Speciation

Question 1

Species

Answer 1

Group of organisms whose members can breed and produce viable and fertile offspring typically by sexual reproduction

Question 2

Species (biological species concept)

Answer 2

A group of individuals that can potentially interbreed in nature and produce viable, fertile offspring
Individuals of different species are reproductively isolated from each other
If individuals from different species interbreed the offspring will not be viable or fertile

Question 3

Species (morphological species concept)

Answer 3

Most species can be classifies based on similarities with respect to measurable physical traits

Question 4

Species (ecological species concept)

Answer 4

Defining species as groups or populations that share the exact same ecological niche-or functional role it plays within an ecosystem

Question 5

Species (genetic species concept)

Answer 5

Define species with respect to similarities solely on basis of molecular data

Question 6

Anagenesis

Answer 6

-Phyletic Evolution (non-branching evolution)
-accumulation of changes that gradually transform a given entire species into a species with different characteristics (evolution within a lineage)
-no net increase in species diversity

Question 7

Cladogenesis

Answer 7

-branching evolution (diversifying evolution)
-one or more species arising from one original species (evolution that results in the splitting of a lineage)
-net increase in species diversity

Question 8

Gradualism
example

Answer 8

-gradual speciation model
- species diverge gradually over time in small steps
ex. small variations over time in a population of wolves- larger ears, longer teeth and a heightened sense of smell
ex. a species of butterfly is yellow and black in color, however a butterfly is born that happens to be orange and yellow in color making it difficult to see. over time the yellow and black die out

Question 9

Punctuated Equilibrium
example

Answer 9

A new species undergoes changes quickly from the parent species, and then remains largely unchanged for long periods of time afterward
ex. species of birds exist in stasis for many thousands of years, suddenly bacteria cause their primary tree of sheltering choice to die.
ex. cheetah species has no spots, due to a gene mutation a cheetah cub is born with spots

Question 10

Biological Species Concept

Answer 10

Based on the potential to interbreed rather than on physical similarity
- similarity between different species - the eastern meadowlark and the western meadowlark have similar body shapes and colorations, they are distinct, their songs and other behaviors are different enough to prevent interbreeding should they meet in the wild
- diversity within a species - as diverse as we may all appear humans belong to a single biological species

Question 11

Why we cannot apply the biological species concept to all situations

Answer 11

-does not apply to organisms that reproduce asexually all or most of the time such as prokaryotes
-no way to evaluate the reproductive isolation of fossils (obviously they cannot mate any longer, although we still have to classify them)

Question 12

Prezygotic Barrier
Which barriers prevent mating attempt and which prevent fertilization following mating

Answer 12

Impede mating between species or hinder the fertilization of ova if members of different species attempt to mate
-prevent mating attempt - habitat, temporal, behavioral
-prevent fertilization attempt - mechanical, gametic

Question 13

Postzygotic Barrier

Answer 13

Prevent zygote from developing into a viable and fertile adult

Question 14

Types of Prezygotic Barriers

Answer 14

Habitat, Temporal, Behavioral, Mechanical, Gametic Isolation

Question 15

Temporal Isolation
example

Answer 15

Species breed at different times (different times of day or different seasons or even years)
ex. western spotted skunk and the eastern spotted skunk overlap in distribution, even though they are very similar, western breed in late summer, eastern in late winter

Question 16

Habitat Isolation
example

Answer 16

Species found in different habitats but in same area that rarely come across each other even though there are no obvious physical barriers
ex. two species of garter snake live in the same area, but one species lives mainly in water, other is mainly terrestrial

Question 17

Behavioral Isolation
example

Answer 17

Every species has its own mating/courting rituals and behaviors and because of this, different species will not attract each other with prevents them from mating
ex. male fireflies have different light flashing patterns and only female of same species recognizes the pattern as being courtship behavior

Question 18

Mechanical Isolation
example

Answer 18

When male and female sex organs are not compatible which means fertilization cannot occur
ex. the direction a snail’s shell spirals, if it spirals in the direction opposite from another snail, they will not be able to mate since their reproductive organs will not align

Question 19

Gametic Isolation
example

Answer 19

Gametes do not unite to form a zygote (so egg and sperm cells are incompatible)
ex. many marine species broadcast their egg and sperm in the water. the gametes or more than one species can encounter each other, but they generally will not fuse
ex. sea urchins, bindin allows sperm cells to penetrate eggs

Question 20

Types of Postzygotic Barriers

Answer 20

Hybrid inviability, hybrid sterility, hybrid breakdown

Question 21

Reduced Hybrid Viability

Answer 21

zygote forms but dies after a few series of cell divisions (genetic information from a male and female parent were insufficient to carry the organism through morphogenesis)
most often the hybrid embryo dies before birth, sometimes the offspring develops fully with mixed traits from each parent, forming a frail, often infertile adult
ex. species of frog

Question 22

Reduced Hybrid Fertility

Answer 22

When the offspring of two parents cannot reproduce (offspring are sterile)
ex. male horse mates with female donkey to produce a hinny that is sterile
ex. male donkey mates with female horse to produce mule- sterile

Question 23

Hybrid Breakdown

Answer 23

Some first-generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile
ex. different rice species can produce fertile hybrid offspring but in the next generation the hybrids offspring die as seeds or grow into weak defective plants

Question 24

Five General Modes of Speciation

Answer 24

Allopatric, Peripatric, Parapatric, Sympatric, Artificial speciation

Question 25

Allopatric

Answer 25

1. One large population is split into two populations that are separated by a physical barrier (desert, river, rockslide)
   - a population can colonize a new habitat (dispersal and colonization)
   - a new physical barrier can split a widespread population into two or more isolated groups (a vicariance event)
2. two populations diverge from each other due to genetic drift
3. two populations become so different that when they come back into contact, can no longer reproduce with each other, due to pre or post zygotic barriers - they are separate species

Question 26

Examples of Allopatric

Answer 26

Galapagos finches
Grand Canyon squirrels

Question 27

Peripatric

Answer 27

When small groups of individuals break off from the larger group and form a new species
one group is much smaller than the other compared to allopatric (founder population)
ex. evolution of the polar bear from the brown bear

Question 28

Parapatric

Answer 28

Occurs when subpopulations of the same species are mostly isolated from each other, but have narrow area where their ranges overlap (narrow contact zone)
-a species is spread out over a larger geographic area

Question 29

Sympatric

Answer 29

1. Occurs in groups that occupy the same geographic area
2. Within one population, two groups start to diverge from each other (with no physical/geographical barrier)
3. The two groups become separate species

Question 30

Example of sympatric

Answer 30

Apple maggot flies
Cichlid fish

Question 31

Artificial Speciation

Answer 31

Creation of new species by people (which is achieved through lab experiments or animal husbandry)

Question 32

How Geographical Isolation can occur via dispersal and vicariance (when it comes to allopatric speciation)

Answer 32

• a population can colonize a new habitat (dispersal and colonization)
• a new physical barrier can split a widespread population into two or more isolated groups (a vicariance event)

Question 33

Founder population (when it comes to peripatric speciation)

Answer 33

the small population of individuals that break off from the larger groups

Question 34

Ring species (when it comes to parapatric speciation)

Answer 34

Supposed to form a chain of intergrading populations (or a connected series of neighboring populations that can interbreed with each other) encircling a geographic barrier, and the terminal forms in the secondary contact coexist without interbreeding
ex. ensatina salamanders and greenish warblers

Question 35

Explain how polyploidy can result in sympatric speciation

Answer 35

Polyploidy is when a plant gets extra sets of its DNA.
This can make it different from its relatives and unable to easily have babies with them.
different plants with extra DNA can still have babies with each other. these new plants become their own special group because they’re different from the old plants

Question 36

Differentiate between autopolyploidy and allopolyploidy

Answer 36

autopolyploid - an individual with more than two sets of chromosomes derived from one species
allopolyploid - a species with multiple sets of chromosomes derived from different species

Question 36

Difference between cladogenesis and anagenesis

Answer 36

Cladogenesis is a process of evolution in which a small subset of an existing species evolves, but not the entire species
-leaves the original species more or less intact, allowing for both the older species and the new species to co-exist

Question 37

similarities between cladogenesis and anagenesis

Answer 37

• types of evolutionary mechanisms
• occur in response to changes in environment
• lead to speciation