Application of Options Theory: Reproductive Strategies Based on Costs
Comparison of Organisms Relative to Size and Time to Maturity: Salmonella Ants King Cobra House Cat Bottle-Nosed Dolphin Humans African Elephant S. Enteritidis (SE) & S. Typhimurium (ST) Gestation: Parent cell divides every 20 mins. (under ideal conditions of 37 C or 98 F) Componotus Japonicus Ophiophagus Hannah Felis Catus Tursiops Truncatus Homo Sapiens Loxodonta Africana Gestation: Egg to larvae approx. 25 days Larvae makes cocoon after 10 -15 days Gestation: 2 months before hatchings emerge Gestation: Pregnancy approx. 60 days Gestation: Pregnancy 11 -12 months Gestation: Pregnancy lasts for 9 months Gestation: 22 months Number of Offspring: N/A Number of Offspring: 30 to 100 ants per year Number of Offspring: Lays 20 -40 eggs Number of Offspring: Approx. 2 -5 kittens Number of Offspring: 1 calf per pregnancy Number of Offspring: 1 child per pregnancy Number of Offspring: 1 calf per pregnancy Maturity: N/A Maturity: Total of 60 days Maturity: Emerges from egg fully developed. Maturity: Male 7 -18 months Female 6 -10 months Maturity: Nurses for 12 -18 months, teaches for 2 years + Maturity: Reach sexual maturity between 16 -18 years Maturity: Reach sexual maturity between 10 -12 years Food: carbon (sugar) source, glucose, amino acids, tryptone Food: seeds, insects, sugar rich foods Food: Domesticated (meat products), small rodents Food: Primarily fish (mackerel, sardines), squid, mollusks Food: Omnivore (consume meat and plants) Food: Herbivore (grass, leaves, fruit, buds, shoots) Smallest / Least time To Maturity Food: Primarily other poisonous and non-poisonous snakes Relative to all Organism Largest / Longest time to Maturity
What does this mean? Is there a correlation between the relative size of the organism and it’s strategy for producing offspring? • R-selection strategy – Characterized by strong variability in population size, tendency for high fertility • K-selection strategy – Near constant population size, slow development, delayed reproduction, and single broodedness Why do organisms choose one over the other?
Reasons Can be found in Costs Due to limited resources, parents must consider the costs associated with producing offspring. Costs can be expressed in terms of: • Resources (R) – include food & shelter • Time (T) – term of pregnancy, raising young, opportunity cost • Cognitive Development (C) – survival skills (hunting), identify & avoid predators
Cost of Producing Offspring Expressing Fixed Cost (FC) as a function of the individual costs components, we have: FC = R + T + C
Reasons for Asexual and Sexual Reproduction in Terms of Cost Asexual reproduction (r-selection strategy) less costly compared to sexual reproduction, can afford high variability/volatility in survival rate of offspring from large population Sexual reproduction (k-selection strategy), cost intensive to parents, increased likelihood of survival for trade-off in lower number of offspring produced
Asexual vs. Sexual Reproduction Mitosis (Asexual) Meiosis (Sexual) DNA double Helix uncoils Splitting chromosome Pair into two separate strands After fertilization, chromosomes recombine 2 daughter cells 4 gametes
Output to Different Levels of Fixed Costs Where output is measured as the number of offspring successful produced: Fixed Costs Rate of Success Offspring
Phenomenon also seen in Allometry In its most general sense, allometry is the study of size and it’s consequence. Source: The Allometry of Growth and Reproduction
Rate of Return Similarity with Options Theory Output Low Fixed Cost High Fixed Cost
Variable Costs Uncertainty and Costs High Volatility Low Volatility Level of Fixed Costs
Affects of Uncertainty on Reproduction High Volatility Level of Fixed Costs As Level of Fixed Costs Increases Death Rate Low Volatility
Uncertainty and the Value of the Option to Reproduce Referring to the options theory where the: d. S = rdt + dz S Where (S) denotes the growth rate of the species (r) is the growth term associated with the rate of success in producing offspring, and ( ) is the volatility in offspring survival. This shows that the growth of the species is dependent on: -the increase of (r), and decrease of ( )
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