Module 11: Speciation

In order for something to become a new species, there has to be a big enough genetic difference that occurs that makes mating with each other unsuccessful impossible. When a new species is formed, it is called speciation. When I was looking up the different way speciation can occur, I found four modes that seemed the most important that I will list below. 

Allopatric: new species formed from geographically isolated populations

Peripatric: new species formed from a small population isolated at the edge of a larger population 

Parapatric: new species formed from a continuously distributed population

Sympatric: new species formed from within the range of an ancestral population 

(Link: https://evolution.berkeley.edu/modes-of-speciation/)

If you are still a little confused, I found this chart to be helpful! In fact, the picture comes from a set of slides created by a professor(?) at the University of Washington. It is chalked full of examples of all these modes as well as a more in depth analysis of what they are!

(Link: http://courses.washington.edu/gs453/lectures/lec23.pdf)

(Edit: it seems like this picture is not loading. It is located on slide 14 on the powerpoint. My bad!)

After reading a bit more into these modes of transportation, I definitely think the speeds of which they happen are all different. As for the fastest mode, I think it would have to be allopatric speciation. This seems to be the mode that happens the most naturally, so therefore it's probably naturally selected. Plus, this only occurs when there is a physical barrier. It seems that once a barrier is put in place, things quickly evolve to be different. Additionally, when a population is split up, it reduces the population size. This means that mutation has a much bigger effect, and can gain a foothold quicker in the population, or that's what I think at least!)

Module 10: Courtship

The Microphis deocata, a pipefish species, is an example of sexual dimorphism, as mentioned in the instructions. I did not know exactly what this term meant, so I looked it up. According to Oxford Languages, sexual dimorphism is the, "distinct difference in size or appearance between the sexes of an animal in addition to difference between the sexual organs themselves" (Oxford Languages). In the video that we were shown, the female had a round protrusion coming off of her, while the male did not. Usually, males have the more interesting or "pretty" features, as they are trying to attract a female in order to mate with them. According to Darwin, sexual selection is responsible for traits specific to a gender. Sexual traits can be divided into two categories: traits that help create a weapon to fight off other competition, or a trait that helps to improve the attractiveness of an animal, (these traits don't have any purpose besides ornamentation), (Scientific American). In the case of the Microphis deocata, I think that the trait in the female is just used for ornamentation and not as a weapon to fight other females off. 

I made a hypothesis before looking at anything about the species of pipeline fish. Below is my hypothesis.

The female Microphis deocata would have the more colorful features with the reason that maybe there aren't many males in the population, so if the females want to mate, they have to stand out. This would make sense on why the males don't need to stand out. If there is a small number of them, then they would not need to compete like they normally might need to.

After making my hypothesis, I looked a little more into the Microphis decoata. In turns out that the male fertilizes the egg in the female, and then the female puts the fertilized egg into the males pouch, (like a seahorse!), (WalterCrews). So, the males are in short supply in this case because they are putting in the extra work of intubating the baby pipefish. So, since the roles of "pregnancy" are reversed, it would make sense that the sex that had the stand out traits would switch too!

Sources:

Oxford Languages: https://www.oxfordlanguages.com

Scientific American: https://www.scientificamerican.com/article/why-are-male-birds-more-c/

WalterCrews: https://praquatics.com/forums/threads/rainbow-belly-pipefish-microphis-deocata.4136/