In the late 20th century the life sciences were revolutionised by molecular studies. The structure of the DNA (deoxyribonucleic acid) molecule, through which living organisms pass on genetic information, had only been known since the early 1950s. It was discovered by James Watson and Francis Crick. Maurice Wilkins, a biophysicist born in New Zealand, was one of the scientists who developed the X-ray crystallography essential to Watson and Crick’s research.
In the 1980s the invention of the polymerase chain reaction (PCR) brought a further revolution in the ability to study the structure of DNA molecules. The PCR process allowed small sections of DNA to be copied many times, creating enough material for effective analysis.
New Zealander Allan Wilson was a biochemist and evolutionary biologist at the University of California at Berkeley. He was the first to test the ‘molecular clock’ theory: because molecules change at a steady rate, comparing the variations of molecules from different species should indicate their evolutionary relationships. In 1967 Wilson and anthropologist Vincent Sarich compared a particular blood protein from humans and chimpanzees. They reached the controversial conclusion that human and chimpanzee species had diverged only about five million years ago.
Wilson went on to study human evolution through mitochondrial DNA, which is passed directly down the female line of ancestry. In 1987 he proposed another controversial theory, that all modern humans could be traced back to one ancestor, ‘Mitochondrial Eve’, who lived in Africa around 200,000 years ago.
Genomics and bioinformatics
A genome is the complete set of DNA in the cell of an organism. From the early 2000s the genomes of many species, including humans, were sequenced. Genomics and other genetic techniques produce masses of information, which have to be analysed by a combination of computing, mathematics and statistics. These systems are known as bioinformatics. Genomics, combined with bioinformatics, has led to great advances in such fields as ecology, evolution, microbiology, epidemiology and biosecurity.
New Zealand institutions carrying out genomic related studies include:
- the Allan Wilson Centre for Molecular Ecology and Evolution – a national collaboration between Massey, Auckland, Canterbury, Victoria and Otago universities
- two Crown research institutes: Plant and Food Research and Landcare Research
- Maurice Wilkins Centre for Molecular Biodiscovery – based at Auckland University and carrying out biomedical and biotechnological studies
- Regulatory Genomics Laboratory at Otago University, which in 2014, led by Dr Chris Brown, concentrated on deciphering genomes
- Bioinformatics Institute New Zealand at the School of Biological Sciences, University of Auckland – which uses advanced mathematics and statistics to investigate a wide range of biological subjects
- New Zealand Genomics – a government-funded body carrying out DNA sequencing, microarray analysis and bioinformatic work.
An international scientific project began in the early 2000s to identify all species of life on earth by a scheme known as ‘DNA barcoding’. The scheme involves sampling and comparing the same specific section of DNA from different organisms, in the hope that this sequence can be used to accurately identify species. In New Zealand and internationally the early studies for this project were carried out on birds. The idea was to build up a genetic picture of a well-known group of species to test the accuracy of the barcode against the existing knowledge of bird identity.
By comparing the DNA sequences of different species, scientists have gained a better idea of their systematics, or evolutionary relationships. Species include:
- the New Zealand parrots – kākā, kākāpō and kea
- takahē and pūkeko, along with swamp hens from neighbouring countries
- New Zealand geckos
- many types of plants including Veronica (formerly Hebe), Dracophyllum and kauri.
Genomic work on systematics has been particularly useful in looking at the relationships of invertebrates. Thomas Buckley of Landcare Research has worked on stick insects, wētā, earthworms and terrestrial molluscs, showing how they came to live in their current habitats. This work has assisted efforts to save rare species such as giant wētā and native snails.
Amateur researchers have always played an important role in science. The internet has expanded the potential for the public’s involvement in science. One such project is the annual garden bird survey when people around New Zealand record the birds they see in their gardens over one hour. The results are then sent in to the co-ordinators of the study. Another project is the the ebird scheme run by Cornell University, in which New Zealand bird watchers can now add observations to an international bird database.
Since 1984 DNA has been sampled from the remains of many extinct animals, including cave bears, mammoths and moa. Ancient DNA studies have given insight into the number of moa species, the relationship between moa and kiwi, and the relationship of New Zealand’s extinct Haast’s eagle to surviving eagle species.
Studies on living and extinct species have indicated that the majority of New Zealand’s plant and animal species are descended from ancestors that reached the islands after the split from the larger continent of Gondwana.