Lecture 21 - Species Concepts

Question 1

Typological Species Concept

Answer 1

group of individuals that differ from other groups by possessing constant diagnostic characters

Question 2

Problems with TSC

Answer 2

• polymorphism within populations
• geographic among population
• sibling or cryptic species

Question 3

Biological Species Concept (BSC)

Answer 3

species are groups of actually or potentially natural populations that are reproductively isolated from such other groups
- “potentially” refers to some population never meet each other, but if they do, they can interbreed, but don’t

Question 4

Prezygotic Isolation

Answer 4

Before sperm and egg meet

-prevents fertilization

Question 5

Postzygotic Isolation

Answer 5

Barriers also occur if hybrids are inviable or sterile

-sperm and egg meet, but hybrids are inviable or sterile

Question 6

What is speciation according to Darwin?

Answer 6

multiplication of species

Question 7

Reproductive Isolating Mechanisms

Answer 7

when speciation occurs when populations evolve

Question 8

How many species currently exist?

Answer 8

About 3 million species have been described

Only about 1.5 million in any detail

Question 9

Why the uncertainty in how many species are there?

Answer 9

1. ) Many groups poorly studied
   - microorganisms and parasites
2. ) Many environments are poorly samples
   - tropical environments
3. ) Molecular approaches are identifying more and more “cryptic species”
   - a cryptic species is indistinguishable from another species at the morphological level, but distinguishable genetically

Question 10

Cryptic Species

Answer 10

indistinguishable from another species morphologically, but distinguishable genetically

Question 11

Non-dimensional Species Concept

Answer 11

species B found within species A (physically

- sympatric and synchronous

Question 12

Multidimensional Species Concept

Answer 12

Species B and Species A are not in the same dimension

- species are allopatric and/or allochronous

Question 13

Problems with BSC

Answer 13

1. ) not applicable to asexual species
2. ) reproductive isolation if often incomplete
3. ) multidimensional concept difficult to verify

Question 14

Evolutionary Species Concept (ESC) - Simpson

Answer 14

an evolutionary species is a lineage evolving separately from others with its own unitary evolutionary role and tendencies

Question 15

Problems with ESC

Answer 15

1. ) arbitrary

2. ) does not provide a mechanism

Question 16

Phylogenetic Species Concept (PSC) - Cracraft

Answer 16

smallest diagnosable monophyletic group of populations within which there is a parental pattern of ancestry and descent

Question 17

Problems with Phylogenetic Species Concept (PSC)

Answer 17

1. ) What characters to use?
   - depending on characters, trees will be diff.
2. ) What level of divergence constitutes a species?
3. ) distinguishing beteween gene trees and species trees
4. ) DOES NOT ADDRESS MECHANISM

Question 18

Which species concept was initially developed to identify fossil species?

Answer 18

The Evolutionary species concept

Question 19

Evidence supporting life on earth 3.5 billion years ago includes the discovery of:

Answer 19

Stromatolites

Question 20

According to mitochondrial DNA data, modern humans evolved in Africa about:

Answer 20

150,000 years ago

Question 21

Identifying Monophyletic groups is fundamental for:

Answer 21

Phylogenetic Species Concept

Question 22

The end-Permian mass extinction occurred approximately:

Answer 22

250 million years ago

Question 23

Recognition Species Concept (RSC)

Answer 23

most inclusive population of biparental organisms that share a common fertilization system

Question 24

Mate-Recognition Systems in RSC

Answer 24

• courtship displays
• timing of reproductive events
• neuroendocrine signals
• design of copulatory organs
• gamete compatibility

Question 25

Problems of Recognition Species Concept (RSC)

Answer 25

1. ) not applicable to asexual species

2. ) recognition systems often go awry