 tudying plant systematics--how various plants are related to each
other, how they are classified, and the evolutionary processes that
have resulted in different species--might be considered a cross between being
a genealogist and a detective.
The interests in this field of Steve O'Kane, assistant
professor of
biology, range from molecular systematic research on the
mustard
family (Brassicaceae) to the floristics of North
America, that
is, from one particular family of plants to the overall study
of the
plants in a particular region.
The members of the mustard family include, among others,
rapeseed,
broccoli, brussels sprouts, cauliflower, and various spices.
O'Kane
is investigating how a handful of genera within this
family--those
with more than three colpi, or pores, in their pollen
grains--are
related. Zeroing in on bladder pod (Lesquerella) and
double-bladder pod (Physaria), he hypothesizes that
these two
genera should actually be classified as one genus.
In fact,
that's
what the evidence suggests. Both bladder pod and
double-bladder pod
are limited mainly to the southwestern United States, and both
include
rare and endangered species. Molecular analysis shows that
the two
are closely related; the hairs on the leaves and stems are
stellate,
or star-shaped, and these hairs normally vary from one
species to
another. In doing molecular research, O'Kane looks at
sequences of
DNA, microsatellite variation, random amplified polymorphic
DNA, and
intersimple sequence repeats to reconstruct evolutionary history.
If biologists like O'Kane can determine how a group of species
evolved, they will have a better understanding of those plants
and be
able to develop a more accurate taxonomy. And that's where
O'Kane's
second major interest, floristics, comes in. As he says, "We
need to
know what's out there."
O'Kane is currently co-editing a multi-year floristics study of the
basin of the San Juan River, which originates in Colorado and drains
parts of New Mexico, Arizona and Utah before emptying into Lake
Powell. This area, which ranges in elevation from 3,000 to over
14,000 feet, contains many hundreds of species in a diversity of
habitats.
So far, the region has been underbotanized because of its remoteness
and rugged terrain.
cont.
|
|
Focusing on an ecological region, rather than
on a particular state or states, makes more sense, according to
O'Kane, because the boundaries are supplied by nature rather than by
political fiat.
O'Kane and his co-editors, after working one year on the
project, estimate they have six more to go. (O'Kane is also
responsible for writing up the mustard and caper families.)
The finished product will contain descriptions and
illustrations of each species as well as keys to families,
genera and species.
In what little spare time he has, O'Kane curates the Grant Herbarium, named after Martin C. Grant, a former UNI biology professor, and his wife Dorothy, who assisted her husband in collecting and mounting the collection's 40,000 specimens, many of them no longer extant in Iowa.
Following is a selected listing of O'Kane's recent publications related to the research discussed above, as well as his E-mail address.
Al-Shehbaz, I.A., & O'Kane, S.L., Jr. (1997). Arabidopsis gamosepala and A. tuemurica belong to Neotorularia. Novon, 7, 93-94.
O'Kane, S.L., Jr. (1995). Clone bank and physical map of Lopezia miniata Lag. ex DC ssp. miniata (Onagraceae) chloroplast DNA. Biochemical Systematics and Ecology, 23, 507-516.
O'Kane, S.L., Jr. (1990). A new species of Erigeron (Asteraceae: Astereae) from Colorado. Madrono, 37, 184-189.
O'Kane, S.L., Jr. (1988). Colorado's rare flora. Great Basin Naturalist, 48, 434-484.
O'Kane, S.L., Jr., & Al-Shehbaz, I.A. (1997). A synopsis of Arabidopsis (Brassicaceae). Novon, 7, 323-327.
O'Kane, S.L., Jr., Schaal, B.A., & Al-Shehbaz, I. (1996). The origins of Arabidopsis suecica (Brassicaceae), as indicated by nuclear rDNA. Systematic Botany, 21, 559-566.
 steve.okane@uni.edu
|
