Abstract Detail

Population Genetics/Genomics

Zapata, Felipe [1], Henriquez, Claudia [2], Ezcurra, Exequiel [3].

Demographic history of red mangroves in the tropical rainforest of El Peten Basin (Yucatan).

Red mangroves (Rhizophora mangle) are one of the dominant tree species of the mangrove ecosystem in the Americas. Like other plants of the mangrove ecosystem, red mangroves have evolved multiple anatomical and physiological adaptations to cope with the stressful conditions that characterize the mangrove ecosystem, such as high salinity, hypoxia, strong UV light, and anaerobic soils. Because mangrove ecosystems occur at the interface of land and tropical saltwaters, red mangroves are restricted to tropical coastal habitats. In the Yucatan peninsula, however, there is a peculiar, isolated population of red mangroves along the San Pedro river in the region of El Peten, surrounded by tropical rainforest, about 50-75 km inland from the gulf coast of Mexico, and 20-40 meters above sea level. The population forms an extensive mangrove vegetation-type ecosystem albeit on freshwater, and is not connected to any coastal mangrove population. When and how this population of red mangroves arrived, established, and thrived in this isolated locality is not understood. In this study, we test the hypothesis that this population is a relict population of the last interglacial (LIG) that occurred during the Late Pleistocene approximately 130,000 years ago. During that time, global sea level was several meters higher than it is today and vast areas of the Yucatan peninsula were under water. We sampled red mangrove individuals from the San Pedro river population as well as from populations along the coast of the Yucatan peninsula, from the Gulf coast to the Caribbean Sea. Population genomics analyses show that the San Pedro river population is genetically distinct to all other populations, yet it shares ancestry with populations from the Gulf coast. Reconstructions of the Yucatan coastline during the LIG show that with a flooding level of approximately 10 m, there is corridor connecting the San Pedro river with the Gulf coast supporting the hypothesis of genetic ancestry. Taken together, these results are consistent with the hypothesis that the San Pedro population is a relict of Late Pleistocene ecosystems. Because the environmental conditions during the LIG match model predictions of future scenarios under ongoing climate change, this study sheds light on studies of plant adaptation to climate change. Moreover, because the San Pedro river is a freshwater system, these results suggest a case of extraordinary fast evolution and adaptation in woody plants.

1 - University Of California, Los Angeles, Department Of Ecology And Evolutionary Biology, 621 Charles E Young Dr S, Los Angeles, CA, 90095, United States
2 - University Of California, Los Angeles, Department Of Ecology And Evolutionary Biology, 621 Charles E Young Dr S, Los Angeles, CA, 90095, USA
3 - Univ. Of California, Botany & Plant Sciences, 900 University Ave., Riverside, CA, 92521, United States

Keywords:
Rhizophoraceae
Climate change
Tropical Rain Forest
glaciation.

Presentation Type: Oral Paper
Session: 47, Population Genetics and Genomics II
Location: 101/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 4:15 PM
Number: 47011
Abstract ID:873
Candidate for Awards:None