3-Species concepts

Question 1

1–BIOLOGICAL SPECIES CONCEPT

Answer 1

criteria used—can individuals mate and produce via offspring or not?

species—is a group of actually or potentially interbreeding individuals that can produce viable, fertile, offspring

requires reproductive barrier

Question 2

types of reproductive barriers

Answer 2

Prezygotic reproductive barriers (before zygote)

Post-zygotic reproductive barriers (after zygote)

Question 3

Prezygotic reproductive barriers

Answer 3

• Hinders mating or prevents fertilization of the egg
• **5 barriers:**
  1. Differences in timing of reproduction (temporal differences)
  2. Habitat isolation (same area but different habitats/microhabitats)
  3. Behavioural (difference in mating rituals)
  4. Mechanical (reproductive structures being incompatible)
  5. Gametic barrier (egg and sperm are incompatible)

Question 4

Post-zygotic reproductive barriers

Answer 4

• Hinders zygote development and Reduced viability/fertility
• 2 common post-zygotic barriers
  • Hybrid in viability (hybrid embryos do not develop properly or don’t reach sexual maturity or fail to mate)
  • Hybrid sterility/less fertile

Question 5

biological species concept limitations

Answer 5

• works well for organisms that sexually reproduce and have not gone extinct
• Cannot be tested on fossil forms
• Not relevant to asexual populations

Question 6

2—MORPHOSPECIES CONCEPT

Answer 6

• oldest of the species concepts
• Criteria—uses differences in morphology to distinguish species
• Can be used for:
  • both living and extinct species
  • Species that reproduce sexually and asexually

Question 7

morphospecies concept limitations

Answer 7

• different species may look very similar
• Individuals of the same species can look different at various life stages

Question 8

3—ECOLOGICAL SPECIES CONCEPT

Answer 8

organisms are classified as the same species if they have the same ecological niche and as different species if they do not

• niche—same habitat, food, predators, etc.
• Advantages: useful for identifying asexual species

Question 9

ecological species concepts limitations

Answer 9

1. Some species change their niche over time
   
   2. Different species can share the same niche

Question 10

4—PHYLOGENETIC SPECIES CONCEPT (PSA)

Answer 10

PSA concept defines a species as the smallest, non-divisible monophyletic group, distinguished by synapomorphies

• ancestral population and its descendants and only those descendants
• Or—smallest set of organisms that share an ancestor and can be distinguished from other sets of organisms by synapmorphies
• Evidence—you need a phylogenetic tree

Question 11

limitations of the Phylogenetic Species Concept

Answer 11

• pros—phylogenetic trees can be used for living and extinct taxa, and sexually and sexually reproducing species
• **Cons—**few phylogenetic trees, and they need a LOOOT of resources to construct