1. Evolution and its Effects on Ecology

2. Making sure to remember….
Ultimate Goal of all offspring is to...
Reproduce!!!!
Food goes to...
1. Survival
2. Growth
3. Reproduction

3. Charles Darwin
1809 – 1882
1859- On the origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life

4. Darwin's major points a. Variation exists in all natural populations
b. Most species have the potential to reproduce at a rate that, if unchecked, would exhaust environmental resources.
c. Since resources are limited, organisms with the most "advantageous" variations will survive. (adaptation)

5. Fitness
Ecological Fitness = the number of offspring produced that live to reproduce.
Because time and energy are limited, species (and individuals) face a "trade-off" between producing many small offspring or a few large ones.
(female cod may lay 4 million eggs in one year; female African elephants undergo 21-months of gestation for a single offspring and then suckles her young for 5 years).
We would say that cod and elephants have very different life histories.
life history: the series of events in an organism’s life from birth to death, including reproduction.

6. Parental Investment and Mate Choice
Parental investment refers to contributions each sex makes in producing and rearing offspring.
usually higher in females
Mate choice occurs when individuals do not mate at random, but appear to make decisions on mates base on quality.
common in females

7. Three Tenants of Natural Selection
Nonrandom survival
Things do not survive randomly
Nonrandom mating
Mating is not a random event
Nonrandom fecundity
The number of offspring produced is not random

8. Disruptive Selection
NUMBER OF INDIVIDUALS
SIZE

9. Disruptive Selection
NUMBER OF INDIVIDUALS
SIZE

10. Directional Selection
NUMBER OF INDIVIDUALS
SIZE

11. Directional Selection
NUMBER OF INDIVIDUALS
SIZE

12. Stabilizing Selection
NUMBER OF INDIVIDUALS
SIZE

13. Stabilizing Selection
NUMBER OF INDIVIDUALS
SIZE

14. Territorial Behavior
Territoriality is behavior in which individual members of a species maintain exclusive use of an area containing a limited resource.
defense against intrusion
made on cost/benefit basis
centered around fitness

15. Competition for Space

16. Reproductive Competition and Sexual Selection
Sexual selection occurs when individuals compete for mating opportunities.
involves both intrasexual and intersexual selection
Intra (same sex)
Courtship rituals
Competition
Inter (mate choice)
leads to evolution of secondary sexual characteristics –antlers, long tail feathers

17. Products of Sexual Selection

18. Reproductive Competition and Sexual Selection
Intrasexual selection
Individuals of one sex compete with each other for the opportunity to mate with individuals of the opposite sex.
Selection will strongly favor sexual dimorphism.
Outcompete other males – larger more dominant
Displays and fighting

19. Intersexual Selection
benefits of mate choice
Males may help rear young, gather food, defend nest, etc..
Indirect benefits
Females may choose healthiest or oldest males.
overall genetic or physiological health
more vigorous offspring

20. Mating Systems Number of mates Needs of offspring
monogamy - one male and one female
polygyny - one male and many females
polyandry - one female and several males
Needs of offspring
altricial - require extensive, prolonged care
precocial - require little parental care

21. Survival strategies Altricial vs precocial young
Number per reproductive effort

22. Factors Favoring Altruism
Altruism - performance of an action that benefits another individual at a cost to the actor (nest helpers)
Natural selection would seem to argue against altruism.
Such acts may not be truly altruistic, and may be benefiting the actor.
Nest helpers may gain parenting experience or inherit territory

23. Factors Favoring Altruism
Reciprocity - Individuals may form partnerships in which mutual exchanges of altruistic acts occur.
Kin selection - By directing aid toward close genetic relatives, an altruist may increase reproductive success of its relatives enough to compensate for the reduction in its own fitness.
The more closely related the individuals, the more likely the potential genetic gain.

24. The End