Tag Archives: ancient DNA

DNA finds kiwi’s origins: Introducing Stewie

A number of biological specimens in Te Papa’s collection, particularly old specimens, lack information about when and where they were collected. This information may have been lost since the specimen was collected or was simply not recorded at the time.

However, all is not lost! Sometimes we can use DNA to determine where a specimen was collected.  We recently used DNA sequences to examine the provenance of a number of Te Papa’s unlabelled kiwi specimens.

One particularly stunning specimen we looked at is this articulated kiwi skeleton. 

Articulated kiwi skeleton from Te Papa's collection. Photo by Lara Shepherd.

Articulated kiwi skeleton from Te Papa’s collection. Photo by Lara Shepherd.

As I mentioned in an earlier blog on kiwi the bones of great spotted kiwi and the three species of brown species are very similar in size and shape and can’t be distinguished. Therefore, this kiwi skeleton could have potentially belonged to any of these four species.

To obtain bone material for our genetic analysis we drilled a small hole underneath the pelvis. Our aim was to minimize the visible damage to the skeleton.

Close-up of the hole we drilled in the pelvis to obtain bone for DNA analysis. Photo by Lara Shepherd.

Close-up of the hole we drilled in the pelvis to obtain bone for DNA analysis. Photo by Lara Shepherd.

 We compared the specimen’s DNA sequence to sequences previously obtained from kiwi from known locations around New Zealand.

The results showed that this kiwi skeleton is a Tokoeka (also known as Southern brown kiwi) from Stewart Island.  This result increases the scientific value of this skeleton and is particularly exciting because there aren’t many kiwi from Stewart Island in museum collections.

Link to our study.

When did little spotted kiwi become extinct on the New Zealand mainland?

Little spotted kiwi  only occur in New Zealand, where there are around 1500 individuals remaining.  They are the smallest kiwi species, about the size of a bantam hen, and are very susceptible to predation by introduced mammals, such as stoats and dogs.  Today they survive on predator-free offshore islands and the fenced mainland sanctuary Zealandia in Wellington.

Little Spotted Kiwi, Apteryx owenii, collected no data, New Zealand. Gift of the The Hawke's Bay Art Gallery and Museum, 1949. Te Papa

Little Spotted Kiwi, Apteryx owenii, collected no data, New Zealand. Gift of the The Hawke’s Bay Art Gallery and Museum, 1949. Te Papa

Although little spotted kiwi currently have a very restricted distribution, deposits of bones (e.g., in caves) indicate that they used to occur throughout New Zealand.  When did little spotted kiwi disappear from the mainland?

Little spotted kiwi in the North Island were already very rare when Europeans settled New Zealand. Only one or two live birds have ever been collected from the North Island mainland for museum collections, both in the 19th century.

In contrast, little spotted kiwi were common on the west coast of the South Island at this time.  When exactly they disappeared from the South Island is unclear, with misidentification with the related great spotted kiwi adding to the confusion.  However, it has been widely reported that South Island little spotted kiwi went extinct in the 1930s.  Other researchers disagree and think that little spotted kiwi were present on the west coast for much longer.

Our recent study has shed light on this debate.  We used DNA to identify to species three dead kiwi found in the South Island that post-date the 1930s.  These kiwi are now held in Te Papa’s bird collection.

Link to our study

We were able to show that a kiwi specimen found in 1952 from central Westland and two other kiwi specimens found in 1978, from NW Nelson and south Westland, were all little spotted kiwi (as opposed to juvenile great spotted kiwi).  This suggests that little spotted kiwi survived, and were widespread, in the South Island until much more recently than generally accepted.

Map of the locations where three post-1940 little spotted kiwi were found (names in black type). Today’s little spotted kiwi all derive from birds that survived on Kapiti Island (red type). Base map supplied by Geographx (http://www.geographx.co.nz/).

Map of the locations where three post-1940 little spotted kiwi were found (names in black type). Today’s little spotted kiwi all derive from birds that survived on Kapiti Island (red type). Base map supplied by Geographx (http://www.geographx.co.nz/).

Little spotted kiwi today all originate from a few individuals from Kapiti Island and are highly inbred with very little genetic diversity.  This may mean they have reduced resistance to new diseases and an increased risk of genetic defects.  If there was more certainty about the identity of the remaining mainland birds in the 1970s perhaps more effort could have been made to locate and move surviving little spotted kiwi to predator-free islands.  This would likely have boosted the genetic diversity surviving in this species today.

This result demonstrates how little we know about our native species, even the prominent ones like our (unofficial) national bird, the kiwi.  If so little was known about kiwi, then what about other reclusive members of our fauna thought to be recently extinct, such as South Island kokako, or less charismatic but equally interesting species, such as our greater short-tailed bat (Mystacina robusta)?

Learn about South Island kokako.

Learn about the greater short-tailed bat.

Using DNA forensics to determine the past distribution of the brown kiwi species rowi.

Yesterday was a special day for 20 rowi (a species of the flightless kiwi) who were flown from the South Island to their new home on Mana Island, near Wellington. It was reported that this was the first time that this species of kiwi had been in the North Island for over a century.

So how do we know that rowi used to be in the North Island?

Kiwi researcher Kristina Ramstad holding a rowi. Photo by Rachael Abbott.

Kiwi researcher Kristina Ramstad holding a rowi. Photo by Rachael Abbott.

Today kiwi are absent from large areas of New Zealand, including the southern North Island (North Island brown kiwi occur from the central North Island northwards).  We know that kiwi used to occur in the southern North Island because their bones have been found in caves and other deposits.  However, trying to identify kiwi species just by looking at the shape and size of their bones is tricky.

Little spotted kiwi is the only species that can be identified from its bones because they are much smaller than the other kiwi species.  The bones of great spotted kiwi and the three species of brown kiwi (rowi, North Island brown kiwi and tokoeka) can’t be identified to species because they overlap in size and shape.

This is the kind of puzzle that DNA can solve. As part of my PhD I examined the past distribution of each kiwi species by sequencing DNA from kiwi bones that had been collected from throughout New Zealand.  Some of these bones were up to several thousand years old, but they still contained small amounts of DNA!

Surprisingly I found that the bones in the southern North Island were most closely related to rowi, rather than the geographically closer North Island brown kiwi.  Today rowi only naturally occur in one small population at Okarito on the West Coast of the South Island and they are the rarest species of  kiwi.  My DNA work showed that they used to occur as far north as the southern Hawke’s Bay. You can read the published results here.

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