Women (and men) can take the next step at Agnes Scott to enter the healthcare field.
College graduates can enroll in our post-baccalaureate pre-medical program for additional
courses needed to enter a medical career.
When the leader of a group is no longer in the picture, a
new leader steps forward to take the reins. But with certain species of fishes,
leading a group or assuming control over a territory involves a switch beyond
changing from follower to leader.
For the bluebanded goby, an aspiring leader may have to make
a more extreme change—altering its sex.
“Sex change is not uncommon in fishes, about five percent of
fish are sex changers,” said Lock Rogers, assistant professor of biology at
Agnes Scott College. “There are no mammals who are naturally sex changers, so
as mammals, it does feel like a strange thing to strategically alter one’s sex,
yet it’s not. It still brings a smile to my face to think about how simultaneously
weird and completely sensible it is for these organisms.”
When they reach a certain size, bluebanded gobies can switch
their sex from female to male in situations where being male is an advantage.
For instance, one male typically leads and mates with a group of many females,
called a harem. If the male dies or
leaves and there is no male to take its place, the largest female will then
become male and assume control of the harem.
To find out more about this interesting sex and power
dynamic, Rogers and Megan Williams ’13, a biology student at Agnes Scott, spent
a few weeks in 2012 studying bluebanded gobies at the USC Wrigley Institute
for Environmental Studies on Catalina Island, 20 miles off the coast of Los
Rogers and Williams dove off the coast of the island, where the
gobies live, to collect harems and temporarily observe their behavior and
reproductive rates in aquaria at the institute before releasing them back into
“When the male dies and the largest female becomes male,
there are sudden pulses of growth among the other females and everyone grows
pretty quickly and moves up the ranks. We’re interested in how these fish
allocate resources for growth versus reproduction, depending on the dynamics of
the harem,” Rogers said.
Rogers and Williams’ experiment involved setting up harems to
include a male plus two females—one large and one medium-sized—in half of the aquaria,
and one male plus a medium and a small female in the other half. With this
group dynamic, half the medium-sized fish were next in line to take over the
harem and as a result had better incentive to use their energy to grow larger and
eventually become male instead of producing eggs. The other half were not in a
position to take over the harem, so they had lower incentive to forgo
reproduction and grow larger.
Though they’re still working to analyze their results, Rogers and Williams expect that the medium-sized females paired with a
smaller female will exhibit relatively low reproductive rates and relatively
high growth rates.
They’re particularly interested in whether these findings
will be consistentwith the behavior
of other sex-changing fish Rogers has studied. Rogers, Williams and Kelly Smith
’12 conducted a related research project in St. Croix, U.S. Virgin Islands,
last summer studying the bluehead wrasse.
“While the field work is always fun and beautiful, seeing
the data and trying to work out whether they reject or confirm our hypothesis back
at Agnes Scott is very exciting,” Rogers said.