Physiological and developmental responses to temperature by the sea anemone Nematostella vectensis

Abstract

Environmental temperature and an organism's ability to respond to it are critical determinants of the geographic distribution of species. Nematostella vectensis is a burrowing sea anemone that inhabits estuaries along the Atlantic coast of North America from Nova Scotia (45°N) to Georgia (31°N). Like other estuarine species, N. vectensis is exposed to large daily (> 20°C) and seasonal (> 25°C) fluctuations in temperature, requiring wide temperature tolerances. At the same time, the natural distribution of this species spans a pronounced thermal cline, which may promote the evolution of different temperature optima and tolerances in populations. We tested the thermal tolerance of N. vectensis adult and developmental stages, which showed all life cycle stages had critical temperatures within 1°C (lethal temperature 39.5 to 40.5°C). When temperature tolerance values were compared with recorded field data, N. vectensis is living in environments very close to their physiological limit. We utilized common garden experiments (13, 21, and 29°C) to test for temperature-specific growth and regeneration rates in N. vectensis from different portions of this species' range. Temperature had a significant effect on growth and regeneration rate in all clonal lines, with a significant negative relationship between latitude of origin and growth rate at 29°C. Individuals from higher latitudes did not exhibit higher growth rates at cooler temperatures. Together, our results show a combination of broad thermal tolerances for developmental and adult stages and evidence for local adaptation to higher temperatures in populations living in lower latitude locations that would be physiologically compromised with future warming.

Ultraviolet radiation significantly enhances the molecular response to dispersant and sweet crude oil exposure in Nematostella vectensis

“…Animals were fed brine 182 shrimp nauplii four times per week, and water was changed weekly. Animals held in these 183 conditions exhibit consistent growth and can be induced to spawn regularly (Reitzel et al 2013, 184…”

Current directions and future perspectives from the third Nematostella research conference

“…He discussed the role of spatial scale in the genetic relationships of natural populations. Over large geographic ranges (hundreds of kilometers), Nematostella has highly structured populations indicating limited genetic exchange between locations (Reitzel et al, 2013b). However, at smaller scales (within 1 km, single estuary), Nematostella shows signs of metapopulation structure where reproductive plasticity and colonization of new habitats occurs at low but quantifiable frequencies.…”

“…Reitzel also described research quantifying physiological variation between populations, consistent with temperature adaptation (Reitzel et al, 2013a). Finally, he discussed efforts to identify regions of the genome under selection through analyses of expressed sequence tags (Reitzel et al, 2010) and whole genome polymorphisms (Reitzel et al, 2013b). Together, geographically structured genetic and phenotypic variation in Nematostella may provide a useful system for discerning the molecular mechanisms that underlie adaptation in a coastal cnidarian.…”

Using Nematostella vectensis to Study the Interactions between Genome, Epigenome, and Bacteria in a Changing Environment

“…Because it is a predominately sessile species, individuals must have wide physiological plasticity and ability to acclimate to thrive in these habitats. Natural populations have been documented in tide pools with temperatures ranging from −1.5 to 41 • C (Reitzel et al, 2013a) and salinities from 9 to 51 ; (reviewed by Hand and Uhlinger, 1994). Within these tidally restricted pools, the environment also has extreme temperature-oscillations with >20 • C fluctuations daily (Figure 2B), exerting cellular stress evidenced by upregulation of heat shock genes (Reitzel, unpublished data).…”

“…Within these tidally restricted pools, the environment also has extreme temperature-oscillations with >20 • C fluctuations daily (Figure 2B), exerting cellular stress evidenced by upregulation of heat shock genes (Reitzel, unpublished data). N. vectensis' native geographic range spans a pronounced thermocline (∼10 • C mean temperature over 10 • latitude) (Hand and Uhlinger, 1994;Reitzel et al, 2008), which appears to have resulted in different thermal optima for growth and tolerance for high temperatures (Reitzel et al, 2013a, Figure 2C). …”