Evolution In Nz


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

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Evolution In Nz

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