Global warming and Bergmann’s rule

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Global warming and Bergmann’s rule

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  1. Nikita Sundara – 1781 4560

    Slide 1 - Nikita Sundara – 1781 4560

    • 300851 Advanced Physiology
    • Autumn 2015
    • Global warming and Bergmann’s rule
  2. What is Bergmann’s rule?

    Slide 2 - What is Bergmann’s rule?

    • “In warm blooded animals, races from warm regions are smaller than races from cold regions” (Mayr 1970)
  3. Importance of this topic

    Slide 3 - Importance of this topic

    • Resilience in the face of climate change
    • Insights into thermal tolerances, thermoregulation and metabolism
  4. Yom Tov (2006)

    Slide 4 - Yom Tov (2006)

    • Main Findings
    • 14 species passerine birds in Britain - Wicken Fen and Treswell Wood
    • Significant linear decreases in mass seen in Wicken Fen
    • Linear increases in wing length in Wicken Fen for 7 out of 11 species
    • Non-linear decreases also found – not consistent with gradual temperatures  additional selective pressures
    • Rate of change in weight similar to that observed in Germany 1981-2003
  5. Yom Tov (2006)

    Slide 5 - Yom Tov (2006)

  6. Yom Tov (2006)

    Slide 6 - Yom Tov (2006)

    • Conclusions
    • Decreases in body weight
    • Global warming is a continuous (linear) process but observations in trends were non-linear
    • Global warming is not sole factor
    • Short-term/local factors account for additional variation
    • Gosler et al (1995) – body weight influences by predation pressure
  7. Meiri and Dayan (2003)

    Slide 7 - Meiri and Dayan (2003)

    • Main Findings
    • Reviewed Bergmann’s rule in birds and mammals
    • Over 72% of birds and 65% of mammal species  valid generalization
    • Majority of species, orders and families complied
    • Studies using body mass = greatest adherence
    • Birds of all body mass show similar tendency
    • Mammals of low body mass show lower tendency
    • Sedentary birds conform more than migratory
  8. Meiri and Dayan (2003)

    Slide 8 - Meiri and Dayan (2003)

  9. Meiri and Dayan (2003)

    Slide 9 - Meiri and Dayan (2003)

    • Conclusion
    • Bergmann’s rule is a valid generalization for birds and mammals
  10. Adams and Church (2007)

    Slide 10 - Adams and Church (2007)

    • Main Findings
    • Measured adult Salamanders
    • Only 3 out of 40 species followed Bergmann’s rule
    • No support in genus, order or class
    • Findings suggest Bergmann’s rule does not apply to amphibians
  11. Adams and Church (2007)

    Slide 11 - Adams and Church (2007)

  12. Adams and Church (2007)

    Slide 12 - Adams and Church (2007)

    • Conclusions
    • Independent contrasts analysis: no relationship between size and temperature
    • Disputes theory that rule is common in amphibians
    • Support for view is based mainly on meta-analysis (Ashton, 2002) whose limited sampling may have affected its conclusions (3 vs. 1618 geographic localities)
  13. Salewski et al (2010)

    Slide 13 - Salewski et al (2010)

    • Main Findings
    • Fluctuations in mean annual temperature – direct links between body temperature and mass
    • Only 5 species showed: ↑temp = ↓mass
  14. Salewski et al (2010)

    Slide 14 - Salewski et al (2010)

    • Conclusions
    • Changes in size not caused by phenotypic plasticity alone
    • Results contrast with Yom Tov (2006) – more direct examination
  15. Gienapp et al (2008)

    Slide 15 - Gienapp et al (2008)

    • Stresses importance of differentiation between microevolutionary (genetic) and plastic (phenotypic) responses
    • Limits to plastic responses – no long-term solutions
    • Rate of climate change too rapid for populations to sustain
    • Many responses perceived as adaption but could be plastic
    • Extinction is likely outcome
  16. “There is almost no species for which we know enough relevant ecology, physiology and genetics to predict its evolutionary response to climate change” – Holt (1990)

    Slide 16 - “There is almost no species for which we know enough relevant ecology, physiology and genetics to predict its evolutionary response to climate change” – Holt (1990)

  17. Please feel free to email any questions to:

    Slide 17 - Please feel free to email any questions to:

    • 17814560@student.uws.edu.au
  18. References

    Slide 18 - References

    • Adams, DC and Church, JO 2007, ‘Amphibians do not follow bergmann’s rule’, Evolution, vol.62, no.2, pp.413-420
    • Gienapp, P Teplitsky, J Alho, S Mills, A and Merila, J 2008. ‘Climate change and evolution: disentangling environmental and genetic responses’, Molecular Ecology, vol.17, no.1, pp.167-178
    • Gosler, AG Greenwood JJD and Perrins, CM 1995, ‘Predation risk and the cost of being fat’, Nature, vol.337, no.1, pp.621-623
    • Holt, RD 1990, ‘The microevolutionary consequences of climate change’, Trends in Ecology and Evolution, vol.5, no.1, pp.311-315
    • Mayr, E 1970 ‘Population, species and evolution’, Harvard University Press.
    • Meiri, S and Dayan, T 2003, ‘On the validity of bergmann’s rule’, Journal of Biogeography, vol.30, no.1, pp.331-351
    • Salewski, V, Hochachka, WM and Fielder, W 2010, ‘Global warming and bergmann’s rule: do central european passerines adjust their body size to rising temperatures?’, Oecologia, vol.162, no.1, pp.247-260
    • Yom-Tov, Y Yom-Tov, S Wright, J Thorne, CJR and Du Feu, R 2006, ‘Recent changes in body weight and wing length among some british passerine birds’, OIKOS, vol.112, no.1, pp.91-101