Sampling Strategy for the Genetic Analysis of Human Remains from Tepe Hissar

Genetic testing has become a critical tool for the examination of ancient human remains. Earlier methods relied exclusively on observations and measurements. DNA analysis can date skeletal remains using radiocarbon dating, identify the sex of the individual, and determine the mtDNA and Y-chromosome haplogroups. Mitochondrial DNA and Y-chromosome haplogroups can be further used to understand kinship, burial practices, and other information about the civilization. For this study, I created a sampling strategy for the genetic analysis of a collection of 397 skeletons excavated during the 1930’s from an Iranian Bronze Age site called Tepe Hissar. DNA analysis can be cost prohibitive and requires samples be extracted and destroyed. A successful sampling strategy mitigates these costs, balancing efficiency and effectiveness to create the smallest sample that remains representative for the entire population. Overall, preservation, location within the site and layers, and their status as an outlier should be considered as major determinants for the representative sample. Preservation is the most important factor followed closely by the status of skeletons as outliers in their respective research studies and the skeletons’ relative geographic location. Although I ranked these factors, all three will be taken into account when determining the final representative sample

Rapid multi-generational acclimation of coralline algal reproductive structures to ocean acidification

The future of coral reef ecosystems is under threat because vital reef-accreting species such as coralline algae are highly susceptible to ocean acidification. Although ocean acidification is known to reduce coralline algal growth rates, its direct effects on the development of coralline algal reproductive structures (conceptacles) is largely unknown. Furthermore, the long-term, multi-generational response of coralline algae to ocean acidification is extremely understudied. Here, we investigate how mean pH, pH variability and the pH regime experienced in their natural habitat affect coralline algal conceptacle abundance and size across six generations of exposure. We show that second-generation coralline algae exposed to ocean acidification treatments had conceptacle abundances 60% lower than those kept in present-day conditions, suggesting that conceptacle development is initially highly sensitive to ocean acidification. However, this negative effect of ocean acidification on conceptacle abundance disappears after three generations of exposure. Moreover, we show that this transgenerational acclimation of conceptacle development is not facilitated by a trade-off with reduced investment in growth, as higher conceptacle abundances are associated with crusts with faster growth rates. These results indicate that the potential reproductive output of coralline algae may be sustained under future ocean acidification.journal articl

Rapid multi-generational acclimation of coralline algal reproductive structures to ocean acidification

International audienceThe future of coral reef ecosystems is under threat because vital reef-accreting species such as coralline algae are highly susceptible to ocean acidification. Although ocean acidification is known to reduce coralline algal growth rates, its direct effects on the development of coralline algal reproductive structures (conceptacles) is largely unknown. Furthermore, the long-term, multigenerational response of coralline algae to ocean acidification is extremely understudied. Here, we investigate how mean pH, pH variability and the pH regime experienced in their natural habitat affect coralline algal conceptacle abundance and size across six generations of exposure. We show that second generation coralline algae exposed to ocean acidification treatments had conceptacle abundances 60% lower than those kept in present day conditions, suggesting that conceptacle development is initially highly sensitive to ocean acidification. However, this negative effect of ocean acidification on conceptacle abundance disappears after three generations of exposure. Moreover, we show that this transgenerational acclimation of conceptacle development is not facilitated by a tradeoff with reduced investment in growth, as higher conceptacle abundances are associated with crusts with faster growth rates. These results indicate that the potential reproductive output of coralline algae may be sustained under future ocean acidification

Seawater carbonate chemistry and conceptacle abundance and size of coralline algae Hydrolithon reinboldii

The future of coral reef ecosystems is under threat because vital reef-accreting species such as coralline algae are highly susceptible to ocean acidification. Although ocean acidification is known to reduce coralline algal growth rates, its direct effects on the development of coralline algal reproductive structures (conceptacles) is largely unknown. Furthermore, the long-term, multi-generational response of coralline algae to ocean acidification is extremely understudied. Here, we investigate how mean pH, pH variability and the pH regime experienced in their natural habitat affect coralline algal conceptacle abundance and size across six generations of exposure. We show that second-generation coralline algae exposed to ocean acidification treatments had conceptacle abundances 60% lower than those kept in present-day conditions, suggesting that conceptacle development is initially highly sensitive to ocean acidification. However, this negative effect of ocean acidification on conceptacle abundance disappears after three generations of exposure. Moreover, we show that this transgenerational acclimation of conceptacle development is not facilitated by a trade-off with reduced investment in growth, as higher conceptacle abundances are associated with crusts with faster growth rates. These results indicate that the potential reproductive output of coralline algae may be sustained under future ocean acidification

Seawater carbonate chemistry and calcification physiology of coralline algae

Crustose coralline algae play a crucial role in the building of reefs in the photic zones of nearshore ecosystems globally, and are highly susceptible to ocean acidification. Nevertheless, the extent to which ecologically important crustose coralline algae can gain tolerance to ocean acidification over multiple generations of exposure is unknown. We show that, while calcification of juvenile crustose coralline algae is initially highly sensitive to ocean acidification, after six generations of exposure the effects of ocean acidification disappear. A reciprocal transplant experiment conducted on the seventh generation, where half of all replicates were interchanged across treatments, confirmed that they had acquired tolerance to low pH and not simply to laboratory conditions. Neither exposure to greater pH variability, nor chemical conditions within the micro-scale calcifying fluid internally, appeared to play a role in fostering this capacity. Our results demonstrate that reef-accreting taxa can gain tolerance to ocean acidification over multiple generations of exposure, suggesting that some of these cosmopolitan species could maintain their critical ecological role in reef formation