ANT2000ANT2000- 10/6/16- Ecogeographic Ruleso Bergmann’s Rule (1847): within a broadly distributed taxonomic grouping, populations with individuals of larger size are found in colder environments, and populations with individuals of smallersize are found in warmer regionso Allen’s Rule (1877): the body shapes and limb proportions of warm-blooded creatures vary by climatic temperature by either minimizing exposed surface area to maximize heat loss in hot climates- Skin Coloro Varies due to  Transparency of skin Amount of carotene Amount of melanino Melanin is a dark pigment produced by melanocytes in the epidermis of the skino People with darker skin have more melanocytes than people with lighter skino Exposure to sunlight increases melanin production, causing skin to “tan” and protecting it from overexposure to UV radiation- Vitamin Do Vitamin D deficiency can lead to all sorts of circulatory, respiratory, and muscle problems. Because vitamin D maintains calcium balance for healthy bone development, deficiency can lead to maladies like ricketso Culture matters too, because vitamin D can be supplied through diet, as well as synthesized with help of sunlight- Polymorphismso For traits controlled by a single gene, like blood type, variations in phenotypes are determined by relative frequencies of alleles across populations. These genetic variants are known as polymorphismso There are three types of alleles for blood type, A, B, O, and four possible phenotypes: A, B, O, ABo Polytypic features occur when polymorphisms are distributed among geographically dispersed populations- Sickle Cell: Balanced Polymorphism o Sickle Cell is an example of a polymorphism due to a mutation that is deleterious in the homozygous genotype If the sickle cell allele is inherited from both parents, the individual will suffer anemia, circulatory problems, and often early deatho Why would its frequency increase and be maintained if it is so dangerous? Indeed, in Western and Central African populations the sickle cell allele reaches levels close to 20%- Malariao Caused by a protozoan parasite carried in mosquitos, malaria is common in the same places where the sickle cell is prevalent It is no coincidence: individuals bearing one sickle cell allele show greater resistance to malaria because their red blood cells offer a less conducive environment for the parasite to reproduce Among “normals” malaria thrives; the homozygotes have virtually total resistance to malaria, but do not otherwise survive often Selection favors the heterozygotes, called balanced polymorphs, thus maintaining the sickle cell allele at substantial frequency- Racial bias that accumulates and is compounded by an array of societalpolicies, practices, and other norms that work to reinforce racism. Too2often taken for granted as “natural” and often overlooked because they are