Bacteria’s impact on native species
Apowerful bacteria may have affected the evolution of native species such as we¯ ta¯ , a new scientific paper suggests.
The paper also shows for the first time that the bacteria, wolbachia, is present in New Zealand and that one lineage is distinct to this country.
Wolbachia is extraordinary, said Massey University’s Mary Morgan-Richards, a professor of evolutionary biology. It’s generally a parasite and thought to infect 40 per cent to 60 per cent of anthropods (insects, spiders and crustaceans) globally.
It is ‘‘one of the most widespread intracellular bacteria on Earth,’’ wrote Benjamin Bridgeman in the paper that resulted from his master’s degree research. There are an estimated 20,000 species in the genera.
The bacteria is most commonly found in the reproductive organs of host insects, where it can prevent viable offspring, cause male death, feminisation, and parthenogenesis, where reproduction occurs without fertilisation. All these effects have serious consequences for the host, ranging from local extinction to loss of males or speciation.
In many cases, wolbachia is probably benign, Morgan-Richards said in an interview. ‘‘But it’s hidden biodiversity that were only starting to understand.’’
It was first identified in 1924 but nobody had tried to find it in New Zealand natives using modern techniques.
Bridgeman, Morgan-Richards and colleagues used DNA and molecular techniques to find wolbachia in six we¯ ta¯ species, as well as 10 other native and introduced insect species.
Analysis showed two wolbachia lineages were present in New Zealand, one of them distinct to this country.
The bacteria was almost certainly present on these islands before human arrival. Polynesians may have introduced new species via the kiore rats, she said, although research will be needed to establish this firmly.
‘‘When you bring in a new species, you’re also bringing in all of its parasites,’’ she said.
Pa¯ keha¯ absolutely introduced known hosts of wolbachia.
The power of wolbachia to affect reproduction could result in new species, Morgan-Richards said.
‘‘In the past, we think this may have had quite an impact on speciation, driving populations to become reproductively isolated from each other.’’
There’s a forest on the North Island with 12 different species of cave we¯ta¯ living in close proximity.
‘‘Cave we¯ ta¯ fall into a family called rhaphidophoridae and there’s way more rhaphidophoridae diversity in New Zealand than elsewhere,’’ she said. ‘‘It may be that some of that diversity is the result of infection by the bacteria wolbachia.’’
If some populations are infected with wolbachia and some not, the result is likely to be new diversity. ‘‘It’s a good place to investigate further,’’ she said.
Insights into baleen whales
In 1987, Professor Ewan Fordyce accidentally discovered part of a whale skull in Antarctica. His paper on that discovery was finally published last week in the journal Current Biology.
The University of Otago’s researcher relied on pockets of funding over decades to unlock the secrets of the whale. ‘‘Imagine that you have an eggshell to extract from a block of concrete and you’re trying not to damage the eggshell by getting rid of the concrete,’’ he said.
The whale swam the Antarctica seas 34 million years ago and is believed to be the second-oldest baleen whale ever found. The evidence suggests that early whales did not have a baleen. Instead they had welldeveloped gums and teeth, which they used to bite large prey.
Until recently, it was thought that filter feeding first emerged when whales still had functioning teeth, but Llanocetus shows this was not the case, Fordyce said.
‘‘When you bring in a new species, you’re also bringing in all of its parasites.’’ Massey University’s Mary Morgan-Richards