Why Do Female Elephant Seals Prefer To Mate With One Male? Biology It is known that elephant seals have a large sex dimorphism in size among all mammals. They have a mixed life style, consisting of an aquatic phase and a land phase (breeding and molting). However, due to their strong aquatic adaptation, their terrestrial mobility is greatly reduced. They feed during their aquatic phase and fast during their land phase. While submerged in their aquatic phase, the elephant seals do a lot of deep sea diving in order to obtain enough food for their yearly land cycle. The seal's land phase is composed of about three month in which they come to land to give birth and mate before going back to their aquatic phase.
Normally appearing on land before their female counterparts, the alpha male elephant seals use this period to declare their dominance on the beach.
Before the females arrive on land the male normally appear on land up to three months before so that they can declare their dominance. According to Daly and Wilson in their book, Sex, Evolution and Behavior, the male elephant seal's " initial concern is the establishment of dominance in relationship among themselves." (Daly and Wilson 64). The more tenured male seals lay claim to the "prime real estate" on the beach followed by the younger bulls. Thus age and experience is the pivot around which dominance turns.
Secondly their agonistic behavior and interactions with other dominant males called alpha males. Alpha males are those seals at the top of the seal hierarchy, which means that they will control their own harem. Males achieve their dominance sometimes by fighting with other alpha males. Their excellent performance in competition between a dominant or more dominant male (due to age) seems to be a fundamental requirement for higher breeding success. In Sexual Selection by Malte Andersson, the author states that "less than one third of the males resident on the beach copulate during a breeding season, and most mating are done by a few males;" the dominant male.
However a male's dominance is constantly being tested and interrupted by threats and challenges from other alpha males. The males also loose a lot of energy during this time which might cause the male his life "immediately after his most successful year on the beach, presumably because of the degenerative effects of his incessant struggle to maintain higher rank," which " has huge payoffs in reproductive success" (Daly and Wilson 64). The males however increase their chances of mating by increasing the rate at which they court females. More attempted mating usually means more actual mating.
The tendency for elephant seals to group upon arrival on land favors the evolution of a harem. In this society, one or two alpha males have control over the females of that group/harem. They seem to have a polypynous mating system and it is known that where males are larger than females a polygyny system will prevail. Most females tend join harems as not to get harassed for mating by other ambitious males.
Even though evidence indicates that females can actively choose their mates, the question of why females elephant seals prefer to mate with one male at random, remains largely unresolved. In some cases, it seems that the females elephant seals favor mating with a larger male simply because he is easy to locate. Reducing the amount of time they take to find a mate may reduce a there risk of being harassed or even killed. For many mammals, natural selection appears to favor females who choose mates that provide them with some direct benefit that will increase their fecundity, their survival or the survival of their offspring. Such benefits might include food, a safe territory or even the prospect of less harassment. It also appears that the females are harassed mainly because there is a shortage of mating for the rest of the males available, which leads to them wanting to mate with the females at any risk or forced copulation.
However, in my opinion the only interest females elephant seals have in a mate is the fact that they provide them with some protection that they get to mate before returning to their aquatic phase of their yearly cycle. As a result, the female does not get to choose who hey mate with, basically they are overpowered by the stronger males.
Since the male elephant seals provide no obvious resources, such as food or affection, females may choose to mate with the males that appear to have the best genes. Females tend to prefer to mate with males having higher courtship rates or a higher rank.
It also seems to be a struggle between sexual selection, the biggest, meanest, elephant seal is trying to drive off all the other male elephant seals and keep a harem to himself. He can then pass on his alpha genes on to his offsprings. And the female's seems to go for the stronger male so that the dominant genes will be past on. The females would not go for a weaker male because they will not be able to provide security for them. Basically the weaker male would give up on the female when attacked by a stronger male and the females would always be harassed or even killed.
With all these evidence I can hypothesis that this goes back to Darwin's survival of the fittest and the fact that the female elephant seals preference is genetically determined. They appear to want the males with the most dominant genes, and these are the males that have the higher dominance among all the males. This is so because the inherited DNA will be pasted on and their offspring will acquire the strong genes so that when they become of age they will most likely be the dominant males.
I can also hypothesis that not being choosy and also accepting mate from a secondary or lower dominant male appears to be the female's tactic in reducing harassment.