Tag Archives: human
The impact of our species on the conditions and fundamental processes on Earth is unmistakable. From carbon emissions to the cities that dominate skylines to the plastics that swirl around in our seas, the evidence of our existence can be found anywhere. And now, a group of geologists considers our impact so drastic that a new epoch – the Anthropocene – should be declared. Whilst this change has gained support in much of the scientific community, others say that the Anthropocene is more about sensationalism or pop culture than science, as clear evidence for a new geological time is lacking. So whilst much of the scientific community, the general public and the media have already embraced the Anthropocene, the search for hard evidence for the start of a human-dominated age continues.
Mostly limited to ocean animals, transparency is thought to help escape predators by blending the animal in with its environment, but is this what actually happens? (Image Credit: Wikicommons, CC BY 3.0).
Transparency reduces predator detection in mimetic clearwing butterflies (2019) Arias et al., Functional Ecology, https://dx.doi.org/10.1111/1365-2435.13315
Predators are one of the strongest forces of selection in the natural world, and as a result it can be quite costly to stand out and be more easily noticed. This means that in order to survive, animals must adapt to avoid predators. Besides running away from what is trying to eat you, your best bet is to evolve body coloration that helps you avoid being seen by a predator.
Animals that rely on blending in will match the color or even the texture of their backgrounds, but when prey species live in areas where they cannot easily blend in (like plankton in the water column) they often evolve to be transparent. Unlike their marine counterparts, transparency is normally rare in terrestrial animals. The clearwing butterfly is one notable exception to this rule, and the authors of today’s paper wanted to test whether or not these clear wings actually reduce predation.
Linking locomotor performance to morphological shifts in urban lizards (2018) Winchell, K. et al., Proceedings of the Royal Society of Biological Sciences, 285, http://dx.doi.org/10.1098/rspb.2018.0229
We know that human construction leads to displacement of many species, regardless of the ecosystem. But just because we put up a city, doesn’t mean that all the species that lived there go disappear. Some stay and adapt to their new surroundings. Understanding how certain types of organism respond to new environments is important when considering our impact on a species.
Today’s paper looks at the response of lizards, in this case anoles, to living in the city. The authors wanted to find out, among other things, whether individuals of the selected species showed different locomotive abilities on natural and man-made surfaces based on whether or not they came from the city or the forest, and whether these corresponded to morphological differences.
Rodents and primates are periodically cited as some of the more intelligent animals on the planet, but it turns out that the large brains that these mammals possess have evolved more than once in their history. (Image Credit: Drow male, Arjan Haverkamp, ltshears, CC BY-SA 4.0, Image Cropped)
Encephalization and longevity evolved in acorrelated fashion in Euarchontoglires but not in other mammals (2018) DeCasien, Alex R., Evolution, DOI: doi:10.1111/evo.13633
Some of the most striking footage from documentaries like the recent “Blue Planet II” involve organisms that display remarkable intelligence (the octopus that uses shells to disguise itself and hide from its shark predators was a particular favorite of mine). As humans, we sometimes assume that we have the best brains on the planet and have somewhat of a monopoly on intelligence, so it’s always fascinating and maybe even surprising to see other animals using their own brains to solve problems. In mammals, brains that are larger than expected have evolved more than once, which is somewhat of a surprise given how costly a big brain is. For example, your brain needs 20% of the oxygen that your body uses, so one out of every five breaths is exclusively for your brain.
Larger brains are also correlated with longer lives, relative to the group that the organism in question belongs to. Historically, studies on brain size and longevity have been dominated by primate species, so the concern was that this long life/large brain trend may only be a primate trend, instead of generalizable to all mammals. The authors of this study wanted to analyze this trend across more mammal groups, in addition to studying the relationship between larger brains and longer lives.
Bushfires like the ones that have ravaged Australia and California this year, could become the new norm for the generation that has been born in the last decade, an example of how our perception of ecological change is defined by what has happened in our lifetime (Image Credit: dm4244, CC BY-SA 4.0, Image Cropped)