you're reading...

Climate Change

The benefits of warmer parents, and who’s your mama … when you’re a coral

Dixon, G.B.; Davies, S.W.; Aglyamova, G.A.; Meyer, E.; Bay, L.K.; Matz, M.V. Genomic determinants of coral heat tolerance across latitudes. Science. 26 June 2015. DOI: 10.1126/science.1251224

Junior takes after his mother.

Junior takes after his mother.

It’s no secret that the globe is warming. It’s also no secret that coral reefs, some of Earth’s most diverse and alluring ecosystems, are potentially doomed. At least, that’s all the hype.

Now for the hope—scientists think that coral might be able to handle moderate increases in temperature. In other words, if we continue to curb our impact on the environment, coral might just be able to scrape by until the going gets better, despite all destruction we have already wrought on these ecosystems.

Organisms can acclimatize to heat stress by adjusting their physiologies, for example, they might alter their baseline metabolism in direct response to their environments. The big question in coral biology is whether heat tolerance can also come from heritable traits. That is, can an organism’s genetic code confer innate heat tolerance that can be passed down from one generation to the next? If this were the case, then we as humble managers of our environments could ostensibly introduce heat tolerance into an ecosystem by breeding heat tolerant strains of coral.

An elegant study recently published by Dixon et al. in Science finds the first evidence that heritable traits can lead to improved heat tolerance in coral. To address this question, they studied coral of the same species separated by a few degrees of latitude and Celsius in the Great Barrier Reef of Australia. They mated two males and females from each population to determine what effects parenthood might have on the heat responses of these populations. They further attempted to identify specific heritable traits associated with survivability of larvae faced with increasing temperatures.

Warmer kin. (Image courtesy of Dixon et al., Science, 2015)

Breading tolerance. A) Sampling locations with a chart showing temperature variability from the two locations. Notice that the northern location is consistently warmer than the southern. B) Matchmaking scheme for crosses. C) Experimental design for comparing gene expression in parents. D) Mortality of different crosses. E) Contribution of different variation in survival explained by  “combined” mom and pop effects, pop effects (sire), mom effects (dam), and interaction. F) Odds of survival depending on parental background. (Image courtesy of Dixon et al., Science, 2015)

After the newborns had developed into larvae, the researchers subjected them to heat stress, ramping up water temperature over the course of a little over a day to just a little bit higher than the highest temperatures encountered in the warmer of the two sampling locations. Not surprisingly, the warm-warm crosses faired the best of all, while the chance of survival in mixed crosses improved chances of survival relative to cold-cold crosses. Interestingly, those with the mother from the warmer environment faired better than those with the father from the warm environment. In other words, anyone with a warm parent found his or her situation much improved, while a strong “maternal effect” was observed for the benefit of crossing warm with cold.

The study also investigated where the variation in survivability was coming from at a molecular level. To do this, they tagged several thousand genes whose expression is correlated with heat tolerance. They found variation in both maternal and paternal genes associated with heat stress, supporting their hypothesis that heat tolerance can be inherited genetically.

Additionally, they sought to address the strong observed maternal effect on survivability. To explain it, they looked to the mitochondria – the organelle (membrane-bound unit within eukaryotic cells) in charge of producing energy for our cells. The mitochondrion itself is an incapacitated bacterium with its own DNA and cell membrane, that can’t survive on its own. Most importantly, we inherit our mitochondria exclusively from our mothers.

Once our environment heats up, so does our metabolism, and so the mitochondria have to work harder. Not surprisingly, the study found that a lot of the genetic variation had to do with both mitochondrial genes, as well as mitochondrial genes encoded within the genome of the actual coral cell itself.

In addition to asking which genes were correlated with heat shock, they also asked whether these genes actually encode capacity of an organism to deal with heat, or if those genes can be conditioned due to environmental sensitization over the course of the organism’s lifetime. To do this, they studied gene expression in the adult parental corals and compared those levels of expression to previous literature on larval gene expression. They found that adult gene expression over an extended period closely resembled that of larvae, indicating that changes in gene expression were actually due to genetic regulation, rather than conditioning.

The work done by Dixon and colleagues strongly suggests a heritable basis for coral heat tolerance. However, they caution that heat tolerance is only one factor corals must face when dealing with climate change. For example, another side effect of our global carbon dioxide emissions is ocean acidification. This study observed that genes that encode “transporters” in the heat-tolerant coral are turned down. Transporters serve many key cellular functions, which include helping the organism get rid of pollutants. Hence, while reduced transporter activity might help the organism deal with heat stress, it might also make coral more vulnerable to pollutants. Evolution is a long process of give and take, and most organisms today have arrived at an optimum over millions of years of random mutation and natural selection. Even if nature does give us some leeway, we must still do our part to curb climate change if coral are to survive.






No comments yet.

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 7 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 9 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 10 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 11 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 12 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com