Biology Reference
In-Depth Information
ter
or Carl Ingemars
son
—hence, the “-son” ending for many Swedish family
names. Upon a student's entrance to the university, a surname was selected
and Carl's family took theirs (Linné) from the great linden or linn tree
(
Tilia
) at the family home. That name, when Latinized, became Linnaeus.
(Later, when Linnaeus was ennobled, he became Carl von Linné.) Halen's
academic name was a simpler derivation: he became Jonas P. Halenius.
In addition to the use of academic names, another unusual aspect of
Swedish academic life was that the professor, rather than the student, usu-
ally wrote the thesis. The student's role was to defend his professor's posi-
tion in Latin and in public debate. The goal was to demonstrate mental agil-
ity, familiarity with the rules of formal disputation, and fl uency in Latin;
the originality of the thesis did not greatly matter. This is evident from
Linnaeus's comment regarding another student's thesis: “Mr. Kalm ought
to dispute pro gradu
de O
(
e
)
conomiae patriae augmento opera L. B. Bjelke.
This he ought to do out of gratitude . . . I will dictate the fi rst version.”
The thesis chosen and written by Linnaeus for Halenius to defend—
Plantae
rariores camschatcenses
—was that some plants in the Kamchatka region of
eastern Russia were similar to ones in eastern North America. It was not
a matter of whether the species were continuous or disjunct between the
two regions, for Linnaeus knew little of the intervening vegetation. It was
an observation that there were plants in eastern Asia similar to ones in far-
away eastern North America. Subsequently, the distributions were found to
be very much disjunct (Gray 1840, 1846; Li 1952; Wen 2001), sometimes
with outliers in moist areas of the American west like the San Francisco Bay
area and in the Middle East. The disjuncts included genera such as
Acer
,
Aesculus
,
Carya
,
Clintonia
(fi g. 9.1),
Cornus
,
Fraxinus
,
Liquidambar
(Ickert-
Bond et al. 2005),
Liriodendron
,
Magnolia
,
Nyssa
,
Sassafras
,
Vitis
, and others.
From the modern perspective, any explanation for the disjunction would
require an accurate phylogeny of the organisms (Xiang et al. 1998) to assess
the areas of possible basal and derived species (i.e., direction of migration),
and an accurate geologic, climatic, and fossil history to reveal the cause(s),
time, and plausible opportunities for migration.
A starting point for considering the origin of the distribution pattern
is to pose the question, “What was it that became disrupted, fragmented,
or that migrated, to yield residual populations in eastern Asia and eastern
North America, and small relictual populations in other temperate enclaves
of the Northern Hemisphere?” The answer, based on the plant fossil re-
cord, is that it was the broad band of deciduous forest and temperate envi-
ronments that extended across much of North America, Asia, and Europe
in the Oligocene, Miocene, and through about the middle Pliocene, with
