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Posts Tagged ‘reproduction’


An Analysis of a Media Portrayal of Goat Pheromones

July 7th, 2014 by cer7

 

Scientists have long searched for a tangible molecule that produces an effect on females called the “male effect” (Murata et. al. 2014). The male effect is a physiological process that causes the reproductive cycle of females to change in the presence of the scent of males. Researchers at the University of Tokyo were looking for a primer pheromone that would cause this change in the ovulation cycle of female goats, and they may have finally found one (Murata et. al. 2014). The researchers collected the smell released from a male goat’s head (known to be a place that secretes the most smell on a goat) and analyzed the chemical components of the mixture. Then, they isolated components and looked at which components elicited the biggest response in the female goat brain. They analyzed the female goat brain by looking at how many times her “GnRH pulse generator” was firing. GnRH is the gonadotropin-releasing hormone that activates LH (luteinizing hormone), which in turn causes female mammals to ovulate by stimulating their eggs to grow. When the GnRH pulse generator fires, GnRH is stimulated, and the researchers reasoned that this process caused ovulation in the female goats. This research could lead to some exciting new knowledge about the reproductive system of female mammals (especially other ruminants) and how it is affected by male pheromones.

The press release from this study was published in Science Daily very soon after the study was published. I found it interesting that the writing in Science Daily puts a heavier emphasis on human implications than does the original paper about the experiment. Science Daily publishes the quote “there is reason to think the findings will apply to other livestock, and perhaps even to humans, too” (Science Daily, 2014).  After reading the original paper from the researchers, I only noticed one mention of human implications, and the authors were discussing how the research would help humans to better breed livestock. The press release also uses words that seem to dumb down the scientific terms that the original study uses. For example, the press release uses the phrase “central reproductive axis” instead of using the actual terms for the neurotransmitters and the parts of the brain. These changes are logical considering that press releases are for a broad audience, and the emphasis of the press release might make the information more accessible to other scientists or the general public. (more…)

Seychelles Warbler Cooperative Breeding

July 2nd, 2014 by Alyson

This is my added edit to the Seychelles Warbler wikipedia page. I added the section for Cooperative Breeding that can be found here: https://en.wikipedia.org/wiki/Seychelles_Warbler#Cooperative_Breeding_Habits

Cooperative Breeding

Seychelles Warblers demonstrate cooperative breeding, a reproductive system in which adult male and female helpers assist the parents in providing care and feeding the young. The helpers may also aid in territory defense, predator mobbing, nest building, and incubation (females only).[1] Breeding pairs with helpers have increased reproductive success and produced more offspring that survived per year than breeding pairs with the helpers removed.[2] Helpers only feed the young of their parents or close relatives and do not feed unrelated young. This is evidence for the kin-selected adaptation of providing food for the young. The indirect fitness benefits gained by helping close kin are greater than the direct fitness benefits gained as a breeder. This could be evidence for the kin-selected adaptation of providing food for the young.

On high-quality territories where there is more insect prey available, young birds were more likely to stay as helpers rather than moving to low-quality territories as breeders.[3] On low quality territories, having a helper is unfavorable because of increased resource competition. Females are more likely to become helpers[4], which may explain the adaptive sex ratio bias seen in the Seychelles warblers. On high quality territories, females produce 90% daughters; on low quality territories, they produce 80% sons. Clutch sex ratio is skewed towards daughters overall.[5] When females are moved to higher quality territories, they produce two eggs in a clutch instead of a single egg, with both eggs skewed towards the production of females. This change suggests that Seychelles Warblers may have pre-ovulation control of offspring sex ratio, although the exact mechanism is unknown. (more…)