tedarling's blog

With the advent of technological innovations humans are now capable of modifying the environment at a previously unprecedented level. Advances in medicine, such as the development of penicillin, have saved countless lives. Modern agricultural methods have vastly improved the amount of food that can be harvested. Building towns and infrastructure has ensured that humans are no longer isolated from each other. At first glance it may seem as though these recent changes in human history would halt evolutionary change. However, modern humans certainly still face challenges to survival and exhibit varying reproductive success - the fodder for evolution.

These researchers studied the relationship between predation and reproduction in hermit
crabs. The researchers studied 100 hermit crabs placed in a water table and exposed to predator
odors. In the presence of these predatory odors, fewer mating pairs were established. This is
likely because mating would place the hermit crabs at a higher risk of predation. The experiment
is very relative to Endler’s because it once again portrays the risks and balances between mating
and predation.

These researchers investigated whether cricket calling-bout length was correlated with predator avoidance behavior. It is known that male crickets call to attract mates, however this behavior also poses as a significant predation risk. Calling lengths were measured using audio monitors over several days. Predator avoidance was measured by analyzing cricket behavior; Specifically, their likelihood to emerge when transferred from a safe shelter to a new potentially dangerous environment. The data show that calling-bout length and latencies to emerge were significantly and positively correlated. The males that called for longer, also took longer to leave their refuge. This experiment related to Elder’s because it also deals with the balance of sexual selection and natural selection. However, this experiment shows that crickets with longer calls have adapted to the increased predation risk by exhibiting more cautious behavior.

Figure 1. Salticus scenicus eating prey. Creative Commons licensed image by Tom Houslay

https://flic.kr/p/nyWmve

All tetrapods have the same body layout, or plan. This is further striking evidence for common descent. Even fish have remnants of limbs from their ancestors. Additionally, animals share similarities in embryonic development. This abundant evidence supports another main theme in Your Inner Fish, that similarities between animals can be explained with common descent. Shubin makes this work of scientific literature more readable for the average person by using reasonable prose and frequent humor. Because of this, I believe this was an extremely effective book. One of the most difficult challenges a scientific author can face is having their book not be read because it is too dense and dull. Shubin wrote a novel about the evolution of the human body and made it enjoyable for the average person, a remarkable feat.

These researchers studied wolf spiders and the relation between mating success and predation. Male wolf spiders are known to court females by drumming dry leaves with their abdomen. However, this action is energetically demanding and poses mortality costs. To study wolf spiders, they constructed a plastic arena and filled it with dry birch leaves. Three males and one female were placed inside, their behaviors were measured and analyzed until the female responded to one of the males. Then a lizard was introduced into the arena and the rank in which the males were predated was determined. The researchers concluded that higher drumming rates benefited males by increasing their mating success. However, mate searching and drumming also directly increased predation risk. This experiment is similar to Endler’s because it deals with the same sexual selection and predation balance. It shows that Endler’s experiments and conclusions regarding guppies can be applied to more species.

These researchers studied the heritability of secondary sexual traits in guppies. Specifically body size, fin lengths, and spot brightness, among others, were measured. To records variation in spot brightness video cameras, photography, and computers were used to analyze differences in spot hue, spot saturation, and spot brightness. The inheritance of male traits was analyzed using offspring parent regressions. The data show that male guppies show high variation in sexual traits. Furthermore, regression analysis showed a significant relationships in traits such as fin lengths, body size, and area of orange spots between fathers and sons. Therefore, indicating that these traits are likely heritable. This experiment is very relative to Endler’s experiment because it shows that these traits are indeed heritable and variable.

In fact, all tetrapods have the same body layout, or plan. Which is yet again striking evidence for common descent. Even fish have remnants of limbs from their ancestors. Furthermore, animals share similarities in embryonic development. This abundant evidence supports another main theme in the book, that similarities between animals can be explained with common descent. Shubin makes this work of scientific literature more readable for the average person by using reasonable prose and frequent humor. Because of this, I believe this was an extremely effective book. One of the most difficult challenges a scientific author can face is having their book not be read because it is too dense and dull. Shubin wrote a novel about the evolution of the human body and made it enjoyable for the average person, a remarkable feat.

In multicellular life all of the cells must be interconnected with intricate process that keep them alive and supplied with energy and other resources. This is one of the reasons why unicellular life proliferated well before multicellular life. Shubin states: “Here’s a humbling thought for all of us worms, fish, and humans: most of life’s history is the story of single-celled creatures. Virtually everything we have talked about thus far—animals with hands, heads, sense organs, even body plans—has been around for only a small fraction of the earth’s history. Take the entire 4.5-billion-year history of the earth and scale it down to a single year… Until June, the only organisms were single-celled microbes, such as algae, bacteria, and amoebae... The first human appears on December 31(Shubin 158).” The novel obviously focuses on the evolution of the humans body. However, Shubin does a remarkable job of keeping everything in perspective and highlighting just how anthropocentric we are. It is important to highlight the sheer number of species that came before us, because we are merely a conglomerate of remarkably similar DNA and morphological features.

Walking may seem as though it consumes a trival amount of time. However, I spend a surprinsing amount of time walking to different destinations every day. Yesterday I walked to Curry Hicks, Herter, the Rec Center, Frank Dining Commons, Morill, the Library, Totman, and to my dorm. I also walked to some of these places several times. The journey grows ever long and perilous.