Alectrurus risora: Does female preference for good quality grassland affect male mating success?
Introduction
The Strange-tailed Tyrant (Alectrurus risora) is a species that is endemic to southern South America. Over the years the species has become globally vulnerable due to severe habitat loss. Over 90% of its habitat has been lost due to fires and human interference. This has caused populations to become concentrated in certain areas, particularly in the Iberá wetlands which is in the province of Corrientes in north-east Argentina (Di Giacomo et al. 2015)
In the wild females use the grass, Imperata brasiliensis, for nesting. A previous study has shown that when a plot of land has sustained a fire in the past breeding season, females avoid
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Conversely, an indirect relationship suggests that the trait decreases fitness.
If the null hypothesis is valid then there must be another factor at play that influences mating success. Therefore, it can be stated that female preference for tall Imperata brasiliensis plants has no effect on the male’s fitness. A male with poor quality territory will have the same mating and reproductive success as the male with better quality territory. Therefore, neither male possesses an advantage over the other.
If the female preference for tall grass does not affect male mating success, then perhaps the elongated, extravagant tail that males sport is what predominantly influences mating success. For example, if researchers noticed that the males with more mates had longer tails than the males with less mates, then the next step would be to conduct a study determining whether mating success is influenced by the length of a male’s tail. In some birds, such as the long-tailed widow bird (Euplectes progne), a male’s mating success is dependent on the length of the tail (Andersson and Andersson 1994).
Literature Cited
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Wise, M. J., Abrahamson, W. G., & Cole, J. A. (2010).The role of nodding stems in the goldenrod–gall–fly interaction: A test of the “ducking” hypothesis. Manuscript submitted for publication, Available from American Journal of Botany. (0900227)Retrieved from http://www.amjbot.org/content/97/3/525.full
The red-cockaded woodpecker, an inhabitant of mature pine forests and pine-grassland ecosystems from Maryland to eastern Texas, has had a troubled history within the last decade (Roise et al, 1990). Ten years ago, James documented a population decline in America’s largest remaining red-cockaded woodpecker population (1991). Of the 2,157 clusters, or living groups, contained in national forests, 693 of them were located in Florid...
In 2012 by Laura A. Kelley and John A. Endler that the male bowerbirds use illusions to promote their mating success. They followed this study up in 2014 due to large amount of controversy with their findings. In their 2012 study, they suggested that male bowerbirds actively maintain size-distance gradients of objects on their bower courts that create forced-perspective illusions for female’s viewing their display from within the bower avenue (IPMSIGB). They argue that the females view males displaying over the court with a predetermined viewing geometry and that it’s essential for forced perspective viewing. They also argue that the males arrange ...
The female reproductive system in birds is reduced in most species to a left ovary and oviduct. This unilateral reduction of the female reproductive system is thought to bear two benefits: it reduces the female’s body and it prevent the potential problem of simultaneously carrying two large fragile eggs within the abdominal cavity. It also balances the body with the liver on the right side adjacent to the left ovary.
According to recent studies, the saolas are categorized as critically endangered, with its population size estimated to the miniscule numbers from 70 up to 7...
"Persistent female choice for a particular male trait values should erode genitive variance in male traits and thereby remove the benefits of choice, yet choice persists” (Miller, Christine and Allen Moore). This phenomenon is know as the Lek Paradox and has puzzled scientists for many years. Throughout all species there has been abundant evidence showing continuous female choice of male traits, yet there is still no definite answer as to what allows for genetic variance to be maintained, and why a specific trait never becomes fixed. Many hypotheses have been theorized and researched, all providing some explanation as to how this variance in species is maintained, from traits signaling resistance to parasites, according to Hamilton and Zuk, to the hypothesis of mutational and environmental affects. Condition-dependence can also provide information as to how the lek paradox is able to exist; this hypothesis will be looked at in this paper.
Some individuals have developed different traits to help them in the process of intra-sexual competition. The organisms with more distinctive traits have greater reproductive success. More genes of those traits are then ‘selected’ and are passed onto the offspring of the organisms. Throughout time variability in these traits becomes
Parental investment is proven to be one of the main causes of gender differences seen in mating strategies (Kenrick et al. 1990). Parental investment is defined as the extent to which a parent sacrifices their own needs to invest in their offspring (Kenrick et al. 1990) and correlates with mating strategies in that the sex with the most invested is choosier. In human populations, because the parental investment for a female is longer than for a male, females tend to be choosier when deciding on a mate (Trivers, 1972). This is evident in the study by Clark and Hatfield who designed an experiment where college students were asked to consent to three questions ranging from a date to having intercourse (Clark & Hatfield, 1989). The results showed...
Social groups of primates closely relate to sexual dimorphism, because how each of their communities interact with one another plays a large role in sexual selection. Sexual selection, as Darwin stated, is a key factor and cause in the morphological dimorphism between sexes of a species. Additionally, sexual selection comes from male competition, which directly correlates to primate’s social structures. For example, genus gorilla is a part of a polygynous mating system, which consists of one male and multiple female. This creates an environment where males must compete with one another to reproduce and create offspring. Due to this competition, males must prove to be strong and attract themselves to females to ensure reproductive success. These strong male traits are favored in sexual selection, because the females are highly particular about the male they mate with, so there become specific male traits that are most desirable. Therefore, in polygynous groups, sexual dimorphism is the greatest (Frayer, Wolpoff, 1985). In comparison, a monogamous primate such as genus hylobate or gibbons has a social structure that consists of a more nuclear based family. There is a lot less male competition because males do not mate with multiple females. Therefore, primates are less dimorphic in monogamous social structures (Frayer, Wolpoff,
In both of these forms of selection, traits or characters are favoured that improve an individuals fitness, or in other words, the ability to pass on the most amount of genes to the next generation relative to other individuals in its population. The two major components that are necessary for an individual to carry on its genes to the next generation are survival and reproduction. As previously mentioned, males and to a lesser extent females, use traits in courtship that interfere with their survivorship. This means that a concession can be made between survivorship and mating success and that natural selection and sexual selection can apply conflicting selection tension on a
In addition Bateman (1948) suggested that sexual selection is defined by the different levels of investment by each sex to their offspring. Females invest more heavily in offspring as fertilisation, gestation and placentation all occur within...
In order to understand the present lifestyles relating to different approaches and tactics applied by humans in mate choice preferences, there is the need to refer to Darwin (1859, 1871) evolutionary perspectives. Darwin (1871) sexual selection is the driving force for males and females reproductive quest for their genes survival. These driving forces have been classified into two categories as intra-sexual and intersexual mate selection.Intersexual selection is male sexual selection process whereby males compete with other males and the females choose the strongest as their ideal partner. Intra-sexual selection occurs when the male species fight among themselves and the strongest gain access to females for
Eastman, J. (1997).14-Crow and Jay Family (Corvidae). Birds of forest, yard, and thicket. (pp. 127- 145). Mechanicsburg, Pa: Stackpole Books. Retrieved from: eBook Collection (EBSCOhost) [Accessed 3 March 2014]
This standard model is known as the seual strategies theory ( Buss & Schmitt, 1993). Buss argues that any species in which differences exist, there will be corresponding sex differences in mating behaviors. The biological reality in humans is that males need minimal investment, a single ejaculation, to reproduce their genes. The cost of female reproduction is traditionally years of investment including gestation, lactation and offspring care. In theory, such one sided investment has resulted in sex-specific selection strategies for reproductive success (Beckes et al. 2009). Human males ‘naturally’ track down opportunities to copulate with as many female partners as possible, specifically those who display signs of fertility. By ‘nature’ human females are more sexually cautious and prefer one male partner who can provide resources to be shared with their offspring. Though emphasis is on sex differences, sexual strategies theorists state that mating behavior--under specific circumstances--can be similar between men and women. The inevitable conclusion from their work is the differences between the sexes regarding mating preferences. The main focus of the sexual strategies theory is that all human mating is inherently strategic. Mating behavior is guided by psychological mechanisms that compel both males and females to desire certain qualities in a mate based
These methods of sexual selection include both before and after mating, and has competition between two males, two females, or competition between both genders of wasps. One of the most obvious forms of sexual selection in social wasps is between females. This is simply that queens of a high rank have higher mating success (Baer 2014). This method of sexual selection follows the natural hierarchy of social wasps, where one wasp is “in charge” (the queen), while others simply do the work for the colony (the workers). The other forms of sexual selection include the male to male competition of territory establishment, where males fight for territories and mark those territories to attract queens, and competition of male ornaments, which is a competition between males to see which one has the best ornaments and a competition between females for them to pick the male with the best ornaments. The males with bigger, darker dorsal spots generally have a better chance of mating (Baer 2014). This causes sexual selection competition between males, who try to have the darkest dorsal spots, and between females, who try to pick males with the darkest dorsal