Marine Iguanas of the Galapagos

Latest update January 10, 2019 Started on November 1, 2018

Despite being described as the 'Imps of Darkness' by Charles Darwin, the Galapagos Marine Iguana is now ranked one of the most remarkable lizards in the world. They may look fierce, but Marine Iguanas are gentle herbivores, feeding exclusively on underwater algae, having the ability to dive as deep as 98 feet!

For the first time, ecologists will investigate their unique locomotion and morphology in the hopes of determining the evolutionary trade-offs that are a result of their aquatic life.

Do Marine Iguanas hold the key to understanding the evolutionary transition to aquatic environments in reptiles?

November 1, 2018
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In The Field

Since 2017, I have been fighting to preserve, protect and understand one of Earth's last natural frontiers, the Galapagos Islands. These isolated islands and their varying ecosystems have taken on almost mythological status, often being referred to as being a living museum and showcase of evolution. Ongoing volcanic activity and the confluence of three ocean currents has led to the development of unusual and extraordinary life, found nowhere else on the planet.

The Galapagos Marine Iguana is no exception, being the only lizard in the world that forages in the cold water of the Pacific Ocean. Despite the species having captured the curiosity of the world through documentaries and film, little is known about their taxonomy, evolution and ecopysiology.

In November and December 2018, I led a team of researchers into the wilds of the Galapagos in an effort to investigate the evolution and ecological considerations of Marine Iguana morphology and movement. Here we spent over 500 hours on some of the most remote and remarkable islands of the Galapagos; each of which is defined by unique wildlife and volcanic landscapes.

During our fieldwork, we examined six subspecies of Marine Iguanas (some of which were only identified in 2017!) and four species of Lava Lizards. We collected morphological and performance data from eighty-four Marine Iguanas and seventy-eight Lava Lizards across five islands.

Each of these sites brought new challenges - from navigating slippery rock landings with expensive technological gear, to finding flat, sandy ground where we could set up our field station. Sometimes it was a matter of walking several kilometres to find the marine iguana colony, whilst other times it was a monstrous swell that our zodiac had to navigate.

Every aspect of the field expedition was an adventure. Please stay tuned to hear more about my experiences and findings! Additionally, I wanted to say a huge thank you to everyone that has supported this expedition. Thanks to you, I have been sent an OpenROV Trident Underwater drone, a valuable research tool that I hope to use to study the aquatic behaviour of Marine Iguanas.

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In 2017, when I was completing my undergraduate degree in Animal Ecology, I attended the Annual Galapagos Conservation and Research Symposium. Whilst I was there I conducted a preliminary research project on Marine Iguana biomechanics. It was during these preliminary studies that I recognised the plight of the Marine Iguanas and the importance of understanding all aspects of their ecology. I aim to further investigate the evolution and ecological considerations of Marine Iguanas locomotion and morphology this November.

I am also a passionate photographer and with my trusty camera, I hope to showcase the beauty of the natural world and its inhabitants, in an effort to inspire others to protect it! Below is a selection of the many photos that I took on my previous expedition to the Galapagos.

To find out more about my data collection methods and findings from my previous trip, I have written several blog posts on my website -

If you have any questions about my research or photography, feel free to get in touch and start a conversation!

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Expedition Background

THE MARINE IGUANA is an ancient and endemic species inhabiting the Galapagos Islands. The species is ranked as one of the most remarkable organisms of the archipelago because of its behavioural and morphological adaptations, feeding exclusively on intertidal and subtidal marine products (Dawson 1976; McLeod et al. 2015). Marine Iguanas are currently considered vulnerable by the IUCN (population estimated to be at 50,000), with isolation having led to the species being highly susceptible to anthropogenic and climatic threats. The status of endemic and native species is a key determinant of research and management programs of the Galapagos National Park, and the recent population decline in the Galapagos Marine Iguana highlights the necessity to address gaps in literature to ensure the species is preserved.

Recent studies have identified that Galapagos Marine Iguanas exhibit a high degree of morphological and genetic diversity, hypothesised to be a result of multiple colonisation events, incipient speciation, and local adaptation (Chiari 2014). Further, it has been noted that the species has a high degree of plasticity in relation to body size, with changes in length being correlated to El Nino events and periods of food shortages (Chiari et al. 2014). Therefore, it can be hypothesised that body shape variation may be functionally important for fitness-related activities and behaviours (Chiari et al. 2014; Mcelroy 2007). Examination of locomotory performance gives an understanding of both the difficulties an individual may encounter in their habitat, and the morphology that aids in overcoming these difficulties (Byrnes and Spence, 2011; Clemente et al., 2016). This is of high relevance to Marine Iguanas as anthropogenic and climatic changes can have a detrimental impact on the environment and thus their fitness.

Despite the relevance of ecomorphological and performance studies to conservation and management, there has been no research to date on the locomotory performance of Marine Iguanas. My project aims to investigate their unique locomotory biomechanics which will provide evolutionary insight into performance trade-offs and morphological modifications for the marine and terrestrial environment. Additionally, such studies are also necessary to understand the major aspects of evolutionary transitions in tetrapod locomotor mechanics, such as the sprawling to erect paradigm, and to evaluate the connection to environmental characteristics. Transition in posture and locomotory performance reflects ecological changes that may have caused expansion of a clade into previously unoccupied niches. Therefore, this research into Marine Iguana performance will allow for effective conservation management strategies to be employed, in turn aiding in population fitness assessments to be carried out and to determine the significance of habitat. Further, this project may also aid in understanding the degree of speciation, as genetic and morphological diversity will aid in the population’s ability to withstand catastrophic events such as the El Nino and future climate change. This will be addressed by evaluating the degree of morphological variation and performance between colonies.

In 2017 during my undergraduate degree, I was selected to represent the University of the Sunshine Coast and attend the second Annual Conservation and Research Symposium (organised by the Galapagos National Park and UNC Galapagos Science Centre). Whilst there, Dr. Christofer Clemente and I conducted a preliminary research project on Marine Iguana biomechanics, alongside the Galapagos Science Centre and the University of North Carolina. During these preliminary studies, I recognised the plight of the Marine Iguanas and the importance of understanding all aspects of their ecology. Following in the footsteps of my idols, I hope to raise awareness and ensure the unique species is conserved through my photographic work and research.

In November 2018, I will be returning to the Galapagos to continue my research. I will be travelling to nine islands and catching 200 lizards in an effort to understand the evolution and ecological considerations of their movement and morphology. I have designed an innovative and portable 'race track', which will allow me to record high-speed footage of the locomotion of Marine Iguanas and Lava Lizards.

Please stay tuned to hear more about my research and Galapagos adventures! Thank you for the support.

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