A Bit of Background Information What is pre- and post-copulatory sexual selection? From the word copulatory, meaning to engage in sexual intercourse, pre-copulatory sexual selection refers to the female's choice in selecting a mate before sexual intercourse takes place. Post-copulatory sexual selection occurs within the female's reproductive track, and it describes the biological selection (whether due to sperm or the female's biology) that results in the fertilization her eggs. Why are guppies good subjects for research in this topic? The most significant reason for using guppies in sexual selection research is because they casually participate in polyandry. This means that in nature a female guppy will mate (willingly or unwillingly) with numerous males at a time, allowing for experiments to be conducted to see which male's sperm fertilizes the most eggs. Why use artificial insemination? Before the use of artificial insemination, the results of such experiments were obscure and varied greatly. There was no way of controlling the males' ejaculate sizes or thier specific sexual contact with the female guppies. By using artificial insemination techniques, these two variables can be controlled: equal quantities of sperm from each male guppy can be isolated, and no sexual contact need ever take place. The increased control over these variables makes it possible to attain reliable results that are directly related to postcopulatory processes. Introduction Sexual selection is a common facet of evolutionary biology that plays a key role in the mating choices of a variety of different species. Competition between the male’s sperm as well as the choice of mate by the female factor into a successful copulation.This experiment examines the precopulatory and postcopulatory behavior of Poecilia reticulata , the guppy. Artificial insemination was used to separate the factors of sexual selection before and after sexual intercourse. “Attractive” males in the guppy population—deemed attractive based on the female guppy’s affinity for them—were those with high levels of carotenoid coloration (orange, yellow, and red). Relative statures were also compared. The purpose of this experiment is to demonstrate, through artificial insemination, the role of postcopulatory sexual selection in a population of guppies. If guppy females are partial to specific traits, the propagation of those traits will be evident. The Methods That Were Used Prior to insemination, the behavior of the guppies involved was analyzed and one adult, non-virgin female and two sexually immature fish were put in observation tanks.
The humuhumu are a very independent and aggressive fish therefore they breed externally,but still heterosexualy.. Once they reach the age of maturity, the female will lay her eggs in the wedges of a coral which will then be fertilized by a male soon after. Then once they are fertilized the female will come back and guard the ...
The Longnose gars reproduction depends on location that the gar is found in. The reproduction does typically happen during the spring or summer months and all dependent on what the water temperature. The female gar will swim into a small, fast moving stream and lay their eggs (Goddard). The Longnose gar eggs are not just normal eggs that most people think of when they think of fish eggs. Their eggs are green and sticky so they can stick to the plants in the fast moving stream (
The gametophytes used in this experiment are of C-ferns. They tend to mature and produce spores at temperature of 28oC and conditions of high humidity. The spores that germinate first are hermaphrodites. Hermaphrodites tend to produce a pheromone called antheridiogen. It is this pheromone that causes later germinating spores to become male.
The courting ritual begins with the males circling females in an offshore mating ground and then the males approach and bite a female’s neck and if she accepts, they mate; if she does not accept, she swims to the bottom of the mating grounds (Deurmit L 2007). Males have long claws to use during mating because other males try to remove the mating male in order to mate with the female (Deurmit L 2007). Caretta caretta are polygynandrous and breed seasonally in the early summer (Deurmit L 2007). With mating, the females have the ability to store sperm throughout the reproductive season (Sakaoka K et al.). This characteristic developed with “changes in the sperm storage tubules (SSTs) in the oviduct” and allows the females to reproduce more (Sakaoka K et al.). This storage helps to combat climate change because Caretta caretta, as a species, only breed during certain temperatures (Sakaoka K et al.). Female loggerhead turtles have developed sperm storage abilities within mating to combat climate
This report is on a virtual experiment based on the real-life experiment accomplished by John Endler and David Reznick of the University of California. The goal is attempting to determine whether or not the level of predation effect’s the color patterns of guppies.
There is a lot of controversy regarding the use of technologies that allow sex selection. Modern science allows parents to choose the sex of their future child. Although this could be an effective way to determine genetic disorders, I do not support screening to be used solely for sex selection as this can lead to social inequality and gender bias.
Wofford, Sarah Jane. "Sex and Fighting: Male and Female Crayfish Utilize Different Assessment Strategies During Agonistic Behavior." MS thesis Graduate College of Bowling Green, 2013. Web.
1996). A study was done to examine the different parent-juvenile interactions of two different species of poeciliids: P. Monacha and P. Lucida. Individual females of the two species were place into chambers that had a mesh net to segregate it and allow juveniles to swim through and escape attack from the parent. The females were kept in these chambers as they birthed offspring and were recorded. It was found that the p. monacha females cannibalised their offspring immediately while the p. lucida females did not (Thibault 1974). The p. monacha juveniles that did escape the initial attack, swum to the bottom and through the mesh net. However, the juvenile p. lucida remained in the same section of the chamber with the female near the water
Females like to choose mates who have very bright colors as it is a sign of the male’s good health and vigor. The natural and sexual selection can affect populations in three ways: directional (environmental conditions change in a consistent direction; one extreme of phenotypes is favored), stabilizing (environmental conditions are relatively constant; intermediate phenotype is favored), and disruptive selection (environment has more than one type of useful resource; both extremes of phenotypes are favored). An example of directional selection is pesticide resistance since only the insects with a resistance are favored; an example of stabilizing selection is that the smallest lizards have a difficulty defending their territory whereas the largest lizards are most likely to be eaten by owls; an example of disruptive selection are the black-bellied seedcrackers since they either have a large beak (which they can use to eat had seeds), or a small beak (which allows them to eat soft seeds). Disruptive selection shows a balanced polymorphism, which is when two or more phenotypes are maintained in a
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
Sex reversal has been observed in reptile species that rely on temperature-dependent sex determination when exposed to high levels of BPA. An example of this can be seen in a study done by Stoker et al. (2003). Researchers found that eggs treated with 90ugBPA/egg produced females when incubated at the male-specific temperature (reviewed by Flint et al., 2012).
4) In some animals, the roles of the genders may be switched. In seahorses, the males are responsible for giving birth and raising the offspring. In this case, males have more at stake and so the males are the “choosier” mate. They choose a female mate based on the female’s characteristics.
Gender stereotypes have existed since the beginning of modern man. We've all heard them before; male dominance and female weakness, a controlled male and a flustered female, aggression and passion, and many others that all basically boil down to the same thing. Emily Martin, in her essay entitled The Egg and the Sperm, takes this problem of gender stereotype to a new and much more serious level. As an anthropologist, Martin is concerned with the socio-cultural impacts on many different aspects of everyday life, including biology. In doing her research for this article, Martin was trying to uncover suspicions she had about socio-cultural gender stereotypes, and the affects they had on the diction used to describe egg and sperm interactions in numerous biology books and research reports.
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
The female red Oophaga pumilios prefers to only mate with red males which leads to speciation. According to GrrlScientist, 4 researchers conducted an 18-month mark-recapture study on this. These researchers captured 677 wild Oophaga pumilios (312 males, 274 females, and 91 juveniles) (GrrlScientist, “Choosy Females Speed Speciation of Poison Dart Frogs.”). When the researchers analyzed the data, they found that 91% of the females mated with red males. With the yellow females, there was no clear pattern on how they mated leaving out that most of the frogs were red. That leaves the frogs that were yellow not being able to breed down. If this was to continue, then the frogs would separate and become different species of different