Couple of Botanists, Literally
Husband-and-wife team brings complementary research and
teaching interests in plant physiology and ecology to Guelph
professors Christina Caruso and Hafiz Maherali share research
space in the Bovey greenhouse.
Photo by Martin Schwalbe
Those scarlet and blue lobelia plants growing in
a section of the Bovey greenhouse have been busy, if the
fuchsia-coloured stalks clustered among them are any indication.
The eye-catching hybrids are an appropriate metaphor for
the mingled research interests and personal lives of their
Profs. Hafiz Maherali and Christina Caruso brought their
complementary research and teaching interests in plant physiology
and ecology to Guelph's Department of Botany in January.
To judge by the matching gold bands both wear in idiosyncratic
fashion on their right hands, that's not all they brought.
As the first married couple hired jointly into the department,
the husband-and-wife team of botanists meets in his-and-her
studies of plant parts and plant evolution. Seated in his
first-floor office in the Axelrod Building - directly across
the hall from Caruso's - Maherali grins as he says: "
She's the flower person, I'm the leaf person."
Where physiology and ecology meet is on the common research
ground of biodiversity, an increasingly hot topic among
the assorted botanists, zoologists and molecular geneticists
in offices and labs throughout the Axelrod Building.
"Their research fits nicely with a developing strength
both within the department and in the College of Biological
Science," says Prof. Richard Reader, chair of the Department
Maherali notes that ecologists or evolutionary biologists
are "all in some way trying to understand how biodiversity
evolved, how did we get here. What's gained by the two of
us working together is that we basically bring a whole-organism
He and Caruso, who are members of the Biodiversity Institute
of Ontario planned for U of G, together hope to learn more
about the push-pull between flower structure and plant physiology
in influencing evolution, including studying a chicken-and-egg
conundrum: Do evolutionary pressures on floral traits account
for speciation of plants, or do physiological changes push
those plants down separate evolutionary paths?
To answer those questions, they're studying two closely
related species of lobelia. The red one, Lobelia cardinalis,
is known among perennial gardeners as cardinal flower. Less
common is its blue cousin, L. siphilitica (so-called
because it was once thought to cure syphilis). Even more
obscure is the fuchsia hybrid nestled among its parents
in that Bovey greenhouse.
Different flower structures in the two parent species mean
that various pollinators prefer one or the other. L.
cardinalis attracts hummingbirds; L. siphilitica,
bees. Whereas the red species prefers boggy ground, the
blue one favours a broader range of wet and dry habitats.
Those differences offer varying but complementary possibilities
for botanists. Where Caruso saw a candidate for testing
ideas about adaptive pollination strategies, Maherali saw
it as a study of drought tolerance.
They also find L. siphilitica intriguing because
it's gynodioecious, meaning some plants carry female-only
flowers, and others mix male and female functions on the
same flowers. What were the ecological and physiological
consequences of one or the other?
"It's an evolutionary question," says Caruso,
who wondered why female-only plants hadn't been squeezed
out by hermaphrodites with their twofold breeding potential.
"They have to make up for a disadvantage."
Their study found that female-only plants compensate for
their disadvantage through a physiological difference that
allows them to run a higher rate of photosynthesis to turn
sunlight into more food.
By cross-breeding the two species, she says, "I'm
trying to capture the genetic basis of differences in floral
and physiological traits. What percentage is due to genetic
This summer, the couple set up a joint experiment to examine
the effects on floral morphology and physiology of growing
the plants in either dry or wet conditions.
The duo might not have met at all if Caruso had followed
her initial path. "I started as an ornithologist,"
she says. She studied both plants and animals at Oberlin
College in Ohio. It was during a pollination study that
she realized that what attracted her was not the pollinator
but the "pollinatee."
Maherali was more interested in the physiology of plants
- how they do what they do. A Calgary native who had studied
the topic as an undergraduate at McGill University, he wanted
to learn more about possible effects of global climate change.
With a graduate scholarship in hand, he headed off for
PhD studies at the University of Illinois, where Caruso
was studying pollination and floral evolution. They met
over pizza one evening after a lecture on plant ecology.
Married in 1998 before graduation, they lived apart for
two years after Caruso landed a post-doctoral fellowship
at Grinnell College in Iowa and Maherali went to Duke University.
After racking up numerous frequent-flier points and long-distance
telephone bills, they were ecstatic when Caruso received
a post-doctoral award to Duke from the American Association
of University Women.
That long-distance experience led to their resolution to
find joint postings at one university, a quest that saw
both turn down promising individual offers. They hit gold
with Guelph, where they now share lab space and are team
teaching a graduate seminar course this semester.
"We end up talking a lot about science at home,"
says Maherali, adding that they often vet each other's research
papers and grant applications. They say they aren't afraid
to criticize each other's work. For relaxation, they've
found another shared interest in tending the vegetable garden
at their recently purchased Guelph home.
Presumably, they've figured out a more equitable division
of labour there than during their school days. Becoming
partners at Illinois and then Duke had paid unexpected mutual
benefits. Each automatically got an extra pair of hands
for lab or fieldwork, but the benefit wasn't necessarily
Maherali helped Caruso complete her dissertation on floral
evolution, which meant he got to spend time in mountain
meadows in Arizona. And what idyllic prospect did he dangle
in return? "She helped me grind ponderosa pine needles