Darwin and Natural Selection
Who proposed that species change over time through natural selection?
Charles Darwin
What is common ancestry?
Similarities in embryonic development among different species suggest this.
When are populations considered separate species?
When they cannot interbreed to produce fertile offspring.
What is population genetics?
The study of how gene (allele) frequencies change in a population over time.
What is macroevolution?
Large-scale evolutionary change over long periods of time that can lead to new species and major groups.
Who is Charles Darwin? and what is Natural Selection?
Charles Darwin was a British naturalist and biologist best known for developing the theory of evolution by natural selection. He proposed that species evolve over time through a process where individuals with traits better suited to their environment are more likely to survive and reproduce, passing those traits to the next generation. Natural selection is the process by which individuals with traits that are better suited to their environment are more likely to survive and reproduce, passing those advantages to the next generation.
What is a Molecular Clock?
A molecular clock estimates the time since two species diverged by comparing DNA or protein sequences.
What is a hybrid?
The offspring of two different species.
What is genetic variation?
Differences in genes or traits among individuals in a population.
What is adaptive radiation?
When one ancestral species rapidly evolves into many different species to fill different ecological niches.
How does evolution happen according to modern science?
Evolution happens when the frequencies of genes (alleles) in a population change over time, combining natural selection with genetics.
What is the difference between homologous and analogous structures, and what does each tell us about evolution?
Homologous structures have a common ancestor and indicate shared evolutionary history, while analogous structures arise independently due to similar environmental pressures (convergent evolution).
What is allopatric speciation?
Allopatric speciation occurs when populations are geographically separated, leading to the formation of new species.
What is the Hardy-Weinberg equilibrium?
A principle that allele frequencies in a population stay the same if no evolution occurs.
What is convergent evolution?
When unrelated species evolve similar traits because they live in similar environments.
How did the finches on the Galápagos Islands help Darwin?
The finches had different beak shapes depending on their food sources, showing how species can adapt to their environment.
What is a transitional fossil? Give an example.
A transitional fossil shows traits intermediate between two major groups, such as Tiktaalik, which has features of both fish and tetrapods.
How can polyploidy cause speciation in plants?
Polyploidy can instantly create reproductive isolation because individuals with extra sets of chromosomes cannot breed with the original population.
How does natural selection affect allele frequencies?
Alleles that give an advantage increase in frequency over time.
What are analogous structures and how do they form?
Structures with similar functions but different origins, formed through convergent evolution.
What role does the environment play in natural selection?
The environment “selects” which traits are helpful, so individuals with those traits survive and reproduce more.
How does embryology provide evidence for evolution among vertebrates?
Similar stages of development in embryos of different species suggest a common ancestry, even if adult forms are very different.
What is a behavioral isolation?
When differences in mating behaviors prevent species from breeding.
What is the difference between microevolution and macroevolution?
Microevolution is small changes in a population’s gene frequencies; macroevolution is large changes over long periods that can create new species.
Why do mass extinctions often lead to adaptive radiation?
They open up ecological niches, allowing surviving species to diversify.