Chapter 13: Speciation And Extinction

Question 0

Define macroevolution?

Answer 0

Describes these large, complex changes in life’s panorama.

Question 1

How has the definition of species evolved over time?

Answer 1

The definition of species has evolved over time through microevolution. The many small scale changes that accumulate in a population by microevolution eventually lead to large scale microevolution.

Question 2

Define species?

Answer 2

Distinct types of organisms.

Question 3

Discuss the system of classification developed by Carolus Linnaeus.

Answer 3

Linnaeus’s classifications organized the great diversity of life and helped scientist communicate with one another. He grouped similar genera into orders, classes, and kingdoms.

Question 4

Define biological species.

Answer 4

As a population, or group of populations, whose members can interbreed and produce fertile offspring.

Question 5

Define speciation.

Answer 5

The formation of new species, occurs when members of a population can no longer successfully interbreed.

Question 6

Discuss the contribution of Ernst Mayr to our understanding of speciation.

Answer 6

Mayors biological species definition, however, provides an objective rule for determining whether each group really is a separate species.

First, the biological species concept cannot apply to asexually reproducing organisms, such as bacteria, archaea, and many fungi and protist.

Second, it’s is likewise impossible to apply the biological species definition to extinct organisms known.

Third, some types of organisms have the potential to interbreed in captivity.

Fourth, for some species, reproductive isolation is not absolute.

Question 7

How do reproductive barriers separate species?

Answer 7

Any interruption in courtship, fertilization, embryo formation, or offspring development can be a reproductive barrier.

Question 8

Compare the five types of prezygotic reproductive isolation.

Answer 8

Ecological isolation- two species that share a habitat will not mate if they are active at different times of day or reach reproductive maturity at different times of the year.

Behavioral isolation- behavioral differences may prevent two closely related species from mating.

Mechanical isolation- in many animals species, male and female parts fit together almost like a key in a lock.

Gametic isolation- if a sperm cannot fertilize an egg cell, then no reproduction will occur.

Question 9

Compare the types of postzygotic reproductive isolation.

Answer 9

Hybrid inviability- a hybrid embryo may die before reaching reproductive maturity, typically because the genes of its parents are incompatible.

Hybrid breakdown- some species produce hybrid offspring that are fertile. When hybrids reproduce however their offspring may have abnormalities that reduce their fitness.

Hybrid infertility- some hybrids are infertile. A familiar example is the mule, a hybrid offspring of a female horse and a donkey.

Question 10

Compare the three main modes of speciation.

Answer 10

Allopatric speciation- no contact between populations.

Parapatric speciation- populations share a border area.

Sympatric speciation- continuous contact between populations.

Question 11

How do spatial arrangements define the mode of speciation?

Answer 11

The most obvious way is to physically separate the population so that they do not exchange genes. Natural selection and genetic drift would then act independently in the two populations.

Question 12

Be familiar with examples of each mode of speciation?

Answer 12

Allopatric speciation- devils hole is a pool in a limestone cavern east of Death Valley national park. The pupfish species that lives there is a product of allopatric speciation.

Parapatric speciation- the little greenbul lives in the rain forest and in economies, which are patches of forest on the border zone with grasslands.

Sympatric speciation- cichlids in the deep waters of lake ejagham have smaller bodies than do shallow-water fish.

Question 13

Compare Sympatric speciation caused by a microclimates and polyploidy.

Answer 13

Polyploidy- which occurs when the number of sets of chromosomes increases.

Microclimates-

Question 14

Compare gradualism and punctuated equilibrium.

Answer 14

Gradualism is held that evolution proceeds in small, incremental changes over many generations.

Punctuated equilibrium- to describe relatively brief bursts of rapid evolution interrupting long periods of little change.

Question 15

Why does punctuated equilibrium explain most examples of allopatric speciation?

Answer 15

W

Question 16

How does punctuated equilibrium explain gaps in the fossil record?

Answer 16

The fossil record they argued, lack some transitional forms because they never existed in a particular location or because there were simply too few organisms to leave fossils.

Question 17

Explain adaptive radiation?

Answer 17

In which a population inhabiting a patchy or heterogeneous environment gives rise to multiple specialized forms in a relatively short time.

Question 18

Define extinction.

Answer 18

When all of its members have died.

Question 19

Define background extinction rate.

Answer 19

Results from the gradual loss of species as populations shrink in the face of new challenges.

Question 20

Define mass extinction.

Answer 20

When a great number of species disappeared over relatively short expanses of time.

Question 21

Discuss three factors which can affect a species risk of extinction.

Answer 21

The change that wipes out a species may be habitat loss, new predators, or new diseases.

Question 22

Define impact theory?

Answer 22

Suggests that meteorites or comets have crashed to Earth, sending dust, soot, and other debris into the sky, blocking sunlight and setting into motion a deadly chain reaction.

Question 23

How might plate tectonics impact extinction rates?

Answer 23

A second theory is that movements of earth’s crust may explain some mass extinctions. The crust, or uppermost layer of the planets surface, is divided into many pieces, called tectonic plates. During earth’s history, movement of tectonic plates caused continental to drift apart, then come back together.

Question 24

Define taxonomy.

Answer 24

Is the science of describing, naming, and classifying species.

Question 25

Define phylogenetics.

Answer 25

Is the study of evolutionary relationships among species.

Question 26

Define systematics.

Answer 26

The study of classification, therefore incorporates two interrelated specialties; taxonomy and phylogenetics.

Question 27

How do systematic differ from taxonomy?

Answer 27

Systematic is the study of classification. Taxonomy is describing, naming, and classifying species.

Question 28

Discuss the taxonomic hierarchy.

Answer 28

The taxonomic hierarchy organizes species into groups.

Question 29

Compare ancestral and derived characteristics.

Answer 29

Ancestral characteristics are inherited attributes that resemble those of the ancestor of a group an organism with derived characters has features that are different from those found in the groups ancestor.

Question 30

How does a cladistic approach to systematic differ from the traditional approach?

Answer 30

In a cladistic approach, biologists use shared derived characters to define groups.

Question 31

Define Clade

Answer 31

A Clade also called a mono phyletic group, is a group of organisms consisting of a common ancestor and all of its descendants;

Question 32

Define parsimonious.

Answer 32

Which is the one that requires the fewest steps to construct.

Question 33

Compare the terms monophyletic, para phyletic and poly phyletic groups

Answer 33

Monophyletic groups is a group of organisms consisting of a common ancestor and all of its descendants; a Clade.

Para phyletic group is a group of organisms consisting of a common ancestor and some, but not all, of its descendants.

Poly phyletic group is a group of species that excludes the most recent common ancestor.

Question 34

What is depicted in a cladogram?

Answer 34

Cladograms depicted nested hierarchies of evolutionary relationships.

Question 35

Define molecular clock.

Answer 35

To estimate the time when the organisms diverged from a common ancestor.

Question 36

Define phylogeny.

Answer 36

Which depict species relationships based on descent from shared ancestors.

Question 37

How did a single mutation in mimulus result in reproductive isolation?

Answer 37

By selective breeding, researches created mimulus plants that resembled their wild type counterparts in every respect-except flower color. They used wild type mutant plants to test hypotheses about reproductive barriers in mimulus .

Question 38

Define endosymbitoic theory.

Answer 38

Proposes that mitochondria and chloroplast originated as free living bacteria that were engulfed by other prokaryotic cells.