Dr. Moalem talks of how humans have similar ancestors with apes from pages 198-204. Humans have less hair than other apes and walk on two legs. The theorem is that humans evolved in an enclosed area of water and land. Moalem explains how being on two legs allows humans to stay further in water, having downward noses allow us to dive, and having less hair lets us be more efficient in water. This connects to big idea #1 in which the process of evolution drives the diversity and unity of life. In the way that we have similar ancestors with apes with specific biological functions to make us more efficient in living in specific environments with water, other animals have evolved as well.
Other animals all evolve depending on their environments to increase rate of survival. One example is the finch. The finch evolved into three species with different beaks. These beaks, depending on where their environments were, helped them eat their food. Like the finch and humans, determine a specific animal and environment. Research how that specific species evolved and find how that biological function increases the rate of survival and reproduction for that specific environment. Have fun!
(Sam Lee salee4@students.d125.org)
According to Big Idea 1, the process of evolution drives the diversity and unity of life. Species must evolve in order to develop selective advantages based on the animals’ living environment. Darwin made his most famous observations while studying the different beak shapes of Galapagos Island finches. The finches each developed their own niche through allopatric speciation (living on the different islands). The finches’ niches proved to be selective advantages because the different niches allowed the finches to feed on the different food sources on each respective island. Darwin’s finch observation is only one example of how specific species evolve in order to have a better chance of surviving in their environment and later reproducing.
ReplyDeleteThe article “Lizards' Camouflage Reveals Evolution in Action” from Discovery investigates the whiptail lizard. The whiptail lizard of White Sands, NM used to be part of a species of brown colored lizards before evolving into a white-scaled lizard species. White Sands, white-scaled… there appears to be a connection. The whiptail lizard evolved the ability of crypsis through camouflage over a span of between 2,000 and 5,000 years, “a blink of the eye in evolutionary terms” (Discovery). The whiptail lizard was able to evolve so quickly because lizards are r-selected, meaning the lizard has short generation time and matures early in life. By blending into the white sand with the lizard’s white scales, the lizard is able to hide itself from predators such as rattlesnakes, roadrunners, and owls. If the whiptail lizard is not eaten by a predator, then the lizard stands a better chance of surviving and reproducing.
The whiptail lizard was able to camouflage itself with the white sand through alteration of the gene specializing in the production of melanin. Dr. Moalem defines melanin as a “specialized pigment that absorbs light” (Moalem 53) and determines skin, feather, or scale color. More melanin results in darker scales while less melanin results in lighter scales. Two ways the whiptail lizard could have adapted its white scales could either be through the elimination of melanin production or a drastic decrease in melanin production. Five thousand years ago, when one lizard had less melanin production than the typical brown lizard, the lighter colored lizard is less visible to predators, survives over the darker lizard, reproduces, and passes on the genes for lighter scales. Directional selection eventually led to the favoring of white lizards. Connecting back to Big Idea 1, the evolution of the whiptail lizard in the White Sands desert led to a species with high fitness and the ability to pass on the highly fit genes.
(Christine Fanning, cfannin4@students.d125.org)