From Plant Press Vol. 14, No. 3 from July 2011.
By Vinita Gowda
Female Purple-throated Carib (Eulampis jugularis) tagged with a unique band for individual identification. Male and female Purple-throated Caribs were monitored over multiple years to understand their dependence and interaction patterns with the native heliconias. (Photo by Vinita Gowda)
For over a century the Caribbean region, held between North and South America, has been an active area of research for people with interests in island biogeography, character evolution, speciation, as well as geology. Most research have invoked both dispersal and vicariance processes to explain the distribution of the local flora and fauna, while ecological interactions such as niche partitioning and ecological adaptations have been used to explain the diversity within the Caribbean region. One of the biggest challenges in understanding island colonization in the Caribbean, however, has been its complex, dynamic and variable geological history, which varies both along a North-South and an East-West axis.
The Caribbean region is divided into the Greater Antilles (Northern Islands) and the Lesser Antilles (Southern Islands). The Lesser Antilles archipelago, the focus of my research interests, is 850 km long with a radius of curvature of 450 km, and consists of 19 islands. The Lesser Antilles stretches from South American continental margin (eastern Venezuela) to the Anegada Passage, which marks its boundary with the Greater Antilles (Puerto Rico-Virgin Islands platform).
Map showing the locations of St. Kitts & Nevis, Dominica, and St. Vincent within the Lesser Antillean chain of islands. Field work and study sites were set up at all the three islands to study heliconias and their interactions with the native hummingbirds. (Photo by Vinita Gowda)
Geologically, the Caribbean region is estimated to have formed in the Cenozoic era (~65 mya), following the separation of North and South America during the Mesozoic era. The volcanic islands, today’s Lesser Antilles, are proposed to have emerged from the tectonically active Aves Arc after a series of subsiding volcanic islands migrated eastward after the Aves Ridge was formed to the West. Although, the Lesser Antilles is commonly referred to as a volcanically active chain of islands, not all of the Lesser Antilles is volcanic. Based on geological origin and elevation all the islands of the Lesser Antilles can be divided into two groups: a) Limestone Caribbees (outer arc: calcareous islands with a low relief, dating to middle Eocene to Pleistocene), and b) Volcanic Caribbees (inner arc: young volcanic islands with strong relief, dating back to late Miocene).
For over more than a decade John Kress, Ethan Temeles (Amherst College) and their team of researchers have been investigating mutualistic interactions between heliconias (Heliconia: Heliconiaceae) and their sexually dimorphic hummingbird pollinators the Purple-throated Caribs (Trochilidae: Eulampis jugularis) throughout the Eastern Caribbean Islands. Based on their studies they proposed the Caribbean Heliconia-hummingbird system as a case for adaptive evolution between the beak morphology of the Purple-throated Caribs and the floral morphology of the two native heliconias (Temeles et al. 2000 Science; Temeles and Kress 2003 Science). My involvement in this project started in September 2002, or more appropriately from July 2002 when I first met John at the Association of Tropical Biology and Conservation (ATBC) meeting in Bangalore, India. At the time, I was investigating a Mussaenda frondosa-insect interaction in the Western Ghats, India and I was ready for new and bigger research challenges.