Chapter 21.1 - The Biological Species Concept

Question 1

Textbook:
What is speciation?

Answer 1

Speciation is the process that produces new species - novel and distinct forms of life.

Question 2

Textbook:
What would happen if there was no speciation?

Answer 2

Without speciation, our world would be inhabited by a single kind of generally adapted organism, instead of the staggering biodiversity we see around us.

Question 3

Textbook:
What is the challenge when defining a species?

Answer 3

Species, as an evolutionary unit, must be fluid and capable of changing, giving rise through evolution to new species. Species are not fixed.

Question 4

Textbook:
What is the BSC and how is it primarily useful?

Answer 4

BSC stands for Biological Species Concept.
It is primarily useful for thinking about species when they can interbreed successfully.

Question 5

Textbook:
How is the BSC defined?

Answer 5

BSC defines a species as:
“Species are groups of actually or potentially interbreeding populations that are reproductively isolated from other such groups.”

Question 6

Textbook:
What does it mean to be reproductively compatible?

Answer 6

Species can produce fertile offspring together. This compatibility is determined by factors such as genetic similarity, anatomical compatibility, and behavioral traits.

Question 7

Textbook:
Can mutations spread outside of species?

Answer 7

No.
Therefore, a species represents a closed gene pool.

Question 8

Textbook:
What are the shortcomings of BSC?

Answer 8

The shortcomings of BSC are:
1. Practical challenges in applying it to organisms due to resource limitations
2. Difficulties in assessing fertility
3. Issues with asexual or extinct organisms
4. Cannot be applied to fossils

Question 9

Textbook:
What complicates the BSC when it comes to hybridization between populations of closely related species?

Answer 9

Hybridization can complicate the BSC.
In some locations, the 2 closely related species may interbreed, producing hybrid offspring, while in others, they may remain reproductively isolated.
This variability challenges the clear-cut distinctions the BSC seeks to make.

Question 10

Textbook:
How does the morphospecies concept define a species?

Answer 10

This concept holds that members of the same species usually look alike.
At the molecular level, members of the same species often have similar DNA sequences that are different from those of other species.

Question 11

Textbook:
What is the Barcode of Life?

Answer 11

The Barcode of Life is a database that links DNA sequences to species.

Question 12

Textbook:
What are the limitations of the morphospecies concept?

Answer 12

A limitation of the morphospecies concept is that it may not account for polymorphisms within a species and can fail to differentiate between similar-looking species.

Question 13

Textbook:
What are cryptic species?

Answer 13

Cryptic species are organisms that appear similar but belong to different species due to differences at the DNA-level. This accounts for polymorphisms.

Question 14

Textbook:
How does the ecological species concept define a species?

Answer 14

The ecological species concept defines species based on their ecological niches, including habitat, nutrition, and water needs.
If two species have similar niches, they may not coexist due to resource competition.

Question 15

Textbook:
How does the ecological species concept help define a species when it comes to asexual organisms?

Answer 15

We can determine whether asexual organisms are distinct species on the basis of differences or similarities in their ecological niches.

Question 16

Textbook:
How does the phylogenetic species concept define a species?

Answer 16

The phylogenetic species concept defines species based on common ancestry and fate. It emphasizes that species share a common ancestor.

Question 17

Textbook:
What is a limitation of the phylogenetic species concept?

Answer 17

This concept emphasizes that species share a common ancestor, but does not specify to what extent.
For example, could we consider all mammals to be a single species due to our common ancestor?
In other words, it may not be specific enough

Question 18

Textbook:
Why has the scientific community been unable to come up with a single, comprehensive, and agreed-upon species?

Answer 18

Species change over time, making it difficult to make a single definition that can be applied in all cases.
A species concept must apply to an overwhelming variety of organisms (from a living microbe to an extinct dinosaur).

Question 19

Textbook:
Given a group of organisms, how would you test whether they all belong to one species or whether they belong to 2 separate species according to the morphospecies concept?

Answer 19

Careful observation of the phenotypic organisms could provide insight into how many species are represented in the group.

Question 20

Textbook:
Which types of organisms do not fit easily into the biological species concept?
Which species concept would work best for these organisms?

Answer 20

Organisms that reproduce asexually, such as bacteria, and those that are extinct cannot fit into the BSC’s definition of a species.
A combination of phylogenetic and ecological species concepts works best for these organisms.

Question 21

Textbook:
Why do morphospecies typically correspond to BSC-defined species?

Answer 21

The BSC defines species on the basis that they can exchange genetic material.
Oftentimes, organisms that can share genetic material generally look alike.