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Gargano M, Colosimo G, Garizio L, Gratton P, Lewbart GA, Gerber GP, Loreti P, Catini A, Bracciale L, De Luca M, Mastrangeli F, Sevilla C, Gentile G. Locating Nesting Sites for Critically Endangered Galápagos Pink Land Iguanas ( Conolophus marthae). Animals (Basel) 2024; 14:1835. [PMID: 38929453 PMCID: PMC11200735 DOI: 10.3390/ani14121835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 06/14/2024] [Accepted: 06/16/2024] [Indexed: 06/28/2024] Open
Abstract
Invasive alien species control is recognized worldwide as a priority action to preserve global biodiversity. However, a lack of general life history knowledge for threatened species can impede the effectiveness of conservation actions. Galápagos pink land iguanas (Conolophus marthae) are endemic to Wolf Volcano, Galápagos, Ecuador. These iguanas are threatened by invasive alien species, particularly feral cats, that may affect their small population size. To guarantee the long-term survival of C. marthae, the Galápagos National Park Directorate is considering, along with an ongoing campaign of feral cat control, the implementation of a head-start program. However, the success of this management strategy necessarily relies on the identification of pink iguana nesting grounds, which were still unknown at the onset of this study. We modeled the movement patterns of male and female iguanas during the reproductive season, using location data collected from custom-made remote tracking devices installed on adult pink iguanas in April 2021. We first calculated for each individual the vector of distances from its starting location, which was defined as net displacement. We then used net displacement as the response variable in a generalized additive mixed model with day of the year as the predictor. Based on the hypothesis that males and females may behaviorally differ after mating, we looked for female-specific migratory behavior suggesting females were moving toward nesting areas. The results obtained confirmed our hypothesis, as females exhibited a distinct migratory behavior, reaching a small plateau area inside of Wolf Volcano's caldera and ca. 400 m below the volcano's northern rim. Moreover, once inside the caldera, females displayed a more aggregated distribution pattern. The movement data obtained allowed Galápagos National Park rangers to locate individual pink iguana nests and subsequently to sight and collect the first observed hatchlings of the species. This work constitutes a necessary baseline to perform dedicated studies of pink iguana nests and emerging hatchling iguanas, which is an essential step toward the development of an effective head-start program.
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Affiliation(s)
- Marco Gargano
- PhD Program in Evolutionary Biology and Ecology, Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy; (M.G.); (L.G.)
| | - Giuliano Colosimo
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Lorenzo Garizio
- PhD Program in Evolutionary Biology and Ecology, Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy; (M.G.); (L.G.)
| | - Paolo Gratton
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy;
| | - Gregory A. Lewbart
- College of Veterinary Medicine, North Carolina State University, 1060 William Moore Drive, Raleigh, NC 27606, USA;
- UNC-Chapel Hill Galapagos Science Center (GSC), Universidad San Francisco de Quito (USFQ), Av. Alsacio Northia, Quito 170901, Ecuador
| | - Glenn P. Gerber
- San Diego Zoo Wildlife Alliance, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA;
| | - Pierpaolo Loreti
- Department of Engineering, University of Rome Tor Vergata, 00133 Rome, Italy; (P.L.); (A.C.); (L.B.)
| | - Alexandro Catini
- Department of Engineering, University of Rome Tor Vergata, 00133 Rome, Italy; (P.L.); (A.C.); (L.B.)
| | - Lorenzo Bracciale
- Department of Engineering, University of Rome Tor Vergata, 00133 Rome, Italy; (P.L.); (A.C.); (L.B.)
| | - Massimiliano De Luca
- Italian National Council of Research, Institute of Marine Engineering, 00133 Rome, Italy;
| | - Francesca Mastrangeli
- Italian National Council of Research, Institute for Microelectronics and Microsystems, 00133 Rome, Italy;
| | - Christian Sevilla
- Galápagos National Park Directorate, Av. Charles Darwin—200102 Puerto Ayora, Is. Santa Cruz, Galápagos 200102, Ecuador;
| | - Gabriele Gentile
- Department of Biology, University of Rome Tor Vergata, 00133 Rome, Italy;
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Genetic structure of Rhinoceros Rock Iguanas, Cyclura cornuta, in the Dominican Republic, with insights into the impact of captive facilities and the taxonomic status of Cyclura on Mona Island. CONSERV GENET 2020. [DOI: 10.1007/s10592-020-01290-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Moss JB, Gerber GP, Laaser T, Goetz M, Oyog T, Welch ME. Conditional female strategies influence hatching success in a communally nesting iguana. Ecol Evol 2020; 10:3424-3438. [PMID: 32273999 PMCID: PMC7141077 DOI: 10.1002/ece3.6139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 11/07/2022] Open
Abstract
The decision of females to nest communally has important consequences for reproductive success. While often associated with reduced energetic expenditure, conspecific aggregations also expose females and offspring to conspecific aggression, exploitation, and infanticide. Intrasexual competition pressures are expected to favor the evolution of conditional strategies, which could be based on simple decision rules (i.e., availability of nesting sites and synchronicity with conspecifics) or on a focal individual's condition or status (i.e., body size). Oviparous reptiles that reproduce seasonally and provide limited to no postnatal care provide ideal systems for disentangling social factors that influence different female reproductive tactics from those present in offspring-rearing environments. In this study, we investigated whether nesting strategies in a West Indian rock iguana, Cyclura nubila caymanensis, vary conditionally with reproductive timing or body size, and evaluated consequences for nesting success. Nesting surveys were conducted on Little Cayman, Cayman Islands, British West Indies for four consecutive years. Use of high-density nesting sites was increasingly favored up to seasonal nesting activity peaks, after which nesting was generally restricted to low-density nesting areas. Although larger females were not more likely than smaller females to nest in high-density areas, larger females nested earlier and gained access to priority oviposition sites. Smaller females constructed nests later in the season, apparently foregoing investment in extended nest defense. Late-season nests were also constructed at shallower depths and exhibited shorter incubation periods. While nest depth and incubation length had significant effects on reproductive outcomes, so did local nest densities. Higher densities were associated with significant declines in hatching success, with up to 20% of egg-filled nests experiencing later intrusion by a conspecific. Despite these risks, nests in high-density areas were significantly more successful than elsewhere due to the benefits of greater chamber depths and longer incubation times. These results imply that communal nest sites convey honest signals of habitat quality, but that gaining and defending priority oviposition sites requires competitive ability.
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Affiliation(s)
- Jeanette B. Moss
- Biological Sciences DepartmentMississippi State UniversityMississippi StateMSUSA
| | - Glenn P. Gerber
- Institute for Conservation ResearchSan Diego Zoo GlobalEscondidoCAUSA
| | - Tanja Laaser
- Cayman Islands Department of EnvironmentGeorge TownCayman Islands
| | - Matthias Goetz
- Department of HerpetologyDurrell Wildlife Conservation TrustJerseyUK
| | - TayVanis Oyog
- Cayman Islands Department of EnvironmentGeorge TownCayman Islands
| | - Mark E. Welch
- Biological Sciences DepartmentMississippi State UniversityMississippi StateMSUSA
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Moss JB, Gerber GP, Welch ME. Heterozygosity-Fitness Correlations Reveal Inbreeding Depression in Neonatal Body Size in a Critically Endangered Rock Iguana. J Hered 2019; 110:818-829. [PMID: 31617903 DOI: 10.1093/jhered/esz060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 10/09/2019] [Indexed: 01/16/2023] Open
Abstract
Inbreeding depression, though challenging to identify in nature, may play an important role in regulating the dynamics of small and isolated populations. Conversely, greater expression of genetic load can enhance opportunities for natural selection. Conditional expression concentrates these opportunities for selection and may lead to failure of detection. This study investigates the possibility for age-dependent expression of inbreeding depression in a critically endangered population of rock iguanas, Cyclura nubila caymanensis. We employ heterozygote-fitness correlations to examine the contributions of individual genetic factors to body size, a fitness-related trait. Nonsignificant reductions in homozygosity (up to 7%) were detected between neonates and individuals surviving past their first year, which may reflect natural absorption of inbreeding effects by this small, fecund population. The majority of variation in neonate body size was attributed to maternal or environmental effects (i.e., clutch identity and incubation length); however, heterozygosity across 22 microsatellite loci also contributed significantly and positively to model predictions. Conversely, effects of heterozygosity on fitness were not detectable when adults were examined, suggesting that inbreeding depression in body size may be age dependent in this taxon. Overall, these findings emphasize the importance of taking holistic, cross-generational approaches to genetic monitoring of endangered populations.
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Affiliation(s)
- Jeanette B Moss
- Biological Sciences Department, Mississippi State University, Mississippi State, MS
| | - Glenn P Gerber
- Institute for Conservation Research, San Diego Zoo Global, Escondido, CA
| | - Mark E Welch
- Biological Sciences Department, Mississippi State University, Mississippi State, MS
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