winners and losers

Question 1

what species/organisms are most affected by warming?

Answer 1

• intertidal
• tropical
• populations at the edge of species distribution ranges
• polar species
• larger animals
• sensitive life history stages

Question 2

why do we need to identify winners and losers?

Answer 2

• predict distribution shifts
• identify likely extinctions
• identify species that may maintain functioning
• help predict effects of climate change by identifying organisms close to their limits

Question 3

What is going to determine if a species is at risk?

Answer 3

the organisms behavioural and physiological mechanisms to buffer climate change,

• mechanisms they have to enhance or maintain tolerance
• some may cope by acclimation (only successful in small temp ranges)

Question 4

Why might intertidal organisms be at risk

Somero, 2010: Stillman 2002 Example

Answer 4

• Tropical and those highest in the intertidal species are more heat tolerant than temperate (Highest LT50)
• The most heat tolerant are the most threatened as current max habitat temps may exceed LT50
• Looked at acclimation capacity of porcelain crabs
• temperate have acclimation capacity, tropically don’t have much
• Those that have evolved the tolerance of highest acclimation capacity have done so at the expense of acclimation capacity of ctmax - most vulnerable to change, small ability to increase thermal tolerance
• temperate have high acclimation capacity for thermal tolerance

Question 5

Why might tropical species be at risk?

Answer 5

• higher latitudes are warming the most
• overtime seen a dip in species richness at the equator
• Northern hemisphere seen a shift in species distribution ranges
  Chaudhary et al 2021, Wiens 2016
• in general evolved in warm and stable environments (Thermal specialists)
• Have narrower performance windows
• Limited acclimation capacity
• predicted extra sensitive to climate change
• predicted mean temp increases comparatively greater in the tropics
  Perez et al 2016, Tewksbury et al 2008

Question 6

what is warming tolerance?

Answer 6

= temperature of habitat - max thermal tolerance

Question 7

What is Thermal safety margin

Answer 7

= Thermal optima - Temp of habitat

Question 8

why are polar organisms at risk?

Answer 8

• many lack the capacity to acclimate to temps even just 3 degrees above environmental temp
• acclimation times longer than required
• some living at near-freezing might have high vulnerability to climate change
• evolved for millions of years under cold stable environmental conditions

Question 9

why does global warming benefit small organisms?

Answer 9

• As temp increases there is a decrease in size at age
• as size increases, thermal tolerance decreases
• Body size 3rd universal ecological response to warming in aquatic systems
  Daufresne et al, 2009
• global warming expected to reduce body size of ectotherms
• the effect of elevated temp on ctmax & aerobic metabolism in the tropical leopard corral grouper varies with size
• smaller fish had greater tolerance (ctmax)
• bigger fish need more energy in warmer waters
• bigger coral trout more thermally sensitive
• smaller have greater ability to maintain max metabolic rate in warmer waters and aerobic scope
  Messmer et al, 2016

Question 10

Why is life stage a risk?

Answer 10

Different life stages have different sensitivities
- early life stages regarded as more sensitive
- early life stages of common flat periwinkle worse at with standing short term extreme thermal challenges but better at surviving moderate temp long-term
- adults have higher ctmax but higher sensitivity to thermal change
- larvae more able to cope with slow chronic warming
- adults can cope behaviourally (hide)
Truebana et al, 2018

• younger, smaller water flea more tolerant than older larger individuals
• larger and older may suffer disproportionately during warming
  Burton and Einum 2020