Lecture 5

Question 1

Asexual Reproduction Advantages

Answer 1

• quick and energy efficient

* Sexual reproduction takes about twice as long as asexual reproduction (in species that do both)

Question 2

Asexual reproduction disadvantages

Answer 2

• Phenotypic diversity depends on
mutation
• ‘Muller’s Ratchet’: Accumulation of deleterious mutations
• Asexual reproduction can’t produce a genome with less deleterious mutations than the parent (sexual reproduction can)

Question 3

Sexual reproduction advantages

Answer 3

• Debated – several theories
• Main advantage (?): Ability to mix and match successful genes (more rare or novel genotypes)
• Organisms with asexual reproduction depend on mutation for genetic variation

Question 4

Sexual reproduction disadvantages

Answer 4

• Energetically costly (courtship, defence…)
• Main disadvantage: males do not directly produce offspring
• ‘twofold’ cost of sex (John Maynard Smith, 1971)

Question 5

Biological Species Concept:

Answer 5

Characterizes species by their ability to interbreed to produce fertile offspring

Question 6

Morphological Species Concept:

Answer 6

Characterizes species by body shape and other morphological features

Question 7

Ecological Species Concept:

Answer 7

Characterizes species in terms of its ecological niche

Question 8

Types of Asexual Reproduction (5)

Answer 8

1. Binary Fission
2. Multiple Fission (Schizogony)
3. Budding
4. Gemmulation
5. Fragmentation

Question 9

Binary Fission

Answer 9

Common among bacteria and protozoa
The parent divides by mitosis into two parts
Each grows into an individual similar to the parent E.g. protozoans like Paramecium

Question 10

Multiple Fission/ Schizogony

Answer 10

Nucleus divides repeatedly
Cytoplasmic division then produces many daughter cells simultaneously
E.g. parasitic protozoa like malaria

Question 11

Budding

Answer 11

• Unequal division of an organism
• Bud is an outgrowth of the parent
• Develops organs and then detaches
• E.g. Occurs in hydra

Question 12

Gemmulation

Answer 12

Formation of a new individual from an aggregation of cells
• Cells are surrounded by a resistant capsule – a “gemmule”
• E.g. Freshwater sponges
• gemmules develop in the fall and survive the winter in the dried or frozen body of the parent

Question 13

Fragmentation

Answer 13

• Like ‘binary fission’ for multicellular
animals
• breaks into two or more fragments that become a new individual
• Different from budding because each fragment grows new parts
• E.g. Occurs in many anemones, sea stars

Question 14

Sexual Reproduction

Answer 14

• Generally involves two parents
• Specialized germ cells unite to form a zygote
• Sexual reproduction recombines parental characters • Results in a more diverse population

Question 15

Types of Sexual Reproduction

Answer 15

Bisexual
hermaphroditism
Parthenogenesis

Question 16

Bisexual reproduction

Answer 16

Most common form

Male and female gametes (sperm or egg) are produced

Question 17

Hermaphroditism

Answer 17

Male and female organs occur in same individual

Most avoid self-fertilization

Question 18

Parthenogenesis

Answer 18

Sexual but can also be categorized as asexual
Embryo develops from unfertilized egg
Sperm may activate but not fuse with egg

Question 19

Oviparous

Answer 19

•Reproduction in which eggs are released by the
female.
• Development of offspring occurs outside the maternal body.
• External or internal fertilization

Question 20

Viviparous

Answer 20

Reproduction in which eggs develop within the female body, which provides nutritional aid
Internal fertilization

Question 21

Ovoviviparous

Answer 21

• Reproduction in which eggs develop within the maternal body without additional nourishment from the parent
• Hatch within the parent or immediately after laying.
• Internal fertilization
• Derive nourishment from yolk, not from mother