Redback Spider Case Study

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.

Mate choice is a product of mate preferences form in the environment of evolutionary adaptiveness (EEA). Sexual selection suggests that females prefer males who they can gain benefits from such as gifts. This is shown in male birds who make nests for females in order to mate with them and also in insects who give nuptial gifts.

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

In insect species with indirect sperm transfer, sperm is packed in a spermatophore that is either externally attached to the female 's genital opening or introduced into her bursa copulatrix. Sperm transfer is not immediate in these species, and consequently mate guarding has been suggested to function as a mechanism of guarding sperm until it is released from the spermatophore into the female (i.e. spermatophore guarding). Spermatophore guarding is relatively common in insect species with external spermatophores (e.g. Orthoptera; Alcock 1994; Simmons 2001), but supposedly absent in species with internal spermatophores and rapid sperm release (Simmons 2001). This study focuses on two hypothesis associated with mate guarding a tactic of many species that adjust their reproductive behaviour according to the apparent risk of sperm competition. The phenomenon of mate guard to consider sperm competition levels and evolution of internal spermatophore guard is wide spread in insects and other animals. We analyse two hypothesis one the rival exclusion followed by the next spermatophore renewal hypothesis. Results showed that as rival was introduced to the arena of mating of the distinctive original male (guard) in many cases showed a strong aggressive behaviour regardless of whether successively avert the rival. In the second hypothesis certainly majority of the incidents showed an attempt of

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.

Answer: It should been done after project. The reason is normally managers got the data after R&D projects before they make the decision of profit. The profit was not certain before and during R&D projects.

Each category of the book is filled with questions that range from why some organisms find copulation boring in their relationships to simple anatomical questions. Dr. Tatiana answers each of the proposed questions with comparisons to other organisms that experience the same situations. By doing this, she further provides readers with information on multiple organisms.

Predatory selection demonstrated heavily on how the predators prefered brighter males and how females then resorted to whatever was left. From my data of mostly drab and mostly bright guppies with the simulation having 30 rivulus, 30 acara, and 30 cichlids, I could see a clear trend. For the mostly drab guppies, in a mere 7 generations or 141 weeks, showed that the predators had wiped out the brighter guppies having a split demographic of 0% of the brightest and bright guppies, 30% for drab guppies and 70% for the drabbest of guppies. In the mostly bright guppy test, it was more even but showed an obvious lean towards the drabber guppies having 20% and 17% for brightest and bright guppies, and 17% and 46% for the drab and drabbest guppies respectively. With all this data, the trend leaned towards having the bright guppies

Analysis on faecal matter showed that turgescence of baboon ano-genital swellings links to the follicular phase of the ovarian cycle, while deturgescence links to the luteal phase, leading to the conclusion that the swellings are under the influence of hormonal control in primates (Gillmann and Gilbert, 1946). This suggests that the role of sexual swellings is to visually indicate the onset of ovulation to male non-human primates. It is observed that swellings indeed attract males independently of olfactory or behavioural cues (Bielert 1982; Saayman 1970) suggesting evolution of this attraction to larger swellings occurred due to the reproductive success associated with it. Males that are able to recognise swellings, discriminate between them and to mate with the female when hers are largest, would have higher chances to sire an infant, resulting in high selection pressure on males to react to swelling state.

In 1981 Owen Lovejoy suggested that behavioral mechanisms were a factor in the switch to bipedalism. This behavioral mechanism helped hominids in reproductive processes. Having the hands free to carry food and other things to the mate and offspring is seen to be a strong selection factor for choosing a mate. Having a such factor helps with reproductive success in a monogamous mating structure similar to what humans have today (Jacobs, 90). When

Males and females differ considerably in how much they each invest in order to make offspring and a result of this, they approach mating with different methods. Researchers and scientists learn and examine these varying mating systems to explain how males and females pair up. A mating system explains the techniques males and females use to pair up when selecting a mate. It is important to begin by reviewing and understanding the reproductive strategies among primates. The major types of mating systems found in primates are monogamy and polygamy. Monogamy is a practice of mating in which one male pairs with one female. Polygamy also known as bisexual, is a pattern of mating in which a male mates with more than one female and a female mates with more than one male (Wong , 2010). Polygamy is then clarified into polygyny and polyandry. Polygyny is when one male mates with multiple females. Polyandry is when one female mates with multiple males. Recognizing the diversity of mating systems will help in understanding the interactive relationship of sexual size dimorphism and behavior in primates.

Red Tailed Catfish mating systems are diverse and sexual selection is expected to be stronger in some lineages than others. In particular, polygynous mating systems and female-only parental care set the stage for potentially strong sexual selection by female choice. But does such intraspecific choosiness target the same coloration traits that also determine assortative mating.

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

The first few chapters discuss in depth both the general rules for mate selection and the differences in mate selection and varying preferences for male and female genders. As explained in the intro the author theorizes that the current behavior of humans in relation to mating behavior can be linked to our evolutionary past. He references Charles Darwin 's theory of evolution and his idea of natural selection, which is the the process through which organisms adapt to their environment and in doing so tend to