lecture 15: life history part 2

Question 1

What is life history

Answer 1

Life history theory predicts how natural selection should shape the way organisms parcel their resources into making babies

Its about tradeoffs and optimization among traits

Question 2

Life history traits:

Answer 2

• size at birth
• growth pattern
• age and size at maturity
• number, size, and sex of offspring
• age and size specific reproductive efforts
• age and size specific survival rates
• lifespan

Question 3

Reproductive efforts

Answer 3

The time and energy that is being put into reproduction

-its the cost to future reproduce success on the parent: reduced survival, fecundity and or growth

Question 4

Altricial

Answer 4

young are born helpless (increase parental fitness at the expense of the young)

-when parents generate a lot of Offspring, I vest little in each with expectation of low survival rates

Question 5

Precocial

Answer 5

• longer gestation, young are born at a more advancers developmental stage (increase the fitness of the young at the expense of the fitness of the parents)
• produce few young but invest heavily in each to maximize survival

Question 6

Semelparity

Answer 6

reproductive strategy involving a single reproductive effort in the lifetime of an organism, followed by death

-trick: like “salmon”

Question 7

Iteroparity

Answer 7

Reproductive strategy in which the individual has repeated repeated reproductive events over its lifetime (but each event with few offspring)

• if reproductive effort yields decreasing returns or if mortality increases as the effort increases, intermetia investment and iteoparity are favored
• trick: like “iterations”

Question 8

r - strategists

Answer 8

short lived, reproduce at a young age, produce lots of babies with little parental care

• small bodies
• altricial, semelpatrious

-trick: “r” like rabbit

Question 9

K - strategists

Answer 9

long lived, mature at a late age, few babies and lots of care
-precorcial, and iteroparous

**note: there are also species that fit in b/w k and r strategiest

-trick: “k” like parental “kare”

Question 10

C-S-R strategies

Answer 10

• this applies mainly to plants and extrinsic factors
  1. Competitors (C): resemble K-strategists, and tend to be larger trees or long lived perennials with delayed reproduction
  
  • higher soil hyphal densities, stronger carbon-sink strength, late production of spores in the growing season
  • higher phosphorous benefits to the host
  • high intensity of competition

2. Stress-tolerators (S): low growth rate, long-lived mycellium, resistance to abiotic stressors (e.g. acidity, low temperature)
   
   • has no equivalent in the r-K strategy
   • more investment in constitutive defence
   • high intensity of stress
3. Ruderal (R): high growth rates. early production of many asexual spores, high hyphal turnover rates, more efficient hyphal healing
   
   • more efficient spore dispersal mechanisms
   • better protection of the hosts against pathogens and herbivores
   • they are essentially r-strategists
   • high intensity of distrubance

Question 11

life history

Answer 11

it’s an optimization problem
-given particular ecological factors that influence fitness and limiting constraints intrinsic to the organism, what combination of life history traits will maximize reproductive success