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MAPPING ANIMAL FITNESS ONTO SEASONAL CLIMATE CHANGE F. Stephen Dobson Department of Biological Sciences College of Science & Mathematics.

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Presentation on theme: "MAPPING ANIMAL FITNESS ONTO SEASONAL CLIMATE CHANGE F. Stephen Dobson Department of Biological Sciences College of Science & Mathematics."— Presentation transcript:

1 MAPPING ANIMAL FITNESS ONTO SEASONAL CLIMATE CHANGE F. Stephen Dobson Department of Biological Sciences College of Science & Mathematics

2 GENERAL TOPIC: PHENOLOGICAL RESPONSES TO CLIMATE CHANGE GENERAL PATTERN: earlier dates of spring phenology with warming - including species at different trophic levels in the same habitats PROBLEM: because trophic links are involved, there may be mismatches between resources & reproduction for some of the species specifically, breeding and peak resource periods may not match up e.g., peak insect abundances and nestling feeding by breeding birds often coincide

3 Evidence of trophic interactions Typical story of timing across trophic levels 1985 - 2005 This study compared plant growth insect development 4 species - song birds an avian predator Both et al. 2009, JAE Budburst Caterpillars Sparrowhawks

4 GENERAL TOPIC: PHENOLOGICAL RESPONSES TO CLIMATE CHANGE SPECIFIC QUESTION: how much of the changes in timing is due to: Plastic responses of phenotypes Genetic adaptations to new conditions Breeding Date cool warm Spring temperature A B

5 Pattern: Laying date is a week later than 20 years ago (b = 0.35 ± 0.05, p < 0.0001) [due to lower fish food abundance] Heritability = h 2 = 0.36 (± 0.05) Selection gradient = S = -0.10 Breeder’s equation: R = h 2  S Conclusion 1: natural selection favors earlier breeding, not later breeding! Conclusion 2: later breeding due to phenotypic plasticity

6 Snow melted off significant later Emergence from hibernation delayed

7 Lower fitness with later emergence OVER 20 YEARS: Emergence 9.4 days later Heritability = h 2 = 0.23 (± 0.05) Selection gradient = S = -0.14 Breeder’s equation: R = h 2  S Conclusion 1: natural selection favors earlier, not later emergence from hibernation! Conclusion 2: later emergence due to phenotypic plasticity Population grew, then declined

8 Δ Fitness & Δ Climate: Summer temperature has gone up: +4.4°C, mean = 16.5°C Summer rainfall has gone down: -3.7mm, mean = 2.5mm Fitness has gone down: r = -0.428 (P = 0.05), with temp r = 0.548 (P = 0.01), with rain Annual Fitness April Snowfall before July Rain & Temperature Nov – Dec Snowfall December Snowpack 0.046 0.468* 0.047 -0.032 April Snowfall after -0.223


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