Document Type

Article

Publication Date

2019

DOI

10.1242/jeb.189225

Publication Title

Journal of Experimental Biology

Volume

222

Pages

189225 (1-13)

Abstract

Variation in environmental characteristics and divergent selection pressures can drive adaptive differentiation across a species' range. Astrangia poculata is a temperate scleractinian coral that provides unique opportunities to understand the roles of phenotypic plasticity and evolutionary adaptation in coral physiological tolerance limits. A. poculata inhabits hard bottom ecosystems from the northwestern Atlantic to the Gulf of Mexico and withstands an annual temperature range up to 20° C. Additionally, A. poculata is facultatively symbiotic and co-occurs in both symbiotic ("brown") and aposymbiotic ("white") states. Here, brown and white A. poculata were collected from Virginia (VA) and Rhode Island (RI), USA and exposed to heat (18-32° C) and cold (18-6° C) temperatures during which respiration (R) of the coral host along with photosynthesis (P) and photochemical efficiency (Fv /Fm) of Breviolum psygmophilum photosymbionts were measured. Thermal performance curves (TPCs) of respiration revealed a pattern of countergradient variation with RI corals exhibiting higher respiration rates overall, and specifically at 6, 15, 18, 22, and 26°C. Additionally, thermal optimum (Topt) analyses show a 3.8° C (brown) and 6.9° C (white) higher Topt in the VA population, corresponding to the warmer in situ thermal environment in VA. In contrast to respiration, no origin effect was detected in photosynthesis rates or Fv/Fm, suggesting a possible host-only signature of adaptation. This study is the first to consider A. poculata's response to both heat and cold stress across symbiotic states and geography and provides insight into the potential evolutionary mechanisms behind the success of this species along the East Coast of the US.

Comments

Green open access after an embargo period of 12 months from publication date of January 30, 2019.

Publisher's version available at: https://dx.doi.org/10.1242/jeb.189225.

Original Publication Citation

Aichelman, H. E., Zimmerman, R. C., & Barshis, D. J. (2019). Adaptive signatures in thermal performance of the temperate coral Astrangia poculata. Journal of Experimental Biology, 222, 189225. doi:10.1242/jeb.189225

ORCID

0000-0001-6999-5518 (Aichelman), 0000-0002-9399-4264 (Zimmerman)

Available for download on Thursday, January 30, 2020

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