Evidence for Evolution
What is a vestigial organ?
A reduced or unused body part inherited from ancestors that once had a function. For example, the human appendix.
What is a gene pool?
The collection of all the genes of all members of a population.
What is Natural Selection?
The process where organisms better adapted to their environment tend to survive and produce more offspring
Traits tends to show a normal distribution, producing a ___ shaped curve.
Bell
What is a deme?
Local population of organisms of the same species that interbreed with each other.
Which of the following is an example of homologous structures?
A) Dolphin fins and shark fins
B) Human arm and bat wing
C) Cat eyes and octopus eyes
D) Penguin wings and shark fins
B) Human arm and bat wing
Name the three types of individuals in a gene pool based on their genotypes for a trait.
Homozygous dominant, heterozygous, and homozygous recessive.
What are the four main principles of natural selection?
Variation, competition, adaptation, and selection.
Name the three modes of Natural Selection
Stabilizing Selection
Directional Selection
Disruptive Selection
When a cline forms a circular shape, it is called a ___ species.
Ring
True or False, Fossils found in deeper rock strata are typically more complex than those in upper layers. Explain your reasoning for T or F.
False, because deeper strata contain older, simpler organisms, while upper layers have more complex, modern organisms.
List two sources of genetic variation in Meiosis.
Crossing over and independent assortment.
Competition arises from ______, leading to struggles for ______.
Overpopulation, resources.
Define stabilizing selection and give an example.
A type of natural selection where individuals with average traits are favored and extreme traits are selected against.
Examples: Human babies with average birth weight survive better than very small or very large babies.
What is the main difference between prezygotic and postzygotic isolating mechanisms?
Prezygotic mechanisms prevent mating or fertilization while Postzygotic mechanisms occur after fertilization and prevent offspring from surviving or reproducing.
Explain how biogeography has evidence for evolution using the example of marsupials in Australia and South America.
Biogeography can show species distribution patterns because of continental drift. Marsupials in Australia and South America share ancestry from when the continents were joined in and after the continents separated, evolution occurred
This is the movement or migration of alleles from one population to another, which are physically _____?
Separated
Define Artificial selection and give the reason why it occurs and an example.
The intentional breeding of plants and animals by humans.
Reason: humans want the favorable trait, such as brown fur on dogs instead of white, because white fur is harder to clean.
Why is stabilizing selection considered the most common mode of natural selection?
Most environments stay stable, so the average phenotype is the most successful.
Define Allopatric speciation and give an example.
The formation of new species when a population is separated by a physical barrier and evolves independently.
Example: A bird population split by a canyon evolves into two different species.
Darwin's theory are five key ideas. Explain how modern species evolve from ancestral ones through natural selection.
Species evolved from common ancestors through natural selection because of - organisms compete, individuals have different traits, and helpful traits become more common over generations.
What is the evolutionary agent for the scenario: A flood kills most of a population, reducing genetic diversity.
Bottleneck effect
Define Variation and give two specific example and their benefits.
The heritable differences in traits like color, size, or behavior among individuals within a population, providing the raw material for evolution.
Examples: Some bacteria naturally possess genetic variations that make them resistant to antibiotics, allowing them to survive treatment and reproduce, and eventually making the whole population resistant.
In polluted environments, darker-colored moths are better camouflaged from predators than lighter ones, leading to higher survival rates and more offspring with the dark.
What is directional selection, and how does it change the distribution of traits in a population?
Directional selection is when one extreme trait is favored over others. This causes the population to shift toward that trait over time. As a result, the bell-shaped curve moves in one direction, and more individuals in the population will have that favored trait.
Which type of speciation is shown by three-spined stickleback fish in the same lake that feed on different food sources and are reproductively isolated?
Sympatric speciation