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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.

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Presentation on theme: "Evolution in NZ  Geological Time Scale  Some useful information.  Significant Geological Events  Biological Factors that have shaped NZ’s Flora and."— 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 ErasEpochsPeriods Age (millions of years) CenozoicQuaternaryRecentPleistocene0.011.8 TertiaryPliocene5 Miocene23 Oligocene35 Eocene57 Paleocene65 Known as K/T boundary MesozoicCretaceous144 Jurassic206

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.


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