The San Bernardino Valley is an oasis of life. Research by entomologist Bob Minckley shows that this area has the highest concentration of bee species in the world.

Minckley collected bees at 45 sites throughout the valley from 2001 to 2009. In a recent paper, Minckley stated that 497 species of bees live within just over 6 square miles of the valley, a modest area for such a study, 10 times smaller than Washington D.C. These 497 species represent 14 percent of all the nearly 4,000 bee species found in the United States.

Minckley hopes his work will help people appreciate the importance of the San Bernardino region and the vast diversity of bee species on Earth. Laurence Packer, an entomologist at York University, says that this research helps reveal where the greatest species richness of bees occurs, which is important for understanding patterns of bee diversity and what drives it. “Such long-term studies, which are relatively rare, are necessary to acquire a good understanding of an area’s diversity, especially in dry places where rainfall varies,” he adds.

One reason for this bee diversity is that the valley lies at a place where vast, abundant biomes（生物群系）live together. Perhaps counterintuitively（违反常理地）, bee diversity is low in the tropics, where plant diversity is the highest. Dry but ecologically diverse areas such as the San Bernardino Valley seem to have the right mixture of variables to ensure high bee diversity.

This hot spot of bee diversity faces several threats. In 2020, the government built 30-foot-high steel fencing along the entire border of the San Bernardino National Wildlife Refuge. The most ecologically damaging aspect caused by the wall’s construction may be the massive quantities of water withdrawn from the place’s aquifer（含水层）to make concrete for the base of the wall. If the lowered levels of water affect plants, then it could potentially hurt the bees as well. For the bees, the drying up of springs will have an impact especially on those species that rely on spring-fed habitats.

New research by scientists at the University of Bristol explains how a “stop－start” pattern of evolution,governed by environmental change,could explain why crocodiles (鳄鱼) have changed so little since the age of the dinosaurs.

Crocodiles today look very similar to ones from 200 million years ago. There are also very few species alive today—just 25. Other animals such as lizards and birds have achieved a diversity of many thousands of species in the same amount of time. Prehistory also saw types of crocodile we don’t see today,including giants as big as dinosaurs,plant－eaters,fast runners and snakelike forms that lived in the sea.

The rate of their evolution is generally slow,but occasionally they evolve more apace because the environment has changed. In particular,this new research suggests that their evolution speeds up when the climate is warmer,and that their body size increases.

Lead author Dr. Max Stockdale said,“Our analysis used a machine learning algorithm (算法) to estimate rates of evolution. Evolutionary rate is the amount of change that has taken place over a given amount of time,which we can work out by comparing measurements from fossils and taking into account how old they are. For our study we measured body size,which is important because it interacts with how fast animals grow,how much food they need,how big their populations are and how likely they are to die out.”

The findings show that the limited diversity of crocodiles and their apparent lack of evolution result from a slow evolutionary rate. It seems the   crocodiles arrived with an already efficient and versatile (多功能的) body   plan that doesn’t require changes. This versatility could be one explanation why crocodiles survived the meteor (流星) impact at the end of the Cretaceous period,in which the dinosaurs died out. Crocodiles generally develop better in warm conditions because they cannot control their body temperature and require warmth from the environment.

Humans spend about one third of their lives sleeping. But some mammals (哺乳动物), like the northern elephant seal, survive with much less sleep.

Researchers in a new study described the unusual sleep pattern of these ocean animals. They found that when these mammals go to feed on trips that can last seven months, they sleep just two hours each day. Those two hours of sleep are made up of short moments of rest lasting only 10 minutes each as they dive deep to avoid predators (捕食者). The only other mammals known to get so little sleep are African elephants.

The researchers placed a head covered with sensors on the heads of the seals that they studied. The sensors recorded sleep signals created by the seals’ brains and heart rate. The sensors also recorded the animals’ location and depth beneath the sea.

The researchers studied female seals because they go out on long open-ocean trips while males feed in coastal waters.

During dives lasting about 30 minutes, the seals went into a deep sleep called slow-wave sleep while keeping a controlled downward movement. When they then experienced rapid-eye-movement (REM) sleep, the seals fell into a turning pattern. Then, at the deepest point of their sleeping dive — up to 377 meters deep — they wake up and swim back to the surface.

Terrie Williams is a scientist at the University of California at Santa Cruz who helped write the study. She said, “It is remarkable that a wild animal will fall into deep, paralytic REM sleep when there are predators on the hunt.” She added that the seals solve this problem by going into deep sleep in the deep parts of the oceans where predators usually do not hunt them.

Williams said the brain’s ability to control awakening the sleeping seals at a depth before they drown is also a discovery about how mammalian brains work. She commented on this saying that it shows the survival control of the seals’ brains.