>> _Darlingtonia_ did rather certainly reach the Cascade Range from the
>>(?S-)E and not from the N.
> I believe there are two errors in the statement: D. californica does not
>occur in the Cascades at all.
Well, so how do you call the mountains in Oregon whence this species is
reported? I would include them in the Cascade Range but I am prepared to
learn (seriously!).
>All reputable biogeographies indicate that the Siskiyou/ Klamath Mountains
>and related Trinity Alps are the center of D. californica's distribution -
>these ancient mountains
How old are they, approximately?
>were for a time an island when the rest of the region
>was ocean or suffered from vulcanism, and the Siskiyous has a rather unique
>flora.The Sierras arose later and suffered heavy glaciation repeatedly.
And still _Darlingtonia_ occurs there now. The mountain ranges you
mentioned might have been the refugia or even the origin whence the genus
spread (after it came there from the (?S-) E, and -I admit- before it
reached the "Cascades") but the recent range is larger. Remember Mt. Shasta
at the "interface" between what I have called the Cascade Range and the
Sierra Nevada is the locus classicus of this species. Nevertheless, I would
like to read some of the biogeographies you mentioned. Could you please
cite one. TNX.
>The
>assumption that the Sarraceniaceae evolved in the S.E. United States is in
>question - there is no fossil record, and are no obvious ancestors living.
Only Tom (v.i.) has stated (something like) this. Indeed, _Sarracenia_
seems to be a rather modern genus in this family with only comparatively
little montane endemism (I wrote "comparatively"!), recent sympatric
speciation, a high degree of hybridization, extended planar distribution in
the temperate zone and excessive range extensions since Pleistocene: most
of the recent range of _S.purpurea_ (almost all of the northern expression
of this taxon) was covered by an ice shield during (most of) the
glaciations.
>The family may just as well have evolved in the west or South America and
>radiated from there to the southeastern mountains and coastal plains.
The latter (origin in NE S AM) seems more likely (to me): _Heliamphora_ is
apparently the most "primitive" genus in the family: the traps are rather
simple (e.g. median wings only partially fused), the flowers are of a very
simple structure with no articulation of the perianth (but with rather
specialized androecium!), the range is of a very conservative tropical
highland type characteristic for a large number of old relict elements (cf.
Dipterocarpaceae, Tetrameristaceae etc.) with comparatively little climatic
change through long periods of time.
Chromosome numbers are rather puzzling: 30 in _Darlingtonia_, 26 in
_Sarracenia_, and 42 in _Heliamphora_.
All the genera of Sarraceniaceae seem to be of rather ancient origin, and
distinct from each other since a long time (perhaps even longer than the
genera in Droseraceae). It is thus difficult to tell at which time the
decisive events of generic delimitation have taken place (possibly before
Tertiary?), and which geographic routes the ancestors of the recent genera
have taken.
However, if we assume that _Darlingtonia_ is at least younger than
_Heliamphora_ (I and several others do/did so), the ancestors of _D._ must
be assumed to have reached the present range from (?S-) E, just like I have
written. Anyway, there is no indication of a northern (Canadian) origin of
_Darlingtonia_ or any other Sarraceniacea.
Dear Tom,
>I seem to recall that the presumption was that S oreophila and S. rubra
>jonesii were considered remnant locations geographically, at least
>partly because of the presumption that dispersion into these locations
>could not have easily occurred otherwise. I thought I also understood
>that at least S. oreophila was considered more primitive - or at least
>was suspected of having characteristics more likely associated with
>more primitive forms of Sarrs.
This is probably true (within _Sarracenia_) but it does not affect the
relationships between the genera of Sarraceniaceae.
>At the same time, I also have my own personal bias
>against believing that the Heliamps. are reflective of some evolutionary
>precursor to the modern Sarrs. Personally, these species seem to me to be an
>effective, unique solution to the problem of insectivory and are not simply
>less evolved, primitive cousins of the SE USA Sarrs.
This is also true but still _Heliamphora_ shows a larger accumulation of
"primitive" (plesiomorphic) traits than _Sarracenia_ (v.s.). So
_Heliamphora_ seems to be morphologically closer (fewer mutations changing
the shape of the plants) to the presumed common ancestor of both genera
(even if they are approx. the same number of generations apart from that
ancestor).
Certainly, if palaeo-_Sarracenia_ had once occurred sympatrically with
palaeo-_Heliamphora_, and if we assume that palaeo-_Sarracenia_ was the
(prae-)genus which has moved away from the place of common origin (which I
would think. At that time possibly still including palaeo-_Darlingtonia_),
then we would have to answer the question why no remnant of
palaeo-_Sarracenia_ managed to survive in the present range of
_Heliamphora_.
Perhaps an answer to this bothersome question is a (hypothetical) scenario
where the decisive evolutionary step was a +/- loose distinction between a
montane ("H") and a planar ("S") type, each of which adapted to a suitable
habitat before the onset of climatic changes. These changes might have
forced the "S" to migrate towards the N (-W?) because the lowland habitats
of what is now the Guyana shield became too inhospitable, and because "S"
was not able to reach higher altitudes rapidly enough, and/or because "S"
was not able to cope with the competition by "H" which was better adapted
to these habitats already, while "H" was captured in these higher
elevations of what is now the summit region of the Tepuis.
OK, I am at a loss somewhat in explaining what happened in the N afterwards
or even how (i.e. which way) Sarraceniaceae came there. "Somehow", a "D"
type emerged which was later trapped in the mountains of the far W of the
US (perhaps even before there was something like the Rockies), while the
"S" type remained planar and somewhat more in the S (-E). The disjunction
between _Sarracenia_ and _Darlingtonia_ is a rather large one now but if we
subtract _Sarracenia purpurea_ (which I have explained to have experienced
very recent range extensions) for the moment, this genus is confined to
subtropical regions nowadays only found in the SE of the US. So again
climatic changes, flooding, etc. may have caused differentiation/
separation of the genera (do perhaps the reputable biogeographies indicate
such? ..."were for a time an island when the rest of the region was ocean"
does nearly seem so!).
Kind regards
Jan