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The domesticated honey bee found in the United States (Apis…

The domesticated honey bee found in the United States (Apis mellifera)—originally from Europe—is slow to sting and stores large amounts of honey, but does not tolerate subtropical conditions (found in areas about 35 degrees north and south of the equator) as well as the “Africanized” honey bee (Apis mellifera scutellata). Because the European honey bee was performing poorly as a honey producer in South America, biologist Warwick Kerr imported the African subspecies to Brazil in the 1950s. He began a breeding experiment to attempt to produce a honeybee more tolerant of the subtropical concitions found in South America. The African honey bee was more tolerant of the environmental conditions, but produced less honey stores and was quite aggressive. In 1957, a mistake by a lab technician resulting in the escape of ~26 African queens. As a result, these African honeybee queens interbred with wild European honeybee populations, forming hybridized bees that we now call “Africanized bees.” The African genotype spread north among European honeybee populations at a rate of about 300 kilometers each year; in 1985 the first Africanized honeybees were discovered in the United States in California. Unexpectedly, European and hybrid hives died out in subtropical areas and the remaining honeybee populations were essentially 100 percent Africanized. In the United States Africanized honeybees are common in the south and southwestern states. How would this be explained in evolutionary genetics terms?

Researchers have long debated different hypotheses for the p…

Researchers have long debated different hypotheses for the phylogeny and classification of species in the bear family, Ursidae. In 2008, researchers obtained complete mitochondrial DNA (mtDNA) genome sequences for the eight living species of bears. Based on these data, the researchers constructed a phylogenetic tree for the family Ursidae. Based on the phylogeny, who is the closest relative of the American black bear?

In some species of oysters found in shallow, rocky waters, b…

In some species of oysters found in shallow, rocky waters, both light and dark-colored shells are common, whereas intermediate-colored oysters are rare. This is likely because lighter oysters are similar in color to the rocks, while dark oysters blend into the shadows cast by the rocks. Intermediate-colored oysters are heavily preyed upon by crabs and other predators due to being more conspicuous. Selection for these two extreme phenotypes is an example of  

The below image represents an atom of a specific hypothetica…

The below image represents an atom of a specific hypothetical element and its own cation.   Which image represents the cation?  Y represents the cation  X represents the cation  What supports your choice?   Cations are larger than their neutral atom Cations are smaller than their neutral atom  Why does this occur?   Because cations lose electrons from the outer most shell, the remaining electrons have a stronger attraction to the nucleus and are pulled closer, thereby making the ion small Because cations gain electrons, the incoming electrons will be repelled by the existing electron and therefore the shell will expand to accommodate them.