The ‘natural’ solution might not be best when your wildlife isn’t natural

Many ecosystems have been degraded or modified, and these are the sorts of systems you target for restoration. But when a system has been altered so much the original species might not be the best choice to bring it back to health. Therefore, says Thomas Jones, you need to look at alternative species.

The Dry Aral Sea

The Dry Aral Sea. Francois de Halleux / Flickr

A paper from BioScience has caught my eye. In Ecologically Appropriate Plant Materials for Restoration Applications Thomas Jones argues that restoration might go better sometimes if you bring in some novel species to a site. What I find interesting is that it tackles the question what does it mean to ‘restore’ an ecosystem? My initial reaction is put it back as it was, but the ecosystem that was there was the product of centuries of interactions. Perhaps putting the final ingredients into a place and expecting a working ecosystem is like expecting some eggs, sugar and flour to spontaneously become a cake.

Bringing in novel species might sound like giving up on restoration and replacing the ecosystem instead. Jones shows that it’s not the case. The abstract includes this section which explains:

Ecologically appropriate plant materials are those that exhibit ecological fitness for their intended site, display compatibility with other members of the plant community, and demonstrate no invasive tendencies. They may address specific environmental challenges, rejuvenate ecosystem function, and improve the delivery of ecosystem services. Furthermore, they may be improved over time, thereby serving to ameliorate the increasingly challenging environments that typify many restoration sites.

In the paper Jones says that, for some ecosystems, local has value rather than local is best. Following this way of thinking, you introduce novel plants so that you can support the local material. If you think of an ecosystem as a whole system, instead of a collection of parts, then this extra support is a success rather than an intrusion. It also helps acknowledge that ecosystems are rarely oases isolated from anywhere else. The restored system might well have novel neighbours. The new species could help make the restored system more robust to challenges from outside.

Another factor is ecosystems aren’t binary between natural and broken. They change with human activity. The longer they’ve been exposed to human activity the farther from natural they move. If the ecosystem you’re restoring isn’t strictly natural then how do you work out what natural is? Jones points out ecosystems are dynamic and not always in stasis.

If Jones is right then restoration is not the same as preservation.

This thought may be disturbing to preservationists, who may view anything less than entirely local plant material as an unwise exchange of restoration orthodoxy for a “slippery slope.” Nevertheless, one cannot continue to rely solely on local genotypes simply because they are local and theoretically best adapted if experience demonstrates otherwise.

It certainly bothers me. The question then becomes do you do what works, or what you wish would work? It’s a good paper and, as I write, free access so definitely worth a visit to read.

Image

The Dry Aral Sea by Francois de Halleux / Flickr. This image licensed under a Creative Commons by-nc-nd licence.

Reference

Jones T. (2013). Ecologically Appropriate Plant Materials for Restoration Applications, BioScience, 63 (3) 211-219. DOI:

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A positive plethora of plant papers!

Image: Ryan Kitko/Wikimedia Commons.

Image: Ryan Kitko/Wikimedia Commons.

Unusually for this column (why give the ‘competition’ a free bit of publicity, after all?), I here wish to promote The Scientist magazine. As a general science news item site it occasionally features plant-related items, but it has surpassed itself with its 1st January 2014 collection. Not only does it feature a wonderful image of the fruit of the lotus plant on its cover, but it also contains four big plant articles(!).

By way of introducing that compilation, Mary Aberlin observes in her editorial that, ‘the panoply of fictional plants offers a large and varied dose of the weird and wonderful. But there’s no need to resort to fiction to find truly unusual plant characteristics’… so, read on! Accordingly, the selection comprises an item by Abby Olena that considers halotropism, a newly identified tropism in roots. This showcases a study by Carlos Galvan-Ampudia et al. that demonstrates active growth of roots of several plant species away from sites of high salt content, and which is not gravitropism. This work begs the question of how many other tropisms might still await discovery in that understudied plant organ.

In ‘Green gold’ Tracy Vence reports on the discovery of gold bioaccumulation in eucalyptus leaves, which was covered on this very blog not so long ago. Megan Scudellari’s article begins by posing the question, ‘What do cells, genes, mutations, transposons, RNA silencing, and DNA recombination have in common?’: the answer – but, of course! – is that all were first discovered in plants; she then considers how plant DNA is challenging preconceptions about the evolution of life (including our own species). And Dan Cossins considers the question of whether plants ‘talk’ to each other. Reviewing a wide-ranging body of work, the conclusion is that plants do communicate and interact with each other, both above and below ground, in surprisingly subtle and sophisticated ways. And by way of demonstrating how the time is right for certain ideas, Kat McGowan has an item in Quanta Magazine on ‘The secret language of plants’.  Almost inevitably these sorts of articles raise the spectre of how intelligent plants are, and that issue is given a good airing in Michael Pollan’s New Yorker article. What a great botanical start to the New Year (which traditionally starts on 10th April…)!

[Visit YouTube for a documentary on plant intelligence, and also if you want to know what plants talk about  – Ed.]

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Diversification and hybridization in Malagasy baobabs

Madagascar is the world’s fourth largest island, and is renowned for its species diversity and endemism. Due to the wide diversity of climatic and ecological conditions on the island, the native biota provides a fascinating context for the study of speciation and plant radiation. On Madagascar, the trees of the genus Adansonia (Bombacoideae, Malvaceae), the baobabs, are prominent in the dry deciduous forests and thickets of the western half of the island. Baobab trees may live for more than 1000 years and are characterized by outcrossing breeding systems with self-incompatibility.

Diversification and hybridization in Malagasy baobabs

Adansonia (Bombacoideae) comprises nine species, six of which are endemic to Madagascar and genetic relationships within these remain unresolved due to conflicting results between nuclear and plastid DNA variation. A recent paper in Annals of Botany analyses nuclear microsatellite variation using Bayesian clustering programs and find a clear interspecific differentiation. They identify early-generation hybrids in contact areas between the species showing overlapping flowering periods and sharing the same pollinators. The results reveal a new, stabilized differentiated entity originating from hybridization in the current absence of the parental species, suggesting a potential role of hybridization in the recent diversification history of the Malagasy baobabs.

 

Tsy, J. M. L. P., Lumaret, R., Flaven-Noguier, E., Sauve, M., Dubois, M. P., & Danthu, P. (2013) Nuclear microsatellite variation in Malagasy baobabs (Adansonia, Bombacoideae, Malvaceae) reveals past hybridization and introgression. Annals of botany, 112(9), 1759-1773

 

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Network epidemiology and plant trade networks

13113R1Epidemic models in complex networks are helping us better understand infectious disease outbreaks. A review by Pautasso and Jeger published in AoB PLANTS focuses on the application of new developments in network epidemiology to the study and management of plant diseases. The main aspects covered are: 1) surveys of social networks, 2) models and data about human mobility, 3) epidemic models in directed and hierarchical networks, 4) studies of dynamic networks, and 5) spatial epidemic simulations integrating network data. Because of the increasing amounts of traded plant commodities and the associated rise in introduced plant pests and pathogens, network theory has a great potential in plant science.

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Auxin, environmental signals and root development (free review article)

Auxin and the integration of environmental signals into plant root development Plants are extremely flexible organisms adaptable to a range of diverse environments. Their intrinsic ability to simultaneously inhabit both above- and below-ground domains makes them unique among most other living organisms, which occupy a single habitat at a given time.

In response to diverse environmental signals, plants modify their development through the perception and integration of exogenous signals into the signalling pathways of plant hormones. Auxin is one of the most versatile plant hormones and plays essential roles in growth and development. The revelation of the existence of an auxin biosynthesis, signalling and transport apparatus in single-celled green algae is a clear indication that auxin has played an important evolutionary role during the adaptation of plants to diverse land environments.

In recent years, significant progress has been made towards understanding how this hormone regulates plant growth and development. However, less is known about the roles of auxin as a regulator of biotic and abiotic stress responses. In this free review article, interesting new insights into the role of auxin as an integrator of environmental signals are highlighted.

Kazan, K. (2013) Auxin and the integration of environmental signals into plant root development. Annals of botany, 112(9), 1655-1665
Background: Auxin is a versatile plant hormone with important roles in many essential physiological processes. In recent years, significant progress has been made towards understanding the roles of this hormone in plant growth and development. Recent evidence also points to a less well-known but equally important role for auxin as a mediator of environmental adaptation in plants.
Scope: This review briefly discusses recent findings on how plants utilize auxin signalling and transport to modify their root system architecture when responding to diverse biotic and abiotic rhizosphere signals, including macro- and micro-nutrient starvation, cold and water stress, soil acidity, pathogenic and beneficial microbes, nematodes and neighbouring plants. Stress-responsive transcription factors and microRNAs that modulate auxin- and environment-mediated root development are also briefly highlighted.
Conclusions: The auxin pathway constitutes an essential component of the plant’s biotic and abiotic stress tolerance mechanisms. Further understanding of the specific roles that auxin plays in environmental adaptation can ultimately lead to the development of crops better adapted to stressful environments.

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Natural History for the Future of Ecology

Biosciences has a couple of free access papers out on Natural History. Natural History’s Place in Science and Society is a 17 author call for action by Tewksbury et al calling on some biologists to identify as Natural Historians.

Musée national d'Histoire naturelle

Musée national d’Histoire naturelle. Photo: Trey Ratcliff / Flickr

The concept puzzled me slightly. I come from a History of Science background and I’m used to thinking of Natural History as the thing that’s not quite Science in the ancient world. Tewksbury et al have a better definition:

[N]atural history is the observation and description of the natural world, with the study of organisms and their linkages to the environment being central.

It’s the second half of the definition that makes the paper interesting and distinct from Biology. The paper gives a number of examples to explain why they think Natural History has a contribution to make in the 21st century, but at the heart of them all is the focus on organisms and their connection to the environment. The connectivity and inter-disciplinary character of Natural History should be part of the zeitgeist, but the authors show this is not the case.
Continue reading

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Avoidance of interspecific pollen transfer in Pedicularis

Avoidance of interspecific pollen transfer in Pedicularis

Avoidance of interspecific pollen transfer in Pedicularis

Plants surrounded by individuals of other co-flowering species may attract more pollinators but can suffer a reproductive cost from interspecific pollen transfer. Yang et al. compare pollination and reproduction in Pedicularis densispica (lousewort) when occurring alone or together with co-flowering Astragalus pastorius. They find that mixed populations attract many more nectar-seeking bumble-bees, which move frequently between the species. However, differences in floral architecture mean that P. densispica is pollinated via the dorsum of the bees whilst A. pastorius receives pollen via the abdomen, thus avoiding interspecific transfer. The overall result is that co-flowering yields more seeds that are heavier and have higher germinability than in pure populations of P. densispica.

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Live cell imaging reveals extensive intracellular cytoplasmic colonization of banana by normally non-cultivable endophytic bacteria

13072R1It is generally believed that endophytic microorganisms are intercellular inhabitants present in either cultivable or non-cultivable form primarily as root colonizers. In a new study in AoB PLANTS, Thomas and Sekhar report extensive cytoplasmic colonization by endophytic bacteria in banana shoot-tissue which prima-facie displayed ‘Brownian movement’. Live cell imaging on tissue sections, callus, cell suspensions and protoplasts directly and after vital / SYTO-9 staining revealed two intracellular niches, namely cytoplasmic and periplasmic. Designated as ‘Cytobacts’ and ‘Peribacts’, these organisms were rarely amenable to cultivation and thus may have escaped the attention of biologists. This article, supported largely by live cell video-imaging, opens the way to studying these intracellular entities.

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