Lecture 1: mating and sex

Question 1

All organisms ___ but not all organisms have __

Answer 1

reproduce

sex

Question 2

reproduction:

Answer 2

production of offspring

Question 3

sex:

Answer 3

fusion of genetic material from two different parents / union of two genomes

Question 4

two forms of asexual reproduction:

Answer 4

asexual & sexual

Question 5

asexual reproduction doesn’t involve

Answer 5

sex.

SEXUAL DOES

Question 6

asexual reproduction:

Answer 6

• copying and proliferation in both unicellular and multicellular organisms.
• easy, cheap, error-free and straight forward

Question 7

asexual reproduction transmits:

Answer 7

intact single parental genome that by definition in successful, but may also transmit any mutations that have happened

Question 8

in asexual reproduction all genes come from

Answer 8

1 parent; genetically identical offspring

Question 9

who carries out asexual reproduction?

Answer 9

– Sponges (although they can also reproduce
sexually)
– Cnidaria (sea anemones, Hydra; again some can be sexual)
– Platyhelminthes (again, some sexual)
– Find examples in nearly all Phyla where
there are sexual and asexual reproduction

Question 10

4 types of asexual reproduction:

Answer 10

• fragmentation/regeneration
• budding
• parthenogenesis
• cycles of asexual/sexual

Question 11

fragmentation/regeneration

Answer 11

• parent body broken into pieces, then develop into adults

- followed by regeneration - regrowth of lost body parts

Question 12

budding

Answer 12

• Offspring grows out of body of parent
• Specialized mass of cells released
from parent that can develop into
offspring

Question 13

Parthenogenesis:

Answer 13

• virgin birth
• fish, insects, few lizards
• unfertilised eggs develop into young but are HAPLOID
• –variety of ways to restore diploidy
• NOT MAMMALS due to imprinted genes (only one chromosome from the mother or father is expressed; thus if have two maternal chromosomes both will express (or neither will be expressed)

Question 14

cycles of asexual/sexual reproduction

Answer 14

– e.g., Aphids
– Depends on E;
lots of food =asex; stressed E = sex
– XX = females, XO = males
(one X chromosome randomly
inactivated)

Question 15

sexual reproduction exists since

Answer 15

1.5-2 billion years (life ~3.8 billion years)

Question 16

two types of gametes =

or two mating types

Answer 16

sperm & eggs

+ and -

Question 17

sexual reproduction involves:

Answer 17

meiosis, leading to recombination and segregation.

-Recombination and segregation can purge deleterious mutations and bring together novel genetic combinations

Question 18

3 fundamental phenomena linked to sexual reproduction:

Answer 18

– Gametogenesis – production of gametes
– Mating – transferring gametes
– Fertilization – fusion of gametes

Question 19

Gametogenesis and fertilisation are

Answer 19

evolutionarily conserved

Question 20

mating is

Answer 20

extraordinarily diverse

Question 21

mating/copulation two types:

Answer 21

external and internal

• synchronise male and female
• – behavioural, chemical cues

Question 22

external mating/fertilisation examples:

Answer 22

• sponge
• cnidaria
• amphibian
• external fertilising fish

Question 23

external fertilisation requires & how does it work

Answer 23

WATER & males and females shed gametes into water

Question 24

how can external fertilisation be a problem?

Answer 24

– Can’t control delivery so
– have to produce many gametes because:
–– delivery difficulties; wave motion, water speed, etc
–– Predation of eggs

Question 25

haemocoelic

Answer 25

the primary body cavity of most invertebrates, containing circulatory fluid.

Question 26

internal mating - mechanisms to transfer and/or accept sperm

Answer 26

Indirect – male deposits sperm in a packet on ground (spermatophore); female picks it up
• Direct (“copulation”)– male and female copulate, sperm transferred directly and either free or in spermatophore
• Haemocoelic penetration – traumatic
insemination; sperm injected into haemocoel

Question 27

broad cast sporing is

Answer 27

a method of external fertilisation - clams, fish amphibians. in more mobile (fish) males will try and place sperm closer to the female

Question 28

Indirect transfer: Sminthurus viridis

Answer 28

• begins to produce stalk
• pushes genital plate directly onto substrate
  -stalk produced and spermatophore droplet is on top
  (raindrop on stem)

Question 29

indirect transfer: Allacma gallica

Answer 29

• male produces many spermatophores on stems in one are
• male then pushes and directs female towards them
• reduces chance of other males eating spermatophores and higher chance female will take one

Question 30

Direct transfer - copulation. Blanket octopus

Answer 30

Male detaches mating arm (hectocotylus) & leaves it to enter female alone.
-female <2m long, male ~1mm

Question 31

Hermaphrodites:

Answer 31

• Individual has both male and female reproductive parts
• Generally not self-fertilizing
• Partners exchange sperm and use that to fertilize their own eggs
• Eggs more expensive than sperm

Question 32

internal mating: Callosobruchus spps

Answer 32

• Penis has spines
• copulation wounds female internally - leads to early death
• female kicks to get male off

Question 33

Traumatic insemination:

Answer 33

• BEDBUGS
• female lacks genital openings
• males pierce membranes and place sperm into the females hemocael

Question 34

sexual cannibalism:

Answer 34

• Female kill state during or after copulation - spiders, insects, amphipods
• WHY?
• not usually for nutrition, may be a male strategy to maximise paternity or a female strategy to prevent paternity monopolisation

Question 35

copulation definition:

Answer 35

sexual intercourse

Question 36

sexual reproduction hijacked: Wolbachia

Answer 36

• Bacteria, common in arthropods including wasps and ants.
• Transferred in eggs but not sperm
• Can kill males in some infected species, or induce parthenogenesis