BIO3082 Lecture Notes - Lecture 9: Pygmy Possum, Golden Toad, American Pika
Lecture 9 – Extinction and Intervention
Factors that make Populations Vulnerable to Extinction
• Climate change
• Habitat destruction
o E.g. for mountain pygmy possum (Burramys parvus): endangered
marsupial endemic to Australian Alps
o Population size ~2500 across 3 subpopulations
o Habitat disturbance from ski resort and road construction
o Declines in distribution of its main food source: moth
o Climate change: causes reduced snow cover and early snow melt: need
insulating cover of snow to hibernate
o Recovery by national government
▪ Habitat expansion through boulder field construction and
revergentation
▪ Population augmentation by captive breeding, release and
monitoring
• Distribution
o Populations with small sizes, narrow ranges or fragmented to
distributions are most vulnerable to extinction
• Resource Need
o Organisms with specialist lifestyles for e.g.
▪ Resilience on a specific diet or habitat – less likely to survive
environmental change
• Genetic Variation
o Populations with low genetic variation will be more vulnerable to
being wiped out by specific pressures (e.g. disease)
o Less able to genetically adapt
• Life Histories
o Organisms with sensitive development stages or short lifespans are
most sensitive to environmental change
What Proportions of Species will Go Extinct from Climate Change
• One sixth of species are threatened with extinction due to anthropogenic
climate change
o Will worsen the ongoing Holocene extinction event
Evaluate Case Studies on Local and Global Extinction
E.g. American Pika
• Unable to cope with physiological pressures of climate change
• Exist in alpine regions in the Rockies
• Have poor capacity to thermoregulate
o Exposure to temperatures of 28˚c for two hours was sufficient to kill
them due to hyperthermia
o Thick coat and high resting body temperature
o Behaviourally thermoregulate by reducing activity and retreating to
microniches
• Restricted to increasingly higher elevations
• Going to experience local extinctions due to climate change
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