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Cells, organisms and systems > 1.5 - Evolutionary choices: sex + life histories > Flashcards

1.5 - Evolutionary choices: sex + life histories Flashcards

1
Q

Why do females invest more in reproduction

A

Females have larger gametes (egg much larger than sperm)

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2
Q

What are the costs of sex (4)

A
  1. sexual population 50:50 M/F if each female has 2 offspring population remains same
  2. half individuals make only sperm (cuts rate of population increase)
  3. have to find mate (conflict)
  4. Risk of reducing fitness
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3
Q

Benefits of sex (3)

A
  1. Genetic variability
  2. Spreads risks - range of phenotypes (some will be adapted to future conditions)
  3. Allows evolutionary change under selection
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4
Q

Name and describe 2 animals that don’t produce sexually (2)

A
  1. Aphids - Primarily parthenogenetic (asexual) - males appear annually
  2. Bdelloid rotifers - given up sex for atleast 30Mya (meiosis + males unknown)
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5
Q

what is a hermaphrodite? and give an example

A
  • Animals that possess both genitalia (no 2 distinct sexes)
  • Snails
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6
Q

what is the relationship between Octopus Bimaculatus and Octopus Bimaculoides?

A

O.bimaculatus and O.bimaculoides are similar and closely related small octopus (live in pacific coast of N.America)

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7
Q

What are the different reproductive strategies of O.Bimaculates and O.Bimaculoides? (2)

A

1.O.Bimaculates - eggs small and hatch into planktonic larvae
2.O.Bimaculoides - eggs large and hatchlings are benthic (bottom living)

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8
Q

Describe the octopus and human life histories (2)

A
  1. Octopus - lays many eggs, reproduces once (semelparous), dies before eggs hatch
  2. Humans - few offspring, born at long intervals, parental care, females live past reproductive age
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9
Q

Name the life history traits (8)

A
  1. Size at birth
  2. Growth pattern
  3. Age + size at maturity
  4. Number + size of offspring
  5. Age and size-specific reproductive investments
  6. Age and size-specific mortality schedules
  7. Length of life
  8. Sex
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10
Q

How many types of survivorship curves are there?

A

3

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11
Q

Describe the type 1 survivorship curve (3)

A
  1. Convex curves
  2. High survival rates in early/middle life
  3. Followed by rapid decline
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12
Q

What type of species does the type 1 survivorship curve represent?

A

Species that care for few offspring

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13
Q

Describe the type 2 survivorship curve (3)

A
  1. Diagonal curves
  2. Mortality rate/ survival probability independent of age
  3. Exponential decline
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14
Q

What species follow the type 2 survivorship curve?

A

some birds and lizards

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15
Q

Describe the type 3 survivorship curve (3)

A
  1. Concave curves
  2. Greatest mortality in early life
  3. Relatively low rates of death for those surviving early life bottleneck
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16
Q

What species does the type 3 survivorship curve represent

A

Species that produce many offspring

17
Q

Give an example of a species represented by the type 3 survivorship curve

A

Atlantic cod - can live >20 years, large female can lay 9M eggs/ year but can reproduce at 2-3 years old

18
Q

Give an example of a species represented by the type 1 survivorship curve

A

T-rex - High neonate mortality proceeds period of relatively low mortality

19
Q

Name + describe the 2 strategies of reproduction (2)

A
  1. Iteroparous - some resources devoted to breeding + survival (repeated reproduction
  2. Semelparous - all resources invested into single reproductive episode
20
Q

What is the name for when some resources are devoted to breeding + survival (repeated reproduction)

A

Iteroparous

21
Q

What is the name for when all resources are invested into single reproductive episode

A

Semelparous

22
Q

What is the male reproductive choice made by Coho salmon?

A

Whether to mature early as Jacks or later as hooknoses

23
Q

How long does it take for Coho salmon to mature into Jacks or Hooknoses? (2)

A
  1. Jacks - 6 months
  2. Hooknoses - 18 months
24
Q

What are the different characteristics of Jacks and Hooknoses? (2)

A
  1. Jacks - small + camouflaged
  2. Hooknoses - larger + brightly coloured
25
Q

What different methods do Jacks and Hooknoses use for reproduction? (2)

A
  1. Jacks - sneak out from behind rocks + attempt to stealthily mate with female
  2. Hooknoses - fight aggressively amongst one another for opportunity to mate
26
Q

What are the positive/negatives of Jacks and Hooknoses different reproductive strategies? (4)

A
  1. Jacks:
    + Higher survival rates
    - More competition for reproduction
  2. Hooknoses:
    + Less direct competition for mating
    - Lower survival rates
27
Q

What chromosomes determine sex in mammals/ flies? (2)

A
  1. M - XY
  2. F - XX
28
Q

What chromosomes determine sex in birds? (2)

A
  1. M - ZZ
  2. F - ZW
29
Q

What are the features of the odd sex chromosome (Y-mammals/flies W-birds)

A

Small + includes only genes associated with relative sex

30
Q

How is sex determined in vertebrates? (2)

A
  • Chromosomally
  • Environment
31
Q

How is sex determined in mammals/birds?

A

Chromosomally (XY/ZW) - other groups more variable

32
Q

What is the term for when sex can change when necessary but never both at same time (many fish have this trait - not chromosomally determined sex)

A

Sequential hermaphroditism

33
Q

Explain how the Bluehead wrasse is an example of sequential hermaphroditism (3)

A
  1. Live in groups of 1 male and several females
  2. Protogynous (female -> male)
  3. If male disappears - largest female changes sex
34
Q

Explain how the Clownfish is an example of sequential hermaphroditism (3)

A
  1. 1 female who breeds with 1 male
  2. Protoandrous (male -> female)
  3. if female lost - senior male takes her place and another male starts to reproduce

Cells, organisms and systems (19 decks)

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