Often, research surrounding non-native — also referred to as invasive (入侵的) — species focuses on the negative impact on the environments they invade. Non-native species represent threats or even disasters; some are even famous for it. But according to a new study from Brown University, while the negative aspects of non-native life, including the increased risk of causing extinction to other species, are mainly talked about, the positives are not always addressed. Researchers say that non-native species also have the ability to increase biodiversity (生物多样性) within habitats.

As far as famously feared non-native species go, zebra mussels are high on the unwanted list. They originated in the waters of Eurasia and have grown to become a major issue in lakes and waterways across the Great Lakes, as well as in states such as Texas and California. In unnatural habitats, they reproduce rapidly, outcompeting native species for resources. Additionally, they attach themselves to hard surfaces, such as pipes and boats, costing millions to remove.

But for its research, the team decided to focus not only on non-native species’ negative impacts but also on what they can contribute to habitats. In forests, the earthworms have the ability to change the ecosystem negatively. However, when earthworms are present in agricultural land, there is a possibility for a 25-percent increase in the productivity of agricultural crops. As far as brown trout — a non-native species in New Zealand — are concerned, locals have embraced the fish, enjoying the economic and recreational benefits of fishing for the species and adding it to their local food.

Biologist Dov Sax, along with co-authors of the Brown University study, says that these benefits are not as uncommon as past research on invasive species may suggest.

“Our new paper argues that the positive impacts of non-native species are neither unexpected nor rare but instead common and important,” says Sax.

Have you ever looked at a seal and thought “Is that the same seal I saw yesterday?” Well, there could soon be an app for that. Taking inspiration from other technology adapted for recognizing primates (灵长目动物) and bears, Krista Ingram, a biologist at Colgate University, developed SealNet, the software that uses deep learning and a convolutional neural network (卷积神经网络) to tell one seal face from another.

The team had to train their software to identify seal faces. “I give it a photograph, it finds the face, and clips it to a standard size,” says Ingram.

They tested the software using 406 different seals and found that SealNet could correctly identify the seals’ faces 85 percent of the time. The team has since expanded its database to include around 1,500 seal faces. As the number of seals logged in the database goes up, so does the accuracy of the identification, Ingram says.

As with all tech, however, SealNet is not always infallible. The software saw seal faces in other body parts, vegetation, and even rocks. In one case, Ingram and her students did a double take at the uncanny (不可思议的) resemblance between a rock and a seal face.

Ingram points to site fidelity (忠诚) as an aspect of seal behavior that SealNet could shed more light on. The team’s trials indicated that some harbor seals return to the same sites year after year. Increasing scientists’ understanding of how seals move around could strengthen arguments for protecting specific areas, says Anders Galatius, an ecologist at Aarhus University in Denmark who was not involved in the project.

At 9 am on Wednesdays, Gaby Rountree waves goodbye to Mila as she is picked up to go to day care in Mexico City. “It has made her so independent, so friendly and so lovely with others,” Ms Rountree says joyfully. She shuts the front door and turns to homeschooling her two children. Mila is not a child, but the family dog.

Schools and nurseries have been shut in Mexico for a year owing to the pandemic. But the doggy day care is booming. Doggy carers offer claw-trims (修剪) and let beloved pets play outdoors. “Many clients now have a home office and are worried about their dogs becoming too attached to them,” explains Montserrat, an owner of a dog day-care center, as she strokes a tiny dog on her lap. The facility, in the rich neighbourhood, also has a camp where dogs can spend a relaxing weekend in the countryside.

Mexico’s rising passion for dogs has coincided (同时发生) with falling human fertility (生育能力). In the mid-1980s, a Mexican woman could expect to have four children; now, only two. In the long run, as people have grown richer and the returns to education have risen, families have shrunk. For some, a dog is a lovable substitute. The most devoted owners buy clothes and throw birthday parties for their dogs. Many restaurants welcome dogs and provide drinking water. Some restaurants even offer a full doggy menu. Parks have “doggy areas”. Pet beauty salons provide not only baths and trims but other methods of relaxation.

Mexico’s spoilt pets are probably enjoying the pandemic more than the locked-down kids. By one estimate, nearly two-thirds of the children have missed a year of school because of coronavirus. For mothers such as Ms Rountree doggy day care offers some relief from Covid-influenced hard boring work. But she will not stop worrying until her children, too, are let off the chain and back into the classroom.