Phenological asynchrony: a ticking time-bomb for seemingly stable populations? (2020) Simmonds et al., Ecology Letters, https://doi.org/110.1111/ele.13603
Image Credit: Ian Kirk from Broadstone, CC BY 2.0, Image Cropped
When we think of climate change we tend to think about extreme weather events and melting ice caps, but the way in which our environment is changing is giving the planet more than just unseasonal weather. Phenology (the timing of biological events in nature) dictates when an organism begins a given part of its life cycle, and changes in phenology are one of the most frequent responses to climate change. Take bees and flowers; bees feed on the flowers of certain plant species, and in turn spread the plants’ pollen for them. They both depend on the other being around at the same time, and if flowers bloomed too early, or if the bees came around before the flowers were “ready” for them, both parties would suffer.
Such a mismatch is known as an asynchrony, and it is hypothesized to cause population declines due to the harmful impacts on one or more of the interacting species involved (see another recent post to understand how the loss of one or more interactions can lead to cascading effects throughout a local community). While many theoretical models have investigated these processes, today’s authors wanted to combine such models with long-term data on the phenology and population size of great tits (Parus major). Great tits rely on a small period of insect abundance to feed their young, and as such the more closely they can match the needs of their young to the abundance of insect populations the more they will increase their fitness.
Image Credit: European Wilderness Society, CC BY 4.0, Image Cropped
What comes to your mind when you think of Wilderness? Maybe it is a dense rainforest filled with a cacophony of bird calls, or plain filled with lagre grazing animals and free-roaming carnivores? They certainly qualify, but by definition, Wilderness is any area that hasn’t (or has only slightly) been modified by human activity in the past. This means that Wilderness areas can be incredibly diverse, from the aforementioned tropical forest to a murky swamp. These areas represent nature in its purest form, with the absence of human interventions allowing for dynamic, open-ended natural processes. These processes not only create marvelous landscapes and offer refuge for species, but also provide many benefits for humans.
Look to the wilderness of Northern Europe and you will find brown bears, grey wolves, wild cats, and some of the best remaining strongholds for large mammals on the continent. Look to the UK on the other hand, and you see a state of overgrazed grasslands, skeletonized hedgerows, and monocultured forests. In the face of the global extinction and climate crisis, even the most praised of Britain’s mammals are facing decline, as the IUCN red list declares one in four species at risk of extinction, and the persecution of wild populations continues.
In this article, I offer a brief summary of some of the UK mammal species that have experienced their share of ups and downs throughout 2020, and hopes for UK mammal conservation for the future.
Image Credit: Maria Grist, CC BY-SA 4.0, Image Cropped
Platypus predation has differential effects on aquatic invertebrates in contrasting stream and lake ecosystems (2020) McLachlan-Troup, Scientific Reports, https://doi.org/10.1038/s41598-020-69957-1
A trophic cascade occurs when a predator’s effects of its prey goes on to affect ‘lower’ levels of that ecosystem. A great example is the effect that sea otters have on kelp: the sea otters prey extensively on sea urchins, which in turn increases the populations of kelp, which the sea urchins prey on. While this is a result of direct predation by otters, often this can occur through a prey species changing its behaviour to avoid the predators.
Yet most ecosystems are more complex than a simple three-level trophic system. Cascades are therefore more likely to occur when the ecosystem is less complex, or when there are well-defined relationships between species, as a result of a predator having preferred prey species or only a few groups of species making up an ecosystem.
This week’s authors investigated how the platypus (our recently-found-to-be-fluorescent friend) influences the abundance and species richness of invertebrates across both rivers and lakes, and whether it’s capable of affecting an ecosystems algae and sediments as well.
An empirical attack tolerance test alters the structure and species richness of plant–pollinator networks (2020) Biella et al., Functional Ecology, https://doi.org/10.1111/1365-2435.13642
Image Credit: Adamantios, CC BY-SA 3.0, Image Cropped
Put simply, ecosystem function is the process that control how nutrients, energy, and organic matter move through an environment. Think about a forest. You have small plants that are eaten by small animals, small animals that are eaten by larger animals, and those larger animals are eaten by even larger animals. When those animals die, they are broken down and consumed by scavengers, fungi, and bacteria. These processes result in a continuous flow of nutrients and energy through the ecosystem. However, if one link (organism) in this chain breaks (goes extinct), the ecosystem could lose its function, and other species that depend on this cycle could go extinct as well.
The way in which a given ecosystem reacts to or recovers from any negative impact that it sustains is key to understanding how ecosystems function. Classically, this is tested with attack tolerance tests, in which all species on a given trophic level are removed and the ecosystem is then monitored to see how/if it maintains its function. In studies of plant-pollinator networks, this is usually modeled with computers, but studies which use natural systems are lacking. Today’s authors wanted to use a natural plant-pollinator system to see what happens.
A young octopus (Graneledone verrucosa) moves across the seafloor. Observed during the Okeanos Explorer Northeast U.S. Canyons 2013 expedition. (Image Credit: NOAA Ocean Exploration & Research, CC BY-SA 2.0, Image cropped)
In nature every death brings new life. A fascinating example are whale-falls: when a whale dies, its carcass will sink down to the ocean floor where it creates a unique ecosystem for bottom-dwelling organisms. Whales’ bodies can weigh up to 200 tons and contain massive amounts of fat and proteins. When a dead whale reaches the ocean floor it brings a lot of resources to an environment which is usually limited by food availability. The fortunate creatures experiencing the whale-fall welcome such a great source of nutrition, and use up everything they can, until the last vertebra is decomposed.