Week 1- Unifying Themes, Biological Hierarchy, and Intro to Evolution

Question 1

Science

Answer 1

• the process of identifying patterns and asking questions that help us to best understand those patterns
• the process of disproving hypotheses in an effort to focus in on the true answer to a question

Question 2

Hypotheses

Answer 2

specific, testable, rejectable statements

Question 3

Theory

Answer 3

• used to explain several related phenomena, to bring together multiple related, demonstrated hypotheses
• has a tremendous amount of evidence supporting the concept and patterns it describes
• theories consist of pattern and process

Question 4

Pattern

Answer 4

refers to the general observations of reprition one sees within a system (akin to the observation phase of the scientific method)

Question 5

Process

Answer 5

• the mechanism, or way in which the pattern occurs
• there may be several processes involved in an identified pattern, and may depend on how specifically the pattern is considered

Question 6

Proximate vs. Ultimate processes/reasons

Answer 6

• proximate refers to what occurs in the short-term (usually measured in fractions of lifetimes)
• ultimate refers to a longer timeframe (most of a lifetime or more)

Question 7

Cell Theory

Answer 7

• Cell Theory states that all organisms are made of cells, and that all cells come from prexisting cells.
• As a result, Cell Theory says that theoretically, one should be able to tell how an organism acts based on how its’ cells act. And, that all life is continuous.

Prior to Cell Theory, it was assumed that cells spontaneously generated. Cell Theory shows that all cells are descended from a common ancestral cell.

Question 8

cells

Answer 8

a naturally occuring compartment bound by a thin, flecible plasma membrane, and contains chemicals in an aqueous solution that perform life functions

Question 9

Evolutionary Theory

Answer 9

• Evolutionary Theory states that all life as we know it, is the product of evolutionary processes
• Evolutionary Theory contains two general ideas: 1. Evolution explains variation, how that variation came about, and what can happen if environmental conditions change.
  2. All species are related to each other through common ancestry.

Question 10

Evolution

Answer 10

The heritable (genetic/allelic) change in a population over time. If certain heritable traits help individuals produce more offspring, then those traits become more common in the population over time.

Natural Selection is the primary mechanism of evolution

Evolution works on the population level, where Natural Selection acts on the individual

Question 11

What is the purpose of the biological hierarchy?

Answer 11

• The biological hierarchy is a framework of organization regarding all life around us.
• It provides us with a simple way of guaranteeing we are talking about the same terms as we consider life across varying scales

Question 12

Biological Hierarchy levels

Answer 12

In order of small-large: atom, molecule, organelles, cells, tissues, organs and organ systems, organisms, populations, communities, ecosystems, and the biosphere

This class focuses on organismal level and higher

Question 13

Organisms

Answer 13

• Individuals. Typically a collection of organ systems, but can be single-celled.
• Individuals are acted on by natural selection.

Question 14

Populations

Answer 14

• Collections of individuals of the same species that are typically interbreeding.
• Evolutionary change affects the population.

Question 15

Communities

Answer 15

• A collection of populations of different species living together in the same area.
• Boundaries may be set up by natural structure, or arbitrarily determined by us

Question 16

Ecosystems

Answer 16

• Communities plus their abiotic factors (water, temperature, geology, sunlight, etc.)
• Although ecosystems are communities plus abiotic factors, we frequently refer to ecosystems as much larger agents than communities.

Question 17

The Biosphere

Answer 17

• All the ecosystems put together
• All that gets in and leaves is heat (solar) energy

Question 18

Biomes

Biomes are not part of the biological hierarchy!!!

Answer 18

• Biome refers to a collection of very similar ecosystems that are largely bounded by global influences like weather and climate.
• For example, the Tropical Rainforest biome is a collection of ecosystems that all share “tropical rainforest” characteristics (but are located in different areas around the globe)

Question 19

Emergent Property

Answer 19

• Emergent properties refer to the trait(s) that provide each higher level in the hierarchy with an advantage over the level below them.
• Basically, each level of the biological hierarchy has a trait that is greater than the sum of its parts (ex. the poulation level has a trait that is greater than the sum of all organisms)

For example, sexual reproduction is an emergent property at the population level. Sexual reproduction cannot occur at the organismal level, but can occur at the population level. In other words, sexual reproduction “emerges” at the population level.

Question 20

What are some things people believed before Darwin?

Answer 20

• People believed all organisms were created by a diving being as recently as 6000 years ago- this is the idea of special creation.
• Species have never changed and are unchangeable.
• Variation between individuals is unimportant or misleading.
• All species are organized into a sequence based on increased size and complexity- this Aristotle’s Great Chain of Being idea.

Question 21

Jean-Baptiste de Lamarck’s Significance

Answer 21

• Lamark was the first to state that species have changed through time (the first formal evolutionary theory).
• Said that species change through time via acquired characteristics- that individuals change as a result of environmental pressures and then pass those traits to offspring. Not true!

Lamark’s thoughts were based on Aristotle’s typological thinking and the belief that simple organisms spontaneously generated.

Question 22

What did Darwin conclude in The Origin of Species that lead usto the Modern Theory of Natural Selection ?

Answer 22

1. Variation, in conjunction with environmental pressure, is the key to understanding diversity and how/why species change.
2. Natural Selection components:
   a. All species have a common ancestor.
   b. All species show changes in characteristics through time.
   c. All species show changes in characteristics in different environments.

Question 23

Evolution vs. Natural Selection

Answer 23

• Evolution is the change in genetic (allelic) frequency within a population over time.
• Natural Selection is a process by which evolution can occur.

Question 24

Natural Selection Requirements

Answer 24

• Trait variation in a population… Without trait variation, there are no traits to select for and against. Variation exists on a contrinuum (are not normally either/or situations)
• Heritability… The traits in question need to be heritable, they need to be passed from parent to offspring via genes.
• Differential survival… There needs to be a difference in survival to reproductive age based on the condition of the trait.
• Differential reproduction… As a result of a condition of the trait, individuals will have more breeding offspring than others, thus passing the genes for that condition into the next generation.

In this class, differential survival and differential reproduction are often lumped together.

Question 25

Fitness

Answer 25

refers to the number of viable offspring you produce in your lifetime

Question 26

Adaptation

Answer 26

* Adaptation is a heritable trait that increases the relative fitness of individuals having the trait * Adaptation can also be viewed as a process by which individuals within a population acquire traits that increase their relative fitness. One organism can be better adapted to a particular environment because the process of adaptation has taken place over a longer period of time.

Question 27

Artificial Selection

Answer 27

* Artificial is a similar process to natural selection, however, the selecting agents (that which drives the evolutionary process) are humans. * Artificial selection is considered "artificial" because the selective pressure is not due entirely to nature (due to non-human environmental conditions), and the resulting desired traits will not always allow the individual to survive and reproduce more offspring in the wild.

Question 28

Three main conclusions from evolutionary theory

Answer 28

* species are related * speces and species diversity changes over time * evolution should be able to be seen in the short-term

Question 29

Macroevolution

Answer 29

* The change of one major taxonomic group into another (ex. fish to amphibians to reptiles) * Or, the creation (or extinction) of species

Question 30

Microevolution

Answer 30

* The change in a population over generations that helps to separate populations from each other genetically * The accumulation of microevolution over a long period may result in the creation of new species (macroevolution)

Question 31

Evidence of Macroevolution

Answer 31

* Includes evidence that some species are related (ex. geographic proximity of similar, non-interbreeding species and homologies). * Includes evidence that species and species diversity changes over time (ex. the fossil record and vestigial traits).

Question 32

Homology

Answer 32

similar traits in separate species due to a shared common ancestor

Question 33

Different types of Homology

Answer 33

* **Genetic Homology**- similar gene sequences between individuals of different species. * **Developmental Homology**- similarities in morphology of embryos of different species * **Structural Homology**- similarities in structure of body parts of different species

Question 34

What can the fossil record tell us about species?

Answer 34

* Not all species were together at one time * Extinction has taken place * Transitional forms exist * Major increases in species complexity takes billions of years * Life began in the sea

Question 35

Vestigial Traits

Answer 35

structures in organisms commonly found in the species that serve little or no function

Question 36

Atavism

Answer 36

a vestigial trait found in very few individuals within a species

Question 37

Evolutionary Trends ## Footnote What are some long-term trends that resulted from macroevolutionary processes over billions of years?

Answer 37

* An increase in multicellularity * An increase in complexity * An increase in ways to capture enrgy for use * An incresae in ways to deal with the environment- biotic and abiotic * An increase in diversity (snowball effect)