Heritable variation in thermal profiles is associated with reproductive success in the world’s largest bird

TY - JOUR

T1 - Heritable variation in thermal profiles is associated with reproductive success in the world’s largest bird

AU - Svensson, Erik I

AU - Schou, Mads F

AU - Melgar, Julian

AU - Waller, John

AU - Engelbrecht, Anel

AU - Brand, Zanell

AU - Cloete, Schalk

AU - Cornwallis, Charlie K

PY - 2024/4/1

Y1 - 2024/4/1

N2 - Organisms inhabiting extreme thermal environments, such as desert birds, have evolved spectacular adaptations to thermoregulate during hot and cold conditions. However, our knowledge of selection for thermoregulation and the potential for evolutionary responses is limited, particularly for large organisms experiencing extreme temperature fluctuations. Here we use thermal imaging to quantify selection and genetic variation in thermoregulation in ostriches (Struthio camelus), the world’s largest bird species that is experiencing increasingly volatile temperatures. We found that females who are better at regulating their head temperatures (“thermoregulatory capacity”) had higher egg-laying rates under hotter conditions. Thermoregulatory capacity was both heritable and showed signatures of local adaptation: females originating from more unpredictable climates were better at regulating their head temperatures in response to temperature fluctuations. Together these results reveal that past and present evolutionary processes have shaped genetic variation in thermoregulatory capacity, which appears to protect critical organs, such as the brain, from extreme temperatures during reproduction.

AB - Organisms inhabiting extreme thermal environments, such as desert birds, have evolved spectacular adaptations to thermoregulate during hot and cold conditions. However, our knowledge of selection for thermoregulation and the potential for evolutionary responses is limited, particularly for large organisms experiencing extreme temperature fluctuations. Here we use thermal imaging to quantify selection and genetic variation in thermoregulation in ostriches (Struthio camelus), the world’s largest bird species that is experiencing increasingly volatile temperatures. We found that females who are better at regulating their head temperatures (“thermoregulatory capacity”) had higher egg-laying rates under hotter conditions. Thermoregulatory capacity was both heritable and showed signatures of local adaptation: females originating from more unpredictable climates were better at regulating their head temperatures in response to temperature fluctuations. Together these results reveal that past and present evolutionary processes have shaped genetic variation in thermoregulatory capacity, which appears to protect critical organs, such as the brain, from extreme temperatures during reproduction.

KW - fitness

KW - heat stress

KW - heritability

KW - thermal adaptation

KW - thermal imaging

KW - thermoregulation

UR - https://www.scopus.com/pages/publications/85188802867

U2 - 10.1093/evlett/qrad049

DO - 10.1093/evlett/qrad049

M3 - Journal article

C2 - 38525029

SN - 2056-3744

VL - 8

SP - 200

EP - 211

JO - Evolution Letters

JF - Evolution Letters

IS - 2

M1 - qrad049

ER -