Evolutionary Behavior: Why Organisms Behave as They Do?

1. Behavior Notes Ecology Available online @ www.redwood.org/stewart

2. I. WHY do organisms behave as they do? • A. Evolution and Natural Selection • 1.Behaviors have evolved(been selected and passed on to the next generation)that help organisms be successful. Neither individuals nor species "try" to evolve. • 2. Natural selection, the process by which evolution occurs, can be summarized in 3 steps: • 1.variation (through mutation and sexual recombination of genetic material) • 2. selection(some variations survive, others do not) • 3.reproduction(and passage of genetically inheritable traits to the next generation).

3. I. WHY do organisms behave as they do? • B. Genetics • 1. Reproductive fitness, the number of surviving offspring and relatives, is a biological measure of an organism's success. • 2. Adaptations are the characteristics that evolve to help organisms survive and maximize fitness. • Physical adaptations: EXAMPLES: the meristem of grass is out of reach of grazers, redwood trees build up chemical defenses called tannins, roses have thorns. • Behavioral adaptations: EXAMPLES will follow. • 3. Though adaptations are genetically-based, behaviors can also be learned. it’s NURTURE AND NATURE!

4. II. HOW is a behavior motivated? Energy Budgets • Organisms only have only so much energy with which to ensure survival and reproduction. Though individual organisms do not necessarily "choose" how to allocate energy, based on benefits and tradeoffs, the following “abc’s” of life are where the energy goes. • a. Growth • b. Defense • c. Reproduction The "ABC's" of Life!

5. II. HOW is a behavior motivated? • EXAMPLES of different energy allocation strategies: • r-strategists grow quickly, create fewer defenses, and allocate more energy towards producing many offspring. • K-strategists grow more slowly, build up more defenses, and allocate energy towards producing fewer offspring. • In addition, individuals and groups exhibit a wide range of behaviors when feeding, fighting, fleeing, and fraternizing. FOR EXAMPLE……….

6. III. WHAT are specific behaviors? • A. Reproductive effort and Parental Care: • Energy invested in reproduction and care of young. Some organisms exhibit minimal parental care for their young. For other organisms, like humans, parental care is essential and long-term for their young. precocial altricial End of Part 1

7. III. WHAT are specific behaviors? • B. Social/Helping Behavior • True _________ (helping another at the expense of one’s own reproductive fitness) is mal-adaptive by definition. Yet helping behaviors and social groups are commonly observed in nature. The following are explanations for helping behaviors: altruism

8. III. WHAT are specific behaviors? • 1.Apparent altruism: • EXAMPLES: • Trickery: Ostriches will care for eggs of another, but other eggs always on outside where predators most likely to eat them instead of the helper's eggs (predator satiation). • Reciprocity: Chimpanzees will give gifts of food in exchange for future help.

9. III. WHAT are specific behaviors? • 2.Relatedness/Kin Selection:Increases inclusive (total or net) fitness. Help of related organisms allow your genes to be passed on through another. • EXAMPLE: Ground squirrels live in family groups. Individuals will make loud alarm calls (which make them obvious to predators) to warn the rest of the (related) group when a predators is spied.

10. III. WHAT are specific behaviors? • 3. Eusociality: A special example of relatedness/kin selection. • EXAMPLE: Bees have a single queen who is the mother of the entire hive. Worker bees are sterile and work only for the benefit of the hive. The workers in the hive are, on average, 75% related to each other. Notes:

12. III. WHAT are specific behaviors? • 4.Group Selection: It is theorized that groups with high levels of altruism could do better (and be selected) as long as there is little “cheating”. End of Part 2

13. III. WHAT are specific behaviors? • C.Selecting Mates • Sexual Selection: Special type of natural selection. Sexual selection is not based on ability to survive. It is based on the ability to attract (based on possession of _________ and/or a _______ characteristic) and be selected by mates of the same species. resources genetic

14. III. WHAT are specific behaviors? • Sexual Selection: • C.Selecting Mates • 1.Intrasexual competition/ selection: male tortises fight for the right to mate with a female. • 2. Intersexual selection: one sex chosen by the other based on display or territory. EXAMPLE 1: Leads to evolution of sexual dimorphism(2 shapes) as is the case with peacocks and mallard ducks. EXAMPLE 2: can be resource-based: the possession of a quality territory, as with blackbirds. Intrasexual: Competition Intersexual: Genes only Intersexual: Resource-based

15. III. WHAT are specific behaviors? • D.Mating Strategies (Systems) • • Organisms/ species form pairs, groups, behaviors, and physical adaptations to maximize fitness based on ecological factors and needs. • EXAMPLE: Albatross birds mate for life (). Elephant females form long-term groups to which single male bulls become attached for a number of years (). monogamy polygamy

16. IV. Observing behavior: • Observations gives a greater understanding of our world and ourselves. Observing is an active process. Ask questions. Don’t assume you know. Use your journal. Be careful to observe what you see, not what you think you see. Remember you don’t know what the organism is “thinking.” Consider: • 1. What?: What’s going on here? Observe, get basic information. Thoroughly record what you see. • 2.How?: How is this behavior stimulated? Observe immediate (proximal) causes of the behavior. • 3. Why?: Why has this behavior evolved (ultimate)? Hypothesize, do further research, consider prior knowledge.

17. IV. Observing behavior: • EXAMPLE behavioral observation and journal entry: • Title: • Location: • Date and Time: • Observations: (Remember: What?, How?, Why?) Dog Anxiety Chimp Intelligence Other End