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Self-extinction due to adaptive change in foraging and anti-predator effort

Self-extinction due to adaptive change in foraging and anti-predator effort. Matsuda H, Abrams PA (1994a) Runaway evolution to self-extinction under asymmetric competition. Evolution 48 :1764-1772.

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Self-extinction due to adaptive change in foraging and anti-predator effort

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  1. Self-extinction due to adaptive change in foraging and anti-predator effort • Matsuda H, Abrams PA (1994a) Runaway evolution to self-extinction under asymmetric competition. Evolution 48:1764-1772. • Matsuda H, Abrams PA (1994b) Timid consumers: self-extinction due to adaptive change in foraging and anti-predator effort. Theor Pop Biol 45:76-91. • Matsuda H, Abrams PA (2004) Effects of predator-prey interactions and adaptive change on sustainable yield. Can J Fish Aq Sci in press

  2. Matsuda & Abrams (1994a, b) • Frequency dependent selection may decrease the population size and the population growth rate. • Therefore, self-extinction due to frequency-dependent selection is possible. • e.g., Timid herbivores (Matsuda & Abrams 1994, Theor. Pop. Biol. )

  3. Tradeoff between antipredator effort and foraging time benthos (constant density R) plant (constant density R) flatfish (change in trait Ĉ & population size N) herbivore (change in trait Ĉ & population size N) fishery (constant density P) carnivore (constant density P)

  4. Model I: Harbivore’s fitness W • W(C) = B(CR) - M(C,P) - d • Optimal foraging time • always decreases as predator increases;

  5. Optimal foraging time • I = ĈR: Foraging intake rate I= (individual’s foraging time)(plant density), • B = ĈR/(1 + bĈR)Benefit B from intake saturates with intake, • Risk M of predation (type II functional response)M = ĈP / (1 + hCN) • C is population mean trait valueh: handling time

  6. Population & evolutionary dynamics • Equilibrium population • N* = Ns (stable level) • N* = Nu (unstable critical level) • N* = 0 (extinct)

  7. figures ESS ESS ESS ESS

  8. A model for exploitation of predator R: prey density; N: consumer density; e1: fishing effort; C: foraging time; q: catchability; V; evolution velocity;

  9. Non-standard fisheries-stock/yield relationship fishing effort may increase stock. Stock△ and yield○ are maximized just before stock collapse. P Stock & yield Y Fishing effort

  10. Feedback control may result in stock collapse. S Target CPUE

  11. Feedback control may result in stock collapse.

  12. We should take account of adaptation in managing endangered species. • Does evolutionary response of species always increase its population size? • No • “the fish may become poorer foragers as the result of fishing, and that this may result in extinction, or at least contribute to reducing their population size.” (Matsuda & Abrams 1994b)

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