The New Zealand Plant Conservation Network

... climate of NZ relative to new Caledonia. The decrease in fruit size with increasing latitude is a well known pattern.

Molloy also notes the relative toughness of the endosperm husk. This is a good bit of evidence for them being different, but I would need some evidence that endosperm toughness does not vary depending on growing conditions.

Molloy also notes leaf differences (he was showing live plants to an audience) but gives no further detail. Again leaf shape is highly plastic and I need to look at the herbarium material to see the differences Molloy notes.

The largest piece of evidence that they are different is that the Forsters described them as such!

The "largest piece of evidence is that the Forsters described them as such?" Them's fighting words for a lineage that diverged from C. dissimilis an estimated 2.3 million years ago, a lineage with a different fruit anatomy and so forth. I have reviewed your interpretation of Wagstaff & Dawson's paper and wish to remind you that the molecular markers used in that study are not the kind one would use for answering your issues but that even so rbcl (a very conservative sequence region) and ITS almost as much both conclusively show that C. laevigatus is distinct from C. dissimilis. Their paper clearly states that, further M. Dawson (pers. comm. November 22 2014) reminded me that there is a chromosomal difference, n = 23 (C. dissimilis) n= 22-23 (C. laevigatus). Endosperm differences are consistent in the wild and in cultivation - Molloy did not use a sample size of one! Nor would anyone else accept your reasoning that 'endosperm toughness may vary due to growing conditions'....

The Miocene aged fossil you discard as evidence is confirmed by B.P.J. Molloy and M. Eagle as C. laevigatus - so not a proto-ancestor either. Low sequence divergence (still BTW 13 base pairs (rbcl + ITS) between them which is HUGE) is typical of the family Corynocarpaceae for the markers used as well. I contend you have interpreted the trees in Wagstaff & Dawson incorrectly, as well as what their paper, and indeed Molloy's states. I have discussed your ideas with Dr(s) Rob Smissen, Brian Molloy and Peter Heenan, and Mr Murray Dawson - all agree your interpretation of the genetic and morphological data presented in their work is incorrect. They await with interest your ecological assessment - for which their are also many alternative explanations.

Thanks Peter, you have put the genetic case well, though I still have a general reservation where genetic studies only sample 1 individual to represent a species - it makes it impossible to judge the degree of intraspecific variation against the quoted level of interespecific variation. If the people you have consulted all are of the opinion that the genetic data is robust, then it makes the alternative explanation more likely - that something screwy is going on with the ecological profile of karaka in NZ. In the interest of the debate would you (or someone else) like to propose alternative explanations for the ecological observations? It would also be very interesting to have the morphological data presented in Molloy's informal conference paper in a more comprehensive and accessible format. This is a useful debate as I have a draft paper containing my ecological data. I'll be in touch with the people you note to get their permission to pers. comm. their support for the genetic study

As a result of Peter providing me with additional info outside of this discussion I am now happy to concede that my hypothesis that karaka is exotic in NZ is unlikely. Which means that there are some very strange things happening (or more not happening) with karaka in NZ which indicate that it does not function in NZ forest ecosystems in a similar fashion to other indigenous tree species. What information that is needed to help clarify the situation is:

1) what is the palatability of karaka fruit to kukupa relative to other fruit?
2) do karaka groves displace other vegetation in Northland?
3) what are the indigenous insect fauna of karaka, particularly species that would impact on fruit germination and seedling survival when compared with species such as taraire or tawa?

Any students out there looking for thesis topics?

And thank you Peter for your patience when I get an idea in my head!

Mike

Phew! Long debate and yes I agree there are aspects of the autecology and general ecology of karaka that are problematic, but then what does one expect of such a peculiar family? Good luck with that paper.