Lecture 12

Question 1

Migration and range shifts have happened routinely through geological time

Answer 1

• Species have some capacity to disperse
• Natural changes usually slow enough for migratory abilities of organisms to allow adjsutments of ranges
• Strong selection can produce rapid evolutionary responses
• But anthroopgenic changes can happen so fast that species may not be able to migrate or evolve

Question 2

What about animals

Answer 2

• Northern range limit has shifted on average 16.9 km per decade
• Upper altitudinal limit has shifted 11.0m per decade
• N = 764 species for latitude, 1367 for altitude (plants + animals)
• Areas that warm faster: more altitudinal and latitudinal change

Question 3

Ranges of tolerance and ecological niche modeling

Answer 3

• Assume that a species is now found in places where conditions are suitable
  
  • Map where a species is found now
  • Measure ecological conditions there to produce an envelope of suitability
  • Use GCM to predict how conditions will change
  • Map where conditions will be suitable in future
• Predict how far range will need to shift

Question 4

Modeling species loss from sky islands with climate change

Answer 4

• Mammals on mountain ranges in Great Basin
• Model assumptions
  
  • Climate warms 3 C
  • Habitat moves upward 500m
  • Habitat area shrinks accordingly
  • Species lost according to habitat loss
• Resampled 25 mountain ranges where pikas had been found earlier
  
  • Pikas extirpated in 7 of 25

Question 5

Pronghorn antelope

Answer 5

• Migratory grazers of open grassland
• Fastest north american mammal
• Skeleton convergently similar to true African cheetah, but mtDNA indicates more closely related to American cougar
• Climate change migrations hampered by human-altered landscapes: wired fences

Question 6

Bramble Cay melomys

Answer 6

• Small rodent only found on Bramble Cay
• Only endemic mammal species of great barrier reef
• Herbivore relying on herbaceous cover for food and shelter
• Population decline: 2002 and 2004, only 10-12 captured
• Emergency response: Capture any remaining individuals for a captive breeding population
  
  • Results: No Bramble Cay melomys were found in 2011 and 2014, no sign of presence on island. Last known sighting was 2009

Question 7

Evolutionary responses to global climate change

Answer 7

• Tracking genetic change is hard
• Easy solution: focus on genetic polymorphisms or mendelian traits
  
  • Phenotype -> Genotype

Question 8

Ladybugs

Answer 8

• Colder than average, melanic favored
• Warmer than average, red favored
• 1980: Colder west to east, more melanics as you go east
• 2004: Temperature gradient erased, decline in melanics eliminated