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Wet Gets Wetter, Dry Gets Drier in the Amazon Rainforest https://ift.tt/Q6NKGof Cintra and colleagues have found that changes in climate aren’t making the Amazon wetter or drier, but both, according to whether it’s the wet or dry season. Their study is based on 30 years of natural climate records locked in tree rings of Cedrela odorata and Macrolobium acaciifolium. The findings have relevance beyond weather patterns across South America. In a press release the authors state: “The Amazon rainforest plays a critical role in global climate regulation… Observed changes in the rainfall cycle could have far-reaching effects on global climate stability.” The research was based on studying oxygen isotope ratios in cores extracted from trees. The rings grow with oxygen from that year’s rainwater locked in the ring. From the tree’s point of view, the isotopes in the water don’t matter, but these isotopes reveal how the rain travelled there. Oxygen-16 and Oxygen-18 get picked up as water evaporates from the ocean to make clouds. Rain falls, gets processed through trees and rises again, to form new clouds to rain further inland. But each time water passes through the process, it’s the lighter Oxygen-16 that’s favoured. So if there are more rainfall events on the way inland, meaning wetter weather, the ratio of Oxygen-16 to Oxygen-18 increases. If there are fewer rainfall events, then the rain is richer in Oxygen-18. Changes in this ratio told Cintra and colleagues how climate had changed since 1980. Extreme river flood levels reach several meters depth, as indicated by the darker shade on the bark of this tree from seasonally flooded forests. Photo: Bruno B L Cintra, University of Birmingham But Cintra and colleagues were able to see beyond yearly averages by comparing two trees. Cedrela odorata grows in the wet season, while Macrolobium acaciifolium, in the floodplains, grows in the dry season. So their isotopes in their tree rings will relate to rainfall in different seasons. The authors write that, in the wet season, the ratio of Oxygen-18 fell by 0.90‰, almost one part in a thousand, indicating an increase in rainfall of 15%-22%. But in the dry season Oxygen-18 ratio increased by 1.14‰, meaning the dry season was 8%-13% drier. The botanists believe that a warming Atlantic is changing how and when rainfall arrives in the Amazon basin. This increasing variability will lead to increased flooding and droughts for for the Amazon and beyond, as far south as Buenos Aires. Preparations for the future appear urgent. Cintra, B.B.L., Gloor, E., Baker, J.C.A., Boom, A., Schöngart, J., Clerici, S., Pattnayak, K. and Brienen, R.J.W. (2025) “Tree ring isotopes reveal an intensification of the hydrological cycle in the Amazon,” Communications Earth & Environment, 6(1), pp. 1–12. https://doi.org/pr26 Cross-posted to Bluesky & Mastodon. Image: Serene Amazon rainforest with lush greenery reflected in river Jean Gc / Pexels. The post Wet Gets Wetter, Dry Gets Drier in the Amazon Rainforest appeared first on Botany One. via Botany One https://botany.one/ June 17, 2025 at 08:28PM

The genetic prison that traps a ghost plant https://ift.tt/26kFyPO Leaves are critical to the survival of most plants. While they cost energy to build and are at risk of attack, these organs are vital to life, as through photosynthesis they capture the energy a plant needs to grow. But Monotropastrum humile, a ghost plant, does things differently. Monotropastrum humile gets its energy from fungi instead. Their roots tap into the local fungal network and pull everything they need from their hosts. That’s why they don’t need chlorophyll so, instead of a lush green, these plants are pallid white, like ghosts. Even though they lack chlorophyll and don’t photosynthesise, these ghost plants still have leaves.  The proportion of the aboveground plant that is leaf is comparable to photosynthetic species, even though the leaves have no obvious use. So why do they do it? Harada and colleagues took a close look at the plants, to see if the leaves were a similar size in all plants. Obviously some plants are bigger than others, but the key was to measure seven traits, to see if the leaves were the same size in proportion to the plant. This unlocked the puzzle. The size of the leaves was in proportion to the size of the flower. The size of the flower is important to the plant, which is thought to attract long-tongued bumble bees. So it must have a flower of a certain size to attract the insects & get pollinated. But this leads to a genetic problem. The petals and sepals are a specialised forms of leaf. Some of the genes that shape the petals and sepals also work on the ghost plant’s leaves. This connects the size of all three, so that shrinking the leaves also shrinks the flowers. Without the leaves there is no flower. This research gets to a feature of genes. Often they don’t have a single function, but have an effect in collaboration with other genes. It explains why sometimes evolution gets ‘stuck’. It may not be able to eliminate one trait without mucking up another crucial function. Harada and colleagues plan to test their ideas by testing the pattern with other ghost plants. They mention examining Pyrola aphylla and Cymbidium species. They believe that the leaves will have to be a minimum size, connected to attracting pollinators to their flowers. Harada, S., Shiba, M., Kurosu, S., Izawa, H., Kurotaki, K., Yasuda, T. and Fukuda, T. (2025) “Why does non-photosynthetic Monotropastrum humile (Ericaceae) have scale leaves?,” Plant-Environment Interactions, 6(3), p. e70060. https://doi.org/10.1002/pei3.70060. Cross-posted to Bluesky & Mastodon. Image: Monotropastrum humile (Ginryo-so), by coniferconifer / Wikimedia Commons CC-BY. The post The genetic prison that traps a ghost plant appeared first on Botany One. via Botany One https://botany.one/ June 13, 2025 at 07:04PM

The hidden complexity of pollinator networks in gardens https://ift.tt/GD7o4wf A common question is “What is the best plant for pollinators?” Research from Brazil suggests this might be exactly the wrong question to ask. Instead of a one-shot solution, you should see serving pollinators as a relay. Different plants are needed for different times, for the same insects. The findings are the result of observations over the course of a year in the city of Maringá, Brazil. Perugini and colleagues tracked 127 flowering plants and 144 pollinator species through the seasons leading to 7,829 recorded interactions to see how plants and pollinators connected. They weren’t just interested in species, but also the traits of flowers. So they measured flower depth, tracked flowering timing, and mapped which pollinators visited which plants. With this data they then drew interaction networks to look for patterns. The major finding was that plant-pollinator networks were highly modular, like separate communities within the garden. Plants with similar flower shapes attracted similar pollinators. Because certain pollinators stayed with certain plants, there were ten communities using the same garden. The key to success was timing. Plants in the same pollinator group flowered at different times of the year. This means the pollinators in the same module could have a supply of food around the year. The authors write that this continuity may be what shapes pollinator assemblages. One of the surprises (to me) is how modular the network was. Perugini et al describe over 80% of the plants as “peripheral”, with interactions within just one module. Only Odontonema tubaeforme was identified as a network hub. This plant is not a native to Maringá. Something Maringá has that other places might not is pollinators active around the year. The pollinators therefore need food throughout the year. This is something that could be done if gardeners plant with a view to timing of flowers, and variety of shapes within the selection of flowers. Perugini and colleagues conclude: “Subtropical and tropical gardens already support significant populations of pollinators, but with more thoughtful consideration of what is planted, they could provide even greater resources for these ecologically important animals.” de Sousa Perugini, L.G., Jorge, L.R., Ollerton, J., Milaneze-Gutierre, M.A. and Rech, A.R. (2025) “High modularity of plant-pollinator interactions in an urban garden is driven by phenological continuity and flower morphology,” Urban Ecosystems, 28(3). https://doi.org/pqsb Read free via https://rdcu.be/epLTL  Cross-posted to Bluesky & Mastodon. Image: Odontonema tubaeforme. Turnstange / Wikimedia Commons The post The hidden complexity of pollinator networks in gardens appeared first on Botany One. via Botany One https://botany.one/ June 06, 2025 at 07:06PM

Is it time to kill the “Mass Extinction” concept? https://ift.tt/NuqSKsd Colin Barras reports on a recent paper by Peng et al that finds a healthy ecosystem barely 75,000 years after the end-Permian extinction, 250 million years ago, thought to be the deadliest mass extinction ever. Barras finds the deadliness of mass extinctions might depend on who you talk to. For example, an extinction we’re all familiar with, the end of the Cretaceous, that was a mass extinction, yes? Barras asked Spencer Lucas “I think that there’s a lot of hyperbole involved in this. It’s a big deal that the non-avian dinosaurs go extinct at the end of the Cretaceous. That said, I don’t think it’s really a mass extinction.” It’s a bold statement and, naturally, not everyone agrees. Barras also talks to tetrapod experts Mike Benton, who is convinced of mass extinctions, and Paul Wignall who provides the quote: “I think it would be fair to say that Lucas’s viewpoint is not mainstream.” A lot of the discussion is about how well the fossil record can capture extinctions across a wide sample of genera. Are fossils missing because the animals that make them are extinct? Are they missing, because not everywhere is conducive to providing fossils? Barras notes Sandra Schachat’s comments that the insect record isn’t as complete as we’d like. Maybe insects suffered from an extinction, or maybe they took evolutionary advantage of changing times around the same period. Then he turns to the plant record, and how biologists think about plants. And how sometimes they don’t. Barras talks to Cascales-Miñana and Cleal who, back in 2013, suggested there were just two mass extinctions for plants, at the end of the Carboniferous period, when it became the Permian, and during the Permian. Barras reports Cleal has an explanation for plant resilience. “Imagine shooting all the elephants in the world: 10 years later, there are still no elephants,” he says. “Now imagine cutting down all the oak trees in the world: 10 years later, there are the beginnings of new oak forests because the acorns germinated.” There’s been more research since then. Nowak et al have argued that the end of the Permian wasn’t a mass extinction event for plants either. As a result Barras asks: “Should we label an event a “mass extinction” if it only affects a limited set of organisms and has little impact on other major groups?” It’s a pity (but understandable) that this is behind the New Scientist and Apple News + paywalls. It’s an engaging article that captures the spirit of scientific debate without portraying one side as stubborn stick-in-the-muds. If you can get access to this it’s well worth your time. It also raises a worry. If plants haven’t had a mass extinctions in the past, then current biodiversity loss in unprecedented. If that’s the case we need reconsider about how we think about both past resilience and present vulnerability. A slightly abridged version is cross-posted to Bluesky & Mastodon. The post Is it time to kill the “Mass Extinction” concept? appeared first on Botany One. via Botany One https://botany.one/ June 03, 2025 at 03:00PM

How Heliamphora turns a first date into a last meal https://ift.tt/TpEIK7C Carnivorous plants have a few problems. One is that they live in nutrient-poor soils, so they have to catch prey to supplement their diet. The other is they’re plants, and can’t wander to hunt prey, they have to persuade the prey to come to them. Liu & Smith have investigated how they do that. Heliamphora plants are carnivorous plants from South America, that have colourful “nectar spoons” to attract insects, and pitcher traps to digest them. Liu & Smith looked at gene expression in Heliamphora tatei to see what genes in the nectar spoon were helping attract the insects. They used RNA sequencing on different plant tissues to see which genes were turned on the nectar spoon that aren’t on in the rest of the plant. They found that sugar transport genes (called SWEET14a) are highly active in nectar spoons, making the sugars needed for insect bait. The twist is that the nectar spoons don’t just produce nectar. The botanists found these organs also produce volatile organic compounds, scents, to attract visitors. Liu & Smith note that some pitchers produce complex compounds to create toxic nectar, but that’s not known here. Instead it seems the nectar is produced to encourage ants to bimble over and around the rim of the trap. The problem for the ants being that Heliamphora tatei has a slippy pitcher, with wax scales, downward pointing hairs and a wet surface, making the sides of the trap extremely slippery. Heliamphora are an interesting clade (related group) of plants. “This clade is endemic to the Guiana Highlands of Venezuela and comprises 24 described species and several yet to be described taxa (>70% of the entire family Sarraceniaceae),” write the authors. Yet not all the Heliamphora are true carnivores. Some like Heliamphora tatei have digestive fluids. Others just have water traps and rely on bacteria to break down prey. Understanding what genetic tricks the plants share, and what is unique could help explain the development of carnivory. The authors conclude: “Our work opens the door for investigating the degree of molecular convergence in prey attraction in other carnivorous plant lineages, many of which use similar combinations of sugary reward and scent volatiles to lure prey.” Liu, S. and Smith, S.D. (2025) “Recruitment of sugar transport and scent volatile genes for prey attraction in the nectar spoon of Heliamphora tatei,” Evolution & Development, 27(2), p. e70009. https://doi.org/10.1111/ede.70009 Cross-posted to Bluesky & Mastodon. Cover: Heliamphora, unknown species. Photo chosen as it emphasises the nectar spoon. Image: Canva. The post How Heliamphora turns a first date into a last meal appeared first on Botany One. via Botany One https://botany.one/ June 03, 2025 at 09:00AM