sexual selection – BioGeoPlanet

In our travels throughout South Africa, we've always treasured our memories of viewing lions in the wild. When observing lions up close, we've wondered "why do the males have manes?" And why is there so much variation in the color of manes? Are the dark ones sexier? Research is showing that the main role of a lion’s mane is to signal vital information about a male’s overall health and fighting ability to potential mates and rivals. Dark-maned males tend to have higher testosterone levels, heal up better after being injured, and survive longer. It appears that dark manes attract more females and intimidate more males than blond manes. Manes Provide Vital Visual Cues According to biologists, interactions between male lions suggest that the bigger the male, the more intimidating he looks to other males, especially the younger ones considering their chances of defeating the resident male(s). Another consideration is the color or darkness of a lion’s mane. Do girls have a thing about strong, dark strangers? Yes, it seems - even in the world of lions! Scientific studies have shown that males with darker manes are almost always chosen over males with lighter manes. Female lions prefer dark-maned males. How do we know? Dr. Craig Packer, with the University of Minnesota, was intrigued about the role of the lion’s mane. He and his team came up with the innovative idea of using life-size stuffed lions to help solve the mystery. The dummy lions were outfitted with light and dark manes of various lengths to see how the other lions would interact with them. They even gave the stuffed lions sexy names like Lothario, Fabio, Romeo, and Julio. The results explained a great deal: females tried to seduce the dark maned dummies, while males avoided the dark ones and attacked the blond ones, especially Lothario, the dummy with the shortest mane. The length of the mane appears to be particularly important in encounters between unfamiliar males estimating the fighting prowess of an unknown rival. Dummy lions with colorful names: (left to right) Romeo (short, dark mane), Fabio (long, blonde mane), Julio (long, dark mane) and Lothario (short, blonde mane). Photo credit The Lion Center. According to Packer’s research, the more testosterone a male lion has in his blood, the darker his mane. Researchers found that males with black manes could heal faster after being bitten or injured and had a much better chance of surviving into the next year compared to males with blond manes. Males with darker manes spend more of their lives as resident males within a pride and are more likely to survive when wounded. Furthermore, their cubs are more likely to reach their second birthday (which also benefits females that chose dark-maned males) and are less likely to be injured. These results suggest that darker maned males provide better protection from other lions, which is the most common cause of injury. The darker the mane the more testosterone being produced, attracting the females and intimidating other males. Interestingly, the manes of individual lions tend to change with time even during adulthood, becoming darker or lighter due to injury or changes in diet. Packer summed up the findings like this: “The most important thing, from the female’s point of view, is that the black-maned males had babies that were better able to survive. So, if a female mates with a black-maned male, she’s going to have more surviving offspring, which is the real thing she gets out of this whole transaction.” Check out that mane – long and dark! Photo by mana5280 on Unsplash Are Manes Primarily for Neck Protection? Lions are the only species of cat that grow manes, so they must serve some specialized function. Until recently, it was widely believed that the primary function of a lion’s mane was to protect his neck from being injured, particularly when fighting other males. If manes offered lions with an evolutionary advantage as a protection against neck injuries, you would think that neck injuries would be associated with higher fatalities, but that’s not the case. Nor are neck injuries more frequent than injuries to other parts of the body. In fact, biologists have found that when lions fight one another, they rarely go for the neck. Instead, they attack more from the rear, targeting the back and the hindquarters. These findings suggest that the primary role of the mane is something other than to provide neck protection. Lion’s Manes and Sexual Selection Lion’s manes are thought to be a product of sexual selection, based on three key features: Only males have manes, i.e., the mane is sexually dimorphic,Manes develop at puberty, and,Manes are highly variable and feature a wide range of colors and lengths. Through sexual selection, animals have evolved specific physical and behavioral attributes that increase their chances of mating and, thereby, passing on their genes. The lion’s mane is one of these physical attributes that has evolved through sexual selection. The mane of a male lion usually starts to darken before his first birthday and continues to do so for the next four to five years. During that time, mane length and testosterone levels also increase. It is important to note that the manes of individual males are not always constant over time. The manes of lions can become lighter or darker, longer or shorter, and can change back and forth. It turns out that an individual lion’s mane changes with the underlying condition of the animal. This is in keeping with our understanding of how sexual selection works; namely that variation in sexually selected traits often reflects changes in the underlying condition of the animal. Check out my in-depth article about Sexual Selection. Birds do it... lions do it... and so do humans! Is there a difference between sexual selection and natural selection? Darwin came to think of it this way: sexual selection is the “struggle for mates,” while natural selection is the “struggle for existence.” Sexual selection is not a subcategory of natural selection, a point that Darwin tried to make abundantly clear. Sexual selection arises from differences in mating success, whereas natural selection is due to variance in all other adaptations to the environment. Natural selection arises when organisms that are better adapted to their environment have higher rates of survival than those less well equipped to do so. As Darwin said, “natural selection is daily and hourly scrutinizing…every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good.” Do Dark Manes Lead to More Sex? We’ve seen that dark manes help to attract females and to intimidate potential male challengers. We can infer from these observations that dark-maned lions do indeed have more sex. Now let’s look at the mechanisms that help to explain the role that manes play in the sex lives of lions. The difficult task of attracting a member of the opposite sex usually involves two distinct mechanisms: 1. Mate choice or intersexual selection (checking out potential mates for suitability); where members of one sex (usually females) choose members of the opposite sex. Traits of this sort, such as coloration (dark vs light manes), long feathers or elaborate calls, usually relate to the male’s condition. Females that prefer dark-maned males may obtain benefits directly, in the form of more offspring, or indirectly, through better genes for their offspring. 2. Male-male competition or intrasexual competition (fighting for the right to mate); where members of the same sex (usually males) compete for access to mates. Traits in this category include armor to protect males from opponents, weapons to disable opponents, or signals of fighting prowess that males use to assess opponents. Females are typically choosier and males typically more competitive (while acknowledging the reverse can also be true). Given that males usually have limited access to females, females tend to choose while males tend to compete. We know that lions can be avid sexual performers. One male lion was observed to mate 157 times in 55 hours by George Schaller, founder of the Lion Project and preeminent field biologist. In summary, a lion’s mane signals vital information about a male’s overall health and fighting ability to potential mates and rivals. Find out Why Lions Roar and Why the Response Can be Deadly! There's more to lions' roars than you might think. Males and females both pay attention when the lion king roars!! It may be his last! Read my article about lion communication to find out why. References The Lion Center Dr. Craig Packer, FounderConsidered the world’s foremost expert on African lions, Dr. Craig Packer is a Distinguished McKnight Professor of Ecology, Evolution and Behavior at the University of Minnesota. He established the world’s first research center dedicated to the study of lions in 1986. Tucker, Abigail, 2010. The Truth About Lions: The world’s foremost lion expert reveals the brutal, secret world of the king of beasts. Smithsonian Magazine, January 2010. West, Peyton M., 2005. "The lion's mane: neither a token of royalty nor a shield for fighting, the mane is a signal of quality to mates and rivals, but one that comes with consequences." American Scientist, vol. 93, no. 3, 2005, p. 226+. Feature photo at the top of the article shows a male lion's mane. Photo by Luke Tanis on Unsplash The Gear We Love to Travel With We love to travel in search of exceptional wildlife viewing opportunities and for life-enhancing cultural experiences. Here is the gear we love to travel with for recording our adventures in safety and comfort: Action Camera: GoPro Hero10 Black – we find these waterproof cameras are invaluable for capturing the essence of our adventures in video format. Still photos are great, but video sequences with all the sights and sounds add an extra dimension. I use short video clips to spice up many of my audiovisual presentations.Long Zoom Camera: Panasonic LUMIX FZ300 Long Zoom Digital Camera – I love this camera for its versatility. It goes from wide angle to 28X optical in a relatively compact design. On safari in Africa I’ve managed to get good shots of lions that the folks with long lenses kept missing – because the lions were too close! I also like the 120 fps slow-motion for action shots of birds flying and animals on the move. I call this my “bird camera.”360 Camera: Insta360 ONE R 360 – 5.7K 360 Degree Camera, Stabilization, Waterproof – see my article How to Take Impossible Shots with Your 360 Camera. This camera is literally like taking your own camera crew with you when you travel! 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