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[BSCI 106] - Final Exam Guide - Comprehensive Notes for the exam (32 pages long!)


Department
Biological Sciences Program
Course Code
BSCI 106
Professor
Marcia Shofner
Study Guide
Final

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UMD
BSCI 106
FINAL EXAM
STUDY GUIDE

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BSCI 106: Lecture 3
Evidence for Evolution
- Natural selection preserves the genes that help organisms that function well in their
environment, but cannot predict future environmental change so can only serve for
current conditions
- Evolution is an ongoing process of dynamic adjustment and not toward any fixed goal.
Evolution as Fact and Theory
- In 1875, people accepted descent with modification.
- Natural selection was not generally accepted until after scientists re-discovered genetics
(1936-1950)
- In 1936-1947, evolution by natural selection paired with Mendel’s discoveries of
genetics because the accepted theory behind diversity and adaptation.
Evidence for Evolution:
1) Homology- Structures with different uses but strikingly similar features. Species are
transformed and existing structures get modified for new uses. (Ex. Vertebrate Limb,
shared developmental patters)
2) Fossil record- general pattern of simpler organisms first, then more complex.
3) Vestigial Structures- Structures that would have had a use in the past but are no longer
useful. Examples include goose bumps and the teeth that are still present in Baleen
whales. Also wings on birds that no longer fly. Pseudogenes – genes that have been
silences due to mutation and do no yield functional products and lack regulatory
sequences.
4) Biogeography- study of distribution of organisms. Related forms evolved in one location
and spread out.
5) DNA/ Genetic Similarities- Amino acid differences in several other animals compared to
humans are similar in a way that makes sense given descent with modification.
6) Direct observation or strong inference of evolutionary change- Ex. Evolution of disease
resistance. Artificial selection in dogs and bacteria.
Summary
- Evolution is testable
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BSCI 106- Lecture 4
Natural Selection Revisited
- Involves variation, which is heritable.
- Based on the struggle to survive in environment.
- Differential reproduction based on heritable variation.
- Changes in heritable characteristics of the population
Darwinian Fitness
- Defined as the capacity to pass on genes to reproducing offspring.
- Depends on: Survival to reproductive age, mating success, fecundity (number of
offspring), and survival to reproductive age by offspring.
Natural Selection Revisited
- Evolution- Changes in allele frequencies in a population over time.
- Natural selection is the only agent of evolution that leads to a fit between
characteristics of organisms and their environment.
- Other agents are: Mutation, migration, genetic drift.
Directional Selection
- Changes the characteristics of a population by favoring individuals that very in one
direction from the mean. Examples are the peppered month that evolved to blend into
trees that were being darkened by air pollution and the Texas long horns who evolved
with extremely long horns to defend their young from predators.
Stabilizing Selection
- Preserves the average characteristics of a population by favoring average individuals. An
example of this is birth weight. Both extremely high and low birth weight have high
mortality so average is favorable.
Disruptive Selection
- Changes the characteristics of a population by favoring individuals that vary in both
directions from the mean of the population. An example is the black-bellied seed
crackers. Middle range of beak size don’t survive because they were poor for handling
small seeds and cant crack large seeds.
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