Intrasexual Selection

Sexual selection was an idea proposed by Darwin and refers to the process in which males and females attempt to maximize their chances of reproductive success. Within a species there are certain characteristics that make individuals attractive to potential mates. An example of this is in peacocks, female peacocks are attracted to males with long brightly colored tails, even though this makes them easier to be spotted by predators. This characteristic then evolves within the species due to how males with this characteristic have a higher chance of reproductive success and their characteristics being passed on to surviving offspring.

Sexual selection can best be described by the definition given by Darwin himself. Sexual selection is “the advantage which certain individuals have over other individuals of the same species solely in respect of reproduction” (Hosken et al, 2011). Sexual selection occurs throughout the animal kingdom, where male frogs dominate through the depth of their croak, and certain peacocks reign superior based on the colour and intricate detail on their tails. They remain superior to their lesser counterparts as they bear more admirable characteristics, from which they are chosen by females of the same species.

Another evolutionary explanation of gender development is mate choice, which suggests that gender role behaviours are related to reproductive strategies. It is thought that men will look for women who are young whereas women are usually more interested in the resources of a mate. This can be explained from an evolutionary perspective as mating with a physically attractive woman

When one male group doesn’t have the luxury of having females, they form or join a group of males similar to a bachelor’s group. In some of these species, the group of males attacks the one male group in order to take his throne and seize the females (Hoglund, J. 1995). Sometimes, the females may get tired of sharing the male with the other females in the group. Hoglund recorded (1995, pg. 76) “so they seek out males from all male groups to mate with during breeding season. Such influxes occur seasonally between blue monkeys (Rowell, 1988), Hanuman Langurs (Boories et al., 1999), ring-tailed lemurs (Sussman, 1992), and sifakas (Richard 1992).” A nonhuman

For this discussion, I chose to examine the reproductive nature of mountain lions and hammer head sharks. Mountain lions are solitary cats that live in various mountainous regions of north and south America, but a male and female come together socially in order to mate during the 3-10 day estrus period. Due to their solitary nature, mountain lions rely on scent marking in different territory as well as a mating call of the female in order to initiate the potential for sex. Typically, when a male and female find each other; they spend several days together during the mating period and he may hunt for her and run mating circles around her. Mountain lions are polygynous and both the males and females will mate with multiple individuals throughout

Judson contributes to onefs understanding of sex among different organisms in that she makes difficult concepts simple to comprehend. Although she uses scientific terminology, she limits it so that anyone can understand the technical information she shares. Judson also describes the types of environments in which each species and

The male is the one to show off to attract a mate. Sometimes you'll see the male pick up a seed, hop over to the female, and the two momentarily touch beaks as she takes the food, this is called “mate feeding”. Females choose their mates based on the male’s qualities such as the size of his black face mask as well as the color of his plumage and bill. When the female agrees to become his mate they sing to each other.

The ASR, for example, is population-specific but its effects underscore the pervasive and recurring issue of sexual conflict. In Rossmanith (2006), male-biased ASR was correlated with increased occurrence of polyandry in the lesser spotted woodpecker (Picoides minor). In song sparrows (Melospiza melodia), males were monogamous at times when there was an excess of males, but were inclined to polygyny with the materialization of female-biased ASR. Liker (2014) summarized that polygamy by males is much more frequent with female-biased ASR than with male-biased ASR, whereas polygamy by females is more common at male-biased ASR. The favorable sex subsequently pursues auspicious mating opportunities and can desert their mate, often to re-nest with a new mate (Pilastro

Sexual sections is one of the processes of natural selection in which there is a competition for sexual reproduction, these competitions can be classified as intersexual or intrasexual. Intersexual competition occurs when one organism, usually female, chooses its partner. Intrasexual competition, on the other hand, happens when species from the same gender compete to sexually reproduce.

“Pair Living Primates have several unique characteristics that set them apart from other nonhuman primates. Monogamous Primates are two primates of different sexes that mate exclusively with one and other. The unique qualities of these animals are a result of the ecological constraints that these primates face. Because of the exclusive and solitary relationship that is monogamy there is a lack of specialized defensive roles by the adult male, which is also extensively involved in paternal care. Monogamous primates are highly territorial and very closely associated, Morphologically, there is a lack of sexual dimorphism amongst pair living primates, this is due to the exclusively and predictable genetic outcome of these animals mating with only

They based their study on the animals’ DNA and to provide evidence that sexual selection acts more strongly on females than on males. They collected Gulf pipefish from the Atlantic coast of Florida. To test monogamy, female pipefish were constrained to mate with a maximum of four males. As a result, much evidence was found to indicate that females experience stronger sexual selection than males in the population of Gulf pipefish. The average number of mates per female was about two while the number of mates per male was exactly one. This evidence is described as polyandry, which in this case produces stronger sexual selection for females. The variance of female mating success was seven times higher than male mating success. The only downfall for this experiment was that some male pipefish that had been collected may had recently given birth and may have been preparing their brood for a succeeding pregnancy. It was also found that mating females were larger in size and more embellished than average, concluding that males may prefer to mate with larger and more embellished females. In conclusion, the Gulf pipefish appears to have an extreme form of polyandry and it is supported that females have a far stringer sexual

Because of the environment an anglerfish lives in the male is always looking for a mate. Male anglerfish are always smaller than female anglerfish. They have evolved to be parasitic as they attach to the female anglerfish for nutrition. The reproduction process of anglerfish, is an interesting example of sexual dysmorphism. A male anglerfish bites into the female anglerfish with its teeth and attaches to the female. As the male’s mouth and the female’s skin weld the male loses all organs except for his testes and his vision. The male anglerfish have large noses to sense the pheromones of a female, and while they are maturing they lose their jaw teeth and their digestive systems becomes delapitated. The tissues of a male and female anglerfish fuse together when an

One day, Jürgen Otto was walking in a forest and nearly stepped on a spider. The spider quickly jumped away and Jürgen had never seen a spider that looked like the spider Jürgen had almost stepped on. He looked on the Internet and in books but only found one picture in a book made in the 1970s. He had discovered the new species called the Peacock Spider. “Peacock Spiders are only about 3 millimeters long and are found only in Australia” (Jürgen Otto, 2005). Jürgen now spends over 40 hours a week studying these spiders Jürgen has found and learned to love Peacock Spiders and document their actions and interests. Jürgen has found over 10 new species of spiders for scientists.

Reproductive monogamy is defined as an exclusive sexual relationship between a female and a male based on their sexual interactions. Social Monogamy refers to male and female’s social living arrangement without sexual interactions. It refers to the living patterns, raising offsprings, and obtaining food. Monogamy is common in birds, but also occurs in invertebrates. Why would a male mammal choose to mate with one female when he can mate with more than one? Why would the male stay around instead of finding another female to live with? Many researchers have attempted to answer this question of why some mammals prefer monogamy over polygamy. Vole rats, one of the species that perform monogamous mating, demonstrate pair boding. Male and female pairs of vole rats have been observed together over several months, and the males stay with females even when the female is not reproductively active. A typical vole family in the wild is almost always consisted of one male, one female, and their offspring. In addition, unlike other species in which females are the only ones taking care of the offspring, vole rats share parental roles and even build nests together. Because they show these monogamous behaviors, they have served as a good species/model to learn about monogamy for neuroscientists. In this paper, monogamy, specifically in vole rats, will be explained along with its proximate and ultimate causes of this adaptation.

In site one, where the Parahomo fracticranius was discovered, it can be assumed that the habitat for the species was an open grassland due to the fact that other fossils of animals that lived in the area were grazers. Since there were 14 remains of both male and female sexes, it can be assumed that the P. fracticranius lived in a large multi-male, multi-female system. Based on the lectures from class, it is known that for most cases, multi-male, multi-female environments result in polypoly mating (Atkisson Lecture: Primate mating systems and primate evo). Therefore, it can be assumed that the P. fracticranius not only engaged in polypoly mating, but they also had some sexual dimorphism and large testes. The evidence that supports the sexual dimorphism claim can be seen when the body size of the female and male are compared since the male’s body size is 41 kg larger than the female’s.