Travel opens the door to learning in the most unexpected ways, offering random lessons that serve as a springboard for further exploration and education. My recent visit to the West Indies island of Antigua (known as Waladli or Wadadli by the native population) with my partner, Saskia Hogenhout, was a testament to this truth, proving that every destination holds a treasure trove of knowledge. From its rich natural history to the distinctive fauna and flora, Antigua broadened our understanding and appreciation of the natural world. Here are five intriguing lessons from this journey.
Under the volcano
From the southern coast of Antigua, you can clearly see the mountainous island of Montserrat, now dubbed the Pompeii of the Caribbean. On 18 July 1995, the once dormant Soufrière Hills volcano erupted, spewing hot rock, gas, and ash, devastating the Georgian-era capital city of Plymouth. Thousands, two-thirds of Montserrat’s population, were forced to flee, leaving over half the island as an exclusion zone, largely closed off ever since.
Gazing at the Soufrière Hills volcano from my idyllic beach spot in Antigua, I reflected on the profound impact of catastrophes on human life and how fortunate I was to enjoy that peaceful moment. We are facing many disasters, from wars and conflicts that kill, displace, and starve hundreds of thousands, to the numerous effects of climate change. This contemplation stirred a deep empathy within me and a pressing desire to contribute to a better understanding and action against such devastating events.
Pest control gone bad
During our time on the island, we encountered three slender, elusive mammals, which turned out to be Urva auropunctata, or the small Indian mongoose. Originating from outside the Caribbean, this carnivore species was introduced from India to Jamaica in 1872, with the intention of controlling black rats (Rattus rattus) that were damaging sugarcane plantations. Later on it spread to at least 33 islands in the Caribbean. A recent study suggested that the small Indian mongoose will continue to spread with climate change, particularly in Eastern Europe where it is already established in Croatia, Bosnia-Herzegovina and Montenegro.
A basic understanding of biology could have informed the plantation owners that this attempt at biocontrol was destined to fail. The small Indian mongoose, being diurnal, and the black rats, nocturnal, seldom crossed paths. Instead, the mongoose preyed on native species, contributing to decimating local populations of birds, lizards, and particularly the Antiguan racer snake (Alsophis antiguae), which was driven to extinction on the main island of Antigua. Thankfully, a remnant population of about 50 snakes on Great Bird Island survived, and subsequent conservation efforts have revived the Antiguan racer to healthy numbers.
Interestingly, our local guide believed the mongoose was introduced to Antigua to manage venomous snakes that posed threats to plantation workers. While this rationale holds true for neighboring Martinique and St. Lucia, home to the highly venomous fer-de-lance or terciopelo (Bothrops lanceolatus), I found no evidence of venomous snakes in Antigua, where the Antiguan racer is, in fact, harmless to humans.
A cactus tale
A hike through Cactus Hill in Southern Antigua unveiled two standout cactus species. First, the peculiar Melocactus intortus, or Turk’s cap cactus, earns its name from the cephalium’s resemblance to a Fez, the headdress popularized during the Ottoman Empire. This connection extends to the naming of the Turks Islands in the Turks and Caicos British Overseas Territory, inspired by the distinctive cactus.
The second species, Pilosocereus royenii, a towering organ pipe cactus (also known as dildo cactus), thrives not only in the West Indies and Quintana Roo, Mexico, but also surprises with its presence in tropical forests, blending seamlessly with the lush vegetation. This seemed incongruous to me, as I’m used to seeing cactus species in desert habitats.
The Cactaceae family, emerging 30 to 35 million years ago, has remarkably adapted to some of the harshest arid environments on Earth. As climate change increasingly affects our agriculture, these resilient plants beckon for closer study, especially now that we have the genome sequences of several cacti species. This opens doors to exploring their adaptive traits. Recently, I had an inspiring conversation with Dario Copetti, a plant biologist at the University of Arizona, Tucson, who is refining the genome sequences of the majestic saguaro cactus (Carnegiea gigantea). His work lays the groundwork for uncovering the extraordinary survival strategies of these desert icons.
Spider hunters
During our nature hike, the sight of a flashing red wasp flying around was unmistakable. I suspect the vibrant red serves as a warning color (aposematic) indicating that this wasp possesses a potent sting for its predators (and, as you’ll discover, humans too). Indeed, this was the red-winged tarantula hawk, Pepsis rubra. These wasps, aptly named tarantula hawks, predominantly prey on tarantulas throughout the Americas.
Tarantula hawks are part of the Pompilidae family — also known as the pompilid or spider-hunting wasps. This family, rich with 5,000 species, comprises primarily solitary wasps that hunt and paralyze their spider prey, lay a single egg in the spider’s abdomen, and then conceal it in a burrow for the larva to develop. For spiders, pompilid wasps must be the stuff of nightmares.
These wasps exhibit genetically determined behaviors specific to their hunting strategies. For instance, one clade of pompilid wasps in the Auplopus genus removes the legs of their spider prey before dragging it to their nest. We witnessed such behavior years ago on Langkawi Island, Malaysia, where a wasp attacked a spider mid-air, and then proceeded to methodically amputating its legs one by one, before dragging it away to burrow and lay a single egg. While gruesome, removing the legs simplifies transport, and all this while, the spider remains alive, paralyzed by the wasp venom, serving as nourishment for the larva. One species from Kerala, India, Auplopus wahisi, even seals the amputated leg to ensure that hemolymph does not leak from the prey.
Many wasps demonstrate similarly predatory behaviors that seem more suited to the plot of horror movies. The colorful emerald cockroach wasp or jewel wasp, Ampulex compressa, from the Ampulicidae family, preys on cockroaches. It executes a precise sequence of actions, including severing one antenna to consume the cockroach hemolymph, then leading the paralyzed insect to its burrow by the remaining antenna. For a glimpse of this methodic behavior, I recommend watching this remarkable video.
Returning to the tarantula hawks,, according to the sting pain index developed by entomologist Justin Schmidt, they can achieve the maximum rank of 4. Schmidt describes the sting of the large tarantula hawk species, Pepsis grossa, as similar to “a running hair dryer dropped into your bubble bath.”
In Antigua, we cautiously avoided Pepsis rubra — though I admit, I did try to catch one. However, we nearly walked into a swarm of these wasps displaying some form of unexplained aggregation behavior along the trail. Fortunately, we avoided any unpleasant encounters and thus had no personal experiences to contribute to Schmidt’s database. However, if any readers are familiar with this behavior, I’d be eager to learn more.
Island endemics
Island ecosystems are renowned for their high frequency of endemic species, a phenomenon stemming from geographical isolation. This unique aspect of endemism has spurred extensive research and contributed significantly to our understanding of evolution and biodiversity. The Galápagos Islands, for instance, played a pivotal role in inspiring Charles Darwin to develop the concept of natural selection. Darwin was particularly fascinated by the diversity in beak size and shape among the Geospiza finches, famously known as Darwin’s finches. Jonathan Weiner’s book “The Beak of the Finch” offers an in-depth look at this topic. It chronicles biologists Peter and Rosemary Grant and their colleagues, who built on Darwin’s foundation, showcasing the rapid pace of evolutionary adaptations among bird species.
Incidentally, reading Weiner’s book and exploring the Grants’ work on rapid evolutionary adaptations was inspiring to me. Not because I was surprised that adaptive evolution can occur swiftly within just a few generations, but rather because to biologists like myself, who study host-pathogen coevolution, this rapid tempo of evolution is entirely expected. We are well acquainted with how the intense selective pressures of antagonistic coevolution can dramatically transform both pathogen and host populations in remarkably short timeframes. In a landmark study by French plant pathologists Guillaume Daverdin and colleagues, a staggering 769 adaptive mutational events were observed in a single gene of a fungal plant pathogen over a two-year period.
In Antigua, part of the Lesser Antilles, we had the pleasure of observing species endemic to these islands. One such bird, the Lesser Antillean Bullfinch (Loxigilla noctis), might seem unremarkable at first glance. However, closer observation reveals its elegant beauty, highlighted by its red throat. Molecular phylogenetic studies have reclassified these birds from being classed with buntings and New World sparrows to being part of the tanagers (Passeriformes: Thraupidae) in the Coerebinae subfamily, the same clade that includes Darwin’s finches. In their comprehensive study, Burns and colleagues emphasize the remarkable diversity of beak forms within the Coerebinae, ranging from nectar-feeders and seed-eaters to insect foragers. This is what they wrote:
Species in Coerebinae show a variety of bill forms, including nectar-feeders (e.g., Coereba, Euneornis), seed-eaters (e.g., Geospiza, Loxigilla, Tiaris), and insect foragers (e.g., Certhidea). Included within this clade are the Darwin’s Finches, a classic example of speciation and adaptive radiation (e.g., Grant, 1999; Grant and Grant, 2008; Lack, 1947). Coerebinae also includes nine species endemic to islands in the Caribbean (E. campestris, Loxigilla portoricensis, L. violacea, L. noctis, L. barbadensis, Melopyrrha nigra, Loxipasser ano- xanthus, Tiaris canorus, and Melanospiza richardsoni) and three species in which a large part of the distribution is Caribbean (C. flaveola, T. olivaceus, T. bicolor). The other two non-Darwin’s Finch species in Coerebinae (T. fuliginosa and T. obscurus) are restricted to South America.
A relative of the Lesser Antillean bullfinch is the St. Kitts Bullfinch, now recognized as its own species, Milopyrrha grandis. This bird’s distribution was once confined to the upper slopes of Mt. Misery in St. Kitts, but its last (albeit controversial) sighting was in 1929. The existence of this bird in the more remote regions of Mt. Misery remains a topic of debate among ornithologists. Some believe it was driven to extinction by two major hurricanes that hit the island in 1899.
While human activity is a significant driver of species extinction, natural disasters like hurricanes showcase the vulnerability of life on our planet. Another example is the Bahama nuthatch (Sitta insularis), which became exceedingly rare following hurricanes in 2016 and 2017 and has not been observed since Category 5 Hurricane Dorian devastated its pine forest habitat in September 2019.
Hurricanes can also serve as agents of natural selection, as discovered by Jonathan Losos, an evolutionary biologist and herpetologist at the University of Missouri, St. Louis. Losos has spent most of his career studying anole lizards (Anolis species) in the Caribbean. In a 2020 paper, he and his collaborators, detailed how anole lizards that survived Hurricanes Irma and Maria in 2017 passed on larger, stronger-gripping toepads to their offspring. Their research also uncovered a trend: lizards exposed to hurricanes more frequently over 70 years tend to have larger toepads. This research underscores the potential impact of climate change and increasing frequency of extreme weather events, like hurricanes, on the evolutionary paths of species.
I was first introduced to Jonathan Losos’ work while exploring convergent evolution. Reading his book “Improbable Destinies” in 2017, on a beach near Kizimkazi in Zanzibar, sparked inspiration for our projects on the convergent evolution of plant immune receptors. Remarkably, insights from lizard evolution have influenced our work on plant immune receptors, illustrating the interconnectedness of ideas and concepts in biology and evolution. This is reflected in the research conducted by my PhD student, Ola (Aleksandra) Bialas, on the evolution of the rice immune receptor Pik-1. Ola’s research revealed that various Pik-1 receptors have convergently evolved through different biochemical pathways to comparable phenotypic results. These results underscore the flexibility and complexity of the evolutionary processes driving immune receptor adaptation in response to plant pathogens.
A few years later, I had the privilege of introducing Jonathan Losos at a webinar focused on island ecosystems. This event was organized by Zakher Bouragaoui, also a herpetologist and a fervent advocate for biodiversity and conservation biology. Zakher, along with Wael Ben Aba, co-founded ATVS (Association Tunisienne de la Vie Sauvage) or the Tunisian Association for Wildlife. This organization, led by a dedicated group of young enthusiasts, has been at the forefront of biodiversity activism in Tunisia. They emphasize the importance of protecting endemic species, considering them a vital part of the country’s unique heritage. Among their various initiatives, they focus on the fragile ecosystems of Mediterranean islands, including data collection efforts in the Kneiss Islands archipelago (Arabic: أرخبيل الكنائس) located about 50 km east off the coast of central Tunisia. Learn more about Zakher and ATVS’s work in the talk “A New Era for Biodiversity Conservation in Tunisia” he gave at the Linnean Society of London.
Back in Antigua, we came across another stunning Caribbean endemic, the Antiguan anole (Anolis leachii). This lizard is native to the twin island nation of Antigua and Barbuda and has also been introduced to Bermuda, an island that was originally devoid of anole lizards. Jonathan Losos (who else) has explored how the introduction of A. leachii, along with two other anole species, to Bermuda has influenced their habitat use and behavioral interactions.
The Antiguan anole is impressively large, reaching lengths of over 10 cm. In Antigua, it shares its habitat with the smaller Anolis wattsi, which we unfortunately did not encounter. It seems Saskia and I have a perfect excuse for another trip to this captivating island. Stay tuned.
Acknowledgements
I’m grateful to my travel companion Saskia Hogenhout for feedback, discussions and the beautiful photos. I also thank our local Antiguan guide Bruce and the many friends and colleagues mentioned in the article for input and inspiration. The article was written with assistance from ChatGPT.
This article is available on a CC-BY license via Zenodo.
Cite as: Kamoun, S. (2024) Five things I learned in Antigua. Zenodo. https://doi.org/10.5281/zenodo.10935103
