4 - Evolution by Natural Selection

What is described as the "Grand unified theory" of biology

Evolution by natural selection.

: What plays a central role in explaining biological adaptation?

Natural selection.

What is the origin of all known forms of life?

All life is believed to be descended from a single common ancestor.

How has diversity in life arisen according to evolution?

Through evolutionary divergence from a common ancestor.

: What does "Common Ancestry" mean?

All life is basically part of one big family tree, sharing a super distant ancestor! 🌳

What is "Descent with Modification"?

It’s evolution’s way of saying: “Kids aren’t exactly like their parents”—species change a little each generation! 🐾

What is "Natural Selection"?

Nature’s talent show: the organisms best suited to their environment survive and pass on their traits. 🏆

What is the main idea of Darwin’s Origin of Species?

Species aren’t fixed; they change over time through natural selection, leading to adaptation and diversity. 🌱🐾

How did Darwin explain the mechanism behind adaptation?

Through natural selection—organisms with advantageous traits are more likely to survive and reproduce. 🏆

What role do variation and inheritance play in Darwin’s theory?

Variation provides the raw material, and inheritance ensures that successful traits are passed to the next generation. 🎨➡👶

How did Darwin view the “tree of life”?

He proposed that all species are connected through common ancestry, branching out over time into diverse forms. 🌳

What evidence did Darwin use in Origin of Species?

Fossils, biogeography, morphology, and artificial selection (breeding) all supported his ideas. 🔍🐦

Why was Origin of Species revolutionary?

It challenged the idea that species are immutable, providing a natural explanation for the diversity of life. ⚡

What does “Dominance of Microbial Evolution” refer to?

Microbes—bacteria, archaea, viruses—evolve faster and dominate evolutionary processes due to their rapid reproduction and adaptability. ⚡🦠

Why do microbes evolve faster than larger organisms?

Short generation times + huge populations = more mutations and quicker adaptation. ⏱💥

How does microbial evolution impact ecosystems?

Microbes drive nutrient cycles, influence host evolution, and can rapidly respond to environmental changes. 🌱🌊

Why is horizontal gene transfer important in microbial evolution?

It allows microbes to swap genes like trading cards, spreading advantageous traits instantly. 🔄🧬

How does microbial evolution relate to human health?

Rapid evolution can lead to antibiotic resistance, emerging pathogens, and challenges in disease control. 🚨💊

How does the speed of evolution compare between microbes and macrobes?

Microbes evolve much faster than macrobial organisms due to short generation times and large populations. ⚡🦠 vs 🐘

What is the “effective population size” ($N_e$) in microbial evolution?

It’s the number of individuals in a population that effectively contribute genes to the next generation.

Why is a large effective population size important for microbes?

• More chances for advantageous mutations to appear. 💡

• Natural selection works better because random chance (genetic drift) has less effect. 🎯

How does population size influence evolution?

Bigger populations = slower reproduction per individual but stronger natural selection and more efficient evolution. ⚖

How does “every enzyme working better” relate to evolution in large populations?

Large populations allow beneficial traits, like more efficient enzymes, to spread effectively through natural selection. 🔧➡🏆

Why do large microbial populations evolve so quickly?

Huge populations + rapid generation times = every possible single base-pair mutation can appear daily in a single patient! ⚡🦠

How do high microbial mutation rates affect vaccines?

Fast-evolving microbes can change quickly, making vaccines less effective over time. 💉❌

Why is antibiotic resistance a major concern?

Microbes evolve rapidly, and resistance can make life-saving antibiotics less effective. ⚠🦠💊

What important antibiotic milestone happened in 1928?

Penicillin was discovered by Alexander Fleming. 🧪✨

What happened in 1935 regarding antibiotics?

Sulfanamide drugs were released as the first systematic antibiotics. 💊🔬

How did antibiotics impact WWII (1943)?

hey saved countless lives by treating infections during the war. 🏥🌍

What did Fleming highlight in his 1945 Nobel Prize acceptance speech?

The risks of antibiotic resistance—he warned that microbes could outsmart antibiotics. 🎖⚠

What was created in 1959 to combat penicillin-resistant bacteria?

Methicillin, a new antibiotic targeting resistant staphylococcus. 🧬💊

What major problem emerged in the 1960s?

Methicillin-resistant Staphylococcus aureus (MRSA) appeared, showing microbes’ rapid evolution. 🦠💥

How is antibiotic resistance being tackled today?

Collaborative global efforts across medicine, agriculture, and industry aim to slow resistance. 🌐🤝

What is a key strategy to combat antibiotic resistance?

Understand microbial evolution and reduce unnecessary antibiotic use. ⚠🦠💊

How can antibiotic application be managed to slow resistance?

Use phased or controlled dosing to minimize the chance for microbes to evolve resistance. ⏱💉

How can new antibiotics be discovered?

Through bioprospecting—searching nature for novel compounds with antibacterial activity. 🌿🔬

What is phage therapy?

Using viruses that specifically kill bacteria to combat infections and slow the evolution of resistance. 🦠🛡

How can slowing antibiotic supply help?

Reduces selective pressure on microbes, slowing the evolution of resistant strains. 🐢💊

How does reproduction type differ between microbes and macrobes?

• Microbes: clonal reproduction (asexual) 🔄🦠

• Macrobes: sexual reproduction (mixing genes) ❤🐘

What is clonal reproduction in microbes?

Asexual reproduction where offspring are genetic copies of the parent, leading to uniform populations and slower evolution. 🔄🦠

How does recombination differ from clonal reproduction?

Recombination mixes genes, increasing genetic diversity and enabling faster evolution. 🎨🧬

Why is recombination important in microbial evolution?

It allows microbes to adapt quickly to new environments or challenges, like antibiotics. ⚡💊

How can recombination be visualized?

Diagrams of gene mixing over generations show new combinations emerging over time. 📊🌱

What is Horizontal Gene Transfer (HGT)?

An alternative route for microbial evolution where genes are swapped between individuals or even species. 🔄🦠

What is conjugation in HGT?

Direct transfer of genetic material between bacteria through physical contact. 🤝🧬

What is transduction in HGT?

Transfer of bacterial genes via viruses called bacteriophages. 🦠➡🦠

What is transformation in HGT?

Uptake of free DNA from the environment by bacteria. 🌱🧬`

Why is HGT important in microbial evolution?

It makes microbial genomes dynamic, enabling rapid adaptation and evolution. ⚡🌍

How does high variability affect the concept of species in microbes?

Microbial “species” genomes are less clearly defined because rapid evolution and gene swapping blur boundaries. 🌐🦠

What evidence supports fast microbial evolution?

Experimental evolution studies show microbes can evolve significant changes within controlled environments over short timescales. ⚡🔬