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Demography of southern leatherside chub in the presence and absence of an introduced predator

Demography of southern leatherside chub in the presence and absence of an introduced predator. Mark C. Belk, Eric Billman, Josh Rasmussen, Karen Mock, Jerald B. Johnson. Predation – complex effects, experimental approaches. Transition matrix – a powerful tool. Vital rates and matrix methods

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Demography of southern leatherside chub in the presence and absence of an introduced predator

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  1. Demography of southern leathersidechub in the presence and absence of an introduced predator Mark C. Belk, Eric Billman, Josh Rasmussen, Karen Mock, Jerald B. Johnson

  2. Predation – complex effects, experimental approaches

  3. Transition matrix – a powerful tool • Vital rates and matrix methods • Combine matrix models with predation experiments • Unravel ecological and evolutionary consequences of predation

  4. Southern leatherside chub (Lepidomedaaliciae) serial mark-recapture experiment on two populations of southern leatherside chub – one that co-occurs with introduced brown trout and one without

  5. Stage-structured model • Serial mark-recapture, 2 locations, 3-4 years, • 3-stages based on size and maturity • Fecundity estimates based on independent samples • Pre-breeding census model, s0, survival of offspring from birth to first counting (1 year), applied to fecundity estimates

  6. Three questions • Are there detectable differences in mortality rate between brown trout and non-brown trout environments? • What are population demographic consequences of brown trout predation? • Which vital rates have the greatest impact on population growth and fitness?

  7. Survival estimates No-predator – Salina Creek Predator – Lost Creek s0 = 0.0014 s0 = 0.0033

  8. Life cycle and transition matrix F2 F3 1 2 G1,2 G1 G2 3 S3 S2 S1

  9. Transition matrices No-predator, Salina Creek Predator, Lost Creek

  10. Demographics

  11. Growth rates of individuals Billman et al. 2011, Eco. Fresh. Fish

  12. Demographics

  13. Elasticity analysis No-predator, Salina Creek Predator, Lost Creek

  14. Conclusions • Are there detectable differences in mortality rate between brown trout and non-brown trout environments? • YES. Pattern is stage-specific and alternates • What are population demographic consequences of brown trout predation? • change in λ, stable stage distribution, T • mainly through modification of growth rates (G) and the s0 component of fecundity.

  15. Conclusions • Which vital rates have the greatest impact on population growth and fitness? • Early growth and fecundity contribute most to population growth and fitness

  16. Application • For fisheries, humans act as predator • Potential for strong ecological effects • Introduced fish • Population demography as tool • e.g. effect of burbot on important fisheries species • Native species conservation • Effect of introduced species • Effect of habitat degradation • Interacting effects

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