Abstract

Supportive data related to the article “Anonymous nuclear markers reveal taxonomic incongruence and long-term disjunction in a cactus species complex with continental-island distribution in South America” (Perez et al., 2016) [1]. Here, we present pyrosequencing results, primer sequences, a cpDNA phylogeny, and a species tree phylogeny.

Abstract

In response to increases in ambient temperature (T_a), many animals increase total evaporative water loss (TEWL) through their skin and respiratory passages to maintain a constant body temperature, a response that compromises water balance. In birds, cutaneous water loss (CWL) accounts for approximately 65% of TEWL at thermoneutral temperatures. Although the proportion of TEWL accounted for by CWL decreases to only 25% at high T_a, the magnitude of CWL still increases, suggesting changes in the barrier function of the skin. The stratum corneum (SC) is composed of flat, dead cells called corneocytes embedded in a matrix of lipids, many of which arrange in layers called lamellae. The classes of lipids that comprise these lamellae, and their attendant physical properties, determine the rate of CWL. We measured CWL at 25, 30, 35, and 40 °C in House Sparrows (Passer domesticus) caught in the winter and summer, and in sparrows acclimated to warm and cold lab environments. We then used Fourier transform infrared spectroscopy to measure lipid–lipid and lipid–water interactions in the SC under different conditions of temperature and hydration, and correlated these results with lipid classes in the SC. As CWL increased at higher temperatures, the amount of gauche defects in lipid alkyl chains increased, indicating that lipid disorder is partially responsible for higher CWL at high temperatures. However, variation in CWL between groups could not be explained by the amount of gauche defects, and this remaining variation may be attributed to greater amounts of cerebrosides in birds with low CWL, as the sugar moieties of cerebrosides lie outside lipid lamellae and form strong hydrogen bonds with water molecules.

Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

Stephen Levas, Andréa G. Grottoli, Verena Schoepf, Matthew Aschaffenburg, Justin Baumann, James E. Bauer, Mark E. Warner. 2015. Coral Reefs pp 1-12. doi:10.​1007/​s00338-015-1390-z

Abstract

Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral—Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11–36 % of daily metabolic demand (CHAR_DOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.