ANTH 1102 1st Edition Lecture 5 Outline of Last LectureI. Continuation of Forces of Microevolution and Macroevolution a) Darwin’s 3 observationsb) What Darwin didn’t knowc) Mutation (A force of Microevolution)Outline of Current LectureI. Continuation of Microevolution and start of Macroevolution and human variationand adaptationCurrent LectureLast Two Forces of Microevolution and Macroevolution Gene Flow:- Only affects population not species- Random in effect on gene pool- Migration; movement of genes between breeding populations (ex. moving to a new community)- Increases diversity within a population- More reproductive possibilities to allow populations to survive Genetic Drift:- Random in effect of gene pool- Random reduction in diversity of alleles in a population- Decreases genetic diversity in breeding populations- Isolation of populations; genetic “bottleneck” events Bottleneck events reduce population size, decreasing genetic diversity and adaptability Restricts reproductive success of large population Humans are believed to share the same traits because of a bottleneck that occurred long ago-Toba Disaster About 70,000 years ago Volcanic super-eruption 6-10 years of volcanic winter Global change Reduced human species to about 10,000-Founder Effect A population with few individuals with genetic information that stays in isolated place Never reabsorbed into general population Small genetic endownmentEx. Inbreeding, religious communities Macroevolution:- Forces of microevolution are forces of macroevolution- Accumulative changes- Different patterns of speciation (or transformation in species) Allopatric: When phenotypic changes occur by a physical or geographic separation Sympatric: change over entire geographic range of a species; time dependent Parapatric: the changing of individuals within a population so theyare no longer part of the same species Common Misconceptions:- Evolution is teleological (displaying or connecting to design or purpose in nature): NO- All traits can be explained from the perspective of adaptation: NO- Our bodies are programmed for the Paleolithic (denoting the early phase of the Stone Age): NO- Genes are paramount in evolutionary change: NO Human Variation and Adaptation:- It’s bio-cultural- External features and internal features- Communities not genetic population- Variation due to interactions among factors: Genetico Ex. Variation in height, genetico Such as Wadlow, an 8’1’’ man with a genetic mutation that allowed him to keep making growth hormones Environmentalo Ex. Variation in height, non-genetico “Growth stunting” could be caused by factors such as,o Nutritiono Stress (emotional or social)o Prenatal Environmento Chronic infectionso Intestinal parasiteso Environmental factors strongly influence genetic variationso Biological Plasticity: Changes in biology due to environmental changes or stresses Socioculturalo Ex. Variation in height, cultural/behavioralo Group level or individual behavior o Such as Paraca skulls and mummy’s head shapes resulting from “head binding”o Changes in anatomy due to corsetry Adaptation is a major source of human phenotypic variation:- Genetic changes (microevoluntionary) Acclimatization (non-genetic physiological changes; may be temporary or permanent; can be inherited) - Ex. goose bumps Individual behavioral changes- Ex. putting on a coat Cultural (group-level behavioral) changes - Ex. drought - Maintained or changed by selection, or based on preferences, accidents- NOT ALL VARIATIONS ARE ADAPTED Just random Adaptation to Temperature- Bergman’s Rule: body shape Variation in body build Slender=warmer climate Stalky=colder climate Surface area adaptability High surface area=lose heat Low surface area= heat retention- Allen’s Rule: Mammals and birds protruding body parts Longer in warmer climates Shorter in colder climates- Acclimatization (temporary changes) Efficient shivering Goose bumps Lewis hunting
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