Evolutionary Theory and Mechanisms

Flashcards covering key concepts from lecture notes on evolution, including historical perspectives, mechanisms, and examples.

What did Darwin believe about the transmission of characters from parents to their offspring?

Darwin believed in 'pangenesis,' where tiny particles called gemmules from all parts of the body contributed to heredity.

Are Darwin's ideas on heredity still commonly accepted today?

No, they have been proven incorrect; heredity is now understood through genetics (DNA, genes, chromosomes).

What does recent analysis of the phylogeny of HIV suggest about developing a functional vaccine?

HIV's rapid mutation and recombination make developing a lasting vaccine very difficult.

Provide an example of a vestigial trait as descent with modification.

The human appendix, which is a remnant of a larger cecum.

Provide an example of direct observation as descent with modification.

Antibiotic resistance in bacteria.

Provide an example from the fossil record as descent with modification.

Transitional forms like Archaeopteryx.

Provide an example of biogeography as descent with modification.

Unique species on islands like Darwin’s finches.

Provide an example of homology as descent with modification.

Similar bone structures in vertebrate limbs.

Is evolution by natural selection unidirectional and irreversible?

No, traits can be lost through reversals or evolve convergently.

What observations did Darwin base his theory of natural selection on?

Variation within species, overproduction of offspring, struggle for existence, and differential survival/reproduction.

Describe the basic structure and function of HIV.

HIV is an RNA retrovirus with surface proteins gp120/gp41 that bind to CD4+ cells and reverse transcriptase that copies RNA into DNA.

Why are viral diseases so hard to treat?

Due to rapid mutation and the use of host cell machinery.

Did natural selection occur in yellow/white snapdragons and medium ground finches?

Yes, as certain traits increased survival/reproduction and allele frequencies changed.

What is the Great Chain of Being?

An old hierarchical concept placing organisms from simple to complex, with humans often at the top.

What important idea did Lamarck contribute to evolution?

Inheritance of acquired traits.

What is a phylogenetic tree?

A diagram showing evolutionary relationships among taxa, consisting of nodes, branches, root, and tips.

What is homoplasy in phylogenetic analysis?

Homoplasy refers to similar traits not derived from common ancestry, which can mislead phylogenetic inference.

What objections did Darwin's critics raise?

Lack of a mechanism for heredity, gaps in the fossil record, and complexity of organs like the eye.

What are the two major themes of Darwin’s theory of evolution?

Descent with modification and natural selection as the mechanism of adaptive change.

What is the difference between artificial and natural selection?

Artificial selection involves humans choosing traits, while natural selection is influenced by environmental factors.

Does selection always lead to evolutionary change?

Not always; evolutionary change requires heritable variation.

What is homology?

Similarity due to shared ancestry.

Give an example of molecular homology and non-molecular homology.

Molecular: Shared genetic code; Non-molecular: Forelimb bones in mammals.

Is artificial selection a good model for natural selection?

Yes, it shows how selection changes populations but is not goal-directed like human-directed breeding.

Define fitness and adaptation in evolutionary terms.

Fitness is relative reproductive success; adaptation is a trait shaped by natural selection.

What questions did Peter and Rosemary Grant ask about Galápagos finches?

Are traits variable, heritable, affect survival/reproduction, and did trait frequencies change across generations?

How do evolutionary trees help us understand classification?

They organize species into groups and show geographic history.

Outline the competing hypotheses for the evolutionary relationships between whales and artiodactyl ungulates.

Hypothesis 1: Whales evolved separately (morphology); Hypothesis 2: Whales nested within artiodactyls (molecular data).

What is a synapomorphy?

A shared derived trait, examples include hair in mammals, feathers in birds, and membrane-bound nucleus in eukaryotes.