7 Species And Speciation

Question 1

Define Biological Species Concept

Answer 1

defines a species as a group of organisms who can interbreed and produce offspring that can successfully reproduce

Question 2

Describe the criteria by which the Biological Species Concept defines a species

Answer 2

• Interbreeding Potential: members of the same species must be able to mate with each other
• Viability of Offspring: offspring must be able to survive and reproduce

Question 3

Explain how gene flow unites populations within a species

Answer 3

Gene flow unites populations within a species by lowering the differences in genetic variation. When members of the same species from different populations interbreed, genes are exchanged.

Question 4

Explain how reproductive isolation divides a species

Answer 4

Reproductive isolation divides a species by blocking gene flow. This causes populations to evolve independently to their environment and becoming distinct enough that they will no longer be able to interbreed successfully

Question 5

Define Alternative Species Concept

Answer 5

an alternative concept to define a species rather than using biological species concept

Question 6

Define Morphological Species Concept. When is it best used to define a species?

Answer 6

alternative concept in defining species based on their morphology.

(best used to define fossils or when reproductive anatomy isn’t available

Question 7

Define Ecological Species Concept

Answer 7

alternative concept in define species based on ecological niches they occupy

(best used to understand how species interact with each other and their environment)

Question 8

Define Pre-zygotic Barriers

Answer 8

Barriers that prevent fertilization of a zygote

Question 9

Define Habitat Isolation. Give an example

Answer 9

2 different species live in same environment, but don’t interbreed due to using the environment differently and not interacting

(ex: 2 different fish species live in the same lake. However, 1 fish species lives in the deep end and the other lives in the shallow end)

Question 10

Define Temporal Isolation. Give an example.

Answer 10

2 different species live in the same environment, but don’t interbreed due to having different mating times

(ex: 2 different fish live in the same lake. However, 1 fish species mates during the summer and the other mates during the winter)

Question 11

Define Behavioral Isolation. Give an example

Answer 11

2 different species not being able to interbreed due to differing behavioral traits

(ex: 2 different bird species are unable to mate due to having different mating calls)

Question 12

Define Mechanical Isolation. Give an example.

Answer 12

2 different species not being able to interbreed due to incompatible reproductive anatomy

(ex: carne corso cannot mate with a chihuahua because its reproductive anatomy is too large)

Question 13

Define Gametic Isolation. Give an example

Answer 13

egg and sperm from 2 different species cannot join together due to differences in biochemical/genetic differences

(ex: differences in surface proteins on sperm or egg cell can prevent them from recognizing each other)

Question 14

Define Post-Zygotic Barriers. Give an example

Answer 14

barriers in reproducing after zygote is formed

(ex: mule cannot reproduce due to having an odd number of chromosomes. It prevents meiosis)

Question 15

Use the idea of barriers to gene flow to describe how one species splits into two reproductively isolated species

Answer 15

Barriers block gene flow (which unites populations into one species). As a result, populations get isolated into different environments where they evolve traits to better survive the new environment. Overtime, the accumulation of traits will make the populations so distinct form each other that they become a new species

Question 16

Use the idea of local adaptation to describe how two isolated populations diverge morphologically and genetically over time

Answer 16

Two isolated populations can have different environments. Through local adaptation, each population will evolve traits fit for their environments. These traits could include morphological changes, which could be passed down generations overtime

Question 17

Define Allopatric Speciation. What are the circumstances that give rise to it? Give an example of a species risen from allopatry.

Answer 17

Rise of a new species due to a geological barrier.

Circumstances that give rise to it: Dispersal, Geographical Isolation, Local Adaptation

Galapagos Finches (mainland separated into islands with different environments)

Question 18

Define Sympatric Speciation. How is different from Allopatric Speciation? What major group of organisms is most likely to speciate sympatrically?

Answer 18

Rise of a new species from a single ancestor in the same area without barriers

It is different from allopatric speciation due to not being caused by barriers.

Plants are most likely to speciate sympatrically

Question 19

Explain how essentialists thinking about species leads to misconceptions about the process of speciation

Answer 19

Essentialists oversimplified the process of speciation. Their idea was that species had an inner nature or “essence” that determined their outward behavior, basically saying that species’ traits were fixed and stable. This idea is wrong because it does not consider variation, which speciation depends on.

Question 20

Explain how reproductive isolation can evolve gradually. Describe the process by which populations become more different from one another, leading eventually to reproductive isolation and complete speciation. Describe the requirements for that process and circumstances under which it usually occurs

Answer 20

As species get separated, they evolve to be very different from each other that they eventually turn into different species, becoming unable interbreed with each other anymore.

The requirements for this process are barriers (prezygotic, postzygotic, allopatric), local adaptation

Question 21

What is a ring species?

Answer 21

a species that has closely-related populations distributed in a ring pattern around a geographical barrier. Every stage around the ring, the populations are similar to its immediate neighbors and can interbreed with them. Populations who are at the ends can’t interbreed due to being reproductively isolated

Question 22

How does a ring species, such as the gulls, illustrate the speciation over space instead of overtime

Answer 22

gulls illustrate speciation through its closely-related populations being distributed in a ring pattern around a geographical barrier. At the ends of the rings are Herring Gulls and Black-Backed Gulls who can’t interbreed due to being reproductively isolated.

Question 23

How does extinction help create the differences we see between living species?

Answer 23

reduces competition for resources and leave behind many vacant niches, allowing new species to emerge

Question 24

The lawyer argued that one species can’t evolve into another because each child is a member of the same species as its parents. In your own words, use the time traveler example to explain to the lawyer why he is wrong

Answer 24

The lawyer is wrong because they aren’t considering the accumulation of changes over time. There will be a significant amount of change to the point where they can’t mate anymore, becoming a new species. The lawyer is using essentialist thinking