Protection from thermal stress in embryo masses of Melanochlamys diomedea

1. Protection from thermal stress in embryo masses of Melanochlamys diomedea Construction, placement, and persistence of embryo masses under natural conditions Variation in habitat temperatures over different spatial and temporal scales Patterns of protein expression and their variation as a function of larval temperature exposure Protection of embryos from heat stress during early developmental stages

2. Protection from thermal stress in embryo masses of Melanochlamys diomedea Natural history of embryo masses Patterns of variation in habitat temperature Heat-inducible expression of novel proteins Is development protected from heat stress?

3. Female mate choice • Males in diverse taxa often have extreme, showy secondary sexual characteristics • Extreme displays may have evolved to attract females • However, biologists are unsure of why females prefer showy males

4. Why do females prefer extreme displays?

5. Temperature protection experiment: methods • 1. A single embryo mass was divided into eight parts. • 2. Four parts were exposed to a 29°C heat shock, and four to 12°C control temperatures. Each set of four was then treated as follows: • One was immediately radiolabeled and processed for heat shock expression • One was exposed to a 35°C heat stress for 0.5 h, and one for 1.5 h, and then both were processed • One was exposed to a 35 °C heat stress and then transferred to seawater to monitor embryos for normal development

6. TEMPERATURE PROTECTION EXPERIMENT

7. Changes in growth by age and sex

8. Males respond to increased dosagemore than females

9. 2 R = 0.37 o ( C) Temperature in tide pools 35 C) o ( 30 25 Temperature on following day 20 15 10 10 15 20 25 30 35 Temperature

10. Maximum temperature is correlated between days 35 R2 = 0.37 30 25 Maximum temperature on next day (°C) 20 15 10 10 15 20 25 30 35 Maximum temperature (°C)

11. Table 3. Results of the selection analysis. Standardized directional selection differentials (s') and gradients (b') for mean ovum and jelly volume, and standardized quadratic selection gradients (h') for variance of characters and covariance between characters

12. Selection gradients for ova and jelly coats

13. Summary • Intertidal habitats present physical challenges to development that can vary on several temporal and spatial scales • Increased temperatures during a spring-tide series can speed development,but • high temperatures also increase risks of high temperature stress especially for early stages that cannot synthesize hsps • Although many masses may be dislodged before they mature, increased water exchange during the spring-tide seriesdoes notappear to result in greater risk of dislodgment • Adults deposit masses with similar frequency during spring- and neap-tide series • less likely to deposit masses following hot days

14. Summary Intertidal habitats present physical challenges to development on several temporal scales Increased temperatures speed development but also increase risk of stress Increased water exchange during the spring-tide series does not increase dislodgment Adults are less likely to deposit masses following hot days

15. development rate risk of heat stress temperatures lead to embryo mass production after hot days Summary Intertidal habitats present physical challenges to development on several time scales mass dislodgment: spring tides = neap tides