evolution and speciation

Question 1

What is the definition of evolution?

Answer 1

A change in the heritable characteristics of a population

This definition distinguishes Darwinian evolution from Lamarckism, as acquired changes that are not genetic are not considered evolution.

Question 2

Evidence for evolution comes from base sequences in what?

Answer 2

• DNA
• RNA
• Amino acid sequences in proteins

Sequence data provides powerful evidence of common ancestry.

Question 3

What type of evidence for evolution is shown by selective breeding of domesticated animals and crop plants?

Answer 3

Variation between different breeds and varieties

This demonstrates how rapidly evolutionary changes can occur.

Question 4

What are homologous structures? Give an example.

Answer 4

Structures that share a common ancestry, e.g. pentadactyl limbs

These structures exemplify evolutionary relationships.

Question 5

What is convergent evolution?

Answer 5

The origin of analogous structures

Analogous structures have the same function but different evolutionary origins, such as the wings of birds and bees.

Question 6

How does speciation occur?

Answer 6

By the splitting of pre-existing species

This process increases the total number of species on Earth.

Question 7

What role does reproductive isolation play in speciation?

Answer 7

It prevents interbreeding between populations

Geographical isolation is one means of achieving reproductive isolation.

Question 8

What are the differences between sympatric and allopatric speciation?

Answer 8

• Sympatric: occurs without geographic isolation
• Allopatric: occurs with geographic separation

Reproductive isolation can also be behavioral or temporal.

Question 9

What is adaptive radiation?

Answer 9

The process allowing closely related species to coexist without competing

This increases biodiversity in ecosystems with vacant niches.

Question 10

What mechanisms prevent the mixing of alleles between species?

Answer 10

• Barriers to hybridization
• Sterility of interspecific hybrids

An example is courtship behavior preventing hybridization in animal species.

Question 11

What is an example of abrupt speciation in plants?

Answer 11

Hybridization and polyploidy

Knotweed or smartweed (genus Persicaria) contains many species formed by these processes.

Question 12

Why is classification needed?

Answer 12

Due to the immense diversity of species

A structured classification facilitates further study.

Question 13

What are the difficulties in classifying organisms using traditional methods?

Answer 13

The traditional hierarchy does not always reflect evolutionary divergence

Organisms have been classified by morphological features, which can be misleading.

Question 14

What is a clade?

Answer 14

A group of organisms that share a common ancestor and characteristics

The most objective evidence for placing organisms in the same clade comes from genetic data.

Question 15

What is the molecular clock?

Answer 15

A method estimating divergence times based on sequence differences

Mutation rates are assumed to be constant but can be affected by various factors.

Question 16

What are the terms root, node, and terminal branch in cladistics?

Answer 16

• Root: common ancestor
• Node: hypothetical common ancestor
• Terminal branch: end point in a cladogram

Nodes represent common ancestors in evolutionary trees.

Question 17

What is the significance of parsimony analysis in cladistics?

Answer 17

It selects the most probable cladogram with the smallest number of sequence changes

This method helps to explain observed sequence variation between clades.

Question 18

What evidence can be used for the classification of organisms into three domains?

Answer 18

Evidence from rRNA base sequences

This reclassification proposed an extra taxonomic level ‘domain’ above kingdoms.

Question 20

What is artificial selection?

Answer 20

The process of selecting individuals with desirable traits for breeding

This method is used to develop domesticated animals and crop plants from wild species.

Question 21

True or false: Artificial selection can cause rapid evolution.

Answer 21

TRUE

Significant changes in domesticated species over short periods demonstrate this.

Question 22

What is the pentadactyl limb?

Answer 22

A limb structure found in amphibians, reptiles, birds, and mammals

It has the same basic bone structure across these vertebrates despite different functions.

Question 23

What type of evolution is described by the adaptation of limbs for different locomotion types?

Answer 23

Adaptive radiation

This occurs when different groups evolve from a common ancestor to suit various environments.

Question 24

What are homologous structures?

Answer 24

Body parts that have evolved from the same part of a common ancestor

They show structural similarities despite differences in function.

Question 25

Fill in the blank: The considerable changes in domesticated animals and crop plants show that **_______** can cause rapid evolution.

Answer 25

artificial selection ## Footnote This suggests that natural selection could also cause significant evolutionary changes over time.

Question 26

What is the significance of the **wild carrot** and **cultivated carrot** comparison?

Answer 26

Demonstrates the effects of artificial selection on traits like color and nutrient content ## Footnote The wild carrot is cream-colored, while the cultivated carrot is bright orange due to high carotene content.

Question 27

What does the term **convergent evolution** refer to?

Answer 27

The evolution of similar traits in different species due to similar functions ## Footnote This results in analogous structures that arise from different evolutionary paths.

Question 28

What is the role of **speciation** in evolution?

Answer 28

The process by which new species arise from existing populations ## Footnote It often involves reproductive isolation and gradual evolutionary changes.

Question 29

List the four groups of vertebrates that have **limbs**.

Answer 29

* Amphibians * Reptiles * Birds * Mammals ## Footnote These groups utilize their limbs for various functions despite having a common structural design.

Question 30

What is the definition of **evolution**?

Answer 30

Change in the heritable characteristics of a population ## Footnote Evolution is how the diversity of life developed, concerning heritable traits inherited by offspring from parents.

Question 31

What mechanism drives **evolution** according to the text?

Answer 31

Natural selection ## Footnote This mechanism is also referred to as Darwinism.

Question 32

True or false: **Lamarckism** is the widely accepted theory for evolution.

Answer 32

FALSE ## Footnote Lamarckism is based on the inheritance of acquired characteristics, which lacks a mechanism for genetic changes.

Question 33

What is the primary evidence supporting the theory of **evolution by natural selection**?

Answer 33

* Antibiotic resistance * Pesticide resistance * Homologous structures * Analogous structures ## Footnote These observations support the theory as a pragmatic truth.

Question 34

What is a **theory** in scientific terms?

Answer 34

A generalization that predicts and explains observations ## Footnote A theory emerges when generalizations are supported by evidence.

Question 35

What does the **impossibility of formal proof** in science imply?

Answer 35

It does not make us doubt that evolution happens ## Footnote The theory of evolution is supported by a vast amount of evidence, making it unlikely to be falsified.

Question 36

What is the relationship between **base sequences** and evolution?

Answer 36

Base sequences of genes can be compared to show evolutionary relationships ## Footnote Closely related species have fewer differences in their base sequences.

Question 37

What does the gradual accumulation of differences in base sequences suggest about species?

Answer 37

They diverge from a common ancestor over time ## Footnote This divergence is explained by the theory of evolution.

Question 38

Fill in the blank: The theory of evolution by natural selection is accepted as a _______ because it explains a broad range of observations.

Answer 38

pragmatic truth ## Footnote This theory is widely supported by scientific evidence.

Question 39

What is the significance of **observed combinations of alleles** in different species?

Answer 39

They provide evidence for evolution ## Footnote These combinations help in understanding evolutionary relationships.