This preview shows page 1. Sign up to view the full content.
Unformatted text preview: ore, genetics or demographics ?
• Genetics DOMINATES AFTER (takes time to accumulate) • Potential for allee effects is enhanced – The influence of population decline on Ne and its
consequences should predominate in leading to
extinction – Reproductive rate depends positively on density
– At low densities, low reproductive rates
– Likely in colonial breeders Warder Clyde Allee • Demography DOMINATES FIRST • Increased risk of demographic stochasticity – The effects of demographic stochasticity should
predominate and lead to extinction before the
effects of genetics can manifest (Lande 1988) – Random differences among individuals in survivorship and
reproduction create variability in population growth rate
– Happens even if individuals have the same average survival and
– Most important in small populations Russell Lande, photo by
Spencer Barrett 7 Image from wikipedia Demographic Stochasticity: E.g. A random lightning strike can kill off
a ll the females in a population if the population is small
-In a larger population, there is a larger chance that some females will
s ur vive and will be able to replenish the population • Importance of alternative world views:
alternative management actions for rare,
endangered, and declining species 8 -Our plan of action depends on which factor is more
i mportant Case study #1: Cheetahs Early view
• Historical bottleneck lowered Ne • Acinonyx jubatus
• Genetically depauperate • Inbreedi...
View Full Document
- Winter '14
- Annotated Lecture S