This little pink lace coral is well surrounded, sure by his family. The lace coral does not spread very far, and often settles next to its relatives – unlike its cousins \u200b\u200breef-building corals, which can disperse great distances thanks to their larvae.
By always staying close to home, each group of corals ends up breeding with a restricted circuit. By remaining isolated, a population can become a new species over time. Such is the case of the pink lace coral off the coast of Brazil, where a hitherto unknown species was identified in a study recently published in the journal reconsidering Coral reefs.
Coral reefs are biodiversity ‘hotspots’: they are home to thousands of species in the tiny cracks and crevices of the reef. Lace coral contributes to this versatility by preferring pinning associated species.
How are new coral species born?
To understand the evolution of lace corals in the Atlantic Ocean, we studied 18 populations of lace corals from the Caribbean, Brazil and Africa. It is remarkable that each group has its own genetic variants, quite far from each other. To achieve such genetic differentiation, very little exchange of larvae or individuals is required to occur.[Près de 80 000 lecteurs font confiance à la newsletter de The Conversation pour mieux comprendre les grands enjeux du monde. Abonnez-vous aujourd’hui]
In the marine environment, many organisms remain related to other members of their tribe through Caterpillars disperse. Many organisms can release their reproductive cells into the water column, allowing them to reproduce with individuals not necessarily nearby. The larvae then develop in the water column and can swim for several days to several weeks, sometimes landing hundreds of kilometers from their home reefs. When they become adults, they are likely to breed with individuals from elsewhere. This is how hard corals reproduce: groups hundreds of kilometers apart maintain ‘contact’ and are genetically similar.
The larvae of garter corals crawl, but do not swim
Rabat corals do not reproduce in this way. To date, the only reproductive behavior Few species of lace coral have been studied. What we do know is that fertilization is internal, not in the water column. Once the fertilized eggs hatch and the larva is ready to leave its mother, it does not swim. It’s creeping… limiting your mileage. Thus most of the larvae settle in their native corals, sometimes even next to their parents.
It is precisely this lack of communication, or the exchange of larvae and individuals between populations, that leads to the isolation needed for the origin of new species. Without the exchange of genetic information, each tribe becomes more and more different over time, until they no longer belong to the same species, and can no longer interbreed with each other.
Although similar to the pink coral of the Caribbean, the coral off the coast of Brazil is so different that it must be considered a new species.
using a “molecular clock” – a technique that estimates the time elapsed between two species by counting the number of mutations between them – it is estimated that pink corals in the Caribbean and Brazil became a separate species about eleven million years ago, around the time of the creation of the Amazon River. Given the few exchanges observed for pink lace corals, if the breeding style was similar in other species, many other “hidden” species would likely have been discovered.