Genetic Management of Threatened Species Notes

Genetic Diversity and Adaptive Potential

  • Genetic diversity is important. The reasons why have to do with:

    • Genetic diversity loss

    • Genetic bottleneck

      • Inbreeding

    • Recessive deleterious allele

    • Genetic drift

Genetic Management for Translocations

  • This section discusses how genetic management is crucial for translocations, which involves moving individuals or populations to new locations.

Regaining Genetic Diversity

  • Genetic admixture is a key method. It involves mixing individuals from different populations to create a new population with increased genetic diversity.

Examples of Genetic Admixture

  • Bighorn sheep (Piorier et al. 2018, Evolutionary Applications)

  • Mountain pygmy possum (Weeks et al. 2017, Nature Communications)

  • Burrowing bettong and Western barred bandicoot (White et al. 2018, Biological Conservation)

Planning Translocations and Captive Breeding

  1. Assess source populations: Evaluate population differentiation, diversity between populations, and inbreeding/relatedness between populations.

Sourcing strategy

  1. Decide sourcing strategy:

    • Founder group size

    • Single vs multiple populations

    • One-way or reciprocal translocations

    • Optimize genetic diversity / minimize kinship of founders

Undertake Translocation

  1. Undertake translocation:

    • Release strategies: mix individuals from different populations together; use soft vs. hard release methods.

    • Maximize breeding opportunities and juvenile survival: establishment breeding (e.g., small pen before release), release with pouch young, cross-fostering, headstarting.

Post-Translocation Monitoring

  1. Post-translocation monitoring:

    • Short-term (1 – 2 generations): Confirm successful breeding/mixing, ensure equal founder contribution, maintain or increase genetic diversity, and decrease inbreeding and/or relatedness.

    • Medium (2 – 3 generations) and Long-term (5+ generations?): Define success criteria (e.g., conservation of 90-95% genetic diversity), implement ongoing management (e.g., supplementation), and assess viability as a future source population.

Rectify Genetic Problems

  1. Rectify genetic problems:

    • Reproductive skew

    • Inbreeding

    • Genetic bottleneck (supplementation)

    • Population divergence (e.g., fenced reserves, islands)

    • Periodic genetic assessment is vital to maintain population viability.

    • Prevention is better than the cure!

Tasmanian Devil Case Study

  • This section transitions into a case study focusing on the Tasmanian devil, discussing both ex situ (captive) and in situ (wild) management strategies.

Molecular Pedigree Reconstruction

  • Molecular pedigree reconstruction involves using genetic data to determine relatedness and reproductive success within a population.

What We Can Learn From Molecular Pedigrees

  • Relatedness

  • Reproductive success

  • Reproductive skew

  • Post-release survival

Relatedness With Other Data

  • Mate choice

  • Drivers of successful reproduction

Relatedness & Inbreeding

  • Most programs assume founders are unrelated, setting population/average inbreeding = 0.

Including Molecular Relationships

  • Including molecular relationships shows more accurate inbreeding levels. For example, Population/average inbreeding might be = 0.037.

Formulas For Estimating Inbreeding

  • F=0.0625F = 0.0625

  • F=0.25F = 0.25

Plight of the Tasmanian Devil

  • Focuses on the distribution of Devil Facial Tumour Disease (DFTD) in Tasmania, highlighting confirmed locations prior to and during 2018.

Founder Relationships

  • Describes founder intake of Tasmanian Devils from 2005-2015, noting relationships among founders.

Graphs

  • pF = Founder relationships

  • mF = Founder relationships

Tasmanian Devil Names

  • Lists names of Tasmanian devils in the study, distinguishing between females (8) and males (12), and their offspring.

Offspring

  • Discusses offspring of the devils, and their reproductive success.

Reproductive Ratios

  • Provides calculations of reproductive ratios: 6 offspring/8 females = 0.75 offspring, 6 offspring / 12 males = 0.5 offspring

Reproductive Skew

  • Reproductive skew is high, with over half of wild-born founders not breeding, highlighting a disparity between pedigree and genetic contributions.

Releases to Maria Island

  • Chronicles releases of Tasmanian devils to Maria Island:

    • 2012 colonization (N = 15)

    • 2013 reinforcement (N = 13)

    • 2017 reinforcement (N = 6)

    • 2019 reinforcement (N = 8)

Connectivity & Diversity

  • Devils have poor connectivity and low diversity compared to other species.

Genetic Admixture on Maria Island

  • Discusses genetic admixture on Maria Island, referencing McLennan et al. 2020 Animal Conservation.

Reproductive Success on Maria Island

  • Highlights reproductive success on Maria Island, comparing introduced females and island-born females, referencing McLennan et al. 2020 Animal Conservation.

Maria Island Pedigree

  • Shows the Maria Island pedigree, correlating Studbook numbers with the number of offspring and percentages of contributions.

Maria Island Inbreeding

  • Tracks inbreeding coefficients over time on Maria Island, referencing McLennan et al. 2018. Conservation Genetics.

  • Summarizes genetic management actions on Maria Island, including the number of devils released and removed from 2012 to 2023.

  • Displays graphs showing standardised heterozygosity and mean kinship from 2012 to 2023.