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Butterworth NJ, Wallman JF, Johnston NP, Dawson BM, Sharp-Heward J, McGaughran A. The blowfly Chrysomya latifrons inhabits fragmented rainforests, but shows no population structure. Oecologia 2023; 201:703-719. [PMID: 36773072 PMCID: PMC10038970 DOI: 10.1007/s00442-023-05333-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 01/27/2023] [Indexed: 02/12/2023]
Abstract
Climate change and deforestation are causing rainforests to become increasingly fragmented, placing them at heightened risk of biodiversity loss. Invertebrates constitute the greatest proportion of this biodiversity, yet we lack basic knowledge of their population structure and ecology. There is a compelling need to develop our understanding of the population dynamics of a wide range of rainforest invertebrates so that we can begin to understand how rainforest fragments are connected, and how they will cope with future habitat fragmentation and climate change. Blowflies are an ideal candidate for such research because they are widespread, abundant, and can be easily collected within rainforests. We genotyped 188 blowflies (Chrysomya latifrons) from 15 isolated rainforests and found high levels of gene flow, a lack of genetic structure between rainforests, and low genetic diversity - suggesting the presence of a single large genetically depauperate population. This highlights that: (1) the blowfly Ch. latifrons inhabits a ~ 1000 km stretch of Australian rainforests, where it plays an important role as a nutrient recycler; (2) strongly dispersing flies can migrate between and connect isolated rainforests, likely carrying pollen, parasites, phoronts, and pathogens along with them; and (3) widely dispersing and abundant insects can nevertheless be genetically depauperate. There is an urgent need to better understand the relationships between habitat fragmentation, genetic diversity, and adaptive potential-especially for poorly dispersing rainforest-restricted insects, as many of these may be particularly fragmented and at highest risk of local extinction.
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Affiliation(s)
- Nathan J Butterworth
- School of Biological Sciences, Monash University, Clayton, VIC, 3800, Australia.
- Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia.
| | - James F Wallman
- Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
- Centre for Sustainable Ecosystem Solutions, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Nikolas P Johnston
- Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
- Department of Ecology and Biogeography, Faculty of Biological and Veterinary Sciences, Nicolaus Copernicus University in Toruń, 87-100, Toruń, Poland
- Centre for Sustainable Ecosystem Solutions, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Blake M Dawson
- Centre for Sustainable Ecosystem Solutions, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Joshua Sharp-Heward
- Centre for Sustainable Ecosystem Solutions, School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Angela McGaughran
- Te Aka Mātuatua - School of Science, University of Waikato, Private Bag 3105, Hamilton, 3240, New Zealand
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Daniel A, Savary P, Foltête JC, Khimoun A, Faivre B, Ollivier A, Éraud C, Moal H, Vuidel G, Garnier S. Validating graph-based connectivity models with independent presence-absence and genetic data sets. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2023; 37:e14047. [PMID: 36661070 DOI: 10.1111/cobi.14047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 11/11/2022] [Accepted: 11/22/2022] [Indexed: 05/11/2023]
Abstract
Habitat connectivity is a key objective of current conservation policies and is commonly modeled by landscape graphs (i.e., sets of habitat patches [nodes] connected by potential dispersal paths [links]). These graphs are often built based on expert opinion or species distribution models (SDMs) and therefore lack empirical validation from data more closely reflecting functional connectivity. Accordingly, we tested whether landscape graphs reflect how habitat connectivity influences gene flow, which is one of the main ecoevolutionary processes. To that purpose, we modeled the habitat network of a forest bird (plumbeous warbler [Setophaga plumbea]) on Guadeloupe with graphs based on expert opinion, Jacobs' specialization indices, and an SDM. We used genetic data (712 birds from 27 populations) to compute local genetic indices and pairwise genetic distances. Finally, we assessed the relationships between genetic distances or indices and cost distances or connectivity metrics with maximum-likelihood population-effects distance models and Spearman correlations between metrics. Overall, the landscape graphs reliably reflected the influence of connectivity on population genetic structure; validation R2 was up to 0.30 and correlation coefficients were up to 0.71. Yet, the relationship among graph ecological relevance, data requirements, and construction and analysis methods was not straightforward because the graph based on the most complex construction method (species distribution modeling) sometimes had less ecological relevance than the others. Cross-validation methods and sensitivity analyzes allowed us to make the advantages and limitations of each construction method spatially explicit. We confirmed the relevance of landscape graphs for conservation modeling but recommend a case-specific consideration of the cost-effectiveness of their construction methods. We hope the replication of independent validation approaches across species and landscapes will strengthen the ecological relevance of connectivity models.
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Affiliation(s)
- Alexandrine Daniel
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne-Franche-Comté, Dijon, France
| | - Paul Savary
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne-Franche-Comté, Dijon, France
- ThéMA, UMR 6049 CNRS, Université de Franche-Comté, Besançon, France
- ARP-Astrance, Paris, France
| | | | - Aurélie Khimoun
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne-Franche-Comté, Dijon, France
| | - Bruno Faivre
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne-Franche-Comté, Dijon, France
| | - Anthony Ollivier
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne-Franche-Comté, Dijon, France
| | - Cyril Éraud
- Office Français de la Biodiversité, Chizé, France
| | | | - Gilles Vuidel
- ThéMA, UMR 6049 CNRS, Université de Franche-Comté, Besançon, France
| | - Stéphane Garnier
- Biogéosciences, UMR 6282 CNRS, Université Bourgogne-Franche-Comté, Dijon, France
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Benscoter AM, D'Acunto LE, Haider SM, Fletcher RJ, Romañach SS. Nest‐site selection model for endangered Everglade snail kites to inform ecosystem restoration. Ecosphere 2023. [DOI: 10.1002/ecs2.4362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Affiliation(s)
| | - Laura E. D'Acunto
- U.S. Geological Survey, Wetland and Aquatic Research Center Davie Florida USA
| | - Saira M. Haider
- U.S. Geological Survey, Wetland and Aquatic Research Center Davie Florida USA
| | - Robert J. Fletcher
- Department of Wildlife Ecology and Conservation University of Florida Gainesville Florida USA
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Reichert BE, Fletcher RJ, Kitchens WM. The demographic contributions of connectivity versus local dynamics to population growth of an endangered bird. J Anim Ecol 2020; 90:574-584. [PMID: 33179773 DOI: 10.1111/1365-2656.13387] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 10/07/2020] [Indexed: 11/30/2022]
Abstract
Conservation and management increasingly focus on connectivity, because connectivity driven by variation in immigration rates across landscapes is thought to be crucial for maintaining local population and metapopulation persistence. Yet, efforts to quantify the relative role of immigration on population growth across the entire range of species and over time have been lacking. We assessed whether immigration limited local and range-wide population growth of the endangered snail kite Rostrhamus sociabilis in Florida, USA, over 18 years using multi-state, reverse-time modelling that accounts for imperfect detection of individuals and unobservable states. Demographic contributions of immigration varied depending on the dynamics and geographic position of the local populations, were scale-dependent and changed over time. By comparing the relative contributions of immigration versus local demography for periods of significant change in local abundance, we found empirical evidence for a disproportionately large role of immigration in facilitating population growth of a centrally located population-a connectivity 'hub'. The importance of connectivity changed depending of the spatial scale considered, such that immigration was a more important driver of population growth at small versus large spatial scales. Furthermore, the contribution of immigration was much greater during time periods when local population size was small, emphasizing abundance-dependent rescue effects. Our findings suggest that efforts aimed at improving local breeding habitat will likely be most effective at increasing snail kite population growth. More broadly, our results provide much needed information on the role of connectivity for population growth, suggesting that connectivity conservation may have the greatest benefits when efforts focus on centrally located habitat patches and small populations. Furthermore, our results highlight that connectivity is highly dynamic over time and that interpreting the effects of connectivity at local scales may not transfer to region-wide dynamics.
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Affiliation(s)
- Brian E Reichert
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA
| | - Robert J Fletcher
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA
| | - Wiley M Kitchens
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL, USA
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Robertson EP, Fletcher RJ, Austin JD. The number of breeders explains genetic connectivity in an endangered bird. Mol Ecol 2019; 28:2746-2756. [DOI: 10.1111/mec.15109] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 04/13/2019] [Accepted: 04/15/2019] [Indexed: 01/25/2023]
Affiliation(s)
- Ellen P. Robertson
- Department of Wildlife Ecology and Conservation University of Florida Gainesville Florida USA
| | - Robert J. Fletcher
- Department of Wildlife Ecology and Conservation University of Florida Gainesville Florida USA
| | - James D. Austin
- Department of Wildlife Ecology and Conservation University of Florida Gainesville Florida USA
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Rapid morphological change of a top predator with the invasion of a novel prey. Nat Ecol Evol 2017; 2:108-115. [PMID: 29180705 DOI: 10.1038/s41559-017-0378-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 10/10/2017] [Indexed: 01/29/2023]
Abstract
Invasive exotic species are spreading rapidly throughout the planet. These species can have widespread impacts on biodiversity, yet the ability for native species, particularly long-lived vertebrates, to respond rapidly to invasions remains mostly unknown. Here we provide evidence of rapid morphological change in the endangered snail kite (Rostrhamus sociabilis) across its North American range with the invasion of a novel prey, the island apple snail (Pomacea maculata), a much larger congener of the kite's native prey. In less than one decade since invasion, snail kite bill size and body mass increased substantially. Larger bills should be better suited to extracting meat from the larger snail shells, and we detected strong selection on increased size through juvenile survival. Using pedigree data, we found evidence of both genetic and environmental influences on trait expression and discovered that additive genetic variation in bill size increased with invasion. However, trends in predicted breeding values emphasize that recent morphological changes have been driven primarily by phenotypic plasticity rather than micro-evolutionary change. Our findings suggest that evolutionary change may be imminent and underscore that even long-lived vertebrates can respond quickly to invasive species. Furthermore, these results highlight that phenotypic plasticity may provide a crucial role for predators experiencing rapid environmental change.
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