    • Flowers tend to be small and unshowy (often white)
  • 17.
    • Pollinators are indigenous short-tongued bees; some butterflies; some beetles and moths; flies; birds and bats.
    • Some plants have specialised:
      • Wood rose and short tailed bat
      • Mistletoe and tuis or bellbirds
      • Hebe – some specialised adaptations for insects.
      • Red flowers for bird pollinators.
  • 18. Dioecious Plants
    • Because of the lack of specialised pollinators, there may be a problem with self-fertilisation occurring more than is desirable.
    • Dioecious plants have male and female reproductive structures on separate plants and so reduce this problem.
  • 19. Animal Specialties.
    • Flightlessness conserved energy in cold conditions and could flourish in the absence of terrestrial mammal predators.
    • Gigantism is another adaptive feature favouring heat retention.
    • Melanism also favours heat retention and energy conservation.
  • 20. Melanism
    • Some NZ birds are dimorphic with a naturally occurring melanic form within the species.
    • The fantail is an example with the melanic form being more common in the South Island, bearing out the heat retention idea.
  • 21. Flightlessness
    • Most common on isolated islands free of mammalian predators.
    • Significant in
      • - Ratites – Moa and Kiwi
      • Rails – Takahe and Weka
      • Adzebill – now extinct.
      • Wrens – four of the extinct wrens were flightless.
      • Kakapo is the world’s only flightless parrot.
      • Weta, earwigs and stick insects also show flightlessness.
  • 22. Reduced Reliance on Flight
    • Many of our bird species are weak fliers – the wattle birds like Kokako – blue-wattled crow, Saddle back and Huia (now extinct)
    • Lesser short-tailed bats (Mystacina tuberculata, spend most of their time foraging on the ground.
  • 23. Gigantism
    • Haast’s Eagle, Adzebill, Moa, flightless goose, Sea Eagle – all extinct.
    • Takahe, Kakapo
    • Giant invertebrates – wetas.
    • Once again, this is a characteristic that was able to develop in the absence of mammalian predators.
  • 24. THE END