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Cooper RD, Shaffer HB. Managing invasive hybrids with pond hydroperiod manipulation in an endangered salamander system. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2024; 38:e14167. [PMID: 37551773 DOI: 10.1111/cobi.14167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 07/07/2023] [Accepted: 07/31/2023] [Indexed: 08/09/2023]
Abstract
When invasive and endangered native taxa hybridize, the resulting admixture introduces novel conservation challenges. Across a large region of central California, a hybrid swarm consisting of admixed endangered California tiger salamanders (CTS) (Ambystoma californiense) and introduced barred tiger salamanders (BTS) (Ambystoma mavortium) has replaced native populations, threatening the genetic integrity of CTS and the vernal pool systems they inhabit. We employed a large-scale, genomically informed field experiment to test whether shortening breeding pond hydroperiod would favor native CTS genotypes. We constructed 14 large, seminatural ponds to evaluate the effect of hydroperiod duration on larval survival and mass at metamorphosis. We tracked changes in non-native allele frequencies with a 5237-gene exon capture array and employed a combination of custom Bayesian and generalized linear models to quantify the effect of pond duration on salamander fitness. Earlier work on this system showed hybrid superiority under many conditions and suggested that hybrids are favored in human-modified ponds with artificially long hydroperiods. Consistent with these earlier studies, we found overwhelming evidence for hybrid superiority. Very short hydroperiods substantially reduced the mass (1.1-1.5 fold) and survival probability (10-13 fold) of both native and hybrid larvae, confirming that hydroperiod likely exerts a strong selective pressure in the wild. We identified 86 genes, representing 1.8% of 4723 screened loci, that significantly responded to this hydroperiod-driven selection. In contrast to earlier work, under our more natural experimental conditions, native CTS survival and size at metamorphosis were always less than hybrids, suggesting that hydroperiod management alone will not shift selection to favor native larval genotypes. However, shortening pond hydroperiod may limit productivity of hybrid ponds, complementing other strategies to remove hybrids while maintaining vernal pool ecosystems. This study confirms and expands on previous work that highlights the importance of hydroperiod management to control invasive aquatic species.
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Affiliation(s)
- Robert D Cooper
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, California, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, Los Angeles, California, USA
| | - H Bradley Shaffer
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, California, USA
- La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, Los Angeles, California, USA
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2
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Cooper RD, Shaffer HB. Allele-specific expression and gene regulation help explain transgressive thermal tolerance in non-native hybrids of the endangered California tiger salamander (Ambystoma californiense). Mol Ecol 2021; 30:987-1004. [PMID: 33338297 DOI: 10.1111/mec.15779] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/30/2020] [Accepted: 12/11/2020] [Indexed: 01/26/2023]
Abstract
Hybridization between native and non-native species is an ongoing global conservation threat. Hybrids that exhibit traits and tolerances that surpass parental values are of particular concern, given their potential to outperform native species. Effective management of hybrid populations requires an understanding of both physiological performance and the underlying mechanisms that drive transgressive hybrid traits. Here, we explore several aspects of the hybridization between the endangered California tiger salamander (Ambystoma californiense; CTS) and the introduced barred tiger salamander (Ambystoma mavortium; BTS). We assayed critical thermal maximum (CTMax) to compare the ability of CTS, BTS and F1 hybrids to tolerate acute thermal stress, and found that hybrids exhibit a wide range of CTMax values, with 33% (4/12) able to tolerate temperatures greater than either parent. We then quantified the genomic response, measured at the RNA transcript level, of each salamander, to explore the mechanisms underlying thermal tolerance strategies. We found that CTS and BTS have strikingly different values and tissue-specific patterns of overall gene expression, with hybrids expressing intermediate values. F1 hybrids display abundant and variable degrees of allele-specific expression (ASE), likely arising from extensive compensatory evolution in gene regulatory mechanisms between CTS and BTS. We found evidence that the proportion of genes with allelic imbalance in individual hybrids correlates with their CTMax, suggesting a link between ASE and expanded thermal tolerance that may contribute to the success of hybrid salamanders in California. Future climate change may further complicate management of CTS if hybrid salamanders are better equipped to deal with rising temperatures.
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Affiliation(s)
- Robert D Cooper
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA
| | - H Bradley Shaffer
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA.,La Kretz Center for California Conservation Science, Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA
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3
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Saint-Pé K, Blanchet S, Tissot L, Poulet N, Plasseraud O, Loot G, Veyssière C, Prunier JG. Genetic admixture between captive-bred and wild individuals affects patterns of dispersal in a brown trout (Salmo trutta) population. CONSERV GENET 2018. [DOI: 10.1007/s10592-018-1095-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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4
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Kovach RP, Hand BK, Hohenlohe PA, Cosart TF, Boyer MC, Neville HH, Muhlfeld CC, Amish SJ, Carim K, Narum SR, Lowe WH, Allendorf FW, Luikart G. Vive la résistance: genome-wide selection against introduced alleles in invasive hybrid zones. Proc Biol Sci 2017; 283:rspb.2016.1380. [PMID: 27881749 DOI: 10.1098/rspb.2016.1380] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 10/25/2016] [Indexed: 12/11/2022] Open
Abstract
Evolutionary and ecological consequences of hybridization between native and invasive species are notoriously complicated because patterns of selection acting on non-native alleles can vary throughout the genome and across environments. Rapid advances in genomics now make it feasible to assess locus-specific and genome-wide patterns of natural selection acting on invasive introgression within and among natural populations occupying diverse environments. We quantified genome-wide patterns of admixture across multiple independent hybrid zones of native westslope cutthroat trout and invasive rainbow trout, the world's most widely introduced fish, by genotyping 339 individuals from 21 populations using 9380 species-diagnostic loci. A significantly greater proportion of the genome appeared to be under selection favouring native cutthroat trout (rather than rainbow trout), and this pattern was pervasive across the genome (detected on most chromosomes). Furthermore, selection against invasive alleles was consistent across populations and environments, even in those where rainbow trout were predicted to have a selective advantage (warm environments). These data corroborate field studies showing that hybrids between these species have lower fitness than the native taxa, and show that these fitness differences are due to selection favouring many native genes distributed widely throughout the genome.
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Affiliation(s)
- Ryan P Kovach
- Northern Rocky Mountain Science Center, US Geological Survey, Missoula, MT 59802, USA
| | - Brian K Hand
- Flathead Biological Station, University of Montana, Polson, MT 59860, USA
| | - Paul A Hohenlohe
- Institute for Bioinformatics and Evolutionary Studies, Department of Biological Sciences, University of Idaho, Moscow, ID 83844, USA
| | - Ted F Cosart
- Flathead Biological Station, University of Montana, Polson, MT 59860, USA.,Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | | | | | - Clint C Muhlfeld
- Northern Rocky Mountain Science Center, US Geological Survey, Missoula, MT 59802, USA.,Flathead Biological Station, University of Montana, Polson, MT 59860, USA
| | - Stephen J Amish
- Flathead Biological Station, University of Montana, Polson, MT 59860, USA.,Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Kellie Carim
- Wildlife Biology Program, University of Montana, Missoula, MT 59812, USA
| | - Shawn R Narum
- Hagerman Genetics Laboratory, Columbia River Inter-Tribal Fish Commission, Hagerman, ID 83332, USA
| | - Winsor H Lowe
- Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Fred W Allendorf
- Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Missoula, MT, USA
| | - Gordon Luikart
- Flathead Biological Station, University of Montana, Polson, MT 59860, USA.,Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Missoula, MT, USA
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Wringe BF, Stanley RRE, Jeffery NW, Anderson EC, Bradbury IR. hybriddetective: A workflow and package to facilitate the detection of hybridization using genomic data in r. Mol Ecol Resour 2017; 17:e275-e284. [PMID: 28776912 DOI: 10.1111/1755-0998.12704] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 06/15/2017] [Accepted: 07/25/2017] [Indexed: 12/20/2022]
Abstract
The ability to detect and characterize hybridization in nature has long been of interest to many fields of biology and often has direct implications for wildlife management and conservation. The capacity to identify the presence of hybridization, and quantify the numbers of individuals belonging to different hybrid classes, permits inference on the magnitude of, and timescale over which, hybridization has been or is occurring. Here, we present an r package and associated workflow developed for the detection, with estimates of efficiency and accuracy, of multigenerational hybrid individuals using genetic or genomic data in conjunction with the program newhybrids. This package includes functions for the identification and testing of diagnostic panels of markers, the simulation of multigenerational hybrids, and the quantification and visualization of the efficiency and accuracy with which hybrids can be detected. Overall, this package delivers a streamlined hybrid analysis platform, providing improvements in speed, ease of use and repeatability over current ad hoc approaches. The latest version of the package and associated documentation are available on GitHub (https://github.com/bwringe/hybriddetective).
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Affiliation(s)
- Brendan F Wringe
- Salmonids Section, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John's, NL, Canada
| | - Ryan R E Stanley
- Coastal Ecosystem Sciences Division, Bedford Institute of Oceanography, Fisheries and Oceans Canada, 1 Challenger Drive, Dartmouth, NS, Canada
| | - Nicholas W Jeffery
- Salmonids Section, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John's, NL, Canada
| | - Eric C Anderson
- Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, CA, USA
| | - Ian R Bradbury
- Salmonids Section, Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John's, NL, Canada
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6
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Multiple uprising invasions of Pelophylax water frogs, potentially inducing a new hybridogenetic complex. Sci Rep 2017; 7:6506. [PMID: 28747630 PMCID: PMC5529583 DOI: 10.1038/s41598-017-06655-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 06/15/2017] [Indexed: 11/25/2022] Open
Abstract
The genetic era has revolutionized our perception of biological invasions. Yet, it is usually too late to understand their genesis for efficient management. Here, we take the rare opportunity to reconstruct the scenario of an uprising invasion of the famous water frogs (Pelophylax) in southern France, through a fine-scale genetic survey. We identified three different taxa over less than 200 km2: the autochthonous P. perezi, along with the alien P. ridibundus and P. kurtmuelleri, which have suddenly become invasive. As a consequence, the latter hybridizes and may now form a novel hybridogenetic complex with P. perezi, which could actively promote its replacement. This exceptional situation makes a textbook application of genetics to early-detect, monitor and understand the onset of biological invasions before they pose a continental-wide threat. It further emphasizes the alarming rate of amphibian translocations, both at global and local scales, as well as the outstanding invasive potential of Pelophylax aliens.
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7
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Guinand B, Vandeputte M, Dupont-Nivet M, Vergnet A, Haffray P, Chavanne H, Chatain B. Metapopulation patterns of additive and nonadditive genetic variance in the sea bass ( Dicentrarchus labrax). Ecol Evol 2017; 7:2777-2790. [PMID: 28428868 PMCID: PMC5395432 DOI: 10.1002/ece3.2832] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 12/19/2016] [Accepted: 01/28/2017] [Indexed: 01/30/2023] Open
Abstract
Describing and explaining the geographic within‐species variation in phenotypes (“phenogeography”) in the sea over a species distribution range is central to our understanding of a variety of eco‐evolutionary topics. However, phenogeographic studies that have a large potential to investigate adaptive variation are overcome by phylogeographic studies, still mainly focusing on neutral markers. How genotypic and phenotypic data could covary over large geographic scales remains poorly understood in marine species. We crossed 75 noninbred sires (five origins) and 26 dams (two origins; each side of a hybrid zone) in a factorial diallel cross in order to investigate geographic variation for early survival and sex ratio in the metapopulation of the European sea bass (Dicentrarchus labrax), a highly prized marine fish species. Full‐sib families (N = 1,950) were produced and reared in a common environment. Parentage assignment of 7,200 individuals was performed with seven microsatellite markers. Generalized linear models showed significant additive effects for both traits and pleiotropy between traits. A significant nonadditive genetic effect was detected. Different expression of traits and distinct relative performances were found for reciprocal crosses involving populations located on each side of the main hybrid zone located at the Almeria‐Oran front, illustrating asymmetric reproductive isolation. The poor fitness performance observed for the Western Mediterranean population of sea bass is discussed as it represents the main source of seed hatchery production, but also because it potentially illustrates nonadaptive introgression and maladaptation.
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Affiliation(s)
- Bruno Guinand
- Département Biologie-Ecologie Université de Montpellier Montpellier France.,UMR CNRS IRD EPHE UM Institut des Sciences de l'Evolution de Montpellier Montpellier France
| | - Marc Vandeputte
- INRA UMR 1313 GABI Domaine de Vilvert Jouy-en-Josas France.,Ifremer UMR 9190 Marine Biodiversity, Exploitation and Conservation Palavas-les-Flots France
| | | | - Alain Vergnet
- Ifremer UMR 9190 Marine Biodiversity, Exploitation and Conservation Palavas-les-Flots France
| | | | - Hervé Chavanne
- Istituto Sperimentale Lazzaro Spallanzani Rivolta d'Adda Italy
| | - Béatrice Chatain
- Ifremer UMR 9190 Marine Biodiversity, Exploitation and Conservation Palavas-les-Flots France
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8
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Schierenbeck KA. Population-level genetic variation and climate change in a biodiversity hotspot. ANNALS OF BOTANY 2017; 119:215-228. [PMID: 28069633 PMCID: PMC5321061 DOI: 10.1093/aob/mcw214] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 07/19/2016] [Accepted: 09/19/2016] [Indexed: 05/06/2023]
Abstract
INTRODUCTION Estimated future climate scenarios can be used to predict where hotspots of endemism may occur over the next century, but life history, ecological and genetic traits will be important in informing the varying responses within myriad taxa. Essential to predicting the consequences of climate change to individual species will be an understanding of the factors that drive genetic structure within and among populations. Here, I review the factors that influence the genetic structure of plant species in California, but are applicable elsewhere; existing levels of genetic variation, life history and ecological characteristics will affect the ability of an individual taxon to persist in the presence of anthropogenic change. FACTORS INFLUENCING THE DISTRIBUTION OF GENETIC VARIATION Persistence in the face of climate change is likely determined by life history characteristics: dispersal ability, generation time, reproductive ability, degree of habitat specialization, plant-insect interactions, existing genetic diversity and availability of habitat or migration corridors. Existing levels of genetic diversity in plant populations vary based on a number of evolutionary scenarios that include endemism, expansion since the last glacial maximum, breeding system and current range sizes. REGIONAL PRIORITIES AND EXAMPLES A number of well-documented examples are provided from the California Floristic Province. Some predictions can be made for the responses of plant taxa to rapid environmental changes based on geographic position, evolutionary history, existing genetic variation, and ecological amplitude. CONCLUSIONS, SOLUTIONS AND RECOMMENDATIONS The prediction of how species will respond to climate change will require a synthesis drawing from population genetics, geography, palaeontology and ecology. The important integration of the historical factors that have shaped the distribution and existing genetic structure of California's plant taxa will enable us to predict and prioritize the conservation of species and areas most likely to be impacted by rapid climate change, human disturbance and invasive species.
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Affiliation(s)
- Kristina A Schierenbeck
- California State University, Chico Department of Biological Sciences, Chico, CA 95929-0515, USA
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9
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Cryptic invasion of Italian pool frogs (Pelophylax bergeri) across Western Europe unraveled by multilocus phylogeography. Biol Invasions 2016. [DOI: 10.1007/s10530-016-1359-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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10
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Jacobsen MW, Smedegaard L, Sørensen SR, Pujolar JM, Munk P, Jónsson B, Magnussen E, Hansen MM. Assessing pre- and post-zygotic barriers between North Atlantic eels (Anguilla anguilla and A. rostrata). Heredity (Edinb) 2016; 118:266-275. [PMID: 27827390 DOI: 10.1038/hdy.2016.96] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 08/13/2016] [Accepted: 08/22/2016] [Indexed: 12/21/2022] Open
Abstract
Elucidating barriers to gene flow is important for understanding the dynamics of speciation. Here we investigate pre- and post-zygotic mechanisms acting between the two hybridizing species of Atlantic eels: Anguilla anguilla and A. rostrata. Temporally varying hybridization was examined by analyzing 85 species-diagnostic single-nucleotide polymorphisms (SNPs; FST ⩾0.95) in eel larvae sampled in the spawning region in the Sargasso Sea in 2007 (N=92) and 2014 (N=460). We further investigated whether genotypes at these SNPs were nonrandomly distributed in post-F1 hybrids, indicating selection. Finally, we sequenced the mitochondrial ATP6 and nuclear ATP5c1 genes in 19 hybrids, identified using SNP and restriction site associated DNA (RAD) sequencing data, to test a previously proposed hypothesis of cytonuclear incompatibility leading to adenosine triphosphate (ATP) synthase dysfunction and selection against hybrids. No F1 hybrids but only later backcrosses were observed in the Sargasso Sea in 2007 and 2014. This suggests that interbreeding between the two species only occurs in some years, possibly controlled by environmental conditions at the spawning grounds, or that interbreeding has diminished through time as a result of a declining number of spawners. Moreover, potential selection was found at the nuclear and the cytonuclear levels. Nonetheless, one glass eel individual showed a mismatch, involving an American ATP6 haplotype and European ATP5c1 alleles. This contradicted the presence of cytonuclear incompatibility but may be explained by that (1) cytonuclear incompatibility is incomplete, (2) selection acts at a later life stage or (3) other genes are important for protein function. In total, the study demonstrates the utility of genomic data when examining pre- and post-zyotic barriers in natural hybrids.
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Affiliation(s)
- M W Jacobsen
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - L Smedegaard
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - S R Sørensen
- National Institute of Aquatic Resources, Charlottenlund, Denmark
| | - J M Pujolar
- Department of Bioscience, Aarhus University, Aarhus, Denmark
| | - P Munk
- National Institute of Aquatic Resources, Charlottenlund, Denmark
| | - B Jónsson
- Northwest Iceland Nature Research Centre, Saudárkrókur, Iceland
| | - E Magnussen
- Faculty of Science and Technology, University of the Faroe Islands, Torshavn, Faroe Islands
| | - M M Hansen
- Department of Bioscience, Aarhus University, Aarhus, Denmark
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11
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The Tangled Evolutionary Legacies of Range Expansion and Hybridization. Trends Ecol Evol 2016; 31:677-688. [DOI: 10.1016/j.tree.2016.06.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/27/2016] [Accepted: 06/29/2016] [Indexed: 01/15/2023]
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12
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Hwang AS, Pritchard VL, Edmands S. Recovery from hybrid breakdown in a marine invertebrate is faster, stronger and more repeatable under environmental stress. J Evol Biol 2016; 29:1793-803. [DOI: 10.1111/jeb.12913] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 05/30/2016] [Indexed: 11/26/2022]
Affiliation(s)
- A. S. Hwang
- Department of Biological Sciences University of Southern California Los Angeles CA USA
| | - V. L. Pritchard
- Department of Biological Sciences University of Southern California Los Angeles CA USA
| | - S. Edmands
- Department of Biological Sciences University of Southern California Los Angeles CA USA
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13
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Kovach RP, Luikart G, Lowe WH, Boyer MC, Muhlfeld CC. Risk and efficacy of human-enabled interspecific hybridization for climate-change adaptation: response to Hamilton and Miller (2016). CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2016; 30:428-430. [PMID: 26918487 DOI: 10.1111/cobi.12678] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/19/2015] [Indexed: 06/05/2023]
Affiliation(s)
- Ryan P Kovach
- U.S. Geological Survey, Northern Rocky Mountain Science Center, Glacier National Park West Glacier, MT, 59936, U.S.A
| | - Gordon Luikart
- Flathead Lake Biological Station, University of Montana, Polson, MT, 59860, U.S.A
| | - Winsor H Lowe
- Division of Biological Sciences, University of Montana, Missoula, MT, 59812, U.S.A
| | | | - Clint C Muhlfeld
- U.S. Geological Survey, Northern Rocky Mountain Science Center, Glacier National Park West Glacier, MT, 59936, U.S.A
- Flathead Lake Biological Station, University of Montana, Polson, MT, 59860, U.S.A
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14
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Massive genetic introgression in threatened northern crested newts (Triturus cristatus) by an invasive congener (T. carnifex) in Western Switzerland. CONSERV GENET 2016. [DOI: 10.1007/s10592-016-0825-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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15
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Abstract
Alien herpetofauna have a broad diversity of ecological and evolutionary impacts, involving seven mechanisms. Ecological impacts usually result from trophic disruptions and may be direct or indirect and top-down or bottom-up; they may vary in scale from single species to communities. A single species may impose impacts involving most or all of these categories. Evolutionary impacts most often result from hybridization and introgression but may include diverse changes in native fauna induced by selection. Impact magnitudes observed to date largely range from moderate to major, but massive impacts (including species extinction) are known for a handful of invasive species. Research remains skewed toward a small sample of all invaders, and major research gaps remain in understanding community-level impacts, the risk posed by competition, determinants of predation impact, the relevance of genetic diversity to impacts, and how to predict impacts.
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Affiliation(s)
- Fred Kraus
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan 48109
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16
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Manifest Density: A Reply to Phillips and Baird. Trends Ecol Evol 2015; 30:565-566. [DOI: 10.1016/j.tree.2015.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 08/14/2015] [Indexed: 11/17/2022]
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17
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Kovach RP, Muhlfeld CC, Boyer MC, Lowe WH, Allendorf FW, Luikart G. Dispersal and selection mediate hybridization between a native and invasive species. Proc Biol Sci 2015; 282:20142454. [PMID: 25473019 DOI: 10.1098/rspb.2014.2454] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hybridization between native and non-native species has serious biological consequences, but our understanding of how dispersal and selection interact to influence invasive hybridization is limited. Here, we document the spread of genetic introgression between a native (Oncorhynchus clarkii) and invasive (Oncorhynchus mykiss) trout, and identify the mechanisms influencing genetic admixture. In two populations inhabiting contrasting environments, non-native admixture increased rapidly from 1984 to 2007 and was driven by surprisingly consistent processes. Individual admixture was related to two phenotypic traits associated with fitness: size at spawning and age of juvenile emigration. Fish with higher non-native admixture were larger and tended to emigrate at a younger age--relationships that are expected to confer fitness advantages to hybrid individuals. However, strong selection against non-native admixture was evident across streams and cohorts (mean selection coefficient against genotypes with non-native alleles (s) = 0.60; s.e. = 0.10). Nevertheless, hybridization was promoted in both streams by the continuous immigration of individuals with high levels of non-native admixture from other hybrid source populations. Thus, antagonistic relationships between dispersal and selection are mediating invasive hybridization between these fish, emphasizing that data on dispersal and natural selection are needed to fully understand the dynamics of introgression between native and non-native species.
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Affiliation(s)
- Ryan P Kovach
- US Geological Survey, Northern Rocky Mountain Science Center, Glacier National Park, West Glacier, MT 59936, USA Flathead Lake Biological Station, Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Polson, MT 59860, USA
| | - Clint C Muhlfeld
- US Geological Survey, Northern Rocky Mountain Science Center, Glacier National Park, West Glacier, MT 59936, USA
| | | | - Winsor H Lowe
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Fred W Allendorf
- Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA
| | - Gordon Luikart
- Flathead Lake Biological Station, Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Polson, MT 59860, USA
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18
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Shaffer HB, Gidiş M, McCartney-Melstad E, Neal KM, Oyamaguchi HM, Tellez M, Toffelmier EM. Conservation genetics and genomics of amphibians and reptiles. Annu Rev Anim Biosci 2015; 3:113-38. [PMID: 25580719 DOI: 10.1146/annurev-animal-022114-110920] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Amphibians and reptiles as a group are often secretive, reach their greatest diversity often in remote tropical regions, and contain some of the most endangered groups of organisms on earth. Particularly in the past decade, genetics and genomics have been instrumental in the conservation biology of these cryptic vertebrates, enabling work ranging from the identification of populations subject to trade and exploitation, to the identification of cryptic lineages harboring critical genetic variation, to the analysis of genes controlling key life history traits. In this review, we highlight some of the most important ways that genetic analyses have brought new insights to the conservation of amphibians and reptiles. Although genomics has only recently emerged as part of this conservation tool kit, several large-scale data sources, including full genomes, expressed sequence tags, and transcriptomes, are providing new opportunities to identify key genes, quantify landscape effects, and manage captive breeding stocks of at-risk species.
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Wall AR, Campo D, Wetzer R. Genetic utility of natural history museum specimens: endangered fairy shrimp (Branchiopoda, Anostraca). Zookeys 2014:1-14. [PMID: 25561827 PMCID: PMC4283361 DOI: 10.3897/zookeys.457.6822] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 09/13/2014] [Indexed: 11/13/2022] Open
Abstract
We examined the potential utility of museum specimens as a source for genetic analysis of fairy shrimp. Because of loss of their vernal pool habitat, some fairy shrimp (including Branchinectasandiegonensis and Branchinectalynchi) are listed as threatened or endangered in Southern California by the United States Fish and Wildlife Service. Management of those species requires extensive population genetics studies and the resolution of important genetic complexity (e.g. possible hybridization between endangered and non-endangered species). Regulations mandating deposition of specimens of listed species have resulted in thousands of specimens accessioned into the Natural History Museum of Los Angeles County that have been preserved in a variety of solutions. We subsampled those specimens, as well as other Anostraca with known collection and preservation histories, to test their potential for genetic analysis by attempting DNA extraction and amplification for mt16SrDNA. Fixation and preservation in not denatured ethanol had a far greater sequencing success rate than other (and unknown) fixatives and preservatives. To maximize scientific value we recommend field preservation in 95% not denatured ethanol (or, if pure ethanol is unavailable, high-proof drinking spirits, e.g. Everclear™, or 151 proof white rum), followed by storage in 95% not denatured ethanol.
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Affiliation(s)
- Adam R Wall
- Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007 USA
| | - Daniel Campo
- University of Southern California, Molecular and Computational Biology, Los Angeles, CA 90089 USA
| | - Regina Wetzer
- Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007 USA
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20
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Searcy CA, Snaas H, Shaffer HB. Determinants of size at metamorphosis in an endangered amphibian and their projected effects on population stability. OIKOS 2014. [DOI: 10.1111/oik.01775] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christopher A. Searcy
- Dept of Evolution and Ecology and Center for Population Biology; Univ. of California; One Shields Avenue Davis CA 95616 USA
| | - Helen Snaas
- HAS Univ. of Applied Sciences; Onderwijsboulevard 221 NL-5223 DE ‘s-Hertogenbosch the Netherlands
| | - H. Bradley Shaffer
- Dept of Ecology and Evolutionary Biology; 621 Charles E. Young Drive South and La Kretz Center for California Conservation Science, 619 Charles E. Young Drive South, Univ. of California; Los Angeles CA 90095 USA
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Hovick SM, Whitney KD. Hybridisation is associated with increased fecundity and size in invasive taxa: meta-analytic support for the hybridisation-invasion hypothesis. Ecol Lett 2014; 17:1464-77. [PMID: 25234578 PMCID: PMC4231983 DOI: 10.1111/ele.12355] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 06/11/2014] [Accepted: 08/14/2014] [Indexed: 02/04/2023]
Abstract
The hypothesis that interspecific hybridisation promotes invasiveness has received much recent
attention, but tests of the hypothesis can suffer from important limitations. Here, we provide the
first systematic review of studies experimentally testing the hybridisation-invasion (H-I)
hypothesis in plants, animals and fungi. We identified 72 hybrid systems for which hybridisation has
been putatively associated with invasiveness, weediness or range expansion. Within this group, 15
systems (comprising 34 studies) experimentally tested performance of hybrids vs. their parental
species and met our other criteria. Both phylogenetic and non-phylogenetic meta-analyses
demonstrated that wild hybrids were significantly more fecund and larger than their parental taxa,
but did not differ in survival. Resynthesised hybrids (which typically represent earlier generations
than do wild hybrids) did not consistently differ from parental species in fecundity, survival or
size. Using meta-regression, we found that fecundity increased (but survival decreased) with
generation in resynthesised hybrids, suggesting that natural selection can play an important role in
shaping hybrid performance – and thus invasiveness – over time. We conclude that the
available evidence supports the H-I hypothesis, with the caveat that our results are clearly driven
by tests in plants, which are more numerous than tests in animals and fungi.
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Affiliation(s)
- Stephen M Hovick
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH, 43210, USA
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22
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Harbicht A, Wilson CC, Fraser DJ. Does human-induced hybridization have long-term genetic effects? Empirical testing with domesticated, wild and hybridized fish populations. Evol Appl 2014; 7:1180-91. [PMID: 25558279 PMCID: PMC4275090 DOI: 10.1111/eva.12199] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 07/13/2014] [Indexed: 11/28/2022] Open
Abstract
Current conservation practices exclude human-generated hybridized populations from protection, as the genetic effects of hybridization in the wild have been observed to be long-lasting based on neutral genetic markers and are considered potentially irreversible. Theory, however, predicts otherwise for genes under selection. We transplanted combinations of wild, domesticated and hybridized populations of a fish species to new environments. We then compared survival, phenotypic variation and plasticity to determine whether hybridization affects adaptive potential after multiple generations of selection in the wild. Although the fitness of our hybridized populations at the onset of hybridization cannot be assessed, our results suggest that within five to eleven generations, selection can remove introduced foreign genes from wild populations that have hybridized with domesticated conspecifics. The end result is hybridized populations that, in terms of survival, phenotypic plasticity, mean trait expression and overall general responses to environmental change, closely resemble neighbouring wild populations. These results have important implications for considering the potential conservation value of hybridized populations and illustrate the effectiveness of selection in a local environment.
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Affiliation(s)
- Andrew Harbicht
- Department of Biology, Concordia University Montreal, QC, Canada
| | - Chris C Wilson
- Aquatic Biodiversity and Conservation Unit, Ontario Ministry of Natural Resources Peterborough, ON, Canada
| | - Dylan J Fraser
- Department of Biology, Concordia University Montreal, QC, Canada
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23
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Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms. Heredity (Edinb) 2014; 112:627-37. [PMID: 24424165 DOI: 10.1038/hdy.2013.145] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 12/09/2013] [Accepted: 12/10/2013] [Indexed: 11/08/2022] Open
Abstract
The two North Atlantic eel species, the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata), spawn in partial sympatry in the Sargasso Sea, providing ample opportunity to interbreed. In this study, we used a RAD (Restriction site Associated DNA) sequencing approach to identify species-specific diagnostic single-nucleotide polymorphisms (SNPs) and design a low-density array that combined with screening of a diagnostic mitochondrial DNA marker. Eels from Iceland (N=159) and from the neighboring Faroe Islands (N=29) were genotyped, along with 94 larvae (49 European and 45 American eel) collected in the Sargasso Sea. Our SNP survey showed that the majority of Icelandic eels are pure European eels but there is also an important contribution of individuals of admixed ancestry (10.7%). Although most of the hybrids were identified as F1 hybrids from European eel female × American eel male crosses, backcrosses were also detected, including a first-generation backcross (F1 hybrid × pure European eel) and three individuals identified as second-generation backcrosses originating from American eel × F1 hybrid backcrosses interbreeding with pure European eels. In comparison, no hybrids were observed in the Faroe Islands, the closest bodies of land to Iceland. It is possible that hybrids show an intermediate migratory behaviour between the two parental species that ultimately brings hybrid larvae to the shores of Iceland, situated roughly halfway between the Sargasso Sea and Europe. Only two hybrids were observed among Sargasso Sea larvae, both backcrosses, but no F1 hybrids, that points to temporal variation in the occurrence of hybridization.
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24
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Regional differences in the abundance of native, introduced, and hybrid Typha spp. in northeastern North America influence wetland invasions. Biol Invasions 2013. [DOI: 10.1007/s10530-013-0481-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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25
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Johnson JR, Ryan ME, Micheletti SJ, Shaffer HB. Short pond hydroperiod decreases fitness of nonnative hybrid salamanders in California. Anim Conserv 2013. [DOI: 10.1111/acv.12029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- J. R. Johnson
- Department of Biology; Western Kentucky University; Bowling Green KY USA
| | - M. E. Ryan
- Department of Civil and Environmental Engineering; University of Washington; Seattle WA USA
| | - S. J. Micheletti
- School of Biological Sciences; Washington State University; Pullman WA USA
| | - H. B. Shaffer
- Department of Ecology and Evolutionary Biology; University of California; Los Angeles CA USA
- La Kretz Center for California Conservation Science; Institute of the Environment and Sustainability; University of California; Los Angeles CA USA
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Ryan ME, Johnson JR, Fitzpatrick BM, Lowenstine LJ, Picco AM, Shaffer HB. Lethal effects of water quality on threatened California salamanders but not on co-occurring hybrid salamanders. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2013; 27:95-102. [PMID: 23140535 DOI: 10.1111/j.1523-1739.2012.01955.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 07/09/2012] [Indexed: 06/01/2023]
Abstract
Biological invasions and habitat alteration are often detrimental to native species, but their interactions are difficult to predict. Interbreeding between native and introduced species generates novel genotypes and phenotypes, and human land use alters habitat structure and chemistry. Both invasions and habitat alteration create new biological challenges and opportunities. In the intensively farmed Salinas Valley, California (U.S.A.), threatened California tiger salamanders (Ambystoma californiense) have been replaced by hybrids between California tiger salamander and introduced barred tiger salamanders (Ambystoma tigrinum mavortium). We conducted an enclosure experiment to examine the effects habitat modification and relative frequency of hybrid and native California tiger salamanders have on recruitment of salamanders and their prey, Pacific chorus frogs (Pseudacris regilla). We tested whether recruitment differed among genetic classes of tiger salamanders (hybrid or native) and pond hydroperiod (seasonal or perennial). Roughly 6 weeks into the experiment, 70% (of 378 total) of salamander larvae died in 4 out of 6 ponds. Native salamanders survived (n = 12) in these ponds only if they had metamorphosed prior to the die-offs. During die-offs, all larvae of native salamanders died, whereas 56% of hybrid larvae died. We necropsied native and hybrid salamanders, tested water quality, and queried the California Department of Pesticide Regulation database to investigate possible causes of the die-offs. Salamander die-offs, changes in the abundance of other community members (invertebrates, algae, and cyanobacteria), shifts in salamander sex ratio, and patterns of pesticide application in adjacent fields suggest that pesticide use may have contributed to die-offs. That all survivors were hybrids suggests that environmental stress may promote rapid displacement of native genotypes.
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Affiliation(s)
- Maureen E Ryan
- Department of Evolution and Ecology, and Center for Population Biology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
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27
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Pritchard VL, Knutson VL, Lee M, Zieba J, Edmands S. Fitness and morphological outcomes of many generations of hybridization in the copepod Tigriopus californicus. J Evol Biol 2012; 26:416-33. [DOI: 10.1111/jeb.12060] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 10/23/2012] [Accepted: 10/24/2012] [Indexed: 12/27/2022]
Affiliation(s)
- V. L. Pritchard
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - V. L. Knutson
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - M. Lee
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - J. Zieba
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
| | - S. Edmands
- Department of Biological Sciences; University of Southern California; Los Angeles CA USA
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Dittrich-Reed DR, Fitzpatrick BM. Transgressive Hybrids as Hopeful Monsters. Evol Biol 2012; 40:310-315. [PMID: 23687396 PMCID: PMC3655218 DOI: 10.1007/s11692-012-9209-0] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 11/06/2012] [Indexed: 01/27/2023]
Abstract
The origin of novelty is a critical subject for evolutionary biologists. Early geneticists speculated about the sudden appearance of new species via special macromutations, epitomized by Goldschmidt’s infamous “hopeful monster”. Although these ideas were easily dismissed by the insights of the Modern Synthesis, a lingering fascination with the possibility of sudden, dramatic change has persisted. Recent work on hybridization and gene exchange suggests an underappreciated mechanism for the sudden appearance of evolutionary novelty that is entirely consistent with the principles of modern population genetics. Genetic recombination in hybrids can produce transgressive phenotypes, “monstrous” phenotypes beyond the range of parental populations. Transgressive phenotypes can be products of epistatic interactions or additive effects of multiple recombined loci. We compare several epistatic and additive models of transgressive segregation in hybrids and find that they are special cases of a general, classic quantitative genetic model. The Dobzhansky-Muller model predicts “hopeless” monsters, sterile and inviable transgressive phenotypes. The Bateson model predicts “hopeful” monsters with fitness greater than either parental population. The complementation model predicts both. Transgressive segregation after hybridization can rapidly produce novel phenotypes by recombining multiple loci simultaneously. Admixed populations will also produce many similar recombinant phenotypes at the same time, increasing the probability that recombinant “hopeful monsters” will establish true-breeding evolutionary lineages. Recombination is not the only (or even most common) process generating evolutionary novelty, but might be the most credible mechanism for sudden appearance of new forms.
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Szűcs M, Eigenbrode SD, Schwarzländer M, Schaffner U. Hybrid vigor in the biological control agent, Longitarsus jacobaeae. Evol Appl 2012; 5:489-97. [PMID: 22949924 PMCID: PMC3407867 DOI: 10.1111/j.1752-4571.2012.00268.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Accepted: 04/18/2012] [Indexed: 11/30/2022] Open
Abstract
Hybridization is an important evolutionary mechanism that can increase the fitness and adaptive potential of populations. A growing body of evidence supports its importance as a key factor contributing to rapid evolution in invasive species, but the effects of hybridization have rarely been assessed in intentionally introduced biological control agents. We investigated hybrids between a Swiss and an Italian population of the beetle, Longitarsus jacobaeae, a biological control agent of Jacobaea vulgaris, by reciprocally crossing individuals in the laboratory. Phenological traits of F1 and F2 hybrid lineages showed intermediate values relative to their parental populations, with some maternal influence. Fitness of the F2 generation, measured as lifetime fecundity, was higher than that of the Italian parent in one of the lineages and higher than that of either parent in the other hybrid lineage. The increased fecundity of hybrids may benefit tansy ragwort biological control by increasing the establishment success and facilitating a more rapid population buildup in the early generations. Even though the long-term consequences of hybridization in this and other systems are hard to predict, intentional hybridization may be a useful tool in biological control strategies as it would promote similar microevolutionary processes operating in numerous targeted invasive species.
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Affiliation(s)
- Marianna Szűcs
- Department of Plant, Soil, and Entomological Sciences, University of IdahoMoscow, ID, USA
- Department of Bioagricultural Sciences and Pest Management, Colorado State UniversityFort Collins, CO, USA
- *Correspondence Marianna Szűcs, Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins, CO 80523-1177, USA. Tel.: 1-970-491-6945; fax: 1-970-491-3862; e-mail:
| | - Sanford D Eigenbrode
- Department of Plant, Soil, and Entomological Sciences, University of IdahoMoscow, ID, USA
| | - Mark Schwarzländer
- Department of Plant, Soil, and Entomological Sciences, University of IdahoMoscow, ID, USA
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Wollebæk J, Heggenes J, Røed KH. Population connectivity: dam migration mitigations and contemporary site fidelity in arctic char. BMC Evol Biol 2011; 11:207. [PMID: 21756324 PMCID: PMC3161007 DOI: 10.1186/1471-2148-11-207] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 07/14/2011] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Animal feeding and spawning migrations may be limited by physical barriers and behavioral interactions. Dam constructions (e.g. hydropower) commonly include gateways for fish migrations to sustain ecological connectivity. Relative genetic impacts of fish passage devices versus natural processes (e.g. hybrid inferiority) are, however, rarely studied. We examined genetic (i.e. microsatellite) population connectivity of highly migrating lake-dwelling Arctic char (Salvelinus alpinus), introduced 20 generations ago, across and within two subalpine lakes separated by a dam with a subterranean tunnel and spill gates after 7 generations. Due to water flow regime, the time window for fish migration is highly restricted. RESULTS Char populations, with similar genetic structuring and diversity observed across and within lakes, were admixed across the dam with fishways during feeding. For spawning, however, statistically significant, but very low population differentiation (θ; 0.002 - 0.013) was found in nine out of ten reproductive site comparisons, reflecting interactions between extensive migration (mean first generation (F0) = 10.8%) and initial site fidelity. Simulations indicated that genetic drift among relatively small effective populations (mean N(e) = 62) may have caused the observed contemporary differentiation. Novel Bayesian analyses indicated mean contributions of 71% F0 population hybrids in spawning populations, of which 76% had maternal or paternal native origin. CONCLUSIONS Ecological connectivity between lakes separated by a dam has been retained through construction of fishways for feeding migration. Considerable survival and homing to ancestral spawning sites in hybrid progeny was documented. Population differentiation despite preceding admixture is likely caused by contemporary reduced reproductive fitness of population hybrids. The study documents the beginning stages of population divergence among spatial aggregations with recent common ancestry.
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Affiliation(s)
- Jens Wollebæk
- The Norwegian School of Veterinary Science, Dep. of Basic Sciences and Aquatic Medicine, Box 8146, Dep. 0033 Oslo, Norway
- Telemark University College, Dep. of Environmental Sciences, Hallvard Eikas Plass, 3800 Bø i Telemark, Norway
| | - Jan Heggenes
- Telemark University College, Dep. of Environmental Sciences, Hallvard Eikas Plass, 3800 Bø i Telemark, Norway
| | - Knut H Røed
- The Norwegian School of Veterinary Science, Dep. of Basic Sciences and Aquatic Medicine, Box 8146, Dep. 0033 Oslo, Norway
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Hwang AS, Northrup SL, Alexander JK, Vo KT, Edmands S. Long-term experimental hybrid swarms between moderately incompatible Tigriopus californicus populations: hybrid inferiority in early generations yields to hybrid superiority in later generations. CONSERV GENET 2011. [DOI: 10.1007/s10592-011-0193-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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