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The features that the lizards make sexy are resistant to stress

The features that the lizards make sexy are resistant to stress

The blue and black badges on the chin and belly of the male lizard help to attract potential friends and defense from the competition. A new study by researchers in Penn State reveals that low levels of stress-related hormones do not affect the color of badges or behaviors used to show badges, which suggests that these properties are resistant to stress. Author: Traci Langkilde, Penn State

The physical characteristics and behaviors that make the lizard sexy – features used to attract potential partners and defend themselves from competitors – may be important enough not to change under stress conditions. A new study by researchers in Penn State reveals that blue and black badges on the neck and abdomen of male lizards – and the signaling behavior used to show them – do not affect the low levels of stress-related hormones, unlike many other features. . A paper describing the results appears in the journal Scientific Reports.

"Wild animals are experiencing stress every day when they escape from the predators, they fight with others through food or face extreme weather conditions," says Kirsti MacLeod, postdoctoral scientist at Penn State at the time of research and chief author of the article. "But they are facing increasing stress because of increased interaction with humans, climate change and other anthropogenic changes." It is therefore becoming increasingly important to understand the many effects of stress on the health of the population. "

The researchers studied the effects of stress on "secondary sexual characteristics", which, like the deer horns or brilliant colored birds, are important to attracting friends or rejecting potential rivals, and ultimately contribute to the ability of the animal to reproduce. Namely, they studied blue and black badges appearing on the neck and abdomen of male lizards.

"Secondary sexual characteristics are advertising boards used by animals to advertise their condition," says MacLeod. "Being scandalous or having greater decorations – such as horns – than your neighbors, can mean the difference between mating and transferring your genes, or not at all." They also help maintain a large territory that can provide resources for your offspring and if stress affects these secondary sexual traits, this can affect individuals who are successful in mating or keeping the territory, which could affect the evolution and the persistence of these populations – although these characteristics are often not considered to be the health of the population.

The research team found that the color of the lizard's badge was not associated with normal levels of corticosteroid stress hormone in their blood. In addition, artificially raising the level of corticosterone, the replication of the altitude that occurs when the lizard encounters a stressor as a predator, repeatedly over several weeks, did not affect the color of the badge.

Apart from researching the physical character of the badge color, the research team also studied how this property is displayed through behavior. Similarly as a male peacock could raise its colorful tail, the lizard's fences perform pinions and heads to show their badges, defend other men, or attract potential partners.

"If stress did not affect color, but it affected behavior, for example, if the lizards stopped working with the pinch, then it would not matter if their color is the same because it is not visible," says MacLeod. "It would be like a big, bright billboard on the ground."

The team found that lifting the stress hormone does not affect the behavior of the signaling, including the number of concussion or head performed by the lizards.

"We know that raising stress hormones can have important effects in these lizard species, including the immune function and behavior that allows them to deal with predators, so these results are particularly interesting," says Traci Langkilde, a professor and head of biology at Penn State . and the senior author of the paper. "It may be that low-level stress is not enough to affect these traits, or that sexual signaling-finding better partners and maintaining better territories-is so important that, when the lizards experience stress, more resources are allocated to maintain them."

Then, researchers plan to investigate whether the maintenance of these signaling properties under stress has an increased physiological cost to other aspects of health and survival of the lizard.

Researchers also emphasize that sharing negative results such as these, which show that a factor of interest has no effect, is precious because they give meaningful information and can challenge house status.

"It's always cool to show that something you expect to have an impact on animals, like stress, it does, but it's equally important to show where there is no impact," said MacLeod. "If we only report results that show that stress has an impact, we can overestimate the effects of stress. Our results indicate that animals are resistant to stress where it is important: in the context of sexual signaling, which is probably critical in determining their ability to succeed reproduce. "

To have stress ancestors improves the immune response to stress

More information:
K. J. MacLeod, etc., glucocorticoids do not affect the secondary sexual character or its expression of behavior in the eastern lizard fences, Scientific Reports (2019). DOI: 10.1038 / s41598-019-41596-1

Pennsylvania State University

Characteristics that the lizards make sexy are resistant to stress (2019, April 17)
taken on April 17, 2019
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