The Neurological Basis of Animal Behavior: Genetic Control and Environmental Influences

1. 40 Animal Behavior

2. Chapter 40 Animal Behavior • Key Concepts • 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • 40.2 Behavior Is Influenced by Development and Learning • 40.3Behavior Is Integrated with the Rest of Function

3. Chapter 40 Animal Behavior • Key Concepts • 40.4 Moving through Space Presents Distinctive Challenges • 40.5 Social Behavior Is Widespread • 40.6 Behavior Helps Structure Ecological Communities and Processes

4. Chapter 40 Opening Question • In what ways might schooling behavior and pairing behavior be advantageous for the individuals involved?

5. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Of all animal characteristics, adjustments of behavior are often the most visible responses to environmental change. • Example: Many migratory animals are changing the timing of their migrations in response to climate change. • Behavioral shifts into new habitats may be the best hope for survival if conditions where they currently live become too warm.

6. Figure 40.1 Migratory Birds Have Returned Earlier to the Netherlands in the Spring as Temperatures Have Risen

7. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • An animal’s nervous system activates and coordinates behaviors. • In humans, particular types of behavior depend on the function of particular brain regions; for example, if Broca’s area is damaged, the person will have difficulty speaking and writing.

8. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Other evidence for the neural basis of behavior comes from the study of highly stereotyped animal behaviors, called fixed action patterns: • Expressed by animals without prior learning and often resistant to modification by learning • Examples: begging behavior by gull chicks, web spinning by spiders

9. Figure 40.2 Expression of a Fixed Action Pattern

10. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Behaviors evolve: if certain alleles produce more adaptive behaviors than others, natural selection can favor those alleles. • Many studies establish that genes can exert important effects on behavior.

11. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Drosophila mutants for the gene per have altered circadian rhythms. • When the flies are kept in constant darkness, episodes of activity followed 19-hour or 29-hour rhythms, depending on the mutation.

12. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Experiments with wild populations of house mice collected from Florida to Maine. • When the wild mice were reared in the lab in identical conditions, mice from progressively more northern populations tended to build bigger nests. • This points to evolution by natural selection of a genetically controlled, behavioral propensity to build bigger nests in populations from locations where big nests are an advantage.

13. Figure 40.3 Nest Building by House Mice from Five Locations

14. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Studies using artificial selection show that behavior can evolve rapidly. • In an experiment with mice, individuals that ran the fastest on a running wheel were selected for mating. • Their offspring were selected in the same way for many generations. • After 13 generations, the selected mice on average ran more than twice as far as control mice.

15. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Further studies showed critical changes in the brains of the selected mice, indicating that a difference had evolved in the neural control of running behavior.

16. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Biological determinism: behaviors of animals are hardwired by genetics • Some simple animals exhibit determinism. • Example: Clams are inflexible in many of their responses to their environment.

17. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Biological determinism was once applied to human behaviors. • At one time, it was believed that mental capacity was correlated with brain size and that the mental capacities of racial groups could be predicted by measuring relative brain sizes.

18. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Although support for the idea of biological determinism waned during WWII and the Holocaust, when people were slaughtered based on the idea of genetic inferiority, there is an increasing trend of support for determinism today. • It is important to remember that articles written for the general public are not always well supported by objective, statistically supported, relevant data for scientific conclusions.

19. Concept 40.1 Behavior Is Controlled by the Nervous System but Is Not Necessarily Deterministic • Behavior is dramatically more flexible than any other biological trait. This is true in part because learning modifies behavior. • New research also shows epigenetic effects on behavior, which can have lifelong influences and may be transmitted from one generation to the next.

20. Concept 40.2 Behavior Is Influenced by Development and Learning • Learning: the ability of an individual animal to modify its behaviors as a consequence of individual experiences • Experiments with mice show that they learn the layout and hiding places of their environment and that this learning helps them escape predation by screech owls.

21. Figure 40.4 Screech Owls Prey on Mice

22. Concept 40.2 Behavior Is Influenced by Development and Learning • Behavioral imprinting: early studies of animal behavior by Konrad Lorenz showed that geese hatchlings learned to view him as their “parent” if he associated with them right after hatching. • This type of learning takes place in a narrow window of time early in postnatal life and, after that, is inflexible.

23. Concept 40.2 Behavior Is Influenced by Development and Learning • Indigo buntings migrate at night and navigate by the stars. • Experiments showed that they must know where the north star is and that this must be learned during the 1st few weeks of life. • In a planetarium, young birds learned to identify any star that the sky appeared to be rotating around.

24. Figure 40.5 The Stars in the Northern Hemisphere Seem to Make Circles around the North Star

25. Concept 40.2 Behavior Is Influenced by Development and Learning • The males of many bird species use specific songs to attract females. • The songs are not inherited, but must be learned in the 1st month after hatching from the father, who is singing nearby the nest. • Particular brain regions are required for this learning. • If a young male learns the song of a different species it will later sing an incorrect song and attract females of the incorrect species.

26. Concept 40.2 Behavior Is Influenced by Development and Learning • An animal’s early experience can have multiple lifelong effects. • Experiments with rats show that individuals whose mothers exhibited high levels of maternal care during the nursing period were less likely to exhibit fear in novel situations when they were adults. • Regulatory genes in stress-response biochemical and hormonal pathways are tagged with epigenetic marks in early life and are maintained throughout life.

27. Concept 40.2 Behavior Is Influenced by Development and Learning • Malnutrition and abandonment in early life are also known to affect epigenetic tagging in rats. • Marks from these early experiences persist into adulthood, altering gene expression and behavior throughout life.

28. Concept 40.2 Behavior Is Influenced by Development and Learning • Migratory locusts in Africa can cause crop devastation. An individual locust can display two different behavioral phenotypes: • Avoiding other individuals—the population is spread out and inconspicuous. • Highly gregarious—the population forms a swarm. • Individuals become a swarm if forced into close contact, that is, if they are forced to feed next to each other because of food shortage.

29. Concept 40.3 Behavior Is Integrated with the Rest of Function • Pronghorn running illustrates that an animal’s behavior often depends on and is integrated with the animal’s other characteristics. • Pronghorn have the highest speeds known in running animals. • To behave in this way, they must have muscles that use aerobic respiration and systems to deliver O2 to the muscles at high rates, such as large lungs and muscle cells packed with mitochondria.

30. Figure 40.6 Pronghorn Run at the Fastest Sustained Speeds of Any Running Animals

31. Concept 40.3 Behavior Is Integrated with the Rest of Function • Toads and frogs evolved different behaviors that depend on the type of ATP synthesis: • Western toads hop away from danger at relatively slow speeds that can be maintained for many minutes. • Leopard frogs hop away from danger at lightning speed but are fatigued quickly. • Toads have high levels of the enzymes needed for aerobic ATP production, frogs have high levels of enzymes needed for anaerobic ATP production.

32. Concept 40.3 Behavior Is Integrated with the Rest of Function • Behaviors are often integrated with body size and growth: • Male elk are reproductively mature at two years of age, but rarely mate before they are five because they must also be big enough and experienced enough to dominate other males. • Young spotted hyenas are limited in their ability to compete with adults during group feeding behavior at a kill because their teeth and jaws are not developed enough to crush bones.

33. Figure 40.7 Young Hyenas Must Mature to Feed on Bone Rapidly

34. Concept 40.4 Moving through Space Presents Distinctive Challenges • Navigation:the act of moving toward a particular destination or along a particular course • Orientation: adopting a position, or a path of locomotion, relative to an environmental cue such as the sun

35. Concept 40.4 Moving through Space Presents Distinctive Challenges • Navigation • Following trails: worker ants that find a food source lay a pheromone trail to guide other ants to the food. • Pheromone:chemical compound or mixture that is emitted into the outside environment that elicits specific behavioral responses from other members of the species

36. Concept 40.4 Moving through Space Presents Distinctive Challenges • Path integration: Cataglyphis ants live underground in hot, dry deserts, but workers forage above ground during the heat of the day. • They find heat-killed insects before the bodies have dried out, and thus get water as well as food. • The workers can always run straight back to the nest using path integration.

37. Figure 40.8 A Foraging Trip by a Worker Ant of a Desert Ant Species (Cataglyphis)

38. Concept 40.4 Moving through Space Presents Distinctive Challenges • The worker ant monitors the length and compass direction of each segment of its outbound path. • Then it puts together the information on segment lengths and directions to know where it is relative to its nest.

39. Figure 40.9 An Insect Odometer (Part 1)

40. Figure 40.9 An Insect Odometer (Part 2)

41. Figure 40.9 An Insect Odometer (Part 3)

42. Concept 40.4 Moving through Space Presents Distinctive Challenges • Orientation • Homing pigeons can fly back to their home nests even after having been transported tens of kilometers away. • One mechanism they use is a sun compass: • The birds must observe the position of the sun and also must know the time of day. They adjust their angle of flight relative to the sun, using their circadian clock to know time of day.

43. Concept 40.4 Moving through Space Presents Distinctive Challenges • If the pigeon’s circadian clock is entrained with artificial light cycles to be 6 hours off, it will fly in a direction 90° from the correct direction.

44. Figure 40.10 The Sun Compass of a Homing Pigeon Requires That the Pigeon Interpret the Sun’s Position in the Sky Based on Knowledge of Time of Day

45. Concept 40.4 Moving through Space Presents Distinctive Challenges • Redundancy in orientation mechanisms is also important. • Homing pigeons can also find their way home on cloudy days. They can detect Earth’s magnetic field and orient to it. • Homing pigeons also sometimes use landmarks such as hills to orient, and they may use odors, low-frequency environmental sounds, and learning from other pigeons.

46. Concept 40.4 Moving through Space Presents Distinctive Challenges • Many insects and birds can determine compass directions by detecting patterns of polarized light in the sky; requires specialized photoreceptors. • The suns rays are reflected by dust, water droplets, and ice crystals in the atmosphere and become polarized, or aligned parallel to one another.

47. Concept 40.4 Moving through Space Presents Distinctive Challenges • The Cataglyphis ants in the desert use prominent landmarks if they are present but orient equally well without them using polarized light. • They also have a sun compass.

48. Concept 40.4 Moving through Space Presents Distinctive Challenges • Honey bee workers can communicate the location of a food source in a specialized behavior called the waggle dance. • During a foraging flight, a worker measures distance to the flowers by visually monitoring the rate at which she flies past local landmarks. • To measure direction, she monitors the angle of her flight relative to the compass position of the sun.

49. Figure 40.11 The Honey Bee Waggle Dance

50. Concept 40.4 Moving through Space Presents Distinctive Challenges • Some animals make fantastic long-distance migrations. • Bar-tailed godwits migrate between Alaska and New Zealand, flying non-stop across the Pacific Ocean for 6 to 9 days.