1. Reproductive Patterns
10/28/08

2. Types of Reproduction

3. Sexual reproduction involves two parents
involves sex cells that contain half of the genetic information (sperm and egg)
offspring receive genes from both parents

4. Asexual Reproduction involves only one parent
offspring are genetically identical to parent
ex) strawberries, bacteria, mushrooms

5. Disadvantages of sexual reproduction
Males do not give birth
Females need to have twice as many young as an asexual organism to maintain the same number of young in the next generation
Increased change of genetic errors and defects
Courtship or mating rituals consume time and energy, can transmit disease, and can inflict injury on males of some species if they compete

6. Advantages of sexual reproduction
Provides greater genetic diversity
Greater chance of reproducing and evolving if environmental conditions change
Males of some species can gather food for the female and young and protect them

7. Reproductive patterns
Opportunists have large numbers of small offspring and competitors have fewer, better developed offspring
Carrying Capacity (K)
time
Number of individuals
K-species
r-species
Population growth (r)

8. R-selected vs. K-selected
R-selected species have a capacity for a high rate of population increase
Have many small offspring
Little to no parental care or protection
Overcome the massive loss of offspring by producing so many that a few will survive
Algae, bacteria, rodents, annual plants (dandelions), and most insects

9. R-selected vs. K-selected
R-selected species are opportunists
Reproduce and disperse rapidly when conditions are favorable or when a disturbance opens up a new habitat or niche for invasion
Adapted to unstable climate and environmental conditions
Generalists
Population fluctuates wildly above and below carrying capacity

10. R-selected vs. K-selected
K-selected species have a lower population growth rate
Have fewer, larger offspring with long life spans
Later reproductive age
Offspring are born fairly large, mature slowly, and have high parental care
Most large mammals, birds of prey, large and long-lived plants

11. R-selected vs. K-selected
K-selected species do well in competitive conditions when their population size is near the carrying capacity of their environment
Specialists
Competitors
Adapted to stable climate and environmental conditions

12. R vs. K selected species

13. Most organisms have reproductive patterns between the extremes of r-selected and K-selected species
The reproductive strategy of a species may give it a temporary advantage, but the availability of a suitable habitat for individuals of a population in a particular area determines its ultimate population size

14. Thinking about the future
If the earth experiences significant warming during this century as projected, is this likely to favor r-selected or K-selected species? Explain your answer.