Evolution

Question 1

Evolution

Answer 1

The change in genetic composition of a population over time
- a population-level process, not an individual level

Question 2

Biological species

Answer 2

Naturally interbreeding population that are reproductively isolated from other such groups.

Question 3

Phylogenic tree (cladogram)

Answer 3

a visual depiction of the evolutionary relationships between organisms.
- nodes are speciation events and represent a common ancestor of descendants (closer the nodes, the more genetically related)

Question 4

Character mapping

Answer 4

Shows origin and elimination of traits in the evolutionary history or groups of organisms.

Question 5

Law of Superposition (relative dating)

Answer 5

When deformation is not present, younger layers (strata) develop on top of older layers.

Question 6

Absolute dating

Answer 6

calculated based on radioactive decay of elements (C, K-Ar, U-Pb).

Question 7

Fossils

Answer 7

mineralized remains or impressions of organisms within rock layers.

Question 8

Biologically extinct

Answer 8

Organisms that no longer exist on earth

Question 9

Extant

Answer 9

Organisms that are still alive today

Question 10

Transitional v.s similar organisms

Answer 10

transitional species are intermediates between two species.

Question 11

What are the three systems that allow multicellular organisms to grow?

Answer 11

Cell proliferation, differentiation, and apoptosis.

Question 12

Developmental biology

Answer 12

how an organism develops from a zygote into a mature adult

Question 13

Homologous v.s analogous structures

Answer 13

Homologous structures are structures shared by two or more species because they were inherited from their common ancestor
Analogous structures are independently evolved structures that are similar due to convergent evolution (such as similar environments)

Question 14

Convergent evolution

Answer 14

A process in which similar selective pressures result in superficially similar characteristics (were NOT inherited from a common ancestor)

Question 15

Ecotypes

Answer 15

develop when populations of the same species differ in some characteristics due to adaptation to differing local severe pressures.
(different versions of the same species due to different environments)

Question 16

Speciation

Answer 16

The formation of new species from a single species due to reproductive isolation allowing genetic differences to accumulate. (Kind of like ecotypes expanding to the point where the ecotypes are different enough to not be able to interbreed)

Question 17

Mechanisms: Natural selection

Answer 17

unguided, non-random survival leading to differential contribution of offspring to the next generation by various genetic types in the same population.
ONLY MECHANISM THAT LEADS TO ADAPTATION
Required conditions:
- Struggle for survival
- Variation in population
- Variation is heritable
- Variation (directly or indirectly) allows for reproductive advantages

Question 18

Adaptation

Answer 18

Having traits that endow greater fitness (reproductive success) in the current environment than other traits.

Question 19

Mechanisms: Sexual selection

Answer 19

a special case of natural selection in which individuals of the same sex compete directly for reproductive access to the other sex or one sex selects mate based on specific traits that cannot be faked and are associated with ‘good genes.’

Question 20

Sexual dimorphism

Answer 20

distinct difference in size or appearance between the sexes of an animal in addition to difference between the sexual organs themselves

Question 21

Mechanisms: Artificial selection

Answer 21

The INTENTIONAL selective breeding by humans of organisms to encourage the occurrence of desirable traits to humans

Question 22

Why has natural selection not led to an organism perfectly engineered for its environment?

Answer 22

• constantly changing environments
• compromises between competing stressors
• other evolutionary mechanisms
• historical constraints on existing variation in traits

Question 23

Mechanisms: Mutation

Answer 23

Change in nucleotide sequence in DNA or RNA that cause the expression of new phenotypes. Source of all variation. Can be positive, negative, or neutral depending on the environmental context.

Question 24

Mechanism: Gene Flow

Answer 24

The movement of genes between individuals of the same species but different populations via sexual reproduction or a different species via non-reproductive means. (Immigration can introduce new alleles and immigration can remove rare alleles)

The movement of genes into or out of a population

Question 25

Allopatric speciation vs Sympatric speciation

Answer 25

Allopatric speciation is when geographical barriers prevent gene flow, whereas Sympatric speciation is when other factors (non-geographical) prevent gene flow (such as sexual selection or genetic incompatibility)

Question 26

Reproductive isolation

Answer 26

results from mechanisms that impede mating between different species, hinder the fertilization of eggs due to genetic (prezygotic) or chemical incompatibilities or impede hybrids from surviving/reproducing (postzygotic).

Question 27

Mechanism: Genetic drift

Answer 27

Stochastic changes in the genetic make-up of a population caused by
- Chance events (random and unpredictable events that leads to…)
- Bottlenecks (when a large population crashes to a relatively few individuals and the genetic makeup of survivors becomes the foundation of future generations)
- Founder effect (When a small group of individuals begin a new population elsewhere and the genetic makeup of the founders becomes the foundation of future generations.

*Existing phenotypes do not effect the survival of the organisms during chance events, Survival must be completely random, otherwise it would be natural selection

Question 28

Hardy-Weinberg (H-W) theorem

Answer 28

a hypothetical population in which a specific gene is not changing over time in a population (not-evolving).

5 necessary conditions:
- no natural or artificial selection
- no mutation
- no gene flow
- no genetic drift (large population)
- no sexual selection (random mating)
basically no mechanisms of evolution

Question 29

Horizontal gene transfer (HGT)

Answer 29

The transfer of genetic material between organisms in a way BESIDES the traditional parent–> offspring relationship. (such as a parasite –> host connection)