Cycads, "living fossil" descendents of the first plants that colonized land and reproduced with seeds, are rapidly going extinct because of invasive pests and habitat loss, especially those species endemic to islands.
But new research on Cycas micronesica published recently as the cover article in Molecular Ecology calls into question the characterization of these plants as relicts (leftovers of formerly abundant organisms), and gives a glimpse into how the remaining plants—those that survived the loss of more than 90% of their population—can be conserved and managed. By sampling what is left of C. micronesica on Guam, researchers, including some from the American Museum of Natural History, found moderate genetic variation within local populations and different levels of gene flow between populations.
"Cycas micronesica is one of the most ecologically important plants on Guam and nearby islands, and it is now rapidly disappearing," says Angélica Cibrián-Jaramillo, a researcher at the American Museum of Natural History and at The New York Botanical Garden. "But with new genomic tools we developed microsatellite markers to quickly assess individual plants. This technique is ideal for species that need quick answers for conservation reasons." Microsatellite markers are short genetic sequences typically used to determine how individuals are related to each other (kinship) and other population studies.
Cycads have been around for about 300 million years and are among the first spermatophytes, or plants that reproduce with seeds. Although this group's large crowns of feathery compound leaves was once common, cycads now number about 300 species throughout the world, and about half of these are threatened or endangered. C. micronesica is found on four island groups in Micronesia.
Within four years, the millions of C. micronesica on Guam were reduced by more than 90%. The primary culprit was an insect that often parasitizes plants (in this case, a scale) that invaded Guam in 2003, although other invasive species including butterflies and feral pigs are contributing to plant mortality. The invasive species are also spreading to other islands.
"This ecological disaster is typical on islands," says Thomas Marler, professor at the University of Guam. "There has been a cascade of invasive species in a short time. This study will give conservation groups information about how to manage the surviving plants: the most efficient way to establish nurseries and where to collect seeds, and how to reintroduce them if the [invasive] insect is brought under control."
For this study, Marler collected leaf samples from all C. micronesica habitats on Guam, and Cibrián-Jaramillo found 18 genetic populations among 24 locations. The results showed that local populations are not genetically poor but instead have moderate genetic variation with some inbreeding, which is what would be expected in longer-lived plants with similar seed dispersal. The amount of genetic flow between Guam's populations was low but very dynamic within regions in the island, which means that plants are similar genetically and the observed variation points to patterns of seed dispersal. Cycas micronesica plants in the north are more likely to be related to each other, while populations in the south are genetically different from each other. This contrast is most likely due to southern Guam's more fragmentary forests, more rivers for seed transportation (C. micronesica seeds are one of the few cycad seeds that float), and the smaller size of seeds, which can be dispersed to greater distances.
"We hope that these results from the plant perspective will fit into the management of invasive insects in general, which is one of the most important drivers of biodiversity loss worldwide and very costly economically," says Rob DeSalle, curator at the American Museum of Natural History who works in the Sackler Institute for Comparative Genomics.
In addition to Cibrián-Jaramillo, Marler, and DeSalle, authors of this paper (Molecular Ecology 19, 2364-2379, doi 10.1111/j.1365-294X.2010.04638.x) include Aidan Daly of the Museum's Sackler Institute for Comparative Genomics and Eric Brenner of New York University. The research was funded by the U.S. Department of Agriculture and the Lewis B. and Dorothy Cullman Program for Molecular Systematics at the American Museum of Natural History and The New York Botanical Garden.
Kristin Elise Phillips | EurekAlert!
100 % Organic Farming in Bhutan – a Realistic Target?
15.06.2018 | Humboldt-Universität zu Berlin
What the size distribution of organisms tells us about the energetic efficiency of a lake
05.06.2018 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...
Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.
Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...
The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.
Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.
An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.
Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...
Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...
13.06.2018 | Event News
08.06.2018 | Event News
05.06.2018 | Event News
19.06.2018 | Physics and Astronomy
19.06.2018 | Life Sciences
19.06.2018 | Physics and Astronomy