ILTS Science: Biology > Natural Selection & Adaptation > Flashcards

Natural Selection & Adaptation Flashcards

Examine genetic variation, Hardy-Weinberg equilibrium, and mechanisms like speciation and genetic drift in relation to species adaptation, survival, and extinction. (72 cards)

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1
Q

Define:

evolution

A

A change in allele frequencies within a population over generations.

This definition reflects the modern synthesis view of evolution.

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2
Q

Who proposed the theory of acquired characteristics?

A

Jean-Baptiste Lamarck

Theory of acquired characteristics is also known as Heritability of acquired characteristics or Lamarckian inheritance.

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3
Q

Who proposed the theory of evolution through natural selection?

A

Charles Darwin

He is known for his key contributions related to this concept.

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4
Q

What does the theory of acquired characteristics propose?

A

Traits acquired during an organism’s lifetime can be inherited by its offspring.

This idea, proposed by Lamarck, was eventually disproven by genetics.

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5
Q

What are the principles of Darwinian evolution?

A
  • Populations evolve, not individuals.
  • Variation exists among individuals.
  • More offspring are produced than can survive.
  • Individuals with favorable traits survive and reproduce.
  • Favorable traits accumulate over generations.
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6
Q

Which theory of evolution is more accepted and why?

A

Darwin’s theory of evolution by natural selection.

It is widely accepted because it is supported by fossil records, genetic evidence, and observable adaptations, unlike Lamarck’s theory.

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7
Q

What is the theory of evolution?

A

Evolution is the process by which species change over time through descent with modification.

Darwin’s theory emphasizes natural selection as the primary mechanism.

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8
Q

Who proposed the theory of evolution in the 1800s?

A

Charles Darwin and Alfred Wallace.

Charles Darwin wrote On the Origin of Species in 1859, proposing the theory of evolution by natural selection.

Alfred Russel Wallace independently conceived a similar theory, and both scientists jointly presented their ideas in 1858 to the Linnean Society of London.

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9
Q

What is biogeography?

A

The study of how different species are distributed in different environments.

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10
Q

How did Alfred Wallace contribute to the theory of evolution?

A

He provided independent findings on natural selection and collaborated with Darwin on scientific publications.

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11
Q

What is the Wallace Effect?

A

A hypothesis by Alfred Wallace stating that natural selection can lead to reproductive isolation and speciation.

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12
Q

Who is considered the father of biogeography?

A

Alfred Wallace

Alfred Wallace’s voyages involved collecting specimens to sell to natural history museums and collections in England.

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13
Q

What did Alfred Wallace believe about the adaptation and evolution of plants and animals?

A

That plants and animals adapted and evolved in response to their environment.

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14
Q

Define:

incipient species

A

Refers to a population that has been geographically isolated and has adapted new traits to their new environment.

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15
Q

How does reproductive isolation occur?

A

When two populations of the same species are separated by some barrier, preventing them from producing viable offspring.

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16
Q

What is allopatric speciation?

A

Occurs when two populations are separated by geographic barriers, leading to reproductive isolation and the creation of two distinct species.

Also known as geographic speciation.

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17
Q

What is genetic drift?

A

Refers to changes in the genotype of a population due to selective pressures and random genetic mutations.

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18
Q

What is the main difference between Wallace and Darwin’s theory of evolution?

A

Wallace believed that plants and animals evolved to their environment, while Darwin believed adaptations were driven by competition.

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19
Q

What did Alfred Wallace conclude?

A
  • The theory of evolution is driven by natural selection.
  • Natural selection is the process where organisms with traits best adapted to their environment survive to pass on those traits to future generations.
  • Wallace also hypothesized that natural selection can contribute to reproductive isolation of incipient species.

Alfred Wallace co-discovered the theory of evolution with Charles Darwin.

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20
Q

What does the Hardy-Weinberg equilibrium equation describe?

A

Genotypic frequency in a population.

Can be used to determine if the genetic makeup of a population is changing.

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21
Q

What are the five criteria that must be met for a population to be in Hardy-Weinberg equilibrium?

A
  • Random mating
  • Large population size
  • No migration between populations
  • No mutations
  • No natural selection
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22
Q

What does the equation 𝑝+𝑞=1 represent in the Hardy-Weinberg Equilibrium equation?

A

The sum of probabilities of passing on the dominant and recessive alleles.

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23
Q

What does the equation 𝑝2+2𝑝𝑞+𝑞2=1 represent in the Hardy-Weinberg Equilibrium equation?

A

The probabilities of different genotype combinations in the population.

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24
Q

How do you calculate Hardy-Weinberg equilibrium?

A

To calculate Hardy-Weinberg equilibrium, first find the frequency of a recessive genotype and set this equal to q^2. Square root both sides to get the frequency of passing on a recessive allele, q. Use the equation p + q = 1 to get p, the probability of passing the dominant allele. Then use p and q to find p^2, the homozygous dominant genotype frequency, and 2pq, the heterozygous genotype frequency.

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25
What is **artificial selection**?
The biological process of humans selecting preferred visible traits in plants and animals and then creating a breeding program to produce offspring with those desired traits. ## Footnote Artificial selection leads to adapting organisms to human needs and improving them faster than natural selection. Examples: * Domestication of dogs from wolves. * Corn from teosinte. * Breeding of fainting or myotonic goats in the United States.
26
What is the **main difference** between natural selection and artificial selection?
* **Natural** selection occurs over long time spans influenced by environmental pressures. * **Artificial** selection by humans can produce specific adaptations within a few years.
27
What are the **two main methods** of artificial selection?
1. Breeder's approach 2. Controlled natural selection ## Footnote **Breeder's approach**: breeding only individuals with higher levels of the desired trait. **Controlled natural selection**: modifying the environment of the organism to favor individuals with a favorable trait adaptation.
28
# Define: selective breeding
The human selection of a breeding pair of organisms to produce offspring with a particular trait in hopes of achieving offspring that express those characteristics. ## Footnote Examples: * Belgian Blue cattle for large lean muscle mass. * Border collies for herding behavior. * Tulips for unique color patterns and petal shapes. * Cruciferous vegetables from wild mustard species.
29
What is involved in the **selective breeding** of plants?
Carefully and manually pollinating plants with desired traits.
30
What are the **negative effects** of artificial selection?
* Reduction of genetic diversity. * An increase in genetic disease caused by mutations, especially when inbreeding is employed.
31
What is **macroevolution**?
The large-scale change in a species over long periods of time, resulting in the divergence of new species.
32
What are **macroevolutionary patterns**?
They help **explain the changes occurring within the gene pool** of species over time.
33
What is **microevolution**?
Refers to changes in gene frequency in a population from **one generation to the next**. ## Footnote Examines small changes over a short period of time. Can occur through: * Migration * Mutation * Genetic drift * Selection (natural and artificial)
34
# Define: stasis
A period of time in which no evolutionary changes occur.
35
What is the **difference** between microevolution and macroevolution?
* **Microevolution** refers to small changes over short periods of time within a population. * **Macroevolution** refers to larger changes over a long time scale within a population.
36
What are the **similarities** between microevolution and macroevolution?
* Both share the same processes of evolutionary change, including mutation, selection, migration, genetic drift, and isolation. * Each can result in shifting the allele frequency in populations over time.
37
# Define: speciation
The emergence of new species as a result of macroevolution.
38
Explain the concept of **isolation mechanisms** in speciation.
They contribute to the divergence of new species during speciation. ## Footnote Examples of isolation mechanisms include geographic, ecological, and temporal isolation.
39
What can result in the **extinction** of a species?
If a species is **no longer suited to survive and reproduce** in its environment, it may go extinct.
40
What is the **impact** of microevolution over time?
It can result in large enough changes that will lead to **macroevolution and speciation**.
41
What are the different types of evolution regarding the patterns of traits in separate species?
* Divergent evolution * Coevolution * Parallel evolution * Convergent evolution
42
What is **divergent evolution**?
When an ancestral species spreads into multiple populations, niches, or geographical locations. ## Footnote Can occur based on the geography of the species or based on the niche of the species.
43
What are the **two types** of speciation that occur under divergent evolution?
* Allopatric speciation * Sympatric speciation
44
What is **sympatric speciation**?
Occurs when an ancestral species evolves into a new species while continuing to occupy the same geographical region, in the absence of physical barriers.
45
What is **coevolution**?
Occurs between two or more species which are **evolutionarily distant** from one another, but influence each other's evolution through natural selection.
46
What is **parallel evolution**?
Occurs when geographically distant and independent species develop and maintain similar original traits due to similar evolutionary pressure or adaption to similar circumstances.
47
What are the **driving mechanisms of the evolution** of species?
The **flow of genes through sexual reproduction**, which results in varieties of offspring, and natural selection.
48
What are the **three different types** of evolution within a specific population?
* Catastrophism * Gradualism * Punctuated equilibrium
49
What is **catastrophism** in evolution?
It suggests organisms are wiped out through **natural disasters**, making way for different organisms.
50
What is **gradualism** in evolution?
It is when a species **branches off into separate species**, slowly and gradually changing through time.
51
What is **punctuated equilibrium** in evolution?
It is when organisms experience long periods of stasis and little evolution before periods of rapid speciation.
52
What is **convergent evolution?**
Occurs when organisms of different origins evolve in similar environments and develop similar traits. ## Footnote Such as sharks and dolphins.
53
What is **phyletic gradualism**?
A pattern of slow, uniform, and gradual evolution between ancestral and present forms.
54
What is the **Founder effect**?
Occurs when a small group of individuals is separated from the ancestral population.
55
How does punctuated equilibrium **occur** when a group enters a new ecological niche?
Organisms may need to adapt to new ways of survival, increasing the rate of evolution and speciation.
56
How is a **species** defined by the biological species concept?
A group of individuals capable of *mating and producing fertile offspring*.
57
What are the **three main stages** of speciation?
1. Separation 2. Divergence 3. Isolation
58
What is **artificial speciation**?
The formation of distinct species as a result of selective breeding by scientists.
59
What are the **steps** of allopatric speciation?
1. Geographic barrier such as an ocean, mountain, or earthquake that physically separates populations of the original species. 2. The two populations accumulate heritable mutations and experience different selective pressures. 3. The two populations become increasingly divergent until reproductively incompatible. 4. Speciation is complete when interbreeding with fertile offspring is no longer possible.
60
What can cause sympatric speciation?
Different ecological niches or genetic changes in a subset of the ancestral species that result in decreased interbreeding.
61
What are the two major types of **reproductive isolation**?
* Pre-zygotic barriers * Post-zygotic barriers
62
What are pre-zygotic barriers?
Reproductive barriers that occur before mating or fertilization. ## Footnote Examples: * Habitat isolation * Temporal isolation * Behavioral isolation * Mechanical isolation
63
What is **habitat isolation**?
When two species **prefer different habitats**, making it unlikely for them to encounter each other.
64
What is **temporal isolation**?
When closely related species have **different mating seasons or cycles**, preventing interbreeding.
65
What is **behavioral isolation**?
When one species does not respond to the **mating ritual** of another species.
66
What is **mechanical isolation**?
**Physical differences** between species that result in an inability to mate.
67
What are post-zygotic barriers?
Barriers that keep hybrid zygotes from developing into healthy, fertile adults. ## Footnote Examples: * Gametic incompatibility * Zygotic mortality * Hybrid inviability
68
What is **gametic incompatibility**?
The situation where **gametes are not compatible**, preventing the formation of hybrids.
69
What is **zygotic mortality**?
When the zygote does not continue to develop and eventually dies.
70
What is **hybrid sterility**?
The **inability** to produce offspring.
71
What is **hybrid breakdown**?
When the direct hybrid offspring can reproduce, but subsequent generations are sterile.
72
Describe the **bottleneck effect**.
A drastic form of genetic drift that occurs when a population's size is drastically reduced.
ILTS Science: Biology
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