Evolutionary Biology

What is evolution?

the process of change in living organisms over time driven by genetic variation and natural selection.

What is macroevolution?

Extensive and ongoing change over the history of life on earth. In other words, the large-scale evolutionary change over long periods of time resulting in new species and major biological transitions.

What is microevolution?

small scale changes in the frequency of gene variants (alleles) within a population across generational time.

How are microevolution and macroevolution related?

microevolutionary changes accumulate overtime leading to macroevolutionary patterns.

What was the purpose of Darwin’s voyage on the H.M.S beagle?

to explore and study natural history around the world, leading to insights on evolution.

What did Darwin observe at the Cape Verde Islands?

Species resembled African organisms despite similar climate to the Galapagos, showing geographic influence on species.

What did Darwin notice about species on the Galápagos Islands?

each island had unique species that resembled south American forms, suggesting adaptation to local environments.

How did the Galápagos observations support evolution?

Such observations show that isolation and environmental differences lead to species variation and evolutionary change.

What major conclusion did Darwin draw from his voyage?

Life changes over time.

What is adaptive radiation?

The evolution of multiple species from a single ancestor, each adapted to different environments and resources.

Why are Galápagos finches important in evolutionary biology?

The exemplify adaptive radiation; similar finches evolve into unique species on different islands.

What caused the finches to evolve differently on each island?

Isolation and variation of food sources lead to natural selection for different beak shapes.

What do the finches’ beak differences represent?

adaptation to specific feed strategies such as cracking seeds or catching insects.

Who proposed the five theories of Darwinism?

Ernst mayr

What are the first three theories of Darwinism?

perpetual change, common descent, and multiplication of species ( all of which are accepted as a fact)

What are the last two theories of Darwinism?

Gradualism & natural selection (all of which are strongly supported but not sufficient enough to explain all evolution).

How does “common descent” explain biodiversity?

All species trace back to shared ancestors, diversifying over time.

Why can’t natural selection explain all evolution?

Other mechanisms like genetic drift, gene flow and mutation also contribute to evolutionary change.

What is the main idea of creationism?

Life and species were created by a supernatural force and do not change over time.

How does evolution differ from creationism?

evolution explains how species change through natural processes; creationism attributes creation to divine intervention.

What does creationism assume about species relationships?

Each species was created independently, without common ancestry.

How old is earth according to evolutionary science?

appx 4.6 billion years old.

How old is Earth according to creationist belief?

Roughly 8,000 years, with species created recently.

What does perpetual change mean in evolution?

the idea that the living world is constantly changing over time.

What undergoes modification in perpetual change?

characteristics of populations of organisms are undergo modification across generations through time.

What evidence supports perpetual change (evidence 1)?

Direct observation of change over time (evidence from living species)

What evidence supports perpetual change (evidence 2)?

Fossil evidence.

What are Examples Of Direct observation of change over time ….

Evidence from living species which include, domesticated animals, pink salmon size in pacific northwest & bacterial population susceptible to antibiotic that develops resistance within a patient or hospital.

Why is perpetual change important in evolutionary theory?

It explains how species evolve and adapt continuously rather than remaining fixed.

How do domesticated animals demonstrate evolution (in regards to perpetual change)?

selective breeding changes traits and produces new varieties.

What evolutionary trend has been observed in Pink Salmon in the Pacific Northwest? ( in regards to perpetual change)

Pink salmon size becomes smaller overtime due to selective fishing pressures.

How does the development of antibiotic resistance in bacteria population illustrate perpetual change?

Bacteria evolve genetic resistance ( antibiotic resistance), showing rapid microevolution.

What do the examples of evidence from living species (direct observation of change overtime) collectively prove?

That evolution is continuous and observable in living species.

What is the “Evidence Of Extinction”?

species do not persist indefinitely (for an unlimited period of time); most go extinct in 1-10 million years.

What is the “Law Of Succession”?

fossils resemble living species in the same region, showing evolutionary continuity.

What does these patterns of fossil evidence confirm? 

These patterns confirm that species arise, change, and disappear; supporting the idea that the living world is perpetually changing

What are the key ideas that relay how fossils prove that life on earth has changed continuously? 

Evidence of Extinction, Law of Succession & Transitional Fossils.

What are transitional fossils?

Transitional fossils are fossils showing intermediate traits between ancestral and descendant species.

Intermediates between….

modern living forms, older and younger fossils, and older fossils and modern forms.

What do transitional fossils reveal about evolution?

Transitional fossils reveal that species evolve gradually through intermediate forms over time.

How do transitional fossils support Darwin’s idea of perpetual change?

They show continuous modification of species across generations and geological eras.

What is uniformitarianism?

The principle that natural laws (of physics and chemistry) and natural process have remained constant throughout Earth’s History.

Who proposed the concept of Uniformitarianism?

Charles Lyell, in Principles of Geology

According to Uniformitarianism, geological events are…..

natural processes (same as the past), occur gradually, and have no inherent directionality.

No Inherent Directionality

evolutionary change doesn’t aim for superiority over the former, it reflects adaptation to environments.

Darwin proposed that all species descended from a….

common ancestor.

What is the branching tree of life called?

Phylogeny

What is Homology?

Structural similarities due to common descent or ancestry, despite differences in function.

What is Analogy?

functional similarities due to NO common descent or ancestry, despite differences in structure.

Homologous characteristics are……

Inherited with some modification from a corresponding feature in a common ancestor.

What is development homology?

Developmental homology is the homology visible in embryonic development.

What is Ontogeny?

Ontogeny is the study of an organism’s development throughout its entire life.

What is common descent?

Common descent is the idea that all species share ancestry but diverged through modifications over time.

What is a common ancestor?

A common ancestor is an earlier species from which two or more different species have descended from.

Why do analogous structures share the same function?

Analogous structures share the same function due to a process called convergent evolution; a process in which a species (although sharing nor common ancestry) face the same environmental pressures and ecological challenges as one another leading them to develop similar adaptations independently.

What is multiplication of species?

Ancestral species split to form multiple species.

What theory of Darwinism is adaptive radiation an example of?

Multiplication of species.

What is ring species?

Ring species are a series of connected populations that can interbreed but not at the ends of the range.

 What example illustrates a ring species? 

Ensatina eschscholtzii salamanders in California. 

What does ring species demonstrate about evolution (in the context of multiplication of species)?

Ring species demonstrate that speciation is gradual and can be observed in progress.

Ring species provide evidence of what?

that one species can split into 2.

Does adaptive radiation occur over a relatively short period of time?

Yes

What is speciation?

Speciation is the evolutionary process by which one species split into two or more distinct species.

What are some various modes of speciation?

allopatric speciation & sympatric speciation.

What is allopatric speciation?

Allopatric speciation is a type of speciation in which populations are separated by a physical barrier (river, land, mountains); geographic isolation.

Wh

What is polyploidy?

Polyploidy is a condition in which additional sets of chromosomes are present in cells.

Does Polyploidy lead to speciation?

Yes

What is gradualism?

Gradualism is the idea that evolutionary changes occur very slowly over long periods of time.

What did darwin propose about gradualism?

Darwin proposed that small phenotypic changes accumulated over thousands to millions of years leading to speciation.

Can evolutionary changes be abrupt?

Yes, this is why gradualism cannot explain all evolution because it suggest that evolutionary change occurs only at a very slow rate over long periods of time.

Do some species evolve rapidly during short periods of time?

Yes

What concept contrasts with gradualism?

Punctuated equilibrium; evolution occurs in bursts rather than slow, continuous change.

What are “Jerks” in the context of evolution?

Rapid events 

What are “creeps” in the concept of evolution?

Slow, steady change. 

What is punctuated equilibrium ?

Punctuated equilibrium is phenotypic evolution concentrated in brief events of branching speciation, separated by long intervals of no phenotypic change. 

What phrase summarizes punctuated equilibrium?

Evolution by jerks as opposed to creeps.

What is natural selection?

Natural selection is the differential survival or reproduction of individuals with different genotypes as a result of their phenotypic characteristics.

What is the advantage of natural selection?

individuals with advantageous traits survive and reproduce more successfully.

What are the four postulates of natural selection?

Variation, heritability, differential survival/reproduction, and non-random survival.

What does VIRS stand for?

Variation in Phenotype + Inheritance + Reproductive excess= selection

Variation

Individuals within a population differ in traits.

Heritability

Some variations are inherited from parents.

differential survival/reproduction (more individuals are born than will survive to reproduce)

some individuals are more successful at survival and reproduction

non-random selection

the best adapted are naturally selected

What is a popular postulate of natural selection?

Survival of the fittest (individuals best adapted to their environment are most likely to reproduce and survive)

What if darwins 4 postulates concerning evolution by natural selection are true?

If they are true, then the composition (genetic) of a population changes from one generation to the next = evolution occurs

On what level does evolution occur ?

At the population level: allele frequencies changes over time

On what level does natural selection act ?

On individuals: those better adapted survive and reproduce 

True Or False : Selection for survival and reproduction happens to individuals , but the composition of the population changes overtime. 

True

Why don’t individuals evolve?

Because traits are fixed during their lifetime: only populations change genetically across generations.

What is fitness ( natural selection)?

Fitness is the ability of an individual to survive and reproduce compared to others in the population.

What is adaptation (Natural selection)?

Adaptation is the trait of an organism that increases its fitness, compared to individuals without the trait.

What is phylogenetics ?

The study of the evolutionary related ness among organisms (tree of life)

What is classification?

groups organisms by common morphological features.

What is Systematics ?

groups organisms by shared evolutionary descent and classification.

What is directional selection (one extreme favored)?

A mode of selection in which one extreme phenotype (trait) is favored, causing a population’s trait distribution to shift to that extreme.

What is the key Idea of directional selection?

selection pushes the trait in one direction.

Example of Directional selection:

Increasing ( not decreasing) body size of horse over time.

What is stabilizing selection (both extremes selected against: intermediates favored)?

A mode of selection in which the extremes of a trait are consistently selected against, favoring individuals with intermediate phenotypes.