It’s time to dip into the ecology file and I thought we’d have a look at how changing environments can trigger an evolutionary change in species. In an article in Scientific Reports, Korean researchers present their findings on an invasive insect, the spotted lanternfly. It’s well known that many plant-eating insects use plant chemicals to make themselves toxic or distasteful to predators. Many of these insects are also brightly colored to clearly advertise their distastefulness.
Most lanternflies live in tropical jungles but one, the spotted lanternfly, originally found in China, has become an invasive species in the United States. According to this study, when spotted lanternflies suck juice from the ailanthus tree, the tree’s bitter sap makes the insects extremely distasteful. Birds may vomit after eating them and learn to avoid them.
As the spotted lanternfly matures, it becomes bright red and begins to feed exclusively on the ailanthus tree. In this way, they coordinate the time when they become bright and visible to predators with the time they become distasteful to those same predators. Birds quickly learn to avoid bitter prey that are brightly colored, and this research shows that coordinated changes in color, host plant preferences and diet are needed to protect the insects from predators. These three factors have allowed the spotted lanternfly to leave its jungle habitat and become a widespread invasive species.
But insects aren’t the only creatures adapting to change. And these creatures could have some impact here on our islands.
According to research published in the journal Marine Ecology Progress Series, an international group of scientists from 17 institutions in six countries compiled a global database of studies dating back to 1974, when record-keeping began. They found that coral reefs are retreating from equatorial waters and establishing new reefs in more temperate regions. The number of young corals on tropical reefs has declined by 85% and doubled on subtropical reefs during the last four decades. The research team examined latitudes up to 35 degrees north and south of the equator and found that the shift of coral reefs is perfectly mirrored on both sides.
As climate change warms the ocean, subtropical environments are becoming more favorable for corals than the equatorial waters where they traditionally thrive. This is allowing drifting coral larvae to settle and grow in new regions and subtropical reefs could provide refuge for other species challenged by climate change.
The researchers believe that only certain types of coral can reach these new locations, based on how far the microscopic larvae can swim and drift on currents before they run out of their limited fat stores. The exact composition of most new reefs is currently unknown, due to the expense of collecting genetic and species diversity data.
Coral reefs are intricately interconnected systems, and it’s the interplay between species that enables their healthy functioning. It’s unclear which other species, such as the coralline algae that facilitate the survival of vulnerable coral larvae, are also expanding into new areas or if young corals can be successful without them.
The researchers say that the changes they’re seeing in coral reef ecosystems are mind-boggling, and much work is needed to document how these systems work and to learn what we can do to save them before it's too late.
The fact that coral reefs are moving into more temperate waters is probably good news. I wonder how it will affect our reefs here in the Marianas.