1
|
Yan J, Song C, Liang J, La Y, Lai J, Pan R, Huang Z, Li B, Zhang P. Moderate Genetic Diversity of MHC Genes in an Isolated Small Population of Black-and-White Snub-Nosed Monkeys ( Rhinopithecus bieti). Animals (Basel) 2024; 14:2276. [PMID: 39123802 PMCID: PMC11310952 DOI: 10.3390/ani14152276] [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: 06/11/2024] [Revised: 08/01/2024] [Accepted: 08/01/2024] [Indexed: 08/12/2024] Open
Abstract
Genetic diversity is an essential indicator that echoes the natural selection and environmental adaptation of a species. Isolated small populations are vulnerable to genetic drift, inbreeding, and limited gene flow; thus, assessing their genetic diversity is critical in conservation. In this study, we studied the genetic diversity of black-and-white snub-nosed monkeys (Rhinopithecus bieti) using neutral microsatellites and five adaptive major histocompatibility complex (MHC) genes. Two DQA1 alleles, two DQB1 alleles, two DRB1 alleles, two DRB5 alleles, and three DPB1 alleles were isolated from a population. The results indicate that neutral microsatellites demonstrate a high degree of heterozygosity and polymorphism, while adaptive MHC genes display a high degree of heterozygosity and moderate polymorphism. The results also show that balancing selection has prominently influenced the MHC diversity of the species during evolution: (1) significant positive selection is identified at several amino acid sites (primarily at and near antigen-binding sites) of the DRB1, DRB5, and DQB1 genes; (2) phylogenetic analyses display the patterns of trans-species evolution for all MHC loci. This study provides valuable genetic diversity insights into black-and-white snub-nosed monkeys, which dwell at the highest altitude and have experienced the harshest environmental selection of all primates globally since the Pleistocene. Such results provide valuable scientific evidence and a reference for making or amending conservation strategies for this endangered primate species.
Collapse
Affiliation(s)
- Jibing Yan
- Shaanxi Key Laboratory of Animal Conservation, College of Life Sciences, Northwest University, Xi’an 710069, China; (J.Y.); (C.S.); (J.L.); (Y.L.); (R.P.)
| | - Chunmei Song
- Shaanxi Key Laboratory of Animal Conservation, College of Life Sciences, Northwest University, Xi’an 710069, China; (J.Y.); (C.S.); (J.L.); (Y.L.); (R.P.)
| | - Jiaqi Liang
- Shaanxi Key Laboratory of Animal Conservation, College of Life Sciences, Northwest University, Xi’an 710069, China; (J.Y.); (C.S.); (J.L.); (Y.L.); (R.P.)
| | - Yanni La
- Shaanxi Key Laboratory of Animal Conservation, College of Life Sciences, Northwest University, Xi’an 710069, China; (J.Y.); (C.S.); (J.L.); (Y.L.); (R.P.)
| | - Jiandong Lai
- Baima Snow Mountain National Nature Reserve Administrative Bureau, Diqing 674500, China;
| | - Ruliang Pan
- Shaanxi Key Laboratory of Animal Conservation, College of Life Sciences, Northwest University, Xi’an 710069, China; (J.Y.); (C.S.); (J.L.); (Y.L.); (R.P.)
- International Center of Biodiversity and Primat Conservation, Dali University, Dali 671003, China
- School of Human Sciences, The University of Western Australia, Perth, WA 6009, Australia
| | - Zhipang Huang
- Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali 671003, China;
| | - Baoguo Li
- Shaanxi Key Laboratory of Animal Conservation, College of Life Sciences, Northwest University, Xi’an 710069, China; (J.Y.); (C.S.); (J.L.); (Y.L.); (R.P.)
- Shaanxi Institute of Zoology, Xi’an 710032, China
- College of Life Science, Yanan University, Yanan 710032, China
| | - Pei Zhang
- Shaanxi Key Laboratory of Animal Conservation, College of Life Sciences, Northwest University, Xi’an 710069, China; (J.Y.); (C.S.); (J.L.); (Y.L.); (R.P.)
| |
Collapse
|
2
|
Benard MF, Burke DJ, Carrino-Kyker SR, Krynak K, Relyea RA. Effects of amphibian genetic diversity on ecological communities. Oecologia 2024; 205:655-667. [PMID: 39078484 DOI: 10.1007/s00442-024-05599-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 07/16/2024] [Indexed: 07/31/2024]
Abstract
The amount of genetic diversity within a population can affect ecological processes at population, community, and ecosystem levels. However, the magnitude, consistency, and scope of these effects are largely unknown. To investigate these issues, we conducted two experiments manipulating the amount of genetic diversity and environmental factors in larval amphibians. The first experiment manipulated wood frog genetic diversity, the presence or absence of caged predators, and competition from leopard frogs to test whether these factors affected survival, growth, and morphology of wood frogs and leopard frogs. The second experiment manipulated wood frog genetic diversity, the presence or absence of uncaged predators, and resource abundance to test whether these factors affected wood frog traits (survival, morphology, growth, development, and behavior) and other components of the ecological community (zooplankton abundance, phytoplankton, periphyton, and bacterial community structure). Genetic diversity did not affect wood frog survival, growth, and development in either experiment. However, genetic diversity did affect the mean morphology of wood frog tadpoles in the first experiment and the abundance and distribution of zooplankton in the second experiment. It did not affect phytoplankton abundance, periphyton abundance, or bacterial community structure. While effect sizes (Cohen's d) of genetic diversity were approximately half those of environment treatments, the greatest effect sizes were for interaction effects between genetic diversity and environment. Our results indicate that genetic diversity can have a large effect on ecological processes, but the direction of those effects is highly dependent upon environmental conditions, and not easily predicted from simple measures of traits.
Collapse
Affiliation(s)
- Michael F Benard
- Department of Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - David J Burke
- Department of Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
- The Holden Arboretum, 9500 Sperry Road, Kirtland, OH, 44094, USA
| | | | - Katherine Krynak
- Department of Biology, Case Western Reserve University, Cleveland, OH, 44106, USA
- Department of Biological and Allied Health Sciences, Ohio Northern University, Ada, OH, USA
| | - Rick A Relyea
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA.
| |
Collapse
|
3
|
Pröhl H, Rodríguez A. Importance of Genetic-Fitness Correlations for the Conservation of Amphibians. Animals (Basel) 2023; 13:3564. [PMID: 38003181 PMCID: PMC10668650 DOI: 10.3390/ani13223564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/09/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Endangered animals suffer from isolation of their habitats. Isolation leads to a reduction in population size as well as a decrease in genetic diversity and a concomitant increase in the risk of extinction. Amphibians are the most endangered vertebrate class. Besides habitat loss, fragmentation and isolation, amphibians are threatened by emerging diseases e.g., chytrid fungus or Ranavirus. By employing experiments, researchers investigate whether changes in genetic diversity within or among isolated populations affect amphibian fitness. While genetic diversity estimates are based on molecular markers, typically microsatellites, fitness is mostly measured as tadpole performance in rearing experiments often under varying environmental conditions. Tadpole performances (e.g., body mass, growth rate and survival) have been found to be negatively affected by low genetic diversity, as several studies have found a positive association between genetic diversity and these fitness traits. Moreover, infection with pathogens also seems to be more likely in individuals or populations with lower genetic diversity. Overall, these genetic-fitness correlations seem to be more pronounced or detectable in smaller, declining populations but not in larger populations. Genomic studies, which sample a larger fraction of the genome, are still scarce in the conservation genetic literature on amphibians. These are likely to increase in upcoming years and may reveal adaptive variants that protect against dangerous pathogens or environmental changes. Altogether, genetic-fitness correlation studies should be a priority in order to develop effective management plans for the genetic rescue of isolated, imperilled amphibian populations.
Collapse
Affiliation(s)
- Heike Pröhl
- Institute of Zoology, University of Veterinary Medicine of Hannover, Bünteweg 17, 30559 Hannover, Germany;
| | | |
Collapse
|
4
|
Brown AL, Anastasiou DE, Schul M, MacVittie S, Spiers LJ, Meyer JL, Manfrino C, Frazer TK. Mixtures of genotypes increase disease resistance in a coral nursery. Sci Rep 2022; 12:19286. [PMID: 36369337 PMCID: PMC9652365 DOI: 10.1038/s41598-022-23457-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 10/31/2022] [Indexed: 11/13/2022] Open
Abstract
Marine infectious diseases are a leading cause of population declines globally due, in large part, to challenges in diagnosis and limited treatment options. Mitigating disease spread is particularly important for species targeted for conservation. In some systems, strategic arrangement of organisms in space can constrain disease outbreaks, however, this approach has not been used in marine restoration. Reef building corals have been particularly devastated by disease and continue to experience catastrophic population declines. We show that mixtures of genotypes (i.e., diversity) increased disease resistance in the critically endangered Acropora cervicornis, a species that is frequently targeted for restoration of degraded reefs in the broader Caribbean region. This finding suggests a more generalized relationship between diversity and disease and offers a viable strategy for mitigating the spread of infectious diseases in corals that likely applies to other foundation species targeted for restoration.
Collapse
Affiliation(s)
- Anya L. Brown
- grid.15276.370000 0004 1936 8091School of Natural Resources and Environment, University of Florida, Gainesville, FL 32611 USA ,grid.27860.3b0000 0004 1936 9684Present Address: Department of Evolution and Ecology & Bodega Marine Lab, University of California, Davis, Bodega Bay, CA 94923 USA
| | - Dagny-Elise Anastasiou
- Central Caribbean Marine Institute, N Coast Road E, Box 37, Little Cayman, KY3-2501 Cayman Islands
| | - Monica Schul
- grid.15276.370000 0004 1936 8091Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, FL 32611 USA
| | - Sophia MacVittie
- Central Caribbean Marine Institute, N Coast Road E, Box 37, Little Cayman, KY3-2501 Cayman Islands ,grid.266096.d0000 0001 0049 1282Department of Molecular Cell Biology, University of California, Merced, Merced, CA USA
| | - Lindsay J. Spiers
- grid.15276.370000 0004 1936 8091Department of Fisheries and Aquatic Sciences, University of Florida, Gainesville, FL 32611 USA ,grid.427218.a0000 0001 0556 4516Florida Fish & Wildlife Conservation Commission, Fish & Wildlife Research Institute, Marathon, FL USA
| | - Julie L. Meyer
- grid.15276.370000 0004 1936 8091Department of Soil, Water, and Ecosystem Sciences, University of Florida, Gainesville, FL 32611 USA
| | - Carrie Manfrino
- Central Caribbean Marine Institute, N Coast Road E, Box 37, Little Cayman, KY3-2501 Cayman Islands
| | - Thomas K. Frazer
- grid.170693.a0000 0001 2353 285XCollege of Marine Science, University of South Florida, St. Petersburg, FL 33701 USA
| |
Collapse
|
5
|
Belasen AM, Amses KR, Clemons RA, Becker CG, Toledo LF, James TY. Habitat fragmentation in the Brazilian Atlantic Forest is associated with erosion of frog immunogenetic diversity and increased fungal infections. Immunogenetics 2022; 74:431-441. [PMID: 35080658 PMCID: PMC11344651 DOI: 10.1007/s00251-022-01252-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/12/2022] [Indexed: 11/05/2022]
Abstract
Habitat fragmentation and infectious diseases threaten wildlife globally, but the interactions of these threats are poorly understood. For instance, while habitat fragmentation can impact genetic diversity at neutral loci, the impacts on disease-relevant loci are less well-studied. We examined the effects of habitat fragmentation in Brazil's Atlantic Forest on amphibian genetic diversity at an immune locus related to antigen presentation and detection (MHC IIB Exon 2). We used a custom high-throughput assay to sequence a fragment of MHC IIB and quantified Batrachochytrium dendrobatidis (Bd) infections in six frog species in two Atlantic Forest regions. Habitat fragmentation was associated with genetic erosion at MHC IIB Exon 2. This erosion was most severe in forest specialists. Significant Bd infections were detected only in one Atlantic Forest region, potentially due to relatively higher elevation. In this region, forest specialists showed an increase in both Bd prevalence and infection loads in fragmented habitats. Reduced population-level MHC IIB diversity was associated with increased Bd infection risk. On the individual level, MHC IIB heterozygotes exhibited a trend toward reduced Bd infection risk, although this was marginally non-significant. Our results suggest that habitat fragmentation increases Bd infection susceptibility in amphibians, mediated at least in part through erosion of immunogenetic diversity. Our findings have implications for management of fragmented populations in the face of emerging infectious diseases.
Collapse
Affiliation(s)
- Anat M Belasen
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA.
| | - Kevin R Amses
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Rebecca A Clemons
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - C Guilherme Becker
- Department of Biology, The Pennsylvania State University, University Park, PA, USA
| | - L Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros, Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
6
|
Nguyen TN, Chen N, Cosgrove EJ, Bowman R, Fitzpatrick JW, Clark AG. Dynamics of reduced genetic diversity in increasingly fragmented populations of Florida scrub jays, Aphelocoma coerulescens. Evol Appl 2022; 15:1018-1027. [PMID: 35782006 PMCID: PMC9234620 DOI: 10.1111/eva.13421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 04/04/2022] [Accepted: 05/04/2022] [Indexed: 11/29/2022] Open
Abstract
Understanding the genomic consequences of population decline is important for predicting species' vulnerability to intensifying global change. Empirical information about genomic changes in populations in the early stages of decline, especially for those still experiencing immigration, remains scarce. We used 7834 autosomal SNPs and demographic data for 288 Florida scrub jays (Aphelocoma coerulescens; FSJ) sampled in 2000 and 2008 to compare levels of genetic diversity, inbreeding, relatedness, and lengths of runs of homozygosity (ROH) between two subpopulations within dispersal distance of one another but have experienced contrasting demographic trajectories. At Archbold Biological Station (ABS), the FSJ population has been stable because of consistent habitat protection and management, while at nearby Placid Lakes Estates (PLE), the population declined precipitously due to suburban development. By the onset of our sampling in 2000, birds in PLE were already less heterozygous, more inbred, and on average more related than birds in ABS. No significant changes occurred in heterozygosity or inbreeding across the 8-year sampling interval, but average relatedness among individuals decreased in PLE, thus by 2008 average relatedness did not differ between sites. PLE harbored a similar proportion of short ROH but a greater proportion of long ROH than ABS, suggesting one continuous population of shared demographic history in the past, which is now experiencing more recent inbreeding. These results broadly uphold the predictions of simple population genetic models based on inferred effective population sizes and rates of immigration. Our study highlights how, in just a few generations, formerly continuous populations can diverge in heterozygosity and levels of inbreeding with severe local population decline despite ongoing gene flow.
Collapse
Affiliation(s)
- Tram N. Nguyen
- Department of Ecology and Evolutionary BiologyCornell UniversityIthacaNew YorkUSA
- Cornell Lab of OrnithologyIthacaNew YorkUSA
| | - Nancy Chen
- Department of BiologyUniversity of RochesterRochesterNew YorkUSA
| | - Elissa J. Cosgrove
- Department of Molecular Biology and GeneticsCornell UniversityIthacaNew YorkUSA
| | - Reed Bowman
- Avian Ecology LabArchbold Biological StationFloridaUSA
| | - John W. Fitzpatrick
- Department of Ecology and Evolutionary BiologyCornell UniversityIthacaNew YorkUSA
- Cornell Lab of OrnithologyIthacaNew YorkUSA
| | - Andrew G. Clark
- Department of Ecology and Evolutionary BiologyCornell UniversityIthacaNew YorkUSA
- Department of Molecular Biology and GeneticsCornell UniversityIthacaNew YorkUSA
| |
Collapse
|
7
|
Smith D, O'Brien D, Hall J, Sergeant C, Brookes LM, Harrison XA, Garner TWJ, Jehle R. Challenging a host-pathogen paradigm: Susceptibility to chytridiomycosis is decoupled from genetic erosion. J Evol Biol 2022; 35:589-598. [PMID: 35167143 PMCID: PMC9306973 DOI: 10.1111/jeb.13987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 02/07/2022] [Indexed: 11/26/2022]
Abstract
The putatively positive association between host genetic diversity and the ability to defend against pathogens has long attracted the attention of evolutionary biologists. Chytridiomycosis, a disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has emerged in recent decades as a cause of dramatic declines and extinctions across the amphibian clade. Bd susceptibility can vary widely across populations of the same species, but the relationship between standing genetic diversity and susceptibility has remained notably underexplored so far. Here, we focus on a putatively Bd-naive system of two mainland and two island populations of the common toad (Bufo bufo) at the edge of the species' range and use controlled infection experiments and dd-RAD sequencing of >10 000 SNPs across 95 individuals to characterize the role of host population identity, genetic variation and individual body mass in mediating host response to the pathogen. We found strong genetic differentiation between populations and marked variation in their susceptibility to Bd. This variation was not, however, governed by isolation-mediated genetic erosion, and individual heterozygosity was even found to be negatively correlated with survival. Individual survival during infection experiments was strongly positively related to body mass, which itself was unrelated to population of origin or heterozygosity. Our findings underscore the general importance of context-dependency when assessing the role of host genetic variation for the ability of defence against pathogens.
Collapse
Affiliation(s)
- Donal Smith
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
- Institute of ZoologyZoological Society of LondonLondonUK
| | | | | | - Chris Sergeant
- Institute of ZoologyZoological Society of LondonLondonUK
| | - Lola M. Brookes
- Institute of ZoologyZoological Society of LondonLondonUK
- Highland Amphibian and Reptile ProjectDingwallUK
- MRC Centre for Global Infectious Disease AnalysisImperial College School of Public HealthLondonUK
- Royal Veterinary CollegeHatfieldUK
| | - Xavier A. Harrison
- Institute of ZoologyZoological Society of LondonLondonUK
- Centre for Ecology and ConservationUniversity of ExeterExeterUK
| | | | - Robert Jehle
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
| |
Collapse
|
8
|
Stilwell NK, Frasca S, Farina LL, Subramaniam K, Imnoi K, Viadanna PH, Hopper L, Powell J, Colee J, Waltzek TB. Effect of water temperature on frog virus 3 disease in hatchery-reared pallid sturgeon Scaphirhynchus albus. DISEASES OF AQUATIC ORGANISMS 2022; 148:73-86. [PMID: 35238323 DOI: 10.3354/dao03645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Ranaviruses are large double-stranded DNA viruses within the genus Ranavirus (family Iridoviridae) that are being detected with increasing frequency among aquacultured and wild fishes. In the USA, multiple sturgeon hatcheries have experienced ranavirus epizootics resulting in significant morbidity and mortality in young-of-year (YOY). Significant economic losses have resulted from repeated outbreaks of frog virus 3 (FV3), the type species for the genus Ranavirus, in YOY pallid sturgeon Scaphirhynchus albus reared at a hatchery within the Missouri River Basin. Water temperature and stocking density are known to influence the severity of ranavirus disease in ectothermic vertebrates. To determine the effect of water temperature on ranavirus disease in hatchery-raised S. albus, we conducted FV3 challenges at 2 temperatures (17 and 23°C) and compared cumulative survival over a 28 d study period. A mean (±SE) survival rate of 57.5 ± 13.2% was observed in replicate tanks of sturgeon maintained at 23°C, whereas no mortality was observed among sturgeon maintained at 17°C. In a second challenge study, we compared the effect of water temperature on disease progression by regularly sampling fish over the study period and evaluating lesions by histopathology and in situ hybridization, and by assessing viral titer and load in external and internal tissues using virus isolation and qPCR, respectively. Results suggest that temperature manipulation may be an effective mitigation strategy that sturgeon hatcheries can employ to minimize ranavirus-associated disease.
Collapse
Affiliation(s)
- Natalie K Stilwell
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Gibson AK. Genetic diversity and disease: The past, present, and future of an old idea. Evolution 2022; 76:20-36. [PMID: 34796478 PMCID: PMC9064374 DOI: 10.1111/evo.14395] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 10/03/2021] [Accepted: 10/08/2021] [Indexed: 01/21/2023]
Abstract
Why do infectious diseases erupt in some host populations and not others? This question has spawned independent fields of research in evolution, ecology, public health, agriculture, and conservation. In the search for environmental and genetic factors that predict variation in parasitism, one hypothesis stands out for its generality and longevity: genetically homogeneous host populations are more likely to experience severe parasitism than genetically diverse populations. In this perspective piece, I draw on overlapping ideas from evolutionary biology, agriculture, and conservation to capture the far-reaching implications of the link between genetic diversity and disease. I first summarize the development of this hypothesis and the results of experimental tests. Given the convincing support for the protective effect of genetic diversity, I then address the following questions: (1) Where has this idea been put to use, in a basic and applied sense, and how can we better use genetic diversity to limit disease spread? (2) What new hypotheses does the established disease-diversity relationship compel us to test? I conclude that monitoring, preserving, and augmenting genetic diversity is one of our most promising evolutionarily informed strategies for buffering wild, domesticated, and human populations against future outbreaks.
Collapse
Affiliation(s)
- Amanda Kyle Gibson
- Department of Biology University of Virginia Charlottesville Virginia 22903
| |
Collapse
|
10
|
Köhnk S, Petros C, Lomas C, Riyad EM, Shameel I, Hawlitschek O, Stelfox M. Stowaways: Marine Leeches Infecting Olive Ridley Sea Turtles Entangled in Ghost Nets in Maldivian Waters. COMP PARASITOL 2021. [DOI: 10.1654/1525-2647-88.2.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Stephanie Köhnk
- Olive Ridley Project, Stone Moor Bottom, Padiham, BB12 7BW, U.K.; and University of Hamburg, Center of Natural History, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany (e-mail: )
| | - Claire Petros
- Olive Ridley Project, Stone Moor Bottom, Padiham, BB12 7BW, U.K. (e-mail: )
| | - Claire Lomas
- Olive Ridley Project, Stone Moor Bottom, Padiham, BB12 7BW, U.K. (e-mail: )
| | - Enas Mohamed Riyad
- Environmental Protection Agency, Handhuvaree Hingun, Malé, Republic of Maldives (e-mail: )
| | - Ibrahim Shameel
- Olive Ridley Project, Stone Moor Bottom, Padiham, BB12 7BW, U.K. (e-mail: )
| | - Oliver Hawlitschek
- University of Hamburg, Center of Natural History, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany (e-mail: )
| | - Martin Stelfox
- Olive Ridley Project, Stone Moor Bottom, Padiham, BB12 7BW, U.K.; and Aquatic Research Facility, Environment Sustainability Research Centre, College of Life and Natural Sciences, University of Derby, U.K. (e-mail: )
| |
Collapse
|
11
|
Reyne M, Dicks K, McFarlane C, Aubry A, Emmerson M, Marnell F, Reid N, Helyar S. Population genetic structure of the Natterjack toad (Epidalea calamita) in Ireland: implications for conservation management. CONSERV GENET 2021. [DOI: 10.1007/s10592-021-01421-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AbstractMolecular methods can play a crucial role in species management and conservation. Despite the usefulness of genetic approaches, they are often not explicitly included as part of species recovery plans and conservation practises. The Natterjack toad (Epidalea calamita) is regionally Red-Listed as Endangered in Ireland. The species is declining and is now present at just seven sites within a highly restricted range. This study used 13 highly polymorphic microsatellite markers to analyse the population genetic diversity and structure. Genetic diversity was high with expected heterozygosity between 0.55 and 0.61 and allelic richness between 4.77 and 5.92. Effective population sizes were small (Ne < 100 individuals), but not abnormal for pond breeding amphibians. However, there was no evidence of historical or contemporary genetic bottlenecks or high levels of inbreeding. We identified a positive relationship between Ne and breeding pond surface area, suggesting that environmental factors are a key determinant of population size. Significant genetic structuring was detected throughout the species’ range, and we identified four genetic entities that should be considered in the species’ conservation strategies. Management should focus on preventing further population declines and future loss of genetic diversity overall and within genetic entities while maintaining adequate local effective population size through site-specific protection, human-mediated translocations and head-start programs. The apparent high levels of genetic variation give hope for the conservation of Ireland’s rarest amphibian if appropriately protected and managed.
Collapse
|
12
|
Soper DM, Ekroth AKE, Martins MJF. Direct evidence for increased disease resistance in polyandrous broods exists only in eusocial Hymenoptera. BMC Ecol Evol 2021; 21:189. [PMID: 34670487 PMCID: PMC8527725 DOI: 10.1186/s12862-021-01925-3] [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: 06/11/2021] [Accepted: 09/24/2021] [Indexed: 11/25/2022] Open
Abstract
Background The ‘genetic diversity’ hypothesis posits that polyandry evolved as a mechanism to increase genetic diversity within broods. One extension of this hypothesis is the ‘genetic diversity for disease resistance’ hypothesis (GDDRH). Originally designed for eusocial Hymenoptera, GDDRH states that polyandry will evolve as an effect of lower parasite prevalence in genetically variable broods. However, this hypothesis has been broadly applied to several other taxa. It is unclear how much empirical evidence supports GDDRH specifically, especially outside eusocial Hymenoptera. Results This question was addressed by conducting a literature review and posteriorly conducting meta-analyses on the data available using Hedges’s g. The literature review found 10 direct and 32 indirect studies with both having a strong publication bias towards Hymenoptera. Two meta-analyses were conducted and both found increased polyandry (direct tests; n = 8, g = 0.2283, p = < 0.0001) and genetic diversity generated by other mechanisms (indirect tests; n = 10, g = 0.21, p = < 0.0001) reduced parasite load. A subsequent moderator analysis revealed that there were no differences among Orders, indicating there may be applicability outside of Hymenoptera. However, due to publication bias and low sample size we must exercise caution with these results. Conclusion Despite the fact that the GDDRH was developed for Hymenoptera, it is frequently applied to other taxa. This study highlights the low amount of direct evidence supporting GDDRH, particularly outside of eusocial Hymenoptera. It calls for future research to address species that have high dispersal rates and contain mixes of solitary and communal nesting. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01925-3.
Collapse
Affiliation(s)
- D M Soper
- Department of Biology, University of Dallas, 1845 E. Northgate Dr., Irving, TX, 75062, USA.
| | - A K E Ekroth
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - M J F Martins
- Interdisciplinary Center for Archaeology and Evolution of Human Behaviour (ICArEHB), Faculdade de Ciências Humanas e Sociais, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal.,Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20013-7012, USA
| |
Collapse
|
13
|
Bensch HM, O'Connor EA, Cornwallis CK. Living with relatives offsets the harm caused by pathogens in natural populations. eLife 2021; 10:e66649. [PMID: 34309511 PMCID: PMC8313236 DOI: 10.7554/elife.66649] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 06/19/2021] [Indexed: 01/23/2023] Open
Abstract
Living with relatives can be highly beneficial, enhancing reproduction and survival. High relatedness can, however, increase susceptibility to pathogens. Here, we examine whether the benefits of living with relatives offset the harm caused by pathogens, and if this depends on whether species typically live with kin. Using comparative meta-analysis of plants, animals, and a bacterium (nspecies = 56), we show that high within-group relatedness increases mortality when pathogens are present. In contrast, mortality decreased with relatedness when pathogens were rare, particularly in species that live with kin. Furthermore, across groups variation in mortality was lower when relatedness was high, but abundances of pathogens were more variable. The effects of within-group relatedness were only evident when pathogens were experimentally manipulated, suggesting that the harm caused by pathogens is masked by the benefits of living with relatives in nature. These results highlight the importance of kin selection for understanding disease spread in natural populations.
Collapse
|
14
|
Bosch J, Mora-Cabello de Alba A, Marquínez S, Price SJ, Thumsová B, Bielby J. Long-Term Monitoring of Amphibian Populations of a National Park in Northern Spain Reveals Negative Persisting Effects of Ranavirus, but Not Batrachochytrium dendrobatidis. Front Vet Sci 2021; 8:645491. [PMID: 34235196 PMCID: PMC8255480 DOI: 10.3389/fvets.2021.645491] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 05/21/2021] [Indexed: 11/25/2022] Open
Abstract
Amphibians are the most highly threatened vertebrates, and emerging pathogens are a serious threat to their conservation. Amphibian chytrid fungi and the viruses of the Ranavirus genus are causing disease outbreaks worldwide, including in protected areas such as National Parks. However, we lack information about their effect over amphibian populations in the long-term, and sometimes these mortality episodes are considered as transient events without serious consequences over longer time-spans. Here, we relate the occurrence of both pathogens with the population trends of 24 amphibian populations at 15 sites across a national Park in northern Spain over a 14-year period. Just one out 24 populations presents a positive population trend being free of both pathogens, while seven populations exposed to one or two pathogens experienced strong declines during the study period. The rest of the study populations (16) remain stable, and these tend to be of species that are not susceptible to the pathogen present or are free of pathogens. Our study is consistent with infectious diseases playing an important role in dictating amphibian population trends and emphasizes the need to adopt measures to control these pathogens in nature. We highlight that sites housing species carrying Ranavirus seems to have experienced more severe population-level effects compared to those with the amphibian chytrid fungus, and that ranaviruses could be just as, or more important, other more high-profile amphibian emerging pathogens.
Collapse
Affiliation(s)
- Jaime Bosch
- Research Unit of Biodiversity (Consejo Superior de Investigaciones Científicas, Universidad de Oviedo, Principado de Asturias), Oviedo University, Mieres, Spain.,Museo Nacional de Ciencias Naturales-Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | | | | | - Stephen J Price
- Genetic Institute, University College London, London, United Kingdom
| | - Barbora Thumsová
- Research Unit of Biodiversity (Consejo Superior de Investigaciones Científicas, Universidad de Oviedo, Principado de Asturias), Oviedo University, Mieres, Spain.,Museo Nacional de Ciencias Naturales-Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Jon Bielby
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| |
Collapse
|
15
|
Gazzola A, Balestrieri A, Scribano G, Fontana A, Pellitteri-Rosa D. Contextual behavioural plasticity in Italian agile frog (Rana latastei) tadpoles exposed to native and alien predator cues. J Exp Biol 2021; 224:238115. [PMID: 33795420 DOI: 10.1242/jeb.240465] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 03/24/2021] [Indexed: 11/20/2022]
Abstract
Predation is a strong driver for the evolution of prey behaviour. To properly assess the actual risk of predation, anuran tadpoles mostly rely on water-borne chemical cues, and their ability to evaluate environmental information is even more crucial when potential predators consist of unknown alien species. Behavioural plasticity - that is, the capacity to express changes in behaviour in response to different environmental stimuli - is crucial to cope with predation risk. We explored the defensive behaviour of Italian agile frog (Rana latastei) tadpoles when exposed to the chemical cues of two predator species, one native (dragonfly larvae) and one alien (red swamp crayfish). Firstly, we observed whether a plastic life history trait (i.e. hatching time) might be affected by native predatory cues. Secondly, we recorded a suite of behavioural responses (activity level, lateralization and sinuosity) to each cue. For assessing lateralization and sinuosity, we developed a C++ code for the automatic analysis of digitally recorded tadpole tracks. Hatching time seemed not to be affected by the potential risk of predation, while both predator species and diet affected tadpoles' defensive behaviour. Tadpoles responded to a predator threat by two main defensive strategies: freezing and 'zig-zagging'. While the first behaviour had previously been reported, the analysis of individual trajectories indicated that tadpoles can also increase path complexity, probably to prevent predators from anticipating their location. We also recorded a decrease in lateralization intensity, which suggests that under predation risk, tadpoles tend to scrutinize the surrounding environment equally on both sides.
Collapse
Affiliation(s)
- Andrea Gazzola
- Dipartimento di Scienze della Terra e dell'Ambiente, Università di Pavia, I-27100 Pavia, Italy
| | - Alessandro Balestrieri
- Dipartimento di Scienze della Terra e dell'Ambiente, Università di Pavia, I-27100 Pavia, Italy
| | - Giovanni Scribano
- Dipartimento di Scienze della Terra e dell'Ambiente, Università di Pavia, I-27100 Pavia, Italy
| | - Andrea Fontana
- Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, I-27100 Pavia, Italy
| | - Daniele Pellitteri-Rosa
- Dipartimento di Scienze della Terra e dell'Ambiente, Università di Pavia, I-27100 Pavia, Italy
| |
Collapse
|
16
|
Metapopulation genetics of endangered reticulated flatwoods salamanders (Ambystoma bishopi) in a dynamic and fragmented landscape. CONSERV GENET 2021. [DOI: 10.1007/s10592-021-01360-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
17
|
Proença DN, Fasola E, Lopes I, Morais PV. Characterization of the Skin Cultivable Microbiota Composition of the Frog Pelophylax perezi Inhabiting Different Environments. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18052585. [PMID: 33807539 PMCID: PMC7967507 DOI: 10.3390/ijerph18052585] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 02/25/2021] [Accepted: 02/28/2021] [Indexed: 12/20/2022]
Abstract
Microorganisms that live in association with amphibian skin can play important roles in protecting their host. Within the scenarios of global change, it is important to understand how environmental disturbances, namely, metal pollution, can affect this microbiota. The aim of this study is to recognize core bacteria in the skin cultivable microbiota of the Perez frog (Pelophylax perezi) that are preserved regardless of the environmental conditions in which the frogs live. The characterization of these isolates revealed characteristics that can support their contributions to the ability of frogs to use metal impacted environments. Frog’s skin swabs were collected from P. perezi populations that inhabit a metal-polluted site and three reference (non-metal polluted) sites. Bacterial strains were isolated, identified, and subjected to an acid mine drainage tolerance (AMD) test, collected upstream from a site heavily contaminated with metals, and tested to produce extracellular polymeric substances (exopolysaccharide, EPS). All frog populations had Acinetobacter in their cutaneous cultivable microbiota. Significant growth inhibition was observed in all bacterial isolates exposed to 75% of AMD. EPS production was considered a characteristic of several isolates. The data obtained is a preliminary step but crucial to sustain that the cultivable microbiota is a mechanism for protecting frogs against environmental contamination.
Collapse
Affiliation(s)
- Diogo Neves Proença
- Department of Life Sciences and Centre for Mechanical Engineering, Materials and Processes, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal;
| | - Emanuele Fasola
- CESAM and Department of Biology, University of Aveiro, 3810-005 Aveiro, Portugal; (E.F.); (I.L.)
| | - Isabel Lopes
- CESAM and Department of Biology, University of Aveiro, 3810-005 Aveiro, Portugal; (E.F.); (I.L.)
| | - Paula V. Morais
- Department of Life Sciences and Centre for Mechanical Engineering, Materials and Processes, University of Coimbra, Calçada Martim de Freitas, 3000-456 Coimbra, Portugal;
- Correspondence: ; Tel.: +35-1239240700
| |
Collapse
|
18
|
Oswald P, Rodríguez A, Bourke J, Wagner N, de Buhr N, Buschmann H, Köckritz-Blickwede MV, Pröhl H. Locality, time and heterozygosity affect chytrid infection in yellow-bellied toads. DISEASES OF AQUATIC ORGANISMS 2020; 142:225-237. [PMID: 33331290 DOI: 10.3354/dao03543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd) infects numerous amphibian species worldwide and is suggested to drive population declines and extinction events. We report a study of Bd infection at the northernmost distribution of the European yellow-bellied toad Bombina variegata. A total of 577 individuals from ponds in 16 study sites were sampled for DNA and Bd throughout the breeding season. Microsatellite genotyping revealed 3 genetic clusters for the host B. variegata with an overall low genetic diversity. One of the clusters displayed a low microsatellite heterozygosity, a high inbreeding coefficient as well as high Bd infection prevalence and intensities. Multi-model estimates identified site, time of sampling, and heterozygosity to be important predictors of an individual's Bd infection status, and identified a strong effect of site on individual Bd infection intensity. The study site effects are suggestive of localized infection peaks, and the increase of individual Bd infection probabilities towards the end of the sampling period suggests cumulative infection during the breeding season. This study highlights the need for regular monitoring of Bd infection variables at multiple localities and times to gain insights into Bd dynamics. Due to the detected relationship between individual Bd infection status and heterozygosity, conservation measures should focus on the maintenance of high genetic diversity and connectivity within and among amphibian populations.
Collapse
Affiliation(s)
- Pia Oswald
- Institute of Zoology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | | | | | | | | | | | | | | |
Collapse
|
19
|
Gibson AK, Nguyen AE. Does genetic diversity protect host populations from parasites? A meta-analysis across natural and agricultural systems. Evol Lett 2020; 5:16-32. [PMID: 33552533 PMCID: PMC7857278 DOI: 10.1002/evl3.206] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/23/2020] [Accepted: 10/27/2020] [Indexed: 11/24/2022] Open
Abstract
If parasites transmit more readily between closely related hosts, then parasite burdens should decrease with increased genetic diversity of host populations. This important hypothesis is often accepted at face value—notorious epidemics of crop monocultures testify to the vulnerability of host populations that have been purged of diversity. Yet the relationship between genetic diversity and parasitism likely varies across contexts, differing between crop and noncrop hosts and between experimental and natural host populations. Here, we used a meta‐analytic approach to ask if host diversity confers protection against parasites over the range of contexts in which it has been tested. We synthesized the results of 102 studies, comprising 2004 effect sizes representing a diversity of approaches and host‐parasite systems. Our results validate a protective effect of genetic diversity, while revealing significant variation in its strength across biological and empirical contexts. In experimental host populations, genetic diversity reduces parasitism by ∼20% for noncrop hosts and by ∼50% for crop hosts. In contrast, observational studies of natural host populations show no consistent relationship between genetic diversity and parasitism, with both strong negative and positive correlations reported. This result supports the idea that, if parasites preferentially attack close relatives, the correlation of genetic diversity with parasitism could be positive or negative depending upon the potential for host populations to evolve in response to parasite selection. Taken together, these results reinforce genetic diversity as a priority for both conservation and agriculture and emphasize the challenges inherent to drawing comparisons between controlled experimental populations and dynamic natural populations.
Collapse
Affiliation(s)
- Amanda Kyle Gibson
- Department of Biology University of Virginia Charlottesville Virginia 22904
| | - Anna E Nguyen
- Department of Biology University of Virginia Charlottesville Virginia 22904
| |
Collapse
|
20
|
Page RB, Conarroe C, Quintanilla D, Palomo A, Solis J, Aguilar A, Bezold K, Sackman AM, Marsh DM. Genetic variation in Plethodon cinereus and Plethodon hubrichti from in and around a contact zone. Ecol Evol 2020; 10:9948-9967. [PMID: 33005356 PMCID: PMC7520177 DOI: 10.1002/ece3.6653] [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: 03/27/2020] [Revised: 07/10/2020] [Accepted: 07/16/2020] [Indexed: 11/21/2022] Open
Abstract
Climate change poses several challenges to biological communities including changes in the frequency of encounters between closely related congeners as a result of range shifts. When climate change leads to increased hybridization, hybrid dysfunction or genetic swamping may increase extinction risk-particularly in range-restricted species with low vagility. The Peaks of Otter Salamander, Plethodon hubrichti, is a fully terrestrial woodland salamander that is restricted to ~18 km of ridgeline in the mountains of southwestern Virginia, and its range is surrounded by the abundant and widespread Eastern Red-backed Salamander, Plethodon cinereus. In order to determine whether these two species are hybridizing and how their range limits may be shifting, we assessed variation at eight microsatellite loci and a 1,008 bp region of Cytochrome B in both species at allopatric reference sites and within a contact zone. Our results show that hybridization between P. hubrichti and P. cinereus either does not occur or is very rare. However, we find that diversity and differentiation are substantially higher in the mountaintop endemic P. hubrichti than in the widespread P. cinereus, despite similar movement ability for the two species as assessed by a homing experiment. Furthermore, estimation of divergence times between reference and contact zone populations via approximate Bayesian computation is consistent with the idea that P. cinereus has expanded into the range of P. hubrichti. Given the apparent recent colonization of the contact zone by P. cinereus, future monitoring of P. cinereus range limits should be a priority for the management of P. hubrichti populations.
Collapse
Affiliation(s)
- Robert B. Page
- Department of Life SciencesTexas A&M University‐San AntonioSan AntonioTXUSA
| | - Claire Conarroe
- Department of BiologyWashington and Lee UniversityLexingtonVAUSA
| | - Diana Quintanilla
- Department of Life SciencesTexas A&M University‐San AntonioSan AntonioTXUSA
| | - Andriea Palomo
- Department of Life SciencesTexas A&M University‐San AntonioSan AntonioTXUSA
| | - Joshua Solis
- Department of Life SciencesTexas A&M University‐San AntonioSan AntonioTXUSA
| | - Ashley Aguilar
- Department of Life SciencesTexas A&M University‐San AntonioSan AntonioTXUSA
| | - Kelly Bezold
- Department of BiologyWashington and Lee UniversityLexingtonVAUSA
| | | | - David M. Marsh
- Department of BiologyWashington and Lee UniversityLexingtonVAUSA
| |
Collapse
|
21
|
Common J, Walker-Sünderhauf D, van Houte S, Westra ER. Diversity in CRISPR-based immunity protects susceptible genotypes by restricting phage spread and evolution. J Evol Biol 2020; 33:1097-1108. [PMID: 32383796 DOI: 10.1111/jeb.13638] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/13/2020] [Accepted: 04/27/2020] [Indexed: 12/26/2022]
Abstract
Diversity in host resistance often associates with reduced pathogen spread. This may result from ecological and evolutionary processes, likely with feedback between them. Theory and experiments on bacteria-phage interactions have shown that genetic diversity of the bacterial adaptive immune system can limit phage evolution to overcome resistance. Using the CRISPR-Cas bacterial immune system and lytic phage, we engineered a host-pathogen system where each bacterial host genotype could be infected by only one phage genotype. With this model system, we explored how CRISPR diversity impacts the spread of phage when they can overcome a resistance allele, how immune diversity affects the evolution of the phage to increase its host range and if there was feedback between these processes. We show that increasing CRISPR diversity benefits susceptible bacteria via a dilution effect, which limits the spread of the phage. We suggest that this ecological effect impacts the evolution of novel phage genotypes, which then feeds back into phage population dynamics.
Collapse
Affiliation(s)
- Jack Common
- ESI and CEC, Biosciences, University of Exeter, Penryn, UK
| | - David Walker-Sünderhauf
- European Centre for Environment and Human Health, ESI, University of Exeter Medical School, Penryn, UK
| | | | - Edze R Westra
- ESI and CEC, Biosciences, University of Exeter, Penryn, UK
| |
Collapse
|
22
|
Bienentreu JF, Lesbarrères D. Amphibian Disease Ecology: Are We Just Scratching the Surface? HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.153] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | - David Lesbarrères
- Department of Biology, Laurentian University, Sudbury, ON P3E 2C6, Canada
| |
Collapse
|
23
|
Nummert G, Aaspõllu A, Kuningas K, Timm U, Hanski IK, Maran T. Genetic diversity in Siberian flying squirrel (Pteromys volans) in its western frontier with a focus on the Estonian population. MAMMAL RES 2020. [DOI: 10.1007/s13364-020-00509-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
24
|
Pabijan M, Palomar G, Antunes B, Antoł W, Zieliński P, Babik W. Evolutionary principles guiding amphibian conservation. Evol Appl 2020; 13:857-878. [PMID: 32431739 PMCID: PMC7232768 DOI: 10.1111/eva.12940] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/05/2020] [Accepted: 02/18/2020] [Indexed: 12/18/2022] Open
Abstract
The Anthropocene has witnessed catastrophic amphibian declines across the globe. A multitude of new, primarily human-induced drivers of decline may lead to extinction, but can also push species onto novel evolutionary trajectories. If these are recognized by amphibian biologists, they can be engaged in conservation actions. Here, we summarize how principles stemming from evolutionary concepts have been applied for conservation purposes, and address emerging ideas at the vanguard of amphibian conservation science. In particular, we examine the consequences of increased drift and inbreeding in small populations and their implications for practical conservation. We then review studies of connectivity between populations at the landscape level, which have emphasized the limiting influence of anthropogenic structures and degraded habitat on genetic cohesion. The rapid pace of environmental changes leads to the central question of whether amphibian populations can cope either by adapting to new conditions or by shifting their ranges. We gloomily conclude that extinction seems far more likely than adaptation or range shifts for most species. That said, conservation strategies employing evolutionary principles, such as selective breeding, introduction of adaptive variants through translocations, ecosystem interventions aimed at decreasing phenotype-environment mismatch, or genetic engineering, may effectively counter amphibian decline in some areas or for some species. The spread of invasive species and infectious diseases has often had disastrous consequences, but has also provided some premier examples of rapid evolution with conservation implications. Much can be done in terms of setting aside valuable amphibian habitat that should encompass both natural and agricultural areas, as well as designing protected areas to maximize the phylogenetic and functional diversity of the amphibian community. We conclude that an explicit consideration and application of evolutionary principles, although certainly not a silver bullet, should increase effectiveness of amphibian conservation in both the short and long term.
Collapse
Affiliation(s)
- Maciej Pabijan
- Institute of Zoology and Biomedical ResearchFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Gemma Palomar
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Bernardo Antunes
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Weronika Antoł
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Piotr Zieliński
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Wiesław Babik
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| |
Collapse
|
25
|
White PS, Choi A, Pandey R, Menezes A, Penley M, Gibson AK, de Roode J, Morran L. Host heterogeneity mitigates virulence evolution. Biol Lett 2020; 16:20190744. [PMID: 31992149 PMCID: PMC7013476 DOI: 10.1098/rsbl.2019.0744] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/19/2019] [Indexed: 01/21/2023] Open
Abstract
Parasites often infect genetically diverse host populations, and the evolutionary trajectories of parasite populations may be shaped by levels of host heterogeneity. Mixed genotype host populations, compared to homogeneous host populations, can reduce parasite prevalence and potentially reduce rates of parasite adaptation due to trade-offs associated with adapting to specific host genotypes. Here, we used experimental evolution to select for increased virulence in populations of the bacterial parasite Serratia marcescens exposed to either heterogeneous or homogeneous populations of Caenorhabditis elegans. We found that parasites exposed to heterogeneous host populations evolved significantly less virulence than parasites exposed to homogeneous host populations over several hundred bacterial generations. Thus, host heterogeneity impeded parasite adaptation to host populations. While we detected trade-offs in virulence evolution, parasite adaptation to two specific host genotypes also resulted in modestly increased virulence against the reciprocal host genotypes. These results suggest that parasite adaptation to heterogeneous host populations may be impeded by both trade-offs and a reduction in the efficacy of selection as different host genotypes exert different selective pressures on a parasite population.
Collapse
Affiliation(s)
- P. Signe White
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
- Population Biology, Ecology, and Evolution Graduate Program, Laney Graduate School, Emory University, Atlanta, GA 30322, USA
| | - Angela Choi
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Rishika Pandey
- Department of Genetics, Franklin College of Arts and Sciences, University of Georgia, Athens, GA 30602, USA
| | - Arthur Menezes
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - McKenna Penley
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Amanda K. Gibson
- Department of Biology, College and Graduate School of Arts and Sciences, University of Virginia, Charlottesville, VA 22904, USA
| | - Jacobus de Roode
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Levi Morran
- Department of Biology, College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| |
Collapse
|
26
|
Bienentreu JF, Grayfer L, Schock DM, Guerreiro M, Mehes-Smith M, DeWitte-Orr SJ, Robert J, Brunetti CR, Lesbarrères D. Sublethal effects of wild-type and a vIF-2α-knockout Frog virus 3 on postmetamorphic wood frogs (Rana sylvatica): potential for a stage-specific reservoir. Facets (Ott) 2020. [DOI: 10.1139/facets-2020-0001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ranaviruses have been associated with rising numbers of mass die-offs in amphibian populations around the globe. However, most studies on ranaviruses to date focused on larval amphibians. To assess the role of postmetamorphic amphibians in the epidemiology of ranaviruses and to determine the role of viral immune-suppression genes, we performed a bath-exposure study on post-metamorphic wood frogs ( Rana sylvatica) using environmentally relevant concentrations of wild-type Frog virus 3 (WT FV3), and a gene-knockout mutant (KO FV3), deficient for the putative immune-suppression gene vIF-2α. We observed a 42% infection rate and 5% mortality across the virus challenges, with infection rates and viral loads following a dose-dependent pattern. Individuals exposed to the knockout variant exhibited significantly decreased growth and increased lethargy compared with wild-type treatments. Although 85% of exposed individuals exhibited common signs of ranavirosis throughout the experiment, most of these individuals did not exhibit signs of infection by 40 d post-exposure. Overall, we showed that even a single short time exposure to environmentally relevant concentrations of ranavirus may cause sublethal infections in postmetamorphic amphibians, highlighting the importance of this life stage in the epidemiology of ranaviruses. Our study also supports the importance of the vIF-2α gene in immune-suppression in infected individuals.
Collapse
Affiliation(s)
| | - Leon Grayfer
- Department of Biological Sciences, George Washington University, Washington, DC 20052, USA
| | - Danna M. Schock
- University Studies and Environmental Technology, Keyano College, Fort McMurray, AB T9H 2H7, Canada
| | - Matthew Guerreiro
- Department of Health Sciences, Wilfrid Laurier University, Waterloo, ON N2L 3C5, Canada
| | | | | | - Jacques Robert
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642, USA
| | - Craig R. Brunetti
- Department of Biology, Trent University, Peterborough, ON K9J 7B8, Canada
| | - David Lesbarrères
- Department of Biology, Laurentian University, Sudbury, ON P3E 2C6, Canada
| |
Collapse
|
27
|
Cabalzar AP, Fields PD, Kato Y, Watanabe H, Ebert D. Parasite-mediated selection in a natural metapopulation of Daphnia magna. Mol Ecol 2019; 28:4770-4785. [PMID: 31591747 DOI: 10.1111/mec.15260] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/17/2019] [Accepted: 09/27/2019] [Indexed: 01/03/2023]
Abstract
Parasite-mediated selection varying across time and space in metapopulations is expected to result in host local adaptation and the maintenance of genetic diversity in disease-related traits. However, nonadaptive processes like migration and extinction-(re)colonization dynamics might interfere with adaptive evolution. Understanding how adaptive and nonadaptive processes interact to shape genetic variability in life-history and disease-related traits can provide important insights into their evolution in subdivided populations. Here we investigate signatures of spatially fluctuating, parasite-mediated selection in a natural metapopulation of Daphnia magna. Host genotypes from infected and uninfected populations were genotyped at microsatellite markers, and phenotyped for life-history and disease traits in common garden experiments. Combining phenotypic and genotypic data a QST -FST -like analysis was conducted to test for signatures of parasite mediated selection. We observed high variation within and among populations for phenotypic traits, but neither an indication of host local adaptation nor a cost of resistance. Infected populations have a higher gene diversity (Hs) than uninfected populations and Hs is strongly positively correlated with fitness. These results suggest a strong parasite effect on reducing population level inbreeding. We discuss how stochastic processes related to frequent extinction-(re)colonization dynamics as well as host and parasite migration impede the evolution of resistance in the infected populations. We suggest that the genetic and phenotypic patterns of variation are a product of dynamic changes in the host gene pool caused by the interaction of colonization bottlenecks, inbreeding, immigration, hybrid vigor, rare host genotype advantage and parasitism. Our study highlights the effect of the parasite in ameliorating the negative fitness consequences caused by the high drift load in this metapopulation.
Collapse
Affiliation(s)
- Andrea P Cabalzar
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Yasuhiko Kato
- Department of Biotechnology, Division of Advance Science and Biotechnology, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Hajime Watanabe
- Department of Biotechnology, Division of Advance Science and Biotechnology, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland.,Tvärminne Zoological Station, Tvärminne, Finland
| |
Collapse
|
28
|
Ekroth AKE, Rafaluk-Mohr C, King KC. Host genetic diversity limits parasite success beyond agricultural systems: a meta-analysis. Proc Biol Sci 2019; 286:20191811. [PMID: 31551053 DOI: 10.1098/rspb.2019.1811] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is evidence that human activities are reducing the population genetic diversity of species worldwide. Given the prediction that parasites better exploit genetically homogeneous host populations, many species could be vulnerable to disease outbreaks. While agricultural studies have shown the devastating effects of infectious disease in crop monocultures, the widespread nature of this diversity-disease relationship remains unclear in natural systems. Here, we provide broad support that high population genetic diversity can protect against infectious disease by conducting a meta-analysis of 23 studies, with a total of 67 effect sizes. We found that parasite functional group (micro- or macroparasite) affects the presence of the effect and study setting (field or laboratory-based environment) influences the magnitude. Our study also suggests that host genetic diversity is overall a robust defence against infection regardless of host reproduction, parasite host range, parasite diversity, virulence and the method by which parasite success was recorded. Combined, these results highlight the importance of monitoring declines of host population genetic diversity as shifts in parasite distributions could have devastating effects on at-risk populations in nature.
Collapse
Affiliation(s)
| | | | - Kayla C King
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| |
Collapse
|
29
|
Carter ED, Miller DL, Peterson AC, Sutton WB, Cusaac JPW, Spatz JA, Rollins‐Smith L, Reinert L, Bohanon M, Williams LA, Upchurch A, Gray MJ. Conservation risk of
Batrachochytrium salamandrivorans
to endemic lungless salamanders. Conserv Lett 2019. [DOI: 10.1111/conl.12675] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Affiliation(s)
- Edward Davis Carter
- Center for Wildlife Health, Department of ForestryWildlife and FisheriesUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
| | - Debra L. Miller
- Center for Wildlife Health, Department of ForestryWildlife and FisheriesUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
- Department of Biomedical and Diagnostic Sciences, College of Veterinary MedicineUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
| | - Anna C. Peterson
- Center for Wildlife Health, Department of ForestryWildlife and FisheriesUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
| | - William B. Sutton
- Department of Agricultural and Environmental SciencesTennessee State University Nashville Tennessee
| | - Joseph Patrick W. Cusaac
- Center for Wildlife Health, Department of ForestryWildlife and FisheriesUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
| | - Jennifer A. Spatz
- Center for Wildlife Health, Department of ForestryWildlife and FisheriesUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
| | - Louise Rollins‐Smith
- Department of PathologyMicrobiology & ImmunologyVanderbilt University Nashville Tennessee
| | - Laura Reinert
- Department of PathologyMicrobiology & ImmunologyVanderbilt University Nashville Tennessee
| | - Markese Bohanon
- Center for Wildlife Health, Department of ForestryWildlife and FisheriesUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
| | - Lori A. Williams
- North Carolina Wildlife Resources Commission Raleigh North Carolina
| | | | - Matthew J. Gray
- Center for Wildlife Health, Department of ForestryWildlife and FisheriesUniversity of Tennessee Institute of Agriculture Knoxville Tennessee
| |
Collapse
|
30
|
The Role of Traditional Livelihood Practices and Local Ethnobotanical Knowledge in Mitigating Chestnut Disease and Pest Severity in Turkey. FORESTS 2019. [DOI: 10.3390/f10070571] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The European chestnut population is enduring multiple compounding exotic pest and disease outbreaks across Turkey. The deeply held value of the chestnut species for the Turkish public is reflected in substantial government conservation programming. Chestnut is predominantly found on state land managed by Turkey’s General Directorate of Forestry (GDF), which generally upholds restrictive policies for chestnut-related livelihood practices other than nut collection and beehive placement. Such policies are justified by a government position that human activities and presence is likely to worsen disease dynamics. Conversely, a growing body of research findings testify that small-scale livelihood practices maintain biological diversity and, furthermore, that this traditional maintenance of diversity has been correlated with decreased pathogen pressure within agroecosystems. However, few studies have investigated this phenomenon in the context of agroforestry systems. At a global ecological moment of increasingly pervasive and severe exotic forest pathogen impact, this paper investigates the influence of diverse small-scale livelihood practices and knowledge on chestnut tree health across the highly heterogenous geography of Turkey. We conducted ethnobotanical questionnaires with 96 chestnut-utilizing households, and chestnut tree health evaluations in georeferenced forest areas they identified, throughout Turkey’s Black Sea, Marmara, and Aegean regions. Using data from 1500 trees, we characterized the effects of subsequently recorded environmental, physiological, and anthropogenic factors on tree health using multiple correspondence analysis (MCA), multiple factor analysis (MFA), and mixed models. Our results show that the traditional human management of tree physiology and ecology has a significant positive effect on tree health, especially through the acts of grafting and culling as well as the maintenance of diversity. We argue that conceptualizing such livelihood systems as human niche construction and maintenance can help forest management agencies to better understand and conserve valuable landscapes, even in increasingly common periods of severe pathogenic pressure.
Collapse
|
31
|
Belasen AM, Bletz MC, Leite DDS, Toledo LF, James TY. Long-Term Habitat Fragmentation Is Associated With Reduced MHC IIB Diversity and Increased Infections in Amphibian Hosts. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2018.00236] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
32
|
Bower DS, Brannelly LA, McDonald CA, Webb RJ, Greenspan SE, Vickers M, Gardner MG, Greenlees MJ. A review of the role of parasites in the ecology of reptiles and amphibians. AUSTRAL ECOL 2018. [DOI: 10.1111/aec.12695] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Deborah S. Bower
- College of Science and Engineering; James Cook University; Townsville Queensland 4811 Australia
- School of Environmental and Rural Science; University of New England; Armidale New South Wales Australia
| | - Laura A. Brannelly
- Department of Biological Sciences; University of Pittsburgh; Pittsburgh Pennsylvania USA
| | - Cait A. McDonald
- Department of Ecology and Evolutionary Biology; Cornell University; Ithaca New York USA
| | - Rebecca J. Webb
- College of Public Health, Medical and Veterinary Sciences; James Cook University; Townsville Queensland Australia
| | - Sasha E. Greenspan
- Department of Biological Sciences; University of Alabama; Tuscaloosa Alabama USA
| | - Mathew Vickers
- College of Science and Engineering; James Cook University; Townsville Queensland 4811 Australia
| | - Michael G. Gardner
- College of Science and Engineering; Flinders University; Adelaide South Australia Australia
- Evolutionary Biology Unit; South Australian Museum; Adelaide South Australia Australia
| | - Matthew J. Greenlees
- School of Life and Environmental Sciences; University of Sydney; Sydney New South Wales Australia
| |
Collapse
|
33
|
Effects of Emerging Infectious Diseases on Amphibians: A Review of Experimental Studies. DIVERSITY-BASEL 2018. [DOI: 10.3390/d10030081] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Numerous factors are contributing to the loss of biodiversity. These include complex effects of multiple abiotic and biotic stressors that may drive population losses. These losses are especially illustrated by amphibians, whose populations are declining worldwide. The causes of amphibian population declines are multifaceted and context-dependent. One major factor affecting amphibian populations is emerging infectious disease. Several pathogens and their associated diseases are especially significant contributors to amphibian population declines. These include the fungi Batrachochytrium dendrobatidis and B. salamandrivorans, and ranaviruses. In this review, we assess the effects of these three pathogens on amphibian hosts as found through experimental studies. Such studies offer valuable insights to the causal factors underpinning broad patterns reported through observational studies. We summarize key findings from experimental studies in the laboratory, in mesocosms, and from the field. We also summarize experiments that explore the interactive effects of these pathogens with other contributors of amphibian population declines. Though well-designed experimental studies are critical for understanding the impacts of disease, inconsistencies in experimental methodologies limit our ability to form comparisons and conclusions. Studies of the three pathogens we focus on show that host susceptibility varies with such factors as species, host age, life history stage, population and biotic (e.g., presence of competitors, predators) and abiotic conditions (e.g., temperature, presence of contaminants), as well as the strain and dose of the pathogen, to which hosts are exposed. Our findings suggest the importance of implementing standard protocols and reporting for experimental studies of amphibian disease.
Collapse
|
34
|
Kaczensky P, Kovtun E, Habibrakhmanov R, Hemami MR, Khaleghi A, Linnell JDC, Rustamov E, Sklyarenko S, Walzer C, Zuther S, Kuehn R. Genetic characterization of free-ranging Asiatic wild ass in Central Asia as a basis for future conservation strategies. CONSERV GENET 2018. [DOI: 10.1007/s10592-018-1086-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
35
|
Campbell LJ, Hammond SA, Price SJ, Sharma MD, Garner TWJ, Birol I, Helbing CC, Wilfert L, Griffiths AGF. A novel approach to wildlife transcriptomics provides evidence of disease-mediated differential expression and changes to the microbiome of amphibian populations. Mol Ecol 2018; 27:1413-1427. [PMID: 29420865 DOI: 10.1111/mec.14528] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 01/01/2023]
Abstract
Ranaviruses are responsible for a lethal, emerging infectious disease in amphibians and threaten their populations throughout the world. Despite this, little is known about how amphibian populations respond to ranaviral infection. In the United Kingdom, ranaviruses impact the common frog (Rana temporaria). Extensive public engagement in the study of ranaviruses in the UK has led to the formation of a unique system of field sites containing frog populations of known ranaviral disease history. Within this unique natural field system, we used RNA sequencing (RNA-Seq) to compare the gene expression profiles of R. temporaria populations with a history of ranaviral disease and those without. We have applied a RNA read-filtering protocol that incorporates Bloom filters, previously used in clinical settings, to limit the potential for contamination that comes with the use of RNA-Seq in nonlaboratory systems. We have identified a suite of 407 transcripts that are differentially expressed between populations of different ranaviral disease history. This suite contains genes with functions related to immunity, development, protein transport and olfactory reception among others. A large proportion of potential noncoding RNA transcripts present in our differentially expressed set provide first evidence of a possible role for long noncoding RNA (lncRNA) in amphibian response to viruses. Our read-filtering approach also removed significantly more bacterial reads from libraries generated from positive disease history populations. Subsequent analysis revealed these bacterial read sets to represent distinct communities of bacterial species, which is suggestive of an interaction between ranavirus and the host microbiome in the wild.
Collapse
Affiliation(s)
- Lewis J Campbell
- Environment and Sustainability Institute, University of Exeter, Penryn, UK.,Institute of Zoology, Zoological Society of London, London, UK
| | - Stewart A Hammond
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Stephen J Price
- Institute of Zoology, Zoological Society of London, London, UK.,UCL Genetics Institute, University College London, London, UK
| | - Manmohan D Sharma
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | | | - Inanc Birol
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Caren C Helbing
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Lena Wilfert
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | | |
Collapse
|
36
|
Hernández-Gómez O, Briggler JT, Williams RN. Influence of immunogenetics, sex and body condition on the cutaneous microbial communities of two giant salamanders. Mol Ecol 2018; 27:1915-1929. [PMID: 29411437 DOI: 10.1111/mec.14500] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 02/06/2023]
Abstract
The complex association between hosts and microbial symbionts requires the implementation of multiple approaches to evaluate variation in host physiology. Within amphibians, heterogeneity in immunogenetic traits and cutaneous microbiota is associated with variation in disease resistance. Ozark (Cryptobranchus alleganiensis bishopi) and eastern hellbenders (C. a. alleganiensis) provide a model system to assess variation in host traits and microbial communities. Ozark hellbenders have experienced declines throughout their range, are federally endangered and experience wound retardation that is absent in the eastern subspecies. Previous microbial investigations indicate differentiation in the composition of the skin microbiota of both hellbender subspecies, but it is not clear whether these patterns are concurrent with diversity in the major histocompatibility complex (MHC) genes. We characterized the MHC IIB and the skin microbiota of hellbenders in Missouri, where both subspecies co-occur though not sympatric. We compared the microbiota composition and MHC diversity between both subspecies and investigated whether individual-level MHC diversity, sex and body condition were associated with microbiota composition. Overall, MHC IIB diversity was lower in Ozark hellbenders compared to the eastern subspecies. Multivariate statistical comparisons identified microbiota differentiation between Ozark and eastern hellbenders. MHC IIB allele presence/absence, allele divergence, body composition and sex defined grouping of hellbender microbiotas within populations. Differentiation of the cutaneous microbiotas and MHC IIB genes between eastern and Ozark hellbenders suggests that differences exist in immunity between the two subspecies. This study demonstrates how simultaneous assessments of host genetic traits and microbiotas can inform patterns of microbial community structure in natural systems.
Collapse
Affiliation(s)
- Obed Hernández-Gómez
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
| | | | - Rod N Williams
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
| |
Collapse
|
37
|
Heterozygosity–behavior and heterozygosity–fitness correlations in a salamander with limited dispersal. POPUL ECOL 2018. [DOI: 10.1007/s10144-017-0604-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
38
|
Mesquita AFC, Lambertini C, Lyra M, Malagoli LR, James TY, Toledo LF, Haddad CFB, Becker CG. Low resistance to chytridiomycosis in direct-developing amphibians. Sci Rep 2017; 7:16605. [PMID: 29192210 PMCID: PMC5709405 DOI: 10.1038/s41598-017-16425-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Accepted: 10/31/2017] [Indexed: 12/13/2022] Open
Abstract
Host-generalist pathogens sporadically infect naive hosts, potentially triggering epizootics. The waterborne fungus Batrachochytrium dendrobatidis (Bd) is linked to declines of hundreds of amphibian species with aquatic larvae. Although several population declines and extinctions attributed to Bd have been reported among cryptic species undergoing direct development away from water, epidemiological studies focused on these terrestrial frogs are lacking. Our field data support that terrestrial direct-developing hosts are less exposed to Bd during their ontogeny than species with aquatic larvae, and thus they might lack adaptive responses against waterborne chytrids. Using controlled laboratory experiments, we exposed wild-caught amphibian species with terrestrial and aquatic life histories to Bd and found that direct developers showed more rapid increases in infection loads and experienced higher mortality rates than species with aquatic larvae. Our findings provide novel information about host responses to generalist pathogens and specifically show that our focal direct developing species have low resistance to Bd infections. Finally, our results underscore that we should not ignore Bd as a potential threat to direct developing species simply because they are less exposed to Bd in nature; instead future amphibian conservation plans should include efforts to safeguard hundreds of direct-developing amphibian species globally.
Collapse
Affiliation(s)
- Andréa F C Mesquita
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Zoologia, and Centro de Aquicultura (CAUNESP), 13506-900, Rio Claro, SP, Brazil
| | - Carolina Lambertini
- Departamento de Biologia Animal, I.B., Universidade Estadual de Campinas, 13083-862, Campinas, SP, Brazil
| | - Mariana Lyra
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Zoologia, and Centro de Aquicultura (CAUNESP), 13506-900, Rio Claro, SP, Brazil
| | - Leo R Malagoli
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Zoologia, and Centro de Aquicultura (CAUNESP), 13506-900, Rio Claro, SP, Brazil
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, 48109, Ann Arbor, MI, USA
| | - Luís Felipe Toledo
- Departamento de Biologia Animal, I.B., Universidade Estadual de Campinas, 13083-862, Campinas, SP, Brazil
| | - Célio F B Haddad
- Universidade Estadual Paulista (UNESP), Instituto de Biociências, Departamento de Zoologia, and Centro de Aquicultura (CAUNESP), 13506-900, Rio Claro, SP, Brazil
| | - C Guilherme Becker
- Department of Biological Sciences, The University of Alabama, 35487, Tuscaloosa, AL, USA.
| |
Collapse
|
39
|
Sandmeier FC, Maloney KN, Tracy CR, Hyde D, Mohammadpour H, Marlow R, DuPré S, Hunter K. Chronic disease in the Mojave desert tortoise: Host physiology and recrudescence obscure patterns of pathogen transmission. Ecol Evol 2017; 7:10616-10629. [PMID: 29299243 PMCID: PMC5743692 DOI: 10.1002/ece3.3480] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/28/2017] [Accepted: 09/01/2017] [Indexed: 01/25/2023] Open
Abstract
A seminatural, factorial‐design experiment was used to quantify dynamics of the pathogen Mycoplasma agassizii and upper respiratory tract disease in the Mojave desert tortoise (Gopherus agassizii) over 2 years. Groups of initially healthy animals were separated into serologically positive (seropositive), seronegative, and artificially infected groups and paired into 23 pens. We found no evidence of long‐term immune protection to M. agassizii or of immunological memory. Initially seronegative, healthy tortoises experienced an equal amount of disease when paired with other seronegative groups as when paired with seropositive and artificially infected groups—suggesting that recrudescence is as significant as transmission in introducing disease in individuals in this host–pathogen system. Artificially infected groups of tortoises showed reduced levels of morbidity when paired with initially seronegative animals—suggesting either a dilution effect or a strong effect of pathogen load in this system. Physiological dynamics within the host appear to be instrumental in producing morbidity, recrudescence, and infectiousness, and thus of population‐level dynamics. We suggest new avenues for studying diseases in long‐lived ectothermic vertebrates and a shift in modeling such diseases.
Collapse
Affiliation(s)
| | - K Nichole Maloney
- Department of Pathology, Microbiology, and Immunology Vanderbilt University Nashville TN USA
| | | | - David Hyde
- Biology Department University of Nevada Reno Reno NV USA
| | - Hamid Mohammadpour
- Department of Microbiology and Immunology University of Nevada Reno Reno NV USA
| | - Ron Marlow
- Biology Department University of Nevada Reno Reno NV USA
| | - Sally DuPré
- Department of Microbiology and Immunology University of Nevada Reno Reno NV USA
| | - Kenneth Hunter
- Department of Microbiology and Immunology University of Nevada Reno Reno NV USA
| |
Collapse
|
40
|
From fish to frogs and beyond: Impact and host range of emergent ranaviruses. Virology 2017; 511:272-279. [PMID: 28860047 DOI: 10.1016/j.virol.2017.08.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 07/29/2017] [Accepted: 08/01/2017] [Indexed: 11/21/2022]
Abstract
Ranaviruses are pathogens of ectothermic vertebrates, including amphibians. We reviewed patterns of host range and virulence of ranaviruses in the context of virus genotype and postulate that patterns reflect significant variation in the historical and current host range of three groups of Ranavirus: FV3-like, CMTV-like and ATV-like ranaviruses. Our synthesis supports previous hypotheses about host range and jumps: FV3s are amphibian specialists, while ATVs are predominantly fish specialists that switched once to caudate amphibians. The most recent common ancestor of CMTV-like ranaviruses and FV3-like forms appears to have infected amphibians but CMTV-like ranaviruses may circulate in both amphibian and fish communities independently. While these hypotheses are speculative, we hope that ongoing efforts to describe ranavirus genetics, increased surveillance of host species and targeted experimental assays of susceptibility to infection and/or disease will facilitate better tests of the importance of hypothetical evolutionary drivers of ranavirus virulence and host range.
Collapse
|
41
|
Cortázar-Chinarro M, Lattenkamp EZ, Meyer-Lucht Y, Luquet E, Laurila A, Höglund J. Drift, selection, or migration? Processes affecting genetic differentiation and variation along a latitudinal gradient in an amphibian. BMC Evol Biol 2017; 17:189. [PMID: 28806900 PMCID: PMC5557520 DOI: 10.1186/s12862-017-1022-z] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/26/2017] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Past events like fluctuations in population size and post-glacial colonization processes may influence the relative importance of genetic drift, migration and selection when determining the present day patterns of genetic variation. We disentangle how drift, selection and migration shape neutral and adaptive genetic variation in 12 moor frog populations along a 1700 km latitudinal gradient. We studied genetic differentiation and variation at a MHC exon II locus and a set of 18 microsatellites. RESULTS Using outlier analyses, we identified the MHC II exon 2 (corresponding to the β-2 domain) locus and one microsatellite locus (RCO8640) to be subject to diversifying selection, while five microsatellite loci showed signals of stabilizing selection among populations. STRUCTURE and DAPC analyses on the neutral microsatellites assigned populations to a northern and a southern cluster, reflecting two different post-glacial colonization routes found in previous studies. Genetic variation overall was lower in the northern cluster. The signature of selection on MHC exon II was weaker in the northern cluster, possibly as a consequence of smaller and more fragmented populations. CONCLUSION Our results show that historical demographic processes combined with selection and drift have led to a complex pattern of differentiation along the gradient where some loci are more divergent among populations than predicted from drift expectations due to diversifying selection, while other loci are more uniform among populations due to stabilizing selection. Importantly, both overall and MHC genetic variation are lower at northern latitudes. Due to lower evolutionary potential, the low genetic variation in northern populations may increase the risk of extinction when confronted with emerging pathogens and climate change.
Collapse
Affiliation(s)
- Maria Cortázar-Chinarro
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden.
| | - Ella Z Lattenkamp
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
- Present address: Department of Neurogenetics of Vocal Communication, Max Planck Institute of Psycholinguistics, Box 310, 6500, Nijmegen, Netherlands
| | - Yvonne Meyer-Lucht
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
| | - Emilien Luquet
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
- Present address: Université Claude Bernard - Lyon I, CNRS, UMR 5023 - LEHNA, 3-6, rue Raphaël Dubois - Bâtiments Darwin C and Forel, 69622 Villeurbanne Cedex 43, Boulevard du 11 novembre, 1918, Lyon, France
| | - Anssi Laurila
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
| | - Jacob Höglund
- Animal Ecology/Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236, Uppsala, Sweden
| |
Collapse
|
42
|
Hua J, Wuerthner VP, Jones DK, Mattes B, Cothran RD, Relyea RA, Hoverman JT. Evolved pesticide tolerance influences susceptibility to parasites in amphibians. Evol Appl 2017; 10:802-812. [PMID: 29151872 PMCID: PMC5680434 DOI: 10.1111/eva.12500] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 05/26/2017] [Indexed: 01/08/2023] Open
Abstract
Because ecosystems throughout the globe are contaminated with pesticides, there is a need to understand how natural populations cope with pesticides and the implications for ecological interactions. From an evolutionary perspective, there is evidence that pesticide tolerance can be achieved via two mechanisms: selection for constitutive tolerance over multiple generations or by inducing tolerance within a single generation via phenotypic plasticity. While both mechanisms can allow organisms to persist in contaminated environments, they might result in different performance trade-offs including population susceptibility to parasites. We have identified 15 wood frog populations that exist along a gradient from close to agriculture and high, constitutive pesticide tolerance to far from agriculture and inducible pesticide tolerance. Using these populations, we investigated the relationship between evolutionary responses to the common insecticide carbaryl and host susceptibility to the trematode Echinoparyphium lineage 3 and ranavirus using laboratory exposure assays. For Echinoparyphium, we discovered that wood frog populations living closer to agriculture with high, constitutive tolerance experienced lower loads than populations living far from agriculture with inducible pesticide tolerance. For ranavirus, we found no relationship between the mechanism of evolved pesticide tolerance and survival, but populations living closer to agriculture with high, constitutive tolerance experienced higher viral loads than populations far from agriculture with inducible tolerance. Land use and mechanisms of evolved pesticide tolerance were associated with susceptibility to parasites, but the direction of the relationship is dependent on the type of parasite, underscoring the complexity between land use and disease outcomes. Collectively, our results demonstrate that evolved pesticide tolerance can indirectly influence host-parasite interactions and underscores the importance of including evolutionary processes in ecotoxicological studies.
Collapse
Affiliation(s)
- Jessica Hua
- Biological Sciences Department Binghamton University (SUNY) Binghamton NY USA
| | - Vanessa P Wuerthner
- Biological Sciences Department Binghamton University (SUNY) Binghamton NY USA
| | - Devin K Jones
- Department of Biological Sciences Rensselaer Polytechnic Institute Troy NY USA
| | - Brian Mattes
- Department of Biological Sciences Rensselaer Polytechnic Institute Troy NY USA
| | - Rickey D Cothran
- Biological Sciences Department Southwestern Oklahoma State University Weatherford OK USA
| | - Rick A Relyea
- Department of Biological Sciences Rensselaer Polytechnic Institute Troy NY USA
| | - Jason T Hoverman
- Department of Forestry and Natural Resources Purdue University West Lafayette IN USA
| |
Collapse
|
43
|
Horner AA, Hoffman EA, Tye MR, Hether TD, Savage AE. Cryptic chytridiomycosis linked to climate and genetic variation in amphibian populations of the southeastern United States. PLoS One 2017; 12:e0175843. [PMID: 28448517 PMCID: PMC5407605 DOI: 10.1371/journal.pone.0175843] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/31/2017] [Indexed: 11/19/2022] Open
Abstract
North American amphibians have recently been impacted by two major emerging pathogens, the fungus Batrachochytrium dendrobatidis (Bd) and iridoviruses in the genus Ranavirus (Rv). Environmental factors and host genetics may play important roles in disease dynamics, but few studies incorporate both of these components into their analyses. Here, we investigated the role of environmental and genetic factors in driving Bd and Rv infection prevalence and severity in a biodiversity hot spot, the southeastern United States. We used quantitative PCR to characterize Bd and Rv dynamics in natural populations of three amphibian species: Notophthalmus perstriatus, Hyla squirella and Pseudacris ornata. We combined pathogen data, genetic diversity metrics generated from neutral markers, and environmental variables into general linear models to evaluate how these factors impact infectious disease dynamics. Occurrence, prevalence and intensity of Bd and Rv varied across species and populations, but only one species, Pseudacris ornata, harbored high Bd intensities in the majority of sampled populations. Genetic diversity and climate variables both predicted Bd prevalence, whereas climatic variables alone predicted infection intensity. We conclude that Bd is more abundant in the southeastern United States than previously thought and that genetic and environmental factors are both important for predicting amphibian pathogen dynamics. Incorporating both genetic and environmental information into conservation plans for amphibians is necessary for the development of more effective management strategies to mitigate the impact of emerging infectious diseases.
Collapse
Affiliation(s)
- Ariel A. Horner
- Department of Biology, University of Central Florida, Orlando, Florida, United States of America
| | - Eric A. Hoffman
- Department of Biology, University of Central Florida, Orlando, Florida, United States of America
| | - Matthew R. Tye
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Tyler D. Hether
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
| | - Anna E. Savage
- Department of Biology, University of Central Florida, Orlando, Florida, United States of America
- * E-mail:
| |
Collapse
|
44
|
Agha M, Price SJ, Nowakowski AJ, Augustine B, Todd BD. Mass mortality of eastern box turtles with upper respiratory disease following atypical cold weather. DISEASES OF AQUATIC ORGANISMS 2017; 124:91-100. [PMID: 28425422 DOI: 10.3354/dao03122] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Emerging infectious diseases cause population declines in many ectotherms, with outbreaks frequently punctuated by periods of mass mortality. It remains unclear, however, whether thermoregulation by ectotherms and variation in environmental temperature is associated with mortality risk and disease progression, especially in wild populations. Here, we examined environmental and body temperatures of free-ranging eastern box turtles Terrapene carolina during a mass die-off coincident with upper respiratory disease. We recorded deaths of 17 turtles that showed clinical signs of upper respiratory disease among 76 adult turtles encountered in Berea, Kentucky (USA), in 2014. Of the 17 mortalities, 11 occurred approximately 14 d after mean environmental temperature dropped 2.5 SD below the 3 mo mean. Partial genomic sequencing of the major capsid protein from 1 sick turtle identified a ranavirus isolate similar to frog virus 3. Turtles that lacked clinical signs of disease had significantly higher body temperatures (23°C) than sick turtles (21°C) during the mass mortality, but sick turtles that survived and recovered eventually warmed (measured by temperature loggers). Finally, there was a significant negative effect of daily environmental temperature deviation from the 3 mo mean on survival, suggesting that rapid decreases in environmental temperature were correlated with mortality. Our results point to a potential role for environmental temperature variation and body temperature in disease progression and mortality risk of eastern box turtles affected by upper respiratory disease. Given our findings, it is possible that colder or more variable environmental temperatures and an inability to effectively thermoregulate are associated with poorer disease outcomes in eastern box turtles.
Collapse
Affiliation(s)
- Mickey Agha
- Department of Wildlife, Fish, and Conservation Biology, University of California, One Shields Avenue, Davis, CA 95616, USA
| | | | | | | | | |
Collapse
|
45
|
McKnight DT, Schwarzkopf L, Alford RA, Bower DS, Zenger KR. Effects of emerging infectious diseases on host population genetics: a review. CONSERV GENET 2017. [DOI: 10.1007/s10592-017-0974-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
46
|
Ball SE, Bovero S, Sotgiu G, Tessa G, Angelini C, Bielby J, Durrant C, Favelli M, Gazzaniga E, Garner TWJ. Islands within an island: Population genetic structure of the endemic Sardinian newt, Euproctus platycephalus. Ecol Evol 2017; 7:1190-1211. [PMID: 28303189 PMCID: PMC5306002 DOI: 10.1002/ece3.2665] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 10/21/2016] [Indexed: 12/04/2022] Open
Abstract
The identification of historic and contemporary barriers to dispersal is central to the conservation of endangered amphibians, but may be hindered by their complex life history and elusive nature. The complementary information generated by mitochondrial (mtDNA) and microsatellite markers generates a valuable tool in elucidating population structure and the impact of habitat fragmentation. We applied this approach to the study of an endangered montane newt, Euproctus platycephalus. Endemic to the Mediterranean island of Sardinia, it is threatened by anthropogenic activity, disease, and climate change. We have demonstrated a clear hierarchy of structure across genetically divergent and spatially distinct subpopulations. Divergence between three main mountain regions dominated genetic partitioning with both markers. Mitochondrial phylogeography revealed a deep division dating to ca. 1 million years ago (Mya), isolating the northern region, and further differentiation between the central and southern regions ca. 0.5 Mya, suggesting an association with Pleistocene severe glacial oscillations. Our findings are consistent with a model of southward range expansion during glacial periods, with postglacial range retraction to montane habitat and subsequent genetic isolation. Microsatellite markers revealed further strong population structure, demonstrating significant divergence within the central region, and partial differentiation within the south. The northern population showed reduced genetic diversity. Discordance between mitochondrial and microsatellite markers at this scale indicated a further complexity of population structure, in keeping with male-biased dispersal and female philopatry. Our study underscores the need to elucidate cryptic population structure in the ecology and conservation strategies for endangered island-restricted amphibians, especially in the context of disease and climate change.
Collapse
Affiliation(s)
- Sarah E. Ball
- Institute of ZoologyThe Zoological Society of LondonLondonUK
| | - Stefano Bovero
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
| | - Giuseppe Sotgiu
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
| | - Giulia Tessa
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
- Dipartimento di Scienze della Vita e Biologia dei SistemiUniversita degli Studi di TorinoTorinoItaly
| | - Claudio Angelini
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
| | - Jon Bielby
- Institute of ZoologyThe Zoological Society of LondonLondonUK
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
| | | | - Marco Favelli
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
| | - Enrico Gazzaniga
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
| | - Trenton W. J. Garner
- Institute of ZoologyThe Zoological Society of LondonLondonUK
- Zirichiltaggi S. W. C. Non‐profit Association for Wildlife ConservationSassariItaly
| |
Collapse
|
47
|
Langeloh L, Behrmann-Godel J, Seppälä O. Natural selection on immune defense: A field experiment. Evolution 2017; 71:227-237. [PMID: 27925174 DOI: 10.1111/evo.13148] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 10/26/2016] [Accepted: 11/15/2016] [Indexed: 12/18/2022]
Abstract
Predicting the evolution of phenotypic traits requires an understanding of natural selection on them. Despite its indispensability in the fight against parasites, selection on host immune defense has remained understudied. Theory predicts immune traits to be under stabilizing selection due to associated trade-offs with other fitness-related traits. Empirical studies, however, report mainly positive directional selection. This discrepancy could be caused by low phenotypic variation in the examined individuals and/or variation in host resource level that confounds trade-offs in empirical studies. In a field experiment where we maintained Lymnaea stagnalis snails individually in cages in a lake, we investigated phenotypic selection on two immune defense traits, phenoloxidase (PO)-like activity and antibacterial activity, in hemolymph. We used a diverse laboratory population and manipulated snail resource level by limiting their food supply. For six weeks, we followed immune activity, growth, and two fitness components, survival and fecundity of snails. We found that PO-like activity and growth were under stabilizing selection, while antibacterial activity was under positive directional selection. Selection on immune traits was mainly driven by variation in survival. The form of selection on immune defense apparently depends on the particular trait, possibly due to its importance for countering the present parasite community.
Collapse
Affiliation(s)
- Laura Langeloh
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland.,Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland
| | | | - Otto Seppälä
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland.,Institute of Integrative Biology, ETH Zürich, 8092, Zürich, Switzerland
| |
Collapse
|
48
|
Sugawara H, Kusano T, Hayashi F. Fine-Scale Genetic Differentiation in a Salamander Hynobius tokyoensis Living in Fragmented Urban Habitats in and Around Tokyo, Japan. Zoolog Sci 2016; 33:476-484. [PMID: 27715415 DOI: 10.2108/zs150196] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Salamanders are expected to differentiate genetically among local populations due to their low dispersal ability, and are potentially susceptible to loss of genetic diversity if the population is isolated by habitat fragmentation. The salamander Hynobius tokyoensis is a lowland lentic breeder and endemic to a narrow area of central Japan. In this urban area, H. tokyoensis habitats are extensively fragmented and several populations are threatened with extinction, but information on genetic divergence and loss of genetic diversity is scarce. We performed mitochondrial (cyt b) and microsatellite (five loci) DNA analyses of 815 individuals from 46 populations in 12 regions across their entire distribution range. As a result, populations were clearly separated into northern and southern groups, and genetic differentiation among the 12 regions was also evident. Regional differentiation appears to be affected by a complex geographical history, but the genetic diversity of each population may have also been affected by recent habitat fragmentation. There were positive correlations between the mitochondrial and microsatellite DNA diversities. Some populations have lost genetic diversity in both mitochondrial and microsatellite DNAs; all such populations were at the peripheral edges of the species distribution range. Thus, even in attempts to restore genetic diversity in a small population by the transfer of outside individuals, efforts must be made to avoid genetic pollution.
Collapse
Affiliation(s)
- Hirotaka Sugawara
- Department of Biology, Tokyo Metropolitan University, Minamiosawa 1-1,Hachioji, Tokyo 192-0397, Japan
| | - Tamotsu Kusano
- Department of Biology, Tokyo Metropolitan University, Minamiosawa 1-1,Hachioji, Tokyo 192-0397, Japan
| | - Fumio Hayashi
- Department of Biology, Tokyo Metropolitan University, Minamiosawa 1-1,Hachioji, Tokyo 192-0397, Japan
| |
Collapse
|
49
|
Earl JE, Chaney JC, Sutton WB, Lillard CE, Kouba AJ, Langhorne C, Krebs J, Wilkes RP, Hill RD, Miller DL, Gray MJ. Ranavirus could facilitate local extinction of rare amphibian species. Oecologia 2016; 182:611-23. [DOI: 10.1007/s00442-016-3682-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 06/14/2016] [Indexed: 11/30/2022]
|
50
|
Wang YC, Yuen R, Feng CC, Sithithaworn P, Kim IH. Assessing the role of landscape connectivity on Opisthorchis viverrini transmission dynamics. Parasitol Int 2016; 66:402-412. [PMID: 27265875 DOI: 10.1016/j.parint.2016.06.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 05/11/2016] [Accepted: 06/01/2016] [Indexed: 01/25/2023]
Abstract
Opisthorchis viverrini (Ov) is one of the most important human parasitic diseases in Southeast Asia. Although the concept of connectivity is widely used to comprehend disease dispersal, knowledge of the influences of landscape connectivity on Ov transmission is still rudimentary. This study aimed to investigate the role of landscape connectivity in Ov transmission between the human and the first intermediate snail hosts. Fieldwork was conducted in three villages respectively in Kamalasai District, Kalasin Province, Phu Wiang District, Khon Kaen Province, and Nong Saeng District, Udon Thani Province. Bithynia snails were collected to examine parasitic infections, water samples were analyzed for fecal contamination, and locations of septic tanks and connections between habitat patches with observable water movement were surveyed. Euclidean distance, topological link and distance, and graph measures were employed to quantify the connectivity between human and snail habitats. The findings showed that snail patches with higher fecal contents were generally located nearer to septic tanks. The statistically significant results for the topological link and distance measures highlighted the importance of water in functionally facilitating Ov transmission. Graph measures revealed differences in landscape connectivity across the sites. The site with the largest landscape component size and the most mutually connected snail patches coincided with the presence of Ov parasite, reinforcing its higher risk for human to snail transmission. The site with the dissected landscape structure potentially limited the transmission. This study underscored the potential effect of landscape connectivity on Ov transmission, contributing to the understanding of the spatial variation of Ov infection risk.
Collapse
Affiliation(s)
- Yi-Chen Wang
- Department of Geography, National University of Singapore, 1 Arts Link, Singapore 117570, Singapore.
| | - Roy Yuen
- Department of Geography, National University of Singapore, 1 Arts Link, Singapore 117570, Singapore
| | - Chen-Chieh Feng
- Department of Geography, National University of Singapore, 1 Arts Link, Singapore 117570, Singapore
| | | | - Ick-Hoi Kim
- Department of Geography, National University of Singapore, 1 Arts Link, Singapore 117570, Singapore
| |
Collapse
|