Article By Deb Carson
In addition to sunshine, paradise here in our corner of the world is chock full of tech innovations and world-class scientific research. Discover notable locals who make a difference, starting with Dr. Deby L. Cassill, whose maternal behavioral research on ants, sea turtles and more are featured this month.
Deby L. Cassill, Ph.D., Associate Professor in Biology at USF St. Petersburg, whose groundbreaking “maternal risk-management model” published recently in the journal Scientific Reports, examines how pressures from natural selection
– predation and resource scarcity
– influence how mothers of various species, including humans, invest in offspring quantity and quality.
For Cassill, life is a journey. Her career path took her from community mental health, to the cost of health care in Florida, to biology. In 2001 she became an Assistant Professor at USF on the St. Petersburg campus, where she’s studied the fascinating social behavior of ants as a conservation biologist. In her own words, she describes what she has learned from ants and sea turtles.
Ants Are Us: No other animal, except ants, mirrors so completely the social structure of humans. Ants were the lens through which I came to understand the hierarchical nature of all social animals, including humans, Ants are a family and a corporation, with the queen as the head-of-household and CEO. The queen, her fertile daughters and her sons comprise the family.
The queen and her thousands of sterile daughters, the workers, comprise the corporation. The working daughters are the labor force that protects and nourishes their queen mother and her fertile offspring. The working daughters construct a permanent subterranean home — no primate, other than humans, constructs permanent shelters — establishes a territory and a far-reaching subterranean transportation system within that territory that allows them to forage, hunt, butcher and transport food back to their home and family members. Interestingly, it’s the aging spinsters, not the males, who patrol the borders and go to war if neighbors invade.
Sea Turtles Are Really, Really Old: Sea turtles emerged during the reign of the dinosaurs and shared the oceans with a rich diversity of other air-breathing reptiles. As the majority of marine reptiles became extinct, the tenacious sea turtles flourished. Why? My model provides a window into how and why sea turtles have survived despite the fact that, on the coastal beaches annually, females abandon egg clutches to the destructive nature of storms, predators and the intrusion of development by humans.
Every organism exists as the result of reproduction. Surprisingly, until my recently published model of maternal risk-management, there was no comprehensive, published theory of reproduction, just a number of
fragmented theories. If we want to understand biodiversity and the rich lives of the animals around us—the sea turtles, the whales, the panthers, the birds, the alligators—we need to understand the reproductive decisions that females, regardless of species, make.
Why do sea turtles abandon their egg clutches when alligators protect their egg clutches and even carry hatchlings to the water? My maternal risk-management model—it’s really a map-of-life—allows us to see and understand how females counterbalance the different kinds of destructive forces of nature. For sea turtles, the solution is to scatter thousands of eggs in small clutches over many breeding seasons, hoping that at least two of them will survive to replace the female and her mate.
What’s Next? The consolidation of all USF campuses coincided with the emergence of Dr. Cassill’s maternal risk management model as a sub-field of Conservation Biology and she’s looking for more funding so graduate students can help to expand her work into how females of any species repopulate ecosystems.
Great article!