Bio GA 2

reinforcement

•If hybrids are less fit than the parent species, then strong selection for prezygotic barriers should reduce hybrid production

•This process is called reinforcement because it reinforces reproductive barriers

•Reinforcement should be stronger for sympatric than allopatric populations

What can happen if hybrids are as fit as their parents?

There can be substantial gene flow between species.

What can happen to reproductive barriers between two parent species?

Reproductive barriers can weaken, leading to fusion into a single species.

What has pollution in Lake Victoria affected in female cichlids?

It has reduced their ability to visually distinguish between males of their own and different species.

What can overwhelm selection for increased reproductive isolation inside a hybrid zone?

Extensive gene flow from outside the hybrid zone

What happens when members of both parent species of Bombina migrate into the hybrid zone?

Ongoing hybridization occurs

How can the rate of speciation be studied?

By observing broad patterns in the fossil record.

What types of data can be used to assess the time interval between speciation events?

Morphological and molecular data.

What does the fossil record indicate about the appearance and disappearance of species?

The fossil record includes many episodes where new species appear suddenly, persist unchanged through several strata, and then disappear.

What is punctuated equilibria?

Punctuated equilibria describes periods of apparent stasis punctuated by sudden change.

How do some species change over time according to the fossil record?

Other species appear to have changed gradually over time.

What does the fossil record suggest about speciation rates?

The fossil record suggests that speciation can be rapid.

What is an example of rapid speciation?

The sunflower Helianthus anomalus was formed by hybridization between two other sunflower species followed by rapid speciation.

Did the number of chromosomes change with the formation of H. anomalus sunflowers?

No, the number of chromosomes did not change with the formation of H. anomalus sunflowers.

What role did natural selection play in hybrid populations of sunflowers?

Natural selection produced extensive genetic change in hybrid populations over short periods of time, resulting in reproductive isolation from both parents.

What is one way speciation can occur?

Speciation might require change in a single gene or many genes.

How does the shell spiral direction affect Japanese Euhadra snails?

The direction of shell spiral affects mating and is controlled by a single gene.

What influences pollinator preference in monkey flowers (Mimulus)?

At least two loci affect flower color, which influences pollinator preference.

How can pollination by hummingbirds or bees affect monkey flowers?

It can lead to reproductive isolation of the flowers.

In some organisms, how is speciation influenced?

Speciation can be influenced by larger numbers of genes and gene interactions.

What happens to differences between organisms during successive speciation events?

Differences accumulate, eventually forming new groups of organisms that differ greatly from their ancestors.

What occurs to some groups of organisms as species are lost?

Other groups shrink in size due to extinction.

What is macroevolution?

Macroevolution is the cumulative effect of many speciation and extinction events.

evolution

•Macroevolution is the broad pattern of evolution above the species level

•The fossil record shows macroevolutionary changes over large time scales, for example:

•the emergence of terrestrial vertebrates

•the impact of mass extinctions

•the origin of key adaptations, such as flight

living vs nonliving things

biotic factors and abiotic factors

What are abiotic ingredients?

Things that aren't living or organic.

What are atoms made up of?

Smaller but unstable ingredients.

What are molecules/compounds formed from?

Elements brought together to make complex structures.

water

•Every living thing needs it

•Many substances love it (hydrophilic)

•Others hate it (hydrophobic)

- polar molecule

What is the first stage in the chemical and physical processes that could produce simple cells?

Abiotic synthesis of small organic molecules

What is the second stage in the process of producing simple cells?

Joining of small molecules into macromolecules

What is the third stage in the production of simple cells?

Packaging of molecules into protocells, droplets with membranes that maintain an internal chemistry different from the environment

What is the fourth stage in the process that could lead to the formation of simple cells?

Origin of self-replicating molecules

how did biotic building blocks originate on earth

•Biotic ingredients = building blocks of organisms

•Proteins

•Nucleic acids

•Fats / lipids

•Carbohydrates

•All of these are organic molecules, which just means they are full of carbon atoms

What has been demonstrated in lab conditions regarding RNA monomers?

Spontaneous abiotic synthesis of all four RNA monomers.

How do RNA polymers form spontaneously?

When a solution of monomers is dripped onto hot sand, clay, or rock.

What role could abiotically synthesized polymers have played on early Earth?

They could have acted as weak catalysts.

What did Haldane & Miller hypothesize about the synthesis of organic molecule building blocks?

It was likely in reducing atmospheric conditions and near volcanoes.

What are key properties of life that may have appeared together in protocells?

Replication and metabolism

How may protocells have formed?

From fluid-filled vesicles with a membrane-like structure

What can spontaneously form vesicles with a lipid bilayer in water?

Lipids and other organic molecules

What effect does adding montmorillonite have on vesicle formation?

It increases the rate of vesicle formation

What can organic molecules attached to montmorillonite do?

They can be absorbed through the vesicle membrane

What properties of life can vesicles exhibit?

Simple growth without dilution of contents, reproduction, metabolism, and maintenance of internal environment different from surroundings

What was likely the first genetic material?

RNA, not DNA

What central role does RNA play in cells?

Protein synthesis

What are ribozymes?

RNA molecules that can catalyze many different reactions

What can ribozymes do with nucleotides?

Make complementary copies of short stretches of RNA

What has been produced through natural selection in laboratory experiments?

Self-replicating ribozymes

How do RNA molecules with different nucleotide sequences behave?

They fold into different shapes

What can copying errors in RNA lead to?

New shapes that enable faster replication with fewer errors

What happens to the RNA molecule with the greatest replication ability?

It leaves the most descendant molecules

earth is billions of years old

•Big bang 13.7 bya

•Earth formed 4.6 bya

•Life on earth 3.8 bya (earliest evidence not in dispute)

What are fossils?

Fossils are the preserved remains or impressions of individual organisms that lived in the past.

What type of rock do most fossils occur in?

Most fossils are found in sedimentary rock.

How do sedimentary rock layers help in dating fossils?

Distinct layers in sedimentary rocks preserve fossils and allow us to approximate their relative age.

What is radioisotope dating?

Radioisotope dating uses carbon and uranium to provide more accurate age estimates of fossils.

What is mineralized organic matter?

Mineralized organic matter forms when minerals seep into and replace organic matter, creating fossils.

What are trace fossils?

Trace fossils are footprints, burrows, or other traces of an organism's activities preserved in the fossil record.

How can entire organisms be preserved?

Entire organisms can be preserved in hardened resin from a tree, known as amber.

In what conditions can larger organisms be preserved?

Larger organisms can be preserved in frozen soil, ice, or acid bogs, but these are not considered 'real' fossils.

What is radiometric dating used for?

To determine the age of fossils based on the decay of radioactive isotopes.

What is a radioactive 'parent' isotope?

An isotope that decays to a 'daughter' isotope at a characteristic rate.

What is a half-life?

The time required for 50% of a parent isotope to decay.

What does the order of fossils in rock strata indicate?

The sequence in which they were formed.

What can we infer about fossils using their order in rock strata?

We can infer their relative ages, but not their actual ages.

What do fossils contain that helps in dating them?

Isotopes that accumulated in the organisms when they were alive.

How can a fossil's age be estimated?

Based on the ratio of carbon-14 to carbon-12 isotopes it contains.

What is the nature of carbon-12 in fossils?

It is stable; the amount does not change after the organism's death.

What happens to carbon-14 after an organism's death?

It slowly decays to nitrogen-14.

What is required to date older fossils?

The use of radioactive isotopes with longer half-lives.

What are the four eons of the geologic record?

Hadean, Archaean, Proterozoic, and Phanerozoic

What are the three eras included in the Phanerozoic eon?

Paleozoic, Mesozoic, and Cenozoic

What do major boundaries between the Paleozoic, Mesozoic, and Cenozoic eras correspond to?

Major extinction events in the fossil record

What is the concept that explains the shared characteristics of all life on Earth?

Unity of life on Earth

What is the term for the change in heritable characteristics of biological populations over successive generations?

Evolution

What does extinction refer to?

The termination of an organism or of a group of organisms, usually a species

What is LUCA?

The last universal common ancestor of all life

Why do all living organisms share many fundamental characteristics?

Because they all descend from the last universal common ancestor

What does the complexity of life on Earth imply?

Life is complicated, with many attempts and failures in evolution

What is a defining characteristic of life related to cellular structure?

Selectively permeable barrier (cell membrane)

What is the defining characteristic of life that involves genetic material?

Inheritance (DNA)

What is the defining characteristic of life that involves producing new organisms?

Replicate (reproduction)

What characteristic of life involves gathering information from the environment?

Get information (perception of the environment)

What is the defining characteristic of life that relates to energy use?

Power & Sustain (metabolism)

What characteristic of life describes the process of reaching maturity?

Become an adult (grow to maturity)

What is the defining characteristic of life that involves changes over time?

Change (adapt & evolve)

What did the last universal common ancestor possess?

All characteristics of life as we currently understand them

What is a microbe?

An organism too small to see with the naked eye.

What is a microbiome?

A community of microbes (such as bacteria, fungi, and viruses) that inhabit a particular environment.

Is the microbiome limited to humans?

No, the entire biosphere is a microbiome that includes macrobiotic life.

What are stromatolites?

Stromatolites are layered rocks that form when prokaryotes bind thin films of sediment together.

What is the significance of fossilized stromatolites dating from 3.5 billion years ago?

They are the earliest evidence of life on Earth.

How long were prokaryotes Earth's sole inhabitants?

Prokaryotes were Earth's sole inhabitants for more than 1.5 billion years.

When did bacteria evolve a type of photosynthesis that releases oxygen as a by-product?

~2.8 billion years ago

What type of cells emerged around 2 billion years ago due to the use of oxygen?

Eukaryotes

What significant biological development occurred around 0.875 billion years ago?

Multicellular life

What was one consequence of increased oxygen levels in Earth's atmosphere?

Extinction of many species

What is the primary origin of most atmospheric oxygen (O2)?

Biological origin

What did early atmospheric oxygen likely react with in the oceans?

Dissolved iron