, 2010). In the present study, we apply inter-species transcriptomics to two, closely related marine flowering plants that occupy different ecological niches ( Den Hartog, 1970 and Phillips and Menez, 1988). The seagrasses, Zostera marina (eelgrass) and

Nanozostera noltii (dwarf eelgrass; formerly Zostera noltii) ( Coyer et al., 2013) diverged ~ 14 Mya ( Kato et al., 2003 and Coyer et al., 2013). They provide the foundational habitat for the seagrass community of many, soft-sediment, coastal systems along European coasts. Z. marina ranges from southern Portugal to northern Norway and Iceland, as well as into warm temperate areas of the Mediterranean, LEE011 where it becomes more sparse ( Borum et al., 2004). In contrast, N. noltii ranges from southern Norway to Mauritania, also including the Mediterranean, Black, Aral, and Caspian Seas ( Phillips and Menez, 1988 and Borum et al., 2004). The two species overlap in their distributional range roughly between the northern Mediterranean and southern Norway. Z. marina is predominantly

subtidal, particularly in warmer southern European locations ( Laugier et al., 1999, Billingham et al., 2003 and Massa et al., 2008), where it experiences relatively constant physical conditions and fewer extreme temperatures due to the balancing effect of the surrounding water column. In more northerly latitudes it occurs both subtidally (northern Denmark) and, to a lesser extent, intertidally, (Wadden Sea) ( Oetjen and Reusch, 2007). At the Thau Lagoon location (Mediterranean coast of France) it is sheltered, permanently supplied with nutrients PF-01367338 and less exposed to environmental extremes ( Laugier et al., 1999). In contrast, N. noltii is predominantly an intertidal species, where it experiences more variable environmental conditions of sea and air exposure, as well as physical stressors such as wind and waves ( Laugier et al., 1999 and Massa

et al., 2008). In the Ria Formosa Lagoon in southern Portugal, N. noltii experiences summer temperatures of 36 °C during tidal exposure, which check details is mainly a function of air temperatures and irradiance due to the thin water columns characteristic of intertidal pools ( Massa et al., 2008 and Massa et al., 2011). In this environment local extinction of Z. marina has been correlated with the warmest summers in the Ria Formosa from 2003 to 2008 ( Massa et al., 2008). Extreme weather events are increasing under global warming scenarios and are predicted to have strong influences on ecosystems and associated species (Easterling et al., 2000 and Walther et al., 2002). Water temperatures of ~ 25 °C are the critical threshold for Z. marina in northern Europe ( Reusch et al., 2005, Nejrup and Pedersen, 2008 and Bergmann et al., 2010), but not for N. noltii. Thus, the northerly range expansion of N.