[Taxacom] NZ biogeographer's exam Q3
gread at actrix.gen.nz
Sat Jan 28 22:02:23 CST 2017
If Cook Strait only last opened 15 000-16 000 years ago (I saw this as the
date used in another paper on marine mussels) it's not going to be very
significant as an ancient barrier for land biota. I imagine it has come
and gone over time. Sure is a barrier since though.
On the article on estuarine Austrovenus stutchburyi - interesting but they
missed out sampling a very large population in Porirua Harbour bordering
Cook Strait (only sampled Wellington Harbour). They also threw in the
possibility of human-mediated translocation messing up the picture (these
are edible cockles), which is a new one to me. There's no supporting
citation for the idea.
On Sun, January 29, 2017 12:37 pm, John Grehan wrote:
> NZ biogeographer's exam Q3
> Why is it not necessary to assume that a Cook Strait boundary in a
> terrestrial group is the result of the sea barrier?
> âIt is natural to assume that a Cook Strait boundary in a terrestrial
> is the result of the sea barrier. Yet many southern groups reach their
> northern limit at the *northern* side of the strait (e.g., the cicada
> strepitans*; Marshell et. al., 2012). In a similar way, many northern
> groups have their southern limits at the southern side of the strait. For
> example,* Hebe parviflora* (PLantaginaceae) is widespread in the eastern
> North Island and has its southern limit along the northeastern shores of
> the South Island (Marlborough Sounds, Cape Campbell) (Bayly and Kellow,
> 2006). These distributions indicate that it is the Cook Strait region â
> the strait itself â that marks the phylogenetic break.
> In a similar pattern to that of these last, terrestrial groups, Ross et a.
> (2012) reported a Cook Strait break in the estuarine bivalve, *Austrovenus
> stuchburyi*, but noted that the break does not coincide exactly with the
> modern strait. Instead, northwest Nelson specimens belong to the North
> Island clade, and Wellington specimens are in the South Island clades.
> Again, the pattern suggests that the modern topography of the Cook Strait
> region is not relevant to the biogeographic break."
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Geoffrey B. Read, Ph.D.
Wellington, NEW ZEALAND
gread at actrix.gen.nz
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