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

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

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

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

Pattern: Laying date is a week later than 20 years ago (b = 0.35 ± 0.05, p < ) [due to lower fish food abundance] Heritability = h 2 = 0.36 (± 0.05) Selection gradient = S = 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

Snow melted off significant later Emergence from hibernation delayed

Lower fitness with later emergence OVER 20 YEARS: Emergence 9.4 days later Heritability = h 2 = 0.23 (± 0.05) Selection gradient = S = 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

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 = (P = 0.05), with temp r = (P = 0.01), with rain Annual Fitness April Snowfall before July Rain & Temperature Nov – Dec Snowfall December Snowpack * April Snowfall after