Individuals and life history traits

Question 1

Populations where evolution becomes obvious because selection

Answer 1

Selection acts on phenotypes, rarely on genotypes
Changes phenotypes and ultimately genotypes available for adaptation within populations

Question 2

Adaptive potential within populations

Answer 2

level of standing genetic variation within population (genetic variability)
Forms the basis by which traits respond to environmental shifts or selection
* Degree of trait change is tempered by the trait’s genetic architecture, the strength and modes of selection, and the level of isolation among populations

super important, can cause evolution within 4 generations

Question 3

survival and fitness (reproductive success) is more easily assessed at ___

Answer 3

individual level

Question 4

Individual Survival / reproduction
Enhancement or diminished by _______

Answer 4

Appropriate habitat to live

Budgeting time and energy among
activities

Partitions energies into growth vs. reproduction

Question 5

How individual allocates its time/energy resources over its lifetime into(5):

Answer 5

• Growth/development
• Maintenance
• Reproduction
• Migration
• Senescence/Mortality(?)

Question 6

Measurable aspects of an individual’s life

Answer 6

• e.g., age, and size at maturity, growth
• reproduction rate(s),
• clutch size,
• mortality rate(s), etc,…

varys among species, pops within species, individuals within pop (sex, age,etc)

Question 7

13 Life history traits linked to survival and reproduction

Answer 7

1. Age and size at maturity
2. Body size – larger fish
3. Longevity – life span

4 and
5. Clutch and egg size, and size at birth
6. Time until hatching/exogenous feeding
7. Larval growth rate and duration
8. Duration of spawning season and number of spawns per year
9. Number of spawnings over the individual’s lifetime
10. Reproductive interval
11. Parental care
12. Gender change and sex ratio variation
13. Geographic patterns and phylogenetic constraints

Question 8

Age and size at maturity trait

Answer 8

Trade-off in many species between late vs. early maturation
* Balance between the 2 strategies
Theoretically, females in population with low large adult survival should reproduce at smaller sizes and earlier ages

Question 9

Fisheries induced evolution in Northern cod

Answer 9

cod used to be very very large (large females producing a lot of eggs), but the large females have been removed for fishing,early 70’s was peak cod harvest which caused fishery to collapse,collapsed a whole economy as well.

Question 10

Size selective fishery for cod

Answer 10

targeted slow growing, highly fecund females with high egg-larvae survivorship

• Decreased key life history traits in most heavily exploited stocks
• decreased age at maturity - decreased growth rates
• decreased annual survival
  Decreased mean female fecundity (# eggs produced)
• Lowered the Standing Genetic Variation in several
  key stocks
• Smaller, fast growing, less productive females dominate the stocks
• Smaller population sizes during peak harvests led to increased risk of losing slow, large-growing highly fecund alleles in the population

Question 11

Body size – larger fish trait

Answer 11

Less susceptible to predation
store more energy, swim faster and further
Survive harsher conditions longer
* Can dominate territorial interactions, more mating opportunities
* Come at some costs, where energy allocated to somatic growth not used for reproduction

Question 12

Longevity – life span trait

Answer 12

Longer life allows for greater numbers of reproductive opportunities
Tempered by:
- Age/size at maturity (when
reproduction status achieved) - Interval between spawning

Question 13

Clutch and egg size, and size at birth
trait

Answer 13

eggs a female produces is its fecundity which can be estimated over a year, within a spawning period or batch, or over the individual’s lifetime

Fecundity Combined with egg size estimates reproductive allotment (Ri ), which describes the percent of the female’s weight devoted to eggs/embryos

When adult survival is poor, females devote more energy to reproduction

Question 14

Size-dependent reproductive allotment (Ri) graph

Answer 14

exponential (hyperallometric)– NOT linear relationship to mass

Question 15

mass Ri relationship ≥ 1 for fish

Answer 15

in fish, rare to have a value less than or equal to 1.
if species has val of 1, then species is following isometric. usually greater than 1(hyperallometric).

Question 16

Time until hatching/exogenous feeding trait

Answer 16

More time as egg:
- Larvae bigger, healthier, better able find food
- Longer time spent in vulnerable stage

Less time as egg:
- Smaller, weaker less able to find food
- Out of vulnerable stage faster

Question 17

Larval growth rate and duration trait

Answer 17

Similar to eggs, larval growth and development also important life history trait
* Rapid growth leads to greater size and a faster exit of high-vulnerable life stages

rapid growth requires more energy
- Higher metabolism
- Better, faster feeding, but also
increased probability of starvation (to maintain high metabolism)

Transforms to juvenile and recruits to safer habitats faster
- Cannot disperse as far, and so have shorter PLD (higher potential for competition)

Question 18

Duration of spawning season and number of spawns per year trait

Answer 18

The number of times/year a female spawns directly impacts Ri, which decreases somatic growth
* Spawning season duration is more a population parameter but can help predict recruitment

Question 19

Number of spawnings over the individual’s lifetime trait

Answer 19

Iteroparous – many iterations of giving birth so many spawns
Semelparous – One mass spawning bout after which individuals die (e.g., Pacific salmon)
Indeterminate spawners – continuously producing and dropping eggs in frequent spawns

Question 20

reproductive interval trait

Answer 20

• Time spent between spawning event in iteroparous species * Ranges from daily intervals to protracted time spans
  sometimes > a year
• Longer intervals increase opportunities for growth and
  replenishment or reserves and can increase Ri
  Spawning intervals often impacted by mortality, where increasing mortality shortens interval(s) length

Question 21

Parental care trait

Answer 21

High impact on reducing mortality of young, with higher parental care
* From none (most common) to both pre and post zygotic
care - Stickleback
- Sunfishes (centrarchids)
- Cichlids (mouth brooders)
* High parental care often associated with lower numbers of well provisioned eggs (investments being made with follow through)
* Increased survival of young at cost of decreased reproductive output of caring parents

Question 22

prezygotic vs postzygotic

Answer 22

Prezygotic isolation occurs before the formation of a zygote can take place. Postzygotic isolation occurs after members of two different species have mated and produced a zygote.

Question 23

Gender change and sex ratio variation trait

Answer 23

male to female = protandry, while female to male = protogyny

Timing determined by current sex ratios and relative probability of reproductive success
* Costs in reproductive output (potential) during transition, which can take weeks, or even months
* Environmental Sex Determination (ESD),

• Important implications for climate change

Question 24

Geographic patterns and phylogenetic constraints trait

Answer 24

traits can differ within species based on geographic location ,traits can convergence among different species in common environments
Suggests environment strong selective impact on life history traits in general

Phylogenetic background can also impose constraints on how far life history traits can change to match environment