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Research on Threatened Species


Real Jardín Botánico de Madrid (CSIC)

New germinations bring hope for the most endangered Spanish plants

The authors of this article describe the results of germinating the seeds of five endangered genera of flowering plants Avellara, Castrilanthemum, Gyrocaryum, Naufraga and Pseudomisopates, highlighting the need to understand the biological cycle of each of these plants that is struggling to survive.

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 The FGCSIC proyecto cero being run by the Real Jardín Botánico de Madrid [Royal Botanic Garden, Madrid - CSIC] has selected five emblematic species for plant conservation in Spain. We could call them botany’s “lynxes” although, para­doxically, little research has been done on them. HIGHLIGHTSProfile: Elena Amat, Pedro Jiménez-Mejías, Inés Álvarez and Pablo Vargas
More­over, these five species are also the sole representatives of their respective genera, and all of them are endemic to the Iberian Peninsula and Balearic Islands: Avellara fistulosa in Doñana and a number of sites in Portugal; Castrilanthemum debeauxii in the mountains of Castril and Guillimona; Gyrocaryum oppositifolium found at one site in Seville, Madrid and León; Naufraga balearica endemic to the Serra de Tramuntana in Majorca; and Pseudomisopates rivas-martinezii from the Sierra de Gredos, Ávila. What is more, these flowers are relicts of Iberian flora. That is to say, they are species that are remote in taxonomic and/or geo­graphic terms. These five plants meet this relict criteria because each is the only species in its genus and no more than three populations of each species remain (Vargas 2010).

In addition to their value to biology, the fact that all five species are at extremely high risk of extinction makes preserving and managing their populations a priority. Otherwise, we could lose this important part of our natural heritage through sheer neglect. Managing these species involves studying the intrinsic and extrinsic factors threatening them. Understanding their biological cycle is crucial to identifying pos­sible intrinsic factors leading to their population’s stagnation or decline. It is also well known that some plants are more vulnerable than others at certain stages, which are therefore critical for adequate growth. The most sensitive stages are primarily germin­ation and the juvenile stage (seedlings). To this end, we set up a series of germination experiments to enable us to determine whether in the early stages of the plants’ life, breaking the seed case represented a problem limiting the species’ ability to prosper. In our experiments, all the seeds underwent a simple stratification treatment (approx. 20 days at 4ºC). They were then planted in the same type of soil (50% sand and 50% humus) and germination was monitored weekly for at least five weeks. Monitoring was continued over a further four months in case other, later seedlings emerged. Our work is added to the conclusions of a study recently published in Nature on Naufraga balearica (Cursach & Rita 2012). This art­icle presents our main findings.

Avellara fistulosa. / Foto: cedida por los autores.

Moderate success with Avellara fistulosa
A total of 233 healthy seeds were collected from two population centres sampled from the sole Spanish population –in Portugal this species is somewhat less threatened– namely, Doñana National Park. The germination rates were average, but promising, even so, with a success rate of over a third (39%). The majority of germin­ations took place in the first two weeks (21% in the first and 17% in the second). No further germinations were observed during the subsequent three month observation period (from the fourth week). However, in a previous trial, one seedling emerged two months after sowing.
The small number of set flowers found on each capitulum stands out, as this could suggest difficulty in pollination. Of the 17 flower capitula counted, six had fewer than ten mature fruits, and only five had more than 20, while the number of
flowers per capitulum was between 15 and 20.

The threat of predation of Castrilanthemum debeauxii fruits
This genus is perhaps the most promising in terms of germination percentages in nature. Seeds were collected from two different populations in Sierra de Guillimona, Granada, with 383 and 81 fruit (achenes). The difference between the samples is due to the difference in the number of individuals in each population. A value of 67.5% germinations indicates a high level of reproductive success, although the population distribution was not the same (79% and 36.4%, respect­ively). As is to be expected from an annual plant, which needs to respond quickly to seasonal rain and temperature cycles in the harsh Mediterranean climate, most germination was seen in the first week (50.2%). In the second week, 10.8% of seeds germinated, and in the third, 4.1%, with hardly any germinations in the fourth and fifth week of monitoring.

However, we discovered an unexpected threat. Castrilanthemum appears to suffer from a further problem relating to its seeds, which must be what determines the differences in germination between the two populations under natural conditions. 54.6% of mature seeds showed signs of predation by a leafminer larva (probably a dipteran). There were differences in predation between the two populations, with 54% of seeds left intact in the larger population and 27% in the smaller one. Given that the ephemeral Castrilanthemum lives in the Baetic mountains alongside abundant congeners of the Leucanthemopsis and Anthemis genera. It may be that the latter act as a population reservoir of this insect pest. In follow-up studies on this species we plan to assess whether the presence of these congeners contributes to increased predation of the irregular and elusive Castrilanthemum.

Naufraga balearica. / Foto: cedida por los autores.

The vulnerable Gyrocaryum oppositifolium
Gyrocaryum’s conservation status is precarious. The site where it was first found (Seville) is within a protected area, but it has not been found again, and its annual habit makes it elusive. More­over, it has no protection in the other two sites where it has been observed regularly in recent years (León and Madrid). For our germination study we have only been able to study the Madrid population, which is the most abundant of the two.

Germination rates were high. Of the 52 seeds sown, 48% had germinated by the end of the first four weeks. The majority of germinations took place in the second week, when peak germination was observed (37%). A further 15 apparently immature seeds were sown, of which three (20%) managed to germinate in the first week. Unfortunately, the seedlings grew very slowly and most died with just two cotyledons and 1-2 pairs of leaves. Even the healthiest did not reach the flowering stage under greenhouse conditions. We hope to repeat the experiment with seeds from Madrid and take measurements of the germin­ation success with seeds from the small population in Ponferrada (León) for the first time.

Naufraga balearica on course for correct management
The study by Joana Cursach and Juan Rita (Universitat de les Illes Balears) obtained promising results for Naufraga balearica. The authors analysed seeds collected in the field and from populations conserved ex situ, and as well as providing other data of great value for future conservation and management of this highly endangered species endemic to the Bale­aric islands. With a germination success rate of between 40% and 100%, the researchers discovered that treatment with moderately high temperatures (25ºC by day and 15ºC by night) were more favourable to germin­ation than lower temperatures. Although seeds did not ger­minate until the first autumn rains in the field, ex situ trials found Naufraga able to germinate shortly after fruit maturation, in mid-summer. Given the similarity of the results obtained with wild and cultivated populations, the study’s authors opted for controlled ex situ production of plants as a means of supporting the wild population, which is currently suffering a sharp decline.

Castrilanthemum debeauxii. / Foto: cedida por los autores.

Fire: the ally of Pseudomisopates rivasmartinezii
This plant endemic to Sierra de Gredos suffers from very low seed viability rates compared to the other four genera in the basic trials. Tests were carried out using seeds from the four populations most remote from one another. The seeds are deeply dormant, such that only 1% germinate unless chilled first. Once seeds were subjected to stratification (freezing) germination rates were 18.5%. Even so this rate was still low compared to the other four genera. Additional treatment, namely cold thermal shock (-70ºC), hot thermal shock (110ºC), adding ash and hormones (gibberellins), and darkness were also tried. Of these treatments, the add­ition of ash, which releases acids stimulating germin­ation, was the most effective, raising germination rates to 35.75%. None of the other treatments had any significant effect compared to simply chilling the seeds. It therefore seems that the combination of cold and fire is the key to obtaining max­imum germination of Pseudomisopates. It is worth noting that the Sierra de Gredos has long been subject to deliberate burning to clear pasture for livestock, such that the gorse scrub is natur­ally pyrophilic. The germination experiment carried out on this species therefore matches the conditions produced by traditional gorse burning. Fire also has a positive effect by eliminating the plant cover shading the seeds during germination. Indeed, the germination rate was just 0.055% when the chilled seeds were kept in the dark.

Pseudomisopates rivas-martinezii. / Foto: cedida por los autores.

The case of Pseudomisopates is similar to that of the giant redwood (Sequoiadendron giganteum), world famous in conservation circles. This colossal tree native to Sierra Nevada (California, USA) lives in a Mediterranean climate (there are five regions in the world with a climate similar to that of the Mediterranean) where fire is frequent and plants have adapted to its destructive effects. The impact of fire on the regeneration of the giant redwood has been the object of study over several decades and the tree is used as a model for any study on the effect of fire on plants. Fire has a dual effect: direct and indir-ect (see the data compiled in Stephen et al. 1999). The direct effects include the fact that the pine cones open at high temperatures. One of the indirect effects is that fire clears the surrounding undergrowth, allowing more light to reach the forest floor. It is this effect that has been found in Pseudomisopates populations.

Gyrocaryum oppositifolium. / Foto: cedida por los autores.

Genetic diversity may also be a factor in the differing results obtained with each population. The seeds from the population in the Lóbrega gorge turned out to be around 26% more viable than those from the other two populations (Conventos and Serrota). The most significant difference between these populations is that the largest and most vigorous population of the species is found in the Lóbrega gorge. This, together with the fact that the plants are self-incompatible, which implies the need for a larger number of crosses between genetically different individuals, could hinder reproduction in small populations. Therefore, Pseudomisopates could be suffering from too many constraints for it to have a healthy seed bank. In short, we are looking at a threatened species that, paradoxically, needs the disturb­ance of fire to be able to perpetuate itself healthily. As a result, its conservation may be tied in which maintaining traditional farming practices using fire. Future research needs to focus on studying the effect of fire through experiments in nature.

The results of germination trials on the five endangered genera are a clear example of the need to understand the bio­logical cycle of each of these plants which is struggling to survive. Otherwise we might lose a valuable part of our natural heritage without even knowing how genera that have lived on the Iberian Peninsula and the Balearic Islands for millions of years germinate, reproduce or die.

Profile: Elena Amat, Pedro Jiménez-Mejías, Inés Álvarez and Pablo Vargas

Elena Amat

Elena Amat is a predoctoral researcher at the Real Jardín Botánico de Madrid where she is working on the FGCSIC project on living fossils in Iberian flora. She wrote her PhD thesis at the Real Jardín Botánico, on conservation biology of two endemic Iberian mountain species: Pseudomisopates rivas-martinezii and Erysimum penyalarense, under the supervision of Dr. Pablo Vargas Gómez.

Pedro Jiménez-Mejías
Pedro Jiménez-Mejfas is a researcher at the Real Jardín Botánico de Madrid, where he has been working for the past year on the FGCSIC project on living fossils in Iberian flora. He has an honours degree in environmental science from the Pablo de Olavide University, Seville, where he obtained his PhD on taxonomy and systematics of sedges under the supervision of Professor Modesto Luceño. He has also spent study visits at Kew Gardens (London, England), Oslo (Norway) and Belgrade (Serbia).

Inés Álvarez
Inés Álvarez is a CSIC staff scientist and deputy director of research at the Real Jardín Botánico-CSIC, where she works on the evolutionary biology of plants line: patterns, processes and mechanisms. She is currently leading a project on the evolution of the genus Anacyclus (Compositae, Anthemideae) (CGL2010-)XX) and taking part in the FGCSIC project on living fossils. She wrote doctoral thesis on the systematics and phylogeny of the genus Doronicum (Compositae, Senecioneae) at the RJB under the supervision Dr. Gonzalo Nieto Feliner. She spent two years as a postdoctoral researcher in the laboratory of Dr. Jonathan Wendel (lowa, USA) researching the polyploid genome of cotton, and held a Ramón y Cajal contract at the RJB before obtaining her current position.

Pablo Vargas
Pablo Vargas is a scientific researcher at Real Jardín Botánico (CSIC), where he has been doing research for the last 25 years. His recent interest has been in the study of macro- and microevolutionary patterns and mechanisms explaining the wide diversity of angiosperms and their disappearance. Among the numerous research projects in which he has been involved, the Atlas of Spain’s Endangered Flora, 2001-2008 stands out, on which he worked as part of a large team of researchers.

Published in No. 09

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  • Lychnos. ISSN: 2171-6463 (Spanish print edition),
    2172-0207 (English print edition), 2174-5102 (online edition)
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