Evolution of Populations - Bio 152

Practice flashcards covering key concepts from the Evolution of Populations lecture.

What is evolution?

Evolution happens to populations, not individuals.

What happened to finch beak depth during the drought?

Larger beaks that could eat larger seeds were favored.

Define a population in the context of biology.

A population is a group of individuals of the same species that live in the same area and can interbreed.

What is an allele?

An allele is one version of a gene.

What does allele frequency measure?

Allele frequency measures how often a specific allele appears in a population.

Define gene pool.

The gene pool is the number of different alleles that exist for a population.

What is the sum of allele frequencies p and q in a population with two alleles?

p + q = 1.

What are the conditions for Hardy-Weinberg equilibrium?

No mutations, large population size, random mating, no migration, no natural selection.

Express the Hardy-Weinberg theorem mathematically.

p² + 2pq + q² = 1.

What does p represent in the Hardy-Weinberg equation?

p is the frequency of the more common allele.

What can allele frequencies represent in reproduction?

They represent the likelihood of having a sperm or egg with that allele.

What role does natural selection play in evolution?

It allows individuals with advantageous traits to survive and reproduce, increasing the frequency of those traits.

Provide an example of natural selection. What did the study of fruitflies show?

The frequency of an insecticide resistance allele increased from 0% to 37% over time.

How can environmental factors influence phenotypes?

Some variations, such as that seen in Nemoria arizonaria caterpillars, can be affected by diet and environment.

What is genetic drift?

Genetic drift is a mechanism of evolution that causes fluctuations in allele frequencies, particularly in smaller populations.

What is the founder effect?

The founder effect occurs when a few individuals become isolated from a larger population, affecting allele frequency.

What is the bottleneck effect?

The bottleneck effect occurs when a population's size suddenly drops, leading to rapid changes in allele frequencies.

Define gene flow.

Gene flow is the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.

What is non-random mating?

Non-random mating occurs when individuals do not choose mates randomly, often preferring partners with similar traits.

What does the fossil record indicate about evolutionary change?

Evolutionary change does not happen at a constant rate but is characterized by periods of little change followed by rapid change.

What major event does the Cambrian Explosion refer to?

A period of rapid evolutionary change starting around 541 million years ago, likely due to increased oxygen in the environment.

List common characteristics of chordates.

Bilateral symmetry, notochord, hollow nerve cord, pharyngeal slits, and muscular tail.

When did vertebrates arise?

Vertebrates arose during the Cambrian explosion.

What defines tetrapods?

Tetrapods are animals with limbs and fingers/toes instead of fins.

Give an example of a transitional fossil.

Tiktaalik, a 375 million-year-old fossil with characteristics of both fish and tetrapods.

Which animals were the first land-dwelling tetrapods?

Amphibians, including frogs and salamanders, which started living out of water about 500 million years ago.

What are amniotic eggs and their significance?

Amniotic eggs allow reptiles (and birds) to reproduce away from water, protecting the eggs better.

Describe the order of Primates.

Primates are distinguished by an especially mobile thumb; monkeys and apes have fully opposable thumbs.

What is Social Darwinism?

An ideology that applies Darwinian principles to societal structures, promoting the idea of genetic superiority among human groups.

What did Darwin’s On the Origin of Species (1859) contribute to Social Darwinism?

It popularized the concept of natural selection, which some applied to justify social hierarchies.

What did the 2002 study reveal about racial and genetic differences?

93-95% of human genetic variation is within populations, and only 3-5% is between groups.

What is the importance of understanding the concept of ancestry?

Many researchers prefer 'ancestry' over 'race' to reference genetic differences among human groups.

Explain common misconceptions about human evolution.

Humans are not descended from chimpanzees; rather, both share a common ancestor.

What does the term hominin refer to?

Pre-human species that include multiple species living simultaneously.

How did Neanderthals relate to modern humans?

Modern humans and Neanderthals overlapped and interbred, leading to the presence of Neanderthal DNA in many modern people.

Describe Ardi, the earliest hominin.

Ardi lived 4.4 million years ago and had a more upright stance than other apes.

What is significant about Australopiths in human evolution?

They show evidence of bipedalism, important for tool use.

When did early Homo species arise and what development did they showcase?

Early Homo arose around 2.4 million years ago, showing larger brain volume and decreased sexual dimorphism.

What was the significance of Homo erectus in human migration?

Homo erectus was the first hominin to migrate out of Africa around 1.8 million years ago.

Describe Neanderthals' cultural behaviors.

Neanderthals buried their dead and made hunting tools from stone and wood.