Rapid Evolution
Rapid Evolution
It has recently been demonstrated that evolution can occur over short time scales - sometimes in as little as a single generation. Understanding which species and populations can rapidly adapt to novel environments - and how this process happens - has important implications for prioritizing and implementing appropriate conservation and management actions in the face of changing environmental conditions (e.g., climate change). Our lab continues to examine how species genetically adapt to novel environments across diverse systems such as Daphnia, Pacific salmon, sea lamprey, and captive breeding programs.
It has recently been demonstrated that evolution can occur over short time scales - sometimes in as little as a single generation. Understanding which species and populations can rapidly adapt to novel environments - and how this process happens - has important implications for prioritizing and implementing appropriate conservation and management actions in the face of changing environmental conditions (e.g., climate change). Our lab continues to examine how species genetically adapt to novel environments across diverse systems such as Daphnia, Pacific salmon, sea lamprey, and captive breeding programs.
Representative publications:
Representative publications:
- Sparks MM, Kraft JC, Blackstone KMS, McNickle GG, Christie MR (2022). Large genetic divergence underpins cryptic local adaptation across ecological and evolutionary gradients. Proceedings of the Royal Society B: Biological Sciences. 289: 20221472.
- Harder AM, Christie MR (2022). Genomic signatures of adaptation to novel environments: hatchery and life-history associated loci in landlocked and anadromous Atlantic salmon (Salmo salar) Canadian Journal of Fisheries and Aquatic Sciences 79:761–770.
- Yin X, Martinez AS, Perkins A, Sparks MM, Harder AM, Willoughby JR, Sepúlveda MS, Christie MR (2021) Incipient resistance to an effective pesticide results from genetic adaptation and the canalization of gene expression Evolutionary Applications 14:847-859.
- Willoughby JR, Harder AM, Tennessen JA, Scribner KT, Christie MR (2018) Rapid genetic adaptation to a novel environment despite a genome-wide reduction in genetic diversity. Molecular Ecology 27:4041-4051.
Genetic Diversity
Genetic Diversity
Genetic diversity is crucial for populations to respond to threats such as novel diseases and climate change. Understanding how extrinsic (e.g., management actions) and intrinsic (e.g., genomic architecture) factors affect genetic diversity is one our research priorities. Our lab has investigated how captive breeding programs, including salmon hatcheries, can unintentionally cause reductions in genetic diversity and has also investigated how introducing non-native species to novel environments can cause large, genome-wide reductions in genetic diversity.
Genetic diversity is crucial for populations to respond to threats such as novel diseases and climate change. Understanding how extrinsic (e.g., management actions) and intrinsic (e.g., genomic architecture) factors affect genetic diversity is one our research priorities. Our lab has investigated how captive breeding programs, including salmon hatcheries, can unintentionally cause reductions in genetic diversity and has also investigated how introducing non-native species to novel environments can cause large, genome-wide reductions in genetic diversity.
Representative publications:
Representative publications:
- Sparks MM, Schraidt CE, Yin X, Seeb LW, Christie MR (In press) Rapid genetic adaptation to a novel ecosystem despite a massive founder effect. Molecular Ecology. PDF
Martinez AS, Willoughby JR, Christie MR (2018) Genetic diversity in fishes is influenced by habitat type and life history variation. Ecology and Evolution 8:12022-12031. PDF
Christie MR, Marine ML, French RA, Waples RS, Blouin MS (2012) Effective size of a wild salmonid population is greatly reduced by hatchery supplementation. Heredity 109:254-260. PDF
Population connectivity in high gene flow systems
Population connectivity in high gene flow systems
Identifying the spatial and temporal boundaries of fish populations is critical for effective fisheries management and conservation. However, the delimitation of fish populations can be challenging because many species are difficult to observe directly in their aquatic environments. Furthermore, fish populations are often connected by dispersal that occurs during a relatively cryptic pelagic larval stage as most fish larvae are minuscule (~1-3mm) and nearly transparent, making them difficult to observe directly. This pelagic larval stage is ubiquitous; many freshwater fishes and over 95% of all marine fishes have a pelagic larval stage as part of their life histories. Being pelagic, currents can transport larvae to populations that are hundreds of kilometers away from where they were spawned. On the other hand, behavioral adaptations, homing mechanisms, and a complex interplay of biophysical processes can result in larvae returning to the same population from where they were spawned. Thus, given the challenges associated with tracking minuscule larvae and the observation that larvae can travel highly variable distances, our lab uses novel, integrative approaches in order to elucidate the degree to which fish populations are connected.
Identifying the spatial and temporal boundaries of fish populations is critical for effective fisheries management and conservation. However, the delimitation of fish populations can be challenging because many species are difficult to observe directly in their aquatic environments. Furthermore, fish populations are often connected by dispersal that occurs during a relatively cryptic pelagic larval stage as most fish larvae are minuscule (~1-3mm) and nearly transparent, making them difficult to observe directly. This pelagic larval stage is ubiquitous; many freshwater fishes and over 95% of all marine fishes have a pelagic larval stage as part of their life histories. Being pelagic, currents can transport larvae to populations that are hundreds of kilometers away from where they were spawned. On the other hand, behavioral adaptations, homing mechanisms, and a complex interplay of biophysical processes can result in larvae returning to the same population from where they were spawned. Thus, given the challenges associated with tracking minuscule larvae and the observation that larvae can travel highly variable distances, our lab uses novel, integrative approaches in order to elucidate the degree to which fish populations are connected.
Representative publications:
Representative publications:
- Schraidt CE, Ackiss AS, Larson WA, Rowe MD, Höök TO, Christie MR (2023) Dispersive currents explain patterns of population connectivity in an ecologically and economically important fish. Evolutionary Applications 16:1284-1301.
- LaRue EA, Emery NC, Briley L, Christie MR (2019) Geographic variation in dispersal distance facilitates range expansion of a lake shore plant in response to climate change. Diversity and Distributions 25:1429-1440.
- Christie MR, Miermans PG, Gaggioti OE, Toonen RJ, White C (2017) Disentangling the relative merits and disadvantages of parentage analysis and assignment tests for inferring population connectivity. ICES Journal of Marine Science 74:1749-1762.
- Christie MR, Tissot BN, Albins MA, Beets JP, Jia Y, Ortiz DM, Thompson SE, Hixon MA (2010) Larval connectivity in an effective network of marine protected areas. PLoS ONE 5:e15715.
Rescue
Rescue
Three forms of rescue are possible for populations facing extinction: demographic, evolutionary, and genetic. Understanding which type of rescue (if any) is appropriate for natural populations is a question our lab focuses on. By understanding the genomic architectures that facilitate rescue, we may be able to predict which species can be left in situ to respond to changing environmental questions and which species will need some form of intervention either in the form of adding individuals from appropriate source populations (genetic rescue) or via captive breeding.
Three forms of rescue are possible for populations facing extinction: demographic, evolutionary, and genetic. Understanding which type of rescue (if any) is appropriate for natural populations is a question our lab focuses on. By understanding the genomic architectures that facilitate rescue, we may be able to predict which species can be left in situ to respond to changing environmental questions and which species will need some form of intervention either in the form of adding individuals from appropriate source populations (genetic rescue) or via captive breeding.