With climate change on track to destroy the world’s coral reefs, scientists race to create a new super-coral that can survive extreme temperatures.
A type of microscopic algae called Symbiodiniaceae lives within most coral’s tissues. The two organisms have been living dependently for hundreds of millions of years in a way that resembles the relationship between humans and trees. The algae consume coral’s waste products, and coral consumes nutrients that the algae photosynthesize. Coral also provides shelter for algae. But when exposed to too much heat or light, the algae release harmful chemicals, so the coral casts them out. Left without their main energy source, the coral will starve to death. This is also bad news for the algae. But natural evolution has provided a biological feedback loop that can help the two reunite.
One of the compounds that algae release when water becomes hot, called DMs, bubbles up to the surface of the water and forms a thin layer, which shields the coral like a natural, on-demand layer of sunscreen. With this protection, the water cools down and algae can return to the coral and reestablish their partnership unless the water is too hot, in which case the coral consumes the components that make up DMs before it can form.
Climate change is becoming too intense for coral and algae to naturally adapt fast enough. Therefore, scientists are testing out different ways to accelerate that adaptation through various methods of assisted evolution. Some teams are currently conducting small field trials of selective breeding, where they identify the most heat-tolerant members of a sample of corals. Then they breed them together to create offspring that can be used to help restore coral reefs. Others are focusing their efforts on speeding up the algae’s adaptation, attempting to increase its heat tolerance in labs.
Ultimately, scientists may implement a cocktail of solutions to save coral reefs. “To create a super-coral, we could, for example, selectively breed heat-tolerant corals and combine that with enhanced algae, ” says van Oppen.
【小题1】What can we learn about Paragraph 2?| A．The algae release damaging substances when exposed to heat. |
| B．The coral eats the waste produced by the algae. |
| C．The algae is to the coral what trees are to humans. |
| D．The coral will die from harmful chemicals when it’s too hot. |
| A．DMS can’t be formed | B．the sunscreen layer is destroyed |
| C．the coral consumes DMS | D．the algae release too much DMS |
| A．By analyzing causes. | B．By making a comparison. |
| C．By presenting approaches. | D．By describing a process. |
| A．The role played by the algae within the coral. |
| B．The way to create a super-coral to save reefs. |
| C．Selective breeding conducted among corals. |
| D．Scientists’ efforts to increase algae’s heat tolerance. |
