Category Archives: Animals

Sex, Aggression & Damselflies

Aggression between two different species of animals is surprisingly common. But what exactly are they fighting over?

Male aggression towards potential reproductive rivals could explain much of it.

UCLA biologists observed and analyzed the behavior of several species of damselflies. Male damselflies typically ignore males of another species when they fly into their territory — unless they’re attempting to mate with a female damselfly.

Female damselflies almost always refuse to mate with males of a different species, said UCLA’s Gregory Grether, but that doesn’t stop some males from trying, especially in cases where the females of both species have similar wing color.

“Male damselflies often have difficulty distinguishing between females of their own species and another species when making split-second decisions about whether to pursue a female,” Grether explained.

Damselflies typically live only a couple of weeks, and have few mating opportunities.

The biologists documented some cases where aggression between species has essentially disappeared because of substantial divergence in wing coloration.

Read more about the damselfly aggression and what it can tell us about human evolution

A New Species of Hummingbird?

UC Riverside researchers have discovered what could be a new species of hummingbird in the Bahamas.

The Bahama Woodstar comprises of two subspecies: Calliphlox evelynae evelynae, found throughout the islands of the Bahamas and Calliphlox evelynae lyrura (“lyrura” for lyre-tailed, refers to the forked tail of males that resembles a classical lyre harp). This lovely creature is only found among the southern Inaguan islands of the Bahama Archipelago.

Based on data from morphology, behavior, genetics and geology, UCR biologist Christopher J. Clark says the two subspecies should be recognized as two distinct species.

“The two subspecies were originally described as separate species, partly on the basis of small differences in the tail feathers between them, but were then classified in 1945 as subspecies of the Bahama Woodstar. It’s time now to call these two distinct species of hummingbirds.”

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A (super cute) defender against asthma and allergies

UCSF-led study found that a child’s risk for developing allergies and asthma is reduced when they are exposed in early infancy to a dog in the household. It has to do with the type of dust indoor/outdoor dogs carry in.

The results were obtained in studies of mice challenged with allergens after earlier exposure to dust from homes with dogs, but the results also are likely to explain the reduced allergy risk among children raised with dogs from birth.

The scientists also identified a specific bacterial species (Lactobacillus johnsonii) within the gut that is critical to protecting the airways against both allergens and viral respiratory infection. When they fed this bacteria alone to mice, they found it could prevent airway inflammation due to allergens or even respiratory syncytial virus (RSV) infection. Severe RSV infection in infancy is associated with elevated asthma risk.

[Image: Tasuku and his BFF, a french bulldog named Muu.]

The lawnmowers of coral reef


In the first global snapshot of its kind, a team of researchers at Scripps Institution of Oceanography has shown how overfishing has impacted seaweed-eating fish that are vital to coral reef health. Study leader Jennifer Smith says there are many species of fish and invertebrates that act as lawnmowers in these fragile ecosystems.

If you take away the lawnmower or the weed whackers in your own yard, you know what happens. You get the weeds growing and they will grow over, out-compete the plants that you are trying to cultivate. The same things happens on a coral reef where, if you don’t have the lawnmowers, these weeds can overgrow and out-compete the corals, which are the ecosystem engineers.

Smith says their study found that populations of plant-eating fish declined by more than half in areas that were overfished.

One of the goals is to help many places develop better management and conservation strategies for their coral reef ecosystem across the Pacific and Caribbean.

What engineers can learn from animals

The mantis shrimp

Genghis Khan bathed in sherbet ice cream.

This is how The Oatmeal described the violent AND beautiful mantis shrimp in their comic: “Why the mantis shrimp is my new favorite animal.

These little guys, along with 20 other animals, will serve as inspiration for a team of engineers and researchers –– led by UC Riverside’s David Kisailus.  Of particular interest is the mantis shrimp’s clubs (or “murder sticks” as they’re referred to in the comic), which it uses to kill prey and break apart oysters, crabs, and mollusks.

Working with biologists and chemists, these engineers will study their biological systems and cellular structures to see if they can use those insights to develop stronger, tougher materials. Natural structures like shells, beaks and antlers are particularly interesting because they are composed of relatively simple materials (aka not industrial strength), yet display incredible strength and mechanical performance.

This multidisciplinary research will highlight the value in biologically-inspired materials allowing the next generation of materials development to take advantage of what nature has known for millennia.

The Frog of War

When biologist Tyrone Hayes discovered that a top-selling herbicide messes with sex hormones, its manufacturer went into battle mode:

In 2001, seven years after joining the biology faculty of the University of California, Berkeley, Tyrone Hayes stopped talking about his research with people he didn’t trust. He instructed the students in his lab, where he was raising three thousand frogs, to hang up the phone if they heard a click, a signal that a third party might be on the line. Other scientists seemed to remember events differently, he noticed, so he started carrying an audio recorder to meetings. “The secret to a happy, successful life of paranoia,” he liked to say, “is to keep careful track of your persecutors.”

Three years earlier, Syngenta, one of the largest agribusinesses in the world, had asked Hayes to conduct experiments on the herbicide atrazine, which is applied to more than half the corn in the United States. Hayes was thirty-one, and he had already published twenty papers on the endocrinology of amphibians. David Wake, a professor in Hayes’s department, said that Hayes “may have had the greatest potential of anyone in the field.” But, when Hayes discovered that atrazine might impede the sexual development of frogs, his dealings with Syngenta became strained, and, in November, 2000, he ended his relationship with the company.

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The riddle of zebras’ stripes

Zebra

Why zebras have black and white stripes is a question that has intrigued scientists and spectators for centuries. A research team led by UC Davis, has now examined this riddle (in a very systematic way).

Many hypotheses for zebra stripes have been proposed since Alfred Russel Wallace and Charles Darwin debated the problem 120 years ago. These include:

  • A form of camouflage
  • Disrupting predatory attack by visually confusing carnivores
  • A mechanism of heat management
  • Having a social function
  • Avoiding ectoparasite attack, such as from biting flies

After analyzing the five hypotheses, the scientists ruled out all but one: avoiding blood-sucking flies. The scientists found that biting flies (such as horseflies and tsetse flies) are the evolutionary driver for zebra stripes.

Why would zebras evolve to have stripes whereas other hooved mammals did not? The study found that, unlike other African hooved mammals living in the same areas as zebras, zebra hair is shorter than the mouthpart length of biting flies, so zebras may be particularly susceptible to annoyance by biting flies.

Yet in science, one solved riddle begets another: Why do biting flies avoid striped surfaces?

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