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Home / Science / Why do crocodiles today look the same as they were 200 million years ago?

Why do crocodiles today look the same as they were 200 million years ago?

I have got Pickups Researched, Bunny’s little cousin, Has a history of more than 50 years, never tire of watching them. These tailless, egg-shaped fluff balls mainly live in cool mountain environments, and piles of gravel are called talus.

In the summer, observers can see Picas diligently stacking grass and leaves into haystacks for food throughout the winter. Their light brown coat blends with the surrounding environment, so they are most easily spotted when they perch on protruding rocks and call to alert other pikas of their presence.

When hikers see me observing pikas in the Sierra Nevada Mountains in California, they often tell me they have read that these animals are going extinct.I have collected a bunch The press release just said.But based on my recent research and a comprehensive review of more than 100 peer-reviewed studies, I believe this explanation is Misleading.

Constrained by climate

As shown in my earlier research, Picas’ biology suggests that they are likely to be affected by climate warming.Most importantly, their normal body temperature is very high, which makes them There is a risk of overheating when working in a warm environment. When the temperature rises, the pika will retreat to a much deeper depth in the talar habitat.

Temperature also plays the role of pickup The ability to move around. Warm weather hinders their activities, while cool temperature allows them to settle in new habitats more freely.

An ancient history is very enlightening here. Pikas first came to North America from Asia, and spread across the entire African continent about 5 million years ago when it was colder. Their remains were found in caves in the Appalachian Mountains and the Mojave Desert, where pikas no longer live.

The American pika lives mainly in alpine and subalpine mountains, extending south from central British Columbia and Alberta to the Rocky Mountains in New Mexico and the Sierra Nevada in California. Andrew Smith of CC BY-ND

As the global climate warms, the pickup population retreats to the mountains of the western United States and Canada. Today, they occupy most of the available talus habitat in these areas, which proves the challenge of the story on the “Pika Hills”.

For example, in a recent survey, 98% of 109 suitable locations in Colorado and 98% of the 329 sites in the central Sierra Nevada.A study of pickup sites across California’s Lassen, Yosemite, Kings Canyon and Sequoia National Parks showed that there is no evidence that pickups are Moving to a new location or higher altitude due to climate change.

Picas in a warm environment

In contrast, most researchers believe that the place where the plague disappears is small, isolated, and often damaged by human activities (such as livestock grazing). These sites are generally lower and warmer than the sites within the core of pikas.

Many of these areas are in Great Basin -Across most areas of Nevada and parts of Utah, Idaho, Wyoming, Oregon and California. A series of studies on the few marginal basin sites previously occupied by pikas has disproportionately contributed to the idea that pikas may be endangered.

to Investigate the big picture In the area, I worked with state and federal officials to conduct a 2017 study that identified 3,250 pickup habitats on-site records. Pickup creatures exist in 2,378 locations, but they were not found in 89 sites until 2005, but not in the 774 sites that only contained signs of old pickups.

The temperature and precipitation range of the extinct and old sites are the same as the sites where pikas still exist. This suggests that non-climatic factors may have caused the pika to disappear from the open space.

The Picas disappeared from some parts of the Great Basin, but climate change may not be the cause. Kmusser/Wikipedia, CC BY-S

Pickups still exist in other very hot places, such as Ghost Town of Bodie, California,nearby Mono Crater And Idaho Lunar Crater National Monument. In these locations, pikas will hide in cool corners of the talus habitat during the hottest hours of the day and often forage at night.

In my research, I also found that compared with high-altitude pika populations, pikas are much less active in these low-altitude areas and make far fewer calls. At low altitudes, pikas eat a diverse diet of large basin plants, such as large sage and bitter gourd, which is significantly different from the plants they eat at high altitudes. Some people failed to even construct their typical large haystacks.

Another atypical pika population in the Columbia River Gorge in Oregon lives near sea level. Here, they are also well adapted to a very different habitat and survive year-round on a moss-based diet.They defended the smallest territory of all pickups, and when the pickups got hot, they just left the talus and Wandering in the shade of the nearby forest.

The future of Picas

Based on my reviews of dozens of studies, the pickup population seems to be safe within its core range-the hills of western North America have a large and well-connected habitat for the talus. In these areas, they can migrate from one habitat to another without passing through areas that are dangerous to their warmth.

The fact that pikas are also adapted to some marginal high-temperature environments shows me that they are more resilient to climate change than many previous research conclusions. Most species show losses near the edges of their geographic range simply because the environment in which the individual animals in these areas are not ideal for them. This does not mean that they are about to become extinct.

Climate change is the most critical issue facing the world today. Therefore, it is especially important for scientists to accurately communicate climate change issues to the public. In my opinion, the fact that pickup rats are responding and changing their behavior in response to changing conditions is encouraging. For future naturalists, this is one of the most fascinating mammals starting to observe nature. News.

Andrew Smith (Andrew Smith) is Professor Emeritus of Life Sciences at Arizona State University.

Disclosure Statement: Andrew Smith (Andrew Smith) will not work for any company or organization that would benefit from this article, advise it, own its shares or obtain funding from it, and did not disclose anything related to his academic appointments Branches.

Reposted with permission from conversation.

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