Converging for the Birds!

This post was written by Rachel Jabaily, currently a post-doc in the lab of Assoc Professor Tim Motley, about the current display in the Kaplan Orchid Conservatory.

Converging for the Birds:

The plant families Orchidaceae (the orchids-25, 000+ species) and Bromeliaceae (the bromeliads- 3200+ species) are not closely related.  But both have a group of species (genus) in the New World with uncannily similar general flower shape and colors. 

In our living collection we have specimens of the orchid genus Stenorrhynchos, a group of ~7 species found in the SW United States, the Caribbean, Central America, Brazil and much of the Andes.  Notice the red, narrowly opened flowers, each protected by a big bract.

Compare the orchid with these pictures of the bromeliad genus Pitcairnia.  This genus is also only found in the New World tropics but has several hundred species.   See how outwardly similar it appears to the Stenorrhynchos inflorescence (branch of flowers)? The similarity is only skin-deep, though; the bromeliad flower’s reproductive parts (pistil and stamen) do not fuse into a column, which defines the orchid family.

This is a great example of convergent evolution, in which lineages of unrelated organisms evolve in similar ways to similar evolutionary pressures.  In this case, the plants evolved to attract hummingbirds as pollinators, which love red, tubular flowers with lots of nectar at the base.

Interestingly, only ~3% of the world’s orchids are pollinated by birds, with the majority of species using bees, wasps and flies as pollinators. Many orchid species have an extremely specific pollinator relationship with a single insect species.  Bromeliads generally utilize much more promiscuous hummingbirds, and may have fewer species than the orchid family because of it!

We have many other examples of living bromeliads in the Kaplan Conservatory- look UP on the pillars and walls for examples of epiphytes (plants that grow on top of other plants in the rainforest) and DOWN in pots by the entryway for larger specimens that have overlapping leaf bases which hold water like a vase for the plant to use later- also an important water source for many animals!

Here are a few more examples from unrelated plant families that have converged on the hummingbird floral syndrome in the New World tropics…

Text and photos by Rachel S. Jabaily, 2011 except photo of Stenorhhynchos: Golden Gate Orchids, and Pitcairnia: J.M. Manzanares

Dr Meredith Kintzing, PhD.

Congratulations to Dr Kintzing who triumphed over personal tragedies to graduate with her PhD in Ecological Sciences in Dec 2010. Meredith joined the PhD program in 2004 under the mentorship of Dr Mark Butler. Meredith's studies involved traveling up and down the east coast from her home here in VA to her main research site in the Florida Keys where she spent the summer, or entire semesters immersed in her "lab". In addition, she was able to fit in classes, trips to scientific meetings and other exotic research sites, as well as the occasional marathon or half marathon. Currently Meredith is a post-doc in the biogeochemistry lab of Chris Martens in the Marine Sciences Department at the University of North Carolina at Chapel Hill.

From Meredith:
Being a graduate student in marine ecology is challenging, exciting, and rewarding. As a graduate student at ODU I had the opportunity to dive the coral reefs of the Florida Keys and Belize while conducting research that addressed interesting scientific questions that also had applications to managing this resource. Like any graduate program it involved a lot of hard work, but on any given day I might see a sea turtle, manatee, or shark in addition to the invertebrates that were the focus of my research. When your “office” is the ocean every day is an adventure.

Research: Human activity has stressed the world’s oceans. Nowhere is this more evident than coral reefs, especially those of the Caribbean. Caribbean reefs began experiencing declines in coral cover in the early 1980s attributable to a number of factors including overfishing, pollution, disease, and loss of key herbivores. I am interested in coral reef communities particularly determining the causes and consequences of their decline. My research focuses on trophic interactions, or who eats whom, on the coral patch reefs of the Florida Keys. My dissertation focused on how the spotted spiny lobster altered patch reef communities. I found the spotted lobster has a broad diet that includes several important herbivorous, or seaweed eating, invertebrates. In addition to consuming herbivores, the spotted lobster also alters the behavior of herbivorous sea urchins causing them to consume less algae. This has important implications for coral reefs as algal overgrowth associate with the diseased induced die-off of this sea urchin is one of primary causes of reef decline in the Caribbean. By gaining a better understanding of how organisms interact on coral reefs we will be able to better preserve and protect them for future generations. 

 http://marine.unc.edu/people/Faculty/martens