Can climate change end up playing cupid between small seals and the ladies? Find out what Dr. Tatiana has to say...
Conceived, written and presented by Eliza Falk, Amatullah Lonandwala and Simonne Guenette for BIOL 4585-001 Evolution of mating systems (J-term, 2021)
Class of 2021(EF and SG) and 2022 (AL) University of Virginia
Dear Dr. Tatiana
I’m a southern elephant seal and it seems that I can’t get a break! All I want to do is find a nice girl to settle down with but they never seem to want me! All the girls flock to one big guy in our harem, it's not fair that he gets all the girls! Why can't he share?
- Lonely in the Antarctic
Hey bud, it sounds like you are in quite the predicament, and we are afraid we don’t have too much good news to offer you, but let's get down to business. First off, what a unique species you are! Southern elephant seals endure the chilly marine environment of the lower southern hemisphere, inhabiting the Antarctic region primarily. Not only can you survive such a cold and barren climate, but you are fierce swimmers, too. Elephant seals are known to hold their breaths for up to 100 minutes, and can dive nearly a mile down into the ocean!
Despite being an impressively tough species, in the world of sex, not all elephant seals are created equal, especially you males. We hate to break it to you, but settling down is simply not the style of your species. Elephant seals are a polygynous species who partake in harems. We know, it's unfair - one guy getting all the girls while the other males are stuck helping him procreate. During your mating season, males will convene at breeding grounds to establish who is #1. Through a series of noises and fighting, the alpha male will be determined, leaving all the losing beta males to roam the beach protecting the harem territory. Body size is one of the most critical factors in determining alpha male success, so this is a good way to evaluate your chance of success. Males Southern Elephant Seals are enormous, ranging from 2,200 to 4,000 kg (4,900 to 8,800 lb) and 4.2 to 5.8 m (14 to 19 ft) in length. So if you’re on the smaller side of this, We hate to be the one to tell you, but you might be out of luck. Females will then arrive at the grounds to mate with the alpha, and while he gets to fool around with all his honies, you will be left to protect him from other potential male intruders. The sad truth of it is, 75% of males in your species will never mate, and their genes will die with them. Although the cost of defending a harem is high, there is a massive payoff for males who are able to maintain control.
Your species is not alone in this harsh system, many other animals participate in harem polygyny. Individuals across the globe find themselves fighting for dominance over resources and mates. At least you don’t need an elaborately-ornamented bod, with bright and coloured plumage, long tail, red wattle and ear-tufts on the head to get the girl! Common pheasants are required to don this apparel, as well as perform a waddle to impress females, and use spurs to battle males for territory and dominance over the harem. Theirs is a complicated love ritual, and males with brighter plumage fare better against other males. One good thing about males of your species is, well, let’s just say it’s good the females aren’t too picky over looks.
The way we see it you have a couple of options to try to win over a mate:
(1) You can try to sneak in a quickie with one of the females who arrives at your harem. Now this is a risky play, for if you are caught by the alpha male, you risk a severe beating down by him. There is also no guarantee that a female is going to be receptive to your pursuits, but fear not because you are probably two or three times her weight! Sexual coercion is common in your species, so if you're willing to risk being caught, you can pounce on the next female you see. Try to wait until the alpha male is preoccupied with another lover to make your move, this should lower your chances of getting caught and having to pay the price.
Tough, but this is actually pretty par for the course. This behavior is found in numerous mammals. Orangutans have two distinct morphs: call-and-wait vs. sneak-and-rape. Dominant males will fight off the sneakers by force, and the slim submissives don’t stand much of a chance against these macho males. Yet, your hairy relatives do offer some hopeful news: these smaller males can actually sire the majority of the females’ offspring in a group. Take this as inspiration: even the largest males can be usurped by an ambitious little guy!
If you’re not willing to risk a pummeling, though, there’s another option. (2) You can hold out in hopes that next year you’ll have a chance at the alpha male position. Southern Elephant Seals reach maturity around 5-6 years into their life, but are often not in position to achieve their alpha status until around age 8. If you think that you're a little on the childish side, maybe wait it out a few seasons and see if you can vie to become the top dog!
A sad reality for your species is the threat climate change poses. In your cousin the northern elephant seal, research has shown that in a changing climate mothers will preferentially care for their sons over their daughters. Why should I care, you might ask? Well, the implications of a male skewed sex ratio in your species could change the nature of your polygynous mating system. With males in abundance and females in scarcity, selective pressures in your population may begin to shift. With fewer females in the population, it might become more advantageous for males to invest more into a single mate, watching over her to ensure fidelity, and potentially even assisting in offspring care. On the other hand, an increase in males in your population may promote even more aggressive behaviors, with competition for dominance of your harem steeper than ever! We would tell you to hit the gym and prepare to have to battle it out, but that’s not exactly the style of your species. Elephant seals fast to maximize their mating chances, so it might be time for you to lay off the squid and fish, and pay more attention to the ladies!
This is not something that will likely affect you in your lifetime, and little research has been conducted in this area. Whether warming temperatures changes elephant seal’s polygynous ways, or threatens extinction of the population entirely, it is likely climate change will have big impacts on your species in the coming decades. However, my advice to you is to keep on keeping on- you never know exactly how things can change and in the world of sexual selection and evolution, it’s always anyone’s game.
Whatever path you choose we wish you the best of luck, and if you're going to try to sneak around with some females in the harem, watch your back!
References
"Southern Elephant Seals of Sea Lion Island – A Long-term Research Project" (PDF). www.eleseal.org. Retrieved 2021-01-13.
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Mark E. Harrison, David J. Chivers(2007) The orangutan mating system and the unflanged male: A product of increased food stress during the late Miocene and Pliocene?, Journal of Human Evolution, Volume 52, Issue 3, Pages 275-293, ISSN 0047-2484, https://doi.org/10.1016/j.jhevol.2006.09.005
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