Tag Archives: species

Johanna Schmitt: Climate Change and Plant Life

We sometimes ignore the effects of climate change on plant life, but the potential severity of these effects isn’t something that should be ignored for long (Image Credit: Pisauakan, CC0)

From the California wildfires to the recent strikes across Australian primary schools, climate change is a topic that only seems to grow in its ubiquity. Yet whilst humans are increasingly focused on more obvious repercussions, such as extreme weather events, animal extinctions and shifting coastlines, we sometimes forget that climate change will have severe repercussions for plant life as well.

I spoke to Professor Johanna Schmitt of the University of California earlier this year to discuss some of those repercussions. Johanna’s team is working to determine how well certain plant species will be able to adapt in the face of rapid climate change.

Sam Perrin (SP): The term climate change is ubiquitous these days, yet we often don’t talk about plants in relation to its effects. What will some of the effects of climate change be on plant life?

Professor Johanna Schmitt, Department of Evolution and Ecology, University of California (JS): Well from a North American perspective, let’s start with seasonality. The growing season is longer, spring is coming earlier, summers are hotter, winters are warmer. And so in a lot of temperate areas trees are leafing out earlier. And in colder areas, there’s potential that they won’t be adapting to the warmer weather, and will continue to act on temperature cues, which would be bad. There’s definitely evidence of changes in phenology, in seasonal timing of phylogenic effects. There certainly is already evidence of shifts northward in some plant species, and local extinction of species in their southernmost populations.

Looking at California, we’ve just come out of a mega-drought. We have cyclical droughts, and they’re getting worse because the temperature’s rising. Among other things, it means the snow packs are much lower in California. That means water supplies are lower, because there’s less and less water from the melting snow pack. If precipitation all comes as rain in the winter, then that reservoir of snow is not there, so there’s no water in the summer for the farmers. And that also means the species in the mountains which previously relied on the water from snow melt can’t get through the summer. So we’re seeing pretty massive forest die-offs. And then in addition to that you have the bark beetles, which decimate trees. In parts of the western United States, these bark beetles can produce an extra generation if the winters aren’t cold enough and so the populations expand. I was hiking in the Rocky Mountain National Park a few years ago and the trees had been torn to shreds by these bark beetles.

And off the back of all this we’ve obviously had huge fires. This last fire year in California was record horrible. That’s something that affects plant life that then affects humans big time.

SP: Will the agriculture industry have to start adapting?

JS: There’s a group at Stanford who have been trying to figure out if there’s a signature of temperature affecting crop yields by looking at historical data. And it appears that higher temperatures are affecting crop yields and they expect that to become an issue in the future. This idea that if there’s more carbon dioxide, that will help fertilise the crops and they’ll do fine doesn’t seem to hold if you go beyond critical temperatures. Bottom line is, yes, people are concerned about crop yields being affected.

SP: Things like drought and forest die-off have become more extreme these days. But there’s a danger of this becoming the new norm for people. How do we fight those shifting baselines?

JS: It’s a really interesting concept. Because the younger generation doesn’t remember stuff that my generation does. For kids today, these California wildfires will be the new normal. When I was a little girl growing up outside of Pennsylvania we used to go ice-skating on the ponds all the time after they would freeze in winter. Nobody does that anymore because the ponds don’t freeze.

You look at the record of temperatures. I take Introduction to Biology lectures, and I show the carbon dioxide curve from Mauna Loa in Hawaii, and I show them that when I was born, CO2 was 320 parts per million, and then show them the increase just in their lifetime. So now, being over 400ppm is the new normal. Kids today won’t ever remember it being less than that. People are getting more used to extreme heat events which we just didn’t have 50 years ago.

Arabidopsis thaliana, which Johanna's lab works with, is a handy model species for looking at the effects of climate change on plant life

Arabidopsis thaliana, which Johanna’s lab works with, is a handy model species for looking at the effects of climate change on plant life (Image Credit: Dawid Skalec)

SP: To what extent can we predict the adaptation of some of these species to climate change?

JS: Not very well, that’s really the take-home message. Foresters have the best ability to do that because they’ve been doing large scale trials, taking genotypes from across a species’ range and growing them in different climates across that range. By doing that you can ask how different genotypes perform in different climates. And that allows you to say how much variation is there within the species across the range, and you can also look at how much variation is there within populations. Take something like budset, the timing of when to set your buds and cease growth, shut down, and go dormant so you don’t get killed by the frost. It’s a pretty hard deadline for conifer trees. But from year to year the frost comes at slightly different times. So some years genotypes that are more risk-averse do better and some years others that are more risk-prone do better, so they’d have alternate good years. And this means variation can help a species persist in a changing climate

So for forest trees there may be a fair amount of potential for adaptation. And now people are starting to look at small endemic plant species. Jill Anderson at the University of Georgia has been doing some really interesting work of late on adaptation to elevation across an altitudinal gradient. They combined genotypes at low, medium and high elevations, and combined those mixed gardens with snow manipulation. They either removed or added snow, and they found was evidence of adaptation for the species which were exposed to snow. So that suggested that the population may have trouble keeping up if we have a declining snow pack.

SP: Why is predicting these changes so difficult?

JS: Well for one thing we don’t really know what scenario we’ll be looking at in a few years. I’m pretty pessimistic given events of the last few years that we’re going to have anything but an aggressive carbon emissions scenario. I think it’s going to depend upon the species. We’re going to have to help out. I think many species are not going to be able to evolve fast enough in place. So we’ll have to intervene with assisted gene flow, but how do we choose which ones we want to assist?

SP: Can you take me through the concept of assisted gene flow?

JS: So we want to find out which climate a species likes and where’s that climate going to be in the future. There’s some cases where in fact the species range in the future will be almost non-overlapping with the range it’s in now. So how’s it going to get there? After the last glacial maximum, when the glaciers retreated the trees were able to keep up, but that was happening in orders of magnitudes slower than the rate that the climate is changing now.

The idea is for crucial keystone species, species that are important to the ecosystem, that we should be helping them to move. And that’s very controversial. Because are you essentially engineering species invasions, with limited knowledge of what that will do to the community that is already there. Assisted migration isn’t that aggressive. The idea is that within an existing species range, you move genotypes around to maximise the genetic variation to cope with the climate that’s coming. So in general that would be making sure you’re saving all the genotypes you can from that southernmost edge before they go extinct. And then moving them polewards to provide genetic material for the new climate.

To read up on the work that Johanna’s lab does, click here.

Populations Can’t Grow without Homes

Sea otters are one of many charismatic species found along the California coast, yet recovery doesn’t seem to be helping them. Is it something about their habitat that is preventing population growth? (Image Credit: “Mike” Michael L. Baird, CC BY 2.0)

Gaps in kelp cover may threaten the recovery of California sea otters  (2018) Nicholson et al., Ecography, DOI:10.1111/ecog.03561

The Crux

In the 18th and 19th centuries, the fur trade was a massive industry in North America. As a result, many species were hunted and trapped to near extinction. The California sea otter (Enhydra lutris) was reduced in population to less than 50 total individuals. The enactment of the Internation Fur Treaty allowed the species (and others) to come back from the brink of extinction, and they now number over 3200 individuals and are spread across 525km of the California coast. Interestingly, although the population is recovering, it has not bounced back as quickly as other protected mammals living in the same habitat. The California sea lion, for example, has a maximum population growth rate more than twice that of the sea otter (11.7% compared to 5%).

Despite the remarkable recovery of the species, the sea otters occupy less than a quarter of their historic range and have not expanded along the coast in 20 years. The authors of this paper wanted to investigate what it is about the sea otters and their habitat that is slowing this population’s growth rate and spread along the coast.

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Where is the Love for Parasites?

Parasites like the leech can be found in many places all over the world, and anyone growing up near freshwater knows to check for them. But many consider these animals "gross", so how can we motivate the public and scientists to care about them?

Parasites like this leech can be found all over the world, and anyone growing up near freshwater knows to check for them. But many consider these animals “gross”, so how can we motivate the public and scientists to care about them? (Image credit: John Douglas, CC BY-SA 2.0)

As someone who works with parasites, I have to confess that I love them. They are beyond interesting, and I delight in telling people about them and what they do to their host organisms to survive. More often than not, people cringe or look like they would rather run away than hear more about such disgusting creatures. I know that as a disease ecologist I am very much in the minority when it comes to how I feel about parasites, but I think it’s important that we understand how vital these organisms are to the natural world, and the benefits they offer to scientists and their research.

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Dingoes May Not Be the Answer to Australia’s Cat Problem

Dingoes are Australia’s largest native predator. but are they capable of suppressing feral cat populations? (Image Credit: Bernard Dupont, CC BY-SA 2.0)

Diet of dingoes and cats in Central Australia: does trophic competition underpin a rare mammal refuge? (2018) McDonald et al., Journal of Mammalogy, DOI:10.1093/jmammal/gyy083

The Crux

Feral cats are a huge problem for wildlife in plenty of continents. However, there’s nowhere they have had quite so severe an effect as in Australia. Mammals between 50g and five kilos have seen huge reductions in numbers, and many species have gone extinct. Yet there are some areas in Australia which appear to present refuges for native mammals, so it’s crucial to understand the mechanisms behind these areas.

The MacDonnell Ranges in South Australia are home to large dingo populations, which prey on the local kangaroo species. Dingoes can also suppress cat populations through direct predation. The purpose of this paper was to investigate to what degree dingo and cat diets overlap, to see whether the presence of dingoes contributes to the formation of a refugee for native mammals.

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Crossing the River Between Fishers and Fish Science

"We need the next generation of scientists to be at the coalface, communicating good scientific information."

Some fish scientists, like recent ASFB delegate Jarod Lyon, have regular contact with fishers who benefit from the work academics and researchers carry out on fish. But is there enough of this sort of communication between the fish science community and fishers? (Image Credit: Jarod Lyon, CC BY-SA 4.0)

When a food source provides almost half a planet with protein, you can expect the people who deliver that food source to play an important role in society. Fishing is no exception. Any country that has a marine or freshwater ecosystem in close proximity will have a fishing community, and that community can play a variety of roles, from something as simple as putting food on people’s tables to campaigning heavily to keep your country from joining the EU.

So it makes sense that fishers should have access to good fish science, at every level. If you’re a multi-million-dollar corporation, you need to know how fish stocks will respond to certain catch levels over a sustained period. If you’re a local or specialised fishing community, you need to know how available your catch will be in five years given temperature increases. And if you’re one person on a boat in a river, you might want to know how best to treat an over- or under-sized fish to ensure it survives being released.

It follows, then, that there should be open communication between fish scientists and fishers. At this year’s Australian Society of Fish Biology conference, I asked a variety of delegates a simple question: Is there open communication?

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Gretta Pecl: Climate Change in Coastal Waters

Gretta Pecl, founder of the Redmap project, which aims to demonstrate tangible effects of climate change to Australia's fishing community

So often the effects of climate change are somewhat intangible to us; the weather may grow warmer, but it’s a slow and gradual process, which can seem entirely at odds with the alarm bells that things like the IPCC report seem to be constantly clanging. As such, demonstrating tangible environmental changes to a community whose livelihood may depend on such changes is a great weapon in the fight against the effects of a warming climate.

With this in mind, marine biologist Gretta Pecl founded the Range Extension Database and Mapping project, also known as Redmap. Redmap aggregates public sightings of fish to show shifts in the distributions of Australia’s marine species, including some that are crucial to our fishers. At the recent ASFB 2018 conference, I sat down with Gretta to talk about changes in marine species distributions, how they’ll affect Australia, and how they might help the public understand the effects of climate change.

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Rethinking Extinction

Sudan, the last male northern white rhino, 3 years before he passed away, rendering the species functionally extinct. But should species like this be the focus of our conservation efforts?

Sudan, the last male northern white rhino, 3 years before he passed away, rendering the species functionally extinct. But should species like this be the focus of our conservation efforts? (Image Credit: Make it Kenya, CC0 Creative Commons)

Last year saw the death of Sudan, the last known northern white rhinoceros in the world. The story went viral, with the usual bemoaning of the way humans treat our planet, followed shortly by the normal rush back into anonymity for the world’s biodiversity. We are currently part of the most dramatic mass extinction event that the planet has ever seen, and more of these stories crop up every year. But is it a problem that the alarm bells are only raised when a creature hits the critically endangered level? Do we need to start paying more attention to population declines before hey hit such low numbers? And how do we even prioritise conservation efforts?

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