Population Genetics and Feeding Ecology of Black Spiny-tailed Iguanas (Ctenosaura similis) Introduced to Keewaydin Island
Andrea Naccarato, M.S.1 Sarah Funck, M.S. 1 Jan B. DeJarnette, Ph.D.2 Phil Allman, Ph.D.2
1Department of Marine and Ecological Sciences, 2Department of Biological Sciences, Florida Gulf Coast University Acknowledgements
Individuals: Organizations: • Win Everham, Ph.D. • Jerry Jackson, Ph.D. • Ernesto Quintero, Ph.D • Ralph Bullens • Derek de Witt • Jordan Donini • Lisa Hamilton • Jared Knott • Julie Ross Article available online from Journal of Herpetology
Lizards in Florida
• Florida has 16 species of native lizards • Florida has 47 species of exotic lizards (Florida Museum of Natural History, University of Florida) Brown anole
Green anole
Common five-lined skink Allman Black spiny-tailed iguana Distribution of C. similis in Florida
Gasparilla Island Cayo Costa Fort Myers Beach County records Keewaydin Island provided by Little Marco Island EDDMapS
EDDMapS. 2015. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Available online at http://www.eddmaps.org/; last accessed January 5, 2015. Black Spiny-tailed Iguana (Ctenosaura similis)
Allman
Native to Mexico and Central America Naccarato Up to 4 feet long Research Questions
1. What is the feeding ecology of introduced C. similis? a. Individual life history b. Environment 2. What is the genetic structure of the
population? Naccarato a. Source location b. Mode of introduction Research Question
How can genetics reveal mode of introduction?
?
Lower genetic Higher genetic diversity diversity Study Site
Naples
Keewaydin Island
Marco Island Keewaydin Island (Rookery Bay)
Habitats:
Noose pole capture
= sampling site
Beach dune Sample Sizes: Population expanded by N = 21 (Genetics) - Nov. ‘09 2009-2010 N = 54 (Feeding) - Nov ‘09, Approx. Mar, May, Aug ‘10 release site Coastal strand (1995)
Methods: Genetics
Dissection: DNA extraction and ND4 gene amplification muscle samples • Sequencing of ND4 gene (n=21) by Operon Results: Genetics
• Identical DNA sequence (ND4 gene) for all KI iguanas • KI sequence matched one published sequence Dissimilarity matrix (pairwise genetic distances)
Sequence Location (ID) 1 2 3 4 1 C. similis, KI, USA (this study) 2 C. similis, Mexicoa 0.013 3 C. similis, Hondurasb 0.103 0.100 4 C. similis, Hondurasc 0.000 0.013 0.103 5 Iguana iguana (outgroup) 0.145 0.148 0.158 0.145 Naccarato et al. 2015 Partial data shown for simplicity Results: Genetics
• Maximum likelihood cladogram for ND4 sequences published for Ctenosaura species
• KI iguanas cluster with C. similis • KI iguanas cluster with sequences from Honduras
Naccarato et al. 2015 Results: Feeding Sarah Funck • Defined 56 prey categories – Leaves, flowers , and fruits of native and non- native plants – Bees, ants, grasshoppers, dragonflies • Mangrove crab, tree snails, brown anoles • Age class and sample period influenced diet
Public domain Results: Feeding
• Diet shift occurs around 100 mm SVL – Smaller iguanas less herbivorous
– Larger iguanas more herbivorous Adults (>180 mm)
Juveniles (<180 mm) 100 mm SVL
Dennis Giardina
52.9% plant prey by volume 82% plant prey by volume (N=25) (N=29) Results: Feeding • Environmental factors also influence C. similis diet 120 Leaves
100 Fruits
Flowers
Animal 80
60
40 Proportion ofIguanas Proportion
20
0 November March May August Sampling Period
Rainfall: 2.8 cm 7.2 cm 4.0 cm 18.1 cm Interpretations: Genetics
Single sequence on KI • Single introduction of small group
KI sequence matched a published sequence • Suggests source population from Honduras • Knowledge to prevent future importation Interpretations: Feeding
Omnivorous diet varies over time • Could lead to decline of native species and spread of invasive plants
Smaller iguanas eat more animal prey • More efficient digestion of animal protein for growth
Conclusions
• C. similis were able to establish a population in a new environment, with an apparently small founder group – Study of nuclear genes underway to confirm low diversity overall • Variable/opportunistic diet a concern for protected species – Nests of sea turtles , gopher tortoises, and shorebirds • Future monitoring and research efforts are warranted to learn more about this potentially invasive lizard
Research Question
How can genetic methods pinpoint the source location? 1. Choose a gene with published sequences (ND4) 2. Learn the sequence of the gene in the introduced pop. 3. Look for a similar/matching sequence in native range
Native Range Introduced Population Location A Location B Location C
Sequence B, Sequence A Sequence B Sequence C From Location B