Evolution in NZ by yurtgc548

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									     Evolution in NZ
Geological  Time Scale
Some useful information.

Significant Geological Events

Biological Factors that have
shaped NZ’s Flora and Fauna.
Eras       Epochs         Periods     Age
                                      (millions
                                      of years)
Cenozoic Quaternary       Recent          0.01
                          Pleistocene     1.8
           Tertiary       Pliocene          5
                          Miocene         23
                          Oligocene       35
                          Eocene          57
                          Paleocene       65
           Known as K/T
           boundary

Mesozoic                  Cretaceous     144
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.
   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.
New Zealand’s flora and
  fauna (biota) are a
mixture of vicariant and
   dispersed types.
      Organisms present during the
      Cretaceous (vicariant groups)
   Dinosaurs                Peripatus
   Ratites                  Giant Land Snails
   Wrens                    Skinks
   Tuatara                  Geckos
   Frogs (Leiopelma)        Beeches
                             Kauris
                             Podocarps
Like being on Noah’s
  Ark! They will drift
  with NZ. They are the
  “Gumboot Gang”
 Significant Events in
NZ’s Geological History
 These specific occurrences
 have made NZ the unique
        place it is.
      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.
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)
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
   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
 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
   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.
             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.
Biological Factors that
  have shaped NZ’s
  Flora and Fauna.
       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)
 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.
          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.
        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.
             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.
                   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.
    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.
               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.
THE END

								
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