Giant Invertebrates: Scientists Deadliest Accidents or Competitive Superiority Through Evolution?
Image credit: Movie poster advertisement for Tarantula (1955), Public Domain, Image Cropped
Image credit: Movie poster advertisement for Tarantula (1955), Public Domain, Image Cropped
Climate anomalies and competition reduce establishment success during island colonization (2022) Nicholson et al., Ecology and Evolution, https://doi.org/10.1002/ece3.9402
The colonisation of islands by species on the move has given rise to some of the most fascinating ecosystems around the world. Think the marsupials of Australia, Papua New Guinea’s Birds of paradise, or the multitudes of weird and wonderful creatures that pop up in tiny unexpected landmasses around the globe. On the flipside, invasive species arriving on islands can hit like veritable hurricanes, with similar (though admittedly slightly slower-moving) effects. Yet for these phenomena to take place, a species first has to make it to an island from the mainland. This isn’t always super easy, seeing as islands may be tiny and hard to find, or way out in the middle of nowhere.
But even if they do arrive, whether or not a species is able to persist depends a lot on circumstance. If a large storm or drought hits (increasingly likely with climate change upping the frequency of extreme weather events) just after a species arrives on an island, it might wipe them out before they’ve even gotten started. A competitor already having set up shop there could decrease a species’ survival chances too. Today’s authors were lucky enough to have introduced a new species to a series of islands with and without competitors, all of which were hit by a drought just after one of the introductions. Let’s see how the populations fared.Read more
This is a guest post by Dr. Monica Mowery.
Title Image Credit: John Tann, CC BY 2.0, image Cropped
Invasive Widow Spiders Perform Differently at Low Temperatures than Conspecifics from the Native Range (2022) Mowery, Anthony, Dorison, Mason & Andrade. Integrative and Comparative Biology. https://doi.org/10.1093/icb/icac073
With increasingly clear effects of global climate change, everyone’s thinking about how we will handle extreme temperatures and weather events as they become more common. Less obvious is the fact that the changing climate is also rearranging global food webs, with many species readjusting in the fact of a new range of temperatures. This might not sound fantastic (and let’s face it, it’s not), but this changing climate may be able to teach us something about how species adapt to higher or lower temperatures.
Temperature plays a key role in determining whether an invasive species can take up residence in a new region. We know that low temperatures can be particularly limiting to newly-invasive species, especially insects and spiders. Yet few studies look at how lower temperature in a new environment can affect the survival, development, and behavior of new invaders.
We tested whether invasive widow spiders from a warm climate (Australia) adapted over generations to the lower temperatures of their invaded habitat in Japan. The move to Japan should require adapting to lower temperatures, but it might not, for a few reasons. Spiders from both locations may be equally good at coping with cooler or warmer temperatures, or, since urban areas are typically warmer than natural habitats, organisms that move between urban habitats might avoid facing the low temperature constraints.
Did You Know: Cities as Heat Islands
It’s hot in cities! One reason for this is the urban heat island effect, where urban areas are several degrees hotter than surrounding natural areas because of all of the heat-absorbing surfaces like roads and buildings. More than half of the human population lives in cities, and as they heat up, it is especially important to understand how some species adapt and even do better in urban environments. Urbanization and climate change can also increase the spread of invasive species. For example, some urban-adapted invasive species thrive in urban habitats that would otherwise be too cold for them to survive and reproduce in. Understanding how urbanization, climate change, and invasions interact can help us predict changes in biodiversity and species distributions in the future.
The Australian redback spider, Latrodectus hasselti, is an invasive species of widow spider, native to Australia. Redback spiders are well-known in Australia for their bite and neurotoxic venom. Redbacks have been transported (likely accidentally along with used cars or produce) to Japan, New Zealand, the Philippines, Papua New Guinea, and India. We compared traits across native and invasive-habitat temperatures in a native population of spiders. The native spiders were collected from Sydney, Australia and the invasive population from Osaka, Japan, where redbacks became established in 1995.
We reared the spiders in the lab for three generations. We first checked for population differences in how spiders responded to extreme temperatures, measuring the lowest and highest temperatures at which spiders were able to maintain normal activity.
Next, we investigated how spiders respond to more moderate temperature differences, such as those in autumn, right before overwintering. When female spiders from each population produced egg sacs, we put the egg sacs for two weeks in either Japan-typical (15 degrees Celsius) or Australia-typical (25 degrees) autumn temperatures, then put all egg sacs at 25 degrees until spiderlings emerged. We predicted that the invasive spiders from Japan would be better adapted to low temperatures than the native Australian population, as they’re used to colder temperatures. We also measured hatching success, development time, and body size.
Once the spiderlings were juveniles, we measured behavioural traits that may be important for survival in nature: boldness – how quickly a spider resumed movement after a simulated predator threat (a puff of air), and exploration – building a web in a new environment.
At extreme high temperatures, spiders from each population were similarly tolerant, with females able to move at temperatures of up to 55 degrees Celsius! Surprisingly, males from the invasive population from Japan were less tolerant of extreme low temperatures, suggesting that they may not overwinter successfully in colder regions. Egg sacs from the Japanese population hatched equally well at low and high temperatures, but egg sacs from the Australian population failed to hatch more often at low temperatures. Native spiders also took longer to emerge from the egg sacs than invasive spiders at low temperatures, which could expose egg sacs to more predation risk.
The Japanese population was bolder and more exploratory at low temperatures, but less bold and less exploratory at high temperatures, whereas the native population was similarly bold and exploratory at both temperatures.
Spiders from Japan, which live in cooler habitats, developed at both low and high temperatures, compared to a native population, which hatched less and developed more slowly when exposed to low temperatures. This study only tested one invasive and one native population, and it would be worthwhile to compare multiple invasive populations from both cooler and warmer habitats, as well as multiple native populations across Australia.
Although the invasive habitat in Japan is more extreme in temperature, spiders also live in more urbanized habitats compared to the native population. Urban habitats are hotter, and we would like to measure what conditions the animals are directly experiencing in the urban and natural habitats, to find out if spiders are able to colonize cooler climates because they thrive in urban heat islands habitats.
Some organisms may be better equipped to deal with changes we are facing with urbanization, habitat fragmentation, and climate change. In the case of Australian redback spiders, within twenty years, we found that an invasive population changed significantly in traits related to thermal performance, which may give them an advantage as temperatures change worldwide.
Behavioral traits are studied less frequently; finding increased variability in an invasive population may provide a clue to how the species can thrive in different environments. Understanding how organisms can establish and spread in environments different from their native ranges can help us predict which species will survive in our increasingly urbanized, changing world.
Dr. Monica Mowery is a Zuckerman STEM postdoctoral fellow in the labs of Yael Lubin and Michal Segoli at Ben-Gurion University of the Negev. She received a B.S. in biology and community health at Tufts University, working on butterfly visual signals and behaviour in Sara Lewis’ lab. Her PhD was conducted in the labs of Maydianne Andrade and Andrew Mason at the University of Toronto Scarborough, where she studied invasion success in widow spiders. You can read more about Monica’s work at her website.
When you think of a desert, what comes to mind?
If you any or all of the above popped into your head, you’d be correct. On earth, roughly a third of all land is desert, but deserts are as diverse as the species that inhabit them. We often think of the merciless sun as a desert icon, yet it is in fact rainfall that is generally the only factor used to classify deserts. A desert is simply any place that receives less than 25 cm of rainfall in a year, which means that deserts are found on every continent, including Antarctica.
How do animals and plants survive in deserts?
Contrary to common belief, deserts can actually have an incredible amount of diversity, although they are not without their challenges. The dry conditions, paired with often extreme temperatures, mean that species that live in deserts have developed a variety of special adaptations that allow them to survive in such challenging conditions. That starts right at the base of the food web, with plants. Some desert plants have a waxy coating or unique leaf structure in order to prevent water loss, and species of cactus go the extra mile by not having any leaves at all. Other plants have widespread roots in order to reach as much underground moisture as possible. These adaptations allow the plants to go many months without any rain.
Animals deal with a lack of rainfall in a different way. Desert tortoises can get water from their food, store it in their body, go months without drinking, and have highly concentrated urine in order to decrease the amount of water they lose over that time period. Reptiles such as lizards have a thick layer of skin that prevents water loss. In Antarctica, a cold desert, penguins are able to take in saltwater and then secrete excess salt, avoiding the need to find freshwater.
What happens when deserts get even dryer?
Animals and plants have both developed unique ways to survive in extreme conditions. However, these extremely specific adaptations might not protect every desert species from the impacts of climate change.
One very important impact of climate change is desertification, which is land degradation that takes place in dry areas and turns fertile land into a desert. Desertification makes an area less habitable for animals, plants, and people. Over the next century, climate change is predicted to lead to decreased rainfall in some areas, along with increased drought (and more severe drought) and higher temperatures. This, coupled with our clearance of vegetation that moderates extreme heat and retains water, means that even more of the planet will become desert. Although desert species are adapted to tough conditions, many species are essentially already living on the edge, and even more severe conditions might push them over the edge. For non-desert species, it will have an even bigger impact.
Desertification leads to a decrease in biodiversity (which here means variety/number of different species in an ecosystem), and can lead to extinction for species that can’t relocate or tolerate harsher conditions. For people, it leads to a decrease in usable land.
In these deserts, often the only way humans can survive there is by having a system to bring in water from somewhere else. In the western United States, 40 million people across 7 states and 30 native tribes rely on water from the Colorado River, and have developed detailed agreements to determine how the water is distributed. As populations grow and available water decreases, there will come a time when there isn’t enough water for everyone, and that time might come earlier than people thought. This summer, the US government directed states to find ways to decrease their water use over the next year. If they don’t, the government will make emergency cuts to water allowances in order to ensure that the water reservoirs don’t get too low.
Currently, there are more than a billion people that live in deserts. As deserts become harder to live in, not everyone has the means to relocate to somewhere better. People living in deserts will have to cope with less fresh water, poor sanitation, malnutrition, an increase in diseases, and more.
So what can we do in order to survive in these deserts?
Even though there already isn’t much water in deserts, people living there will have to find ways to use even less water in order to preserve what we have. Indigenous people have been successfully living in deserts for thousands of years, using strategies like moving to cooler areas during the hotter seasons and only growing crops that suit the environment and season. If we want to succeed, we should listen to indigenous communities and adopt these strategies.
We’ll also need to take steps to become more sustainable so that we can share resources like water and ensure that no one has to go without it. We can adapt our infrastructure by taking actions such as installing rainwater harvesting systems and increasing available shade. Living in the desert is incredibly challenging, and it’s not going to get any cooler, but if we learn from those that’ve been here longer than us, we can make the desert our home as well.
How Indigenous Knowledge Can Help Us Combat Climate Change | Climate Reality Project
Holly Albrecht is currently an educator/zookeeper, and holds a Bachelors degree in Conservation Biology from the University of Arizona. She is passionate about ichthyology, herpetology, and using education/outreach to get people interested in conservation and the natural world.
Image Credit: Gilles San Martin, CC BY-SA 2.0, Image Cropped
Activity of forest specialist bats decreases towards wind turbines at forest sites (2022) Ellerbrok et al., Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.14249
Wind turbines are a constant source of controversy. The planet needs more renewable energy, yet wind turbines represent a threat to many bird populations. There have been a plethora of studies just in the last two years focussing on the impact of the turbines on birds. Yet furrier fliers often get overlooked, and it should come as no surprise that wind turbines can be a large source of mortality for bats as well.
Previously wind turbines were usually built out at sea, or in open, cleared land. Yet there has been a move over the last decade to building more wind turbines in forested areas. Moving further into forests could represent a larger threat for bats, so do they show any behaviour that could help them avoid wind turbines? That’s what today’s researchers wanted to find out.Read more
While some have sneered at the UK cowering in the face of such heat, there’s no doubting that 40 degrees is pretty scorching, especially in a country where the infrastructure just isn’t built to take it. The full ramifications of these heatwaves are yet to be seen, but the loss of life, and financial costs rising from damage to property and infrastructure, plus the health issues caused by ongoing drought and heatstroke, are only likely to rise as the week goes on.
Now that we’ve covered the depressing stuff that’s happening currently, let’s focus on the future. Is this the new norm?Read more
Low potential for evolutionary rescue from climate change in a tropical fish (2020) Morgan et al., PNAS, https://doi.org/10.1073/pnas.2011419117
As the planet warms thanks to climate change, the massive bodies of water that are our oceans grow hotter. Since they’re larger, and much poorer conductors of heat, they don’t tend to vary in temperature as much as the land does, which means many species will have to get used to longer, warmer periods.
If species can adapt to hotter temperatures through thermal acclimation, ecosystems may not be too harshly affected. However if they’re unable to adapt, marine ecosystems may undergo rapid changes as they lose native species. Today’s researchers looked at a key study species – the zebrafish – in order to figure out how well fish can respond to increasing temperatures.Read more
Image Credit: bertknot, CC BY-SA 2.0, Image Cropped
Image Credit: Patrick Kavanagh, CC BY 2.0, Image Cropped
How melanism affects the sensitivity of lizards to climate change (2022) Mader et al. , Functional Ecology, https://doi.org/10.1111/1365-2435.13993
Image credit: Tony Rebelo, CC BY-SA 4.0, via Wikimedia Commons
Climate change is a fact of life. Every day we uncover more of the negative effects it will have on the various animals, plants, and fungi in the natural world. Species range contractions are one such effect, and they occur when the area that a given species normally occupies shrinks. They are directly linked to a species’ risk of extinction, with this risk growing as a species inability to adapt to new environments grows. Though the theory sounds logical, many of the exact mechanisms behind range contractions are still unknown.
Ectotherms are organisms that depend on the surrounding environment to regulate their own body temperature, making them particularly vulnerable to climate change. Many different biological mechanisms are involved in regulating temperature, but the ability to reflect solar radiation is a key player. Indeed, the ability of organisms to reflect solar radiation (aka energy from sunlight) is part of the thermal melanism hypothesis (see Did You Know?). Melanistic (darker) organisms may be favored under climate change, due to the protection against UV radiation provided by melanin. However, melanistic individuals are more prone to increased heating, which can be bad. Today’s authors sought to understand how climate change would affect melanistic organisms.Read more