Lecture 31

Question 1

Some kinds of stresses species experience:

Answer 1

• Human environmental modification

- Climate

Question 2

Performance niche:

Answer 2

• The optimum temperature/aridity for a species to live in
• CTMin - Optimum - CTMax
  (critical thermal)
  -

Question 3

Drought in the Australian alps:

Answer 3

• Increased environmental extremities, instead of 1 every hundred years, multiple in the past 15 years
• Altering the environment for species

Question 4

• Evolution can decrease extinction risk and evolved responses are common:

Answer 4

• Bill size and shape in birds (galapogus finch)
• Thermal responses in ants
• Heavy metal and pesticide tolerance often evolves in non-target species

Question 5

Adaptive variation under selection - we need:

Answer 5

• Variation
• Variation to have a genetic basis
• Fitness differences associated with variants
• And variation not accounted for by population processes

Question 6

Population processes:

Answer 6

• Two populations separated for a couple of hundred generations
• The pattern in allele frequency and genetic diversity is related to origin
• We have to understand the origin of the populations, and if/when they split recently

Question 7

Assessing adaption through clines:

Answer 7

• Clinical assessments
• Longitudinal studies of populations
• Gene isolation
• Conservation

Question 8

What is a cline?

Answer 8

• A gradient in a trait or allele frequency that correlates with a gradient you are interested in
• Temperature
• Rainfall
• Elevation

Question 9

Linear regression of lead length and plant circumference with altitude:

Answer 9

• Temperature, rainfall, soil moisture, UV radiation etc
• Using elevation as a resonal proxy for climate
• Skinny plants with long leaves at the base, short stout plants 200m higher
• Rule out population processes

Question 10

Option 1 for testing:

Answer 10

• Compare patterns in traits with patterns in neutral markers, eg) microsatellites
• If neutral markers show same pattern, historical processes are probably responsible
• Test how the allele frequency relates to the latitude
• A neutral marker should show no significant relationship, but the selected allele should

Question 11

Option 2:

Answer 11

• Indirectly test for selection on traits through parallel patterns across species/locations, expected patterns of selection
• Directly test for selection on traits through transplants, measurements of selection

Question 12

Reciprocal transplant experiments:

Answer 12

• Plants are adapted to their certain mountainside and their elevation.
• This was determined by testing leaf length, with altitude and transplanting three high and three low elevation sites.
• This showed that plants from a high elevation site grow best at a high elevation site, and don’t grow well at a low elevation site
• The circumference was also measured and a fitness curve was generated

Question 13

Blackcap migraiton to overwintering sites:

Answer 13

• These birds migrate from Spain to the UK
• 10% of the birds started migrating to Germany around 10 years ago
• This was found to be genetically based
• Consequence of this change, UK migrants return earlier so they get more time to breed and find mates
• Could be the start of a speciation event

Question 14

Shifting latitudinal clines in avian body size:

Answer 14

• Correlate with global warming in Australian passerines
• Wing length was measured as a proxy for body size
• Mean in body size decreases as they move further south, since 1950
• No time effect on nutritional status, so climate was likely to be a strong factor.

Question 15

Genes underlying climatic adaptation can also show longitudinal shifts:

Answer 15

• Body colour
• Body size
• Also genes!
• Frequency of the AdhS allele decreases as you move further south
• This cline was the same over time, but the position of the cline has moved lower