HHMI BioInteractive

Coral reefs, how they are threatened by climate change, and how to protect them.

To test whether corals can become more resistant to bleaching, Dr. Steve Palumbi and colleagues performed a series of experiments in the U.S. National Park of American Samoa off of Ofu Island. This BioInteractive activity includes a student worksheet and educator instructions.

All data files from Barshis et al. 2014

All data files from Tepolt and Palumbi 2015.

All data files from Seneca and Palumbi 2015.

Abstract: Reef corals are highly sensitive to heat, yet populations resistant to climate change have recently been identified. To determine the mechanisms of temperature tolerance, we reciprocally transplanted corals between reef sites experiencing distinct temperature regimes and tested subsequent physiological and gene expression profiles. Local acclimatization and fixed effects, such as adaptation, contributed about equally to heat tolerance and are reflected in patterns of gene expression. In less than 2 years, acclimatization achieves the same heat tolerance that we would expect from strong natural selection over many generations for these long-lived organisms. Our results show both short-term acclimatory and longer-term adaptive acquisition of climate resistance. Adding these adaptive abilities to ecosystem models is likely to slow predictions of demise for coral reef ecosystems.

Offers an evolutionary history of Darwin's finches since their origin almost 3 million years ago. By continuously tracking finch populations over a period of four decades, this title uncovers the causes and consequences of significant events leading to evolutionary changes in species.

All data files from Grant and Grant 2014.

Abstract: Introgressive hybridization, i.e. hybridization with backcrossing, can lead to the fusion of two species, but it can also lead to evolution of a new trajectory through an enhancement of genetic variation in a new or changed ecological environment. On Daphne Major Island in the Galápagos archipelago, ~1–2% of Geospiza fortis finches breed with the resident G. scandens and with the rare immigrant species G. fuliginosa in each breeding season. Previous research has demonstrated morphological convergence of G. fortis and G. scandens over a 30-year period as a result of bidirectional introgression. Here we examine the role of hybridization with G. fuliginosa in the evolutionary trajectory of G. fortis. Geospiza fuliginosa (~12 g) is smaller and has a more pointed beak than G. fortis (~17 g). Genetic variation of the G. fortis population was increased by receiving genes more frequently from G. fuliginosa than from G. scandens (~21 g). A severe drought in 2003–2005 resulted in heavy and selective mortality of G. fortis with large beaks, and they became almost indistinguishable morphologically from G. fuliginosa. This was followed by continuing hybridization, a further decrease in beak size and a potential morphological fusion of the two species under entirely natural conditions.

All data files from Grant and Grant 2015.

These two activities support the film The Origin of Species: The Beak of the Finch. They provide students with the opportunity to analyze data collected by Princeton University evolutionary biologists Peter and Rosemary Grant.

Four decades of research on finch species that live only on the Galápagos Islands illuminate how species form and multiply. 

This activity provides a case study in human evolution that connects genotype, phenotype, culture, and graphical analysis skills.

Follow human geneticist Spencer Wells, Director of the Genographic Project of the National Geographic Society, as he tracks down the genetic changes associated with the ability to digest lactose as adults.