Chap 51 Behavioral Ecology

Costa Rican Moth Automeris

I. Behavioral Ecology Behavioral ecology is based on how animal behavior is controlled, how it evolves, develops and contributes to reproductive success and survival, based on observations. Behavior can be defined as anything an animal does and how it does it. Ethology is the study of how animals behave in their natural environment.

A male African cichlid (Neolamprologus tetracephalus) Dorsal fin Anal fin

Proximate and Ultimate Causes of Behavior Proximate causes: “How” question Ultimate causes: “Why” questions ie. Red crowned cranes

A courting pair of East Asian red-crowned cranes (Grus japonicus)

Famous Ethologists Niko Tinbergen of Netherlands Karl von Frisch of Austria Konrad Lorenz of Austria ** Won the Nobel Prize in 1973, establishing the conceptual foundations on which modern behavioral ecology is built.

Fixed Action Patterns (FAP) FAP’s are a sequence of unlearned behaviors that are unchangeable, once initiated they are usually carried to completion. An FAP is triggered by an external sensory stimulus  SIGN STIMULUS ie. Male three-spined stickleback fish Link

Figure 51.3 Sign stimuli in a classic fixed action pattern (a) A male three-spined stickleback fish shows its red underside. The realistic model at the top, without a red underside, produces no aggressive response in a male three-spined stickleback fish. The other models, with red undersides, produce strong responses. (b) The realistic model at the top, without a red underside, produces no aggressive response in a male three-spined stickleback fish. The other models, with red undersides, produce strong responses.

BEHAVIOR: A male stickleback fish attacks other male sticklebacks that invade its nesting territory.

Imprinting A behavior that includes both learning and innate components that is generally irreversible. Sensitive period: a limited phase during development that is the only time when certain behaviors can be learned. ie. Konrad Lorenz graylag geese

BEHAVIOR: Young geese follow and imprint on their mother.

II. Behaviors and the genetic component Much research has shown that behavior is the result of interactions between the genes and the environment. If the behavior is developmentally fixed  INNATE BEHAVIOR

Directed Movements Movements that range from small (millimeters) to large (kilometers) are under genetic influence  DIRECTED MOVEMENTS ie. Kinesis Taxis Migration

Figure 51.7 A kinesis and a taxis Dry open area Moist site under leaf Direction of river current (a) Kinesis increases the chance that a sow bug will encounter and stay in a moist environment. (b) Positive rheotaxis keeps trout facing into the current, the direction from which most food comes.

Animal signals and communication A signal is a behavior that causes a change in another animals behavior. Many of these behaviors are energy efficient. The type of signal used to transmit information is closely related to an animal’s lifestyle and environment. ie. chemical communication auditory communication

Figure Are the different songs of closely related green lacewing species under genetic control? The F 1 hybrid offspring sing a song in which the length of the standard repeating unit is similar to that sung by the Chrysoperla plorabunda parent, but the volley period, that is, the interval between vibration volleys, is more similar to that of the Chrysoperla johnsoni parent. RESULTS Charles Henry, Lucía Martínez, and ent Holsinger crossed males and females of Chrysoperla plorabunda and Chrysoperla johnsoni, two morphologically identical species of lacewings that sing different courtship songs. EXPERIMENT The results of this experiment indicate that the songs sung by Chrysoperla plorabunda and Chrysoperla johnsoni are under genetic control. CONCLUSION Standard repeating unit Volley period F 1 hybrids, typical phenotype SONOGRAMS Chrysoperla plorabunda parent Vibration volleys Standard repeating unit Chrysoperla johnsoni parent Volley period crossed with Standard repeating unit The researchers recorded and compared the songs of the male and female parents with those of the hybrid offspring that had been raised in isolation from other lacewings. Volley period

Genes influence mating and parental behaviors Huddling behavior in monogamous prairie voles (Microtus ochrogaster)

III. Environment interacting with genes Quality of diet Nature of social interaction Opportunities for learning

Figure How does dietary environment affect mate choice by female Drosophila mojavensis? The difference in mate selection shown by females that developed on different diets indicates that mate choice by females of Sonoran populations of D. mojavensis is strongly influenced by the dietary environment in which larvae develop. William Etges raised a D. mojavensis population from Baja California and a D. mojavensis population from Sonora on three different culture media: artificial medium, agria cactus (the Baja host plant), and organ pipe cactus (the Sonoran host plant). From each culture medium, Etges collected 15 male and female Baja D. mojavensis pairs and 15 Sonoran pairs and observed the numbers of matings between males and females from the two populations. EXPERIMENT When D. mojavensis had been raised on artificial medium, females from the Sonoran population showed a strong preference for Sonoran males (a). When D. mojavensis had been raised on cactus medium, the Sonoran females mated with Baja and Sonoran males in approximately equal frequency (b). RESULTS CONCLUSION Proportion of matings by Sonoran females (a) ArtificialOrgan pipe cactus Agria cactus Culture medium With Baja males With Sonoran males (b)

Table 51.1 Influence of Cross-Fostering on Male Mice

Learning Learning is the modification of behavior based on specific experiences. Different kinds: 1. Habituation 2. Spatial learning 3. Cognitive maps 4. Associative learning 5. Cognition/problem solving 6. Genetic/environments interactions

Habituation Loss of responsiveness to stimuli that convey little or no information “cry-wolf” effect May increase fitness by allowing the nervous system to focus on stimuli that signal the presence of food, mates or real danger as opposed to stimuli that are irrelevant.

Spatial learning The modification of behavior based on experience with the spatial structure of the environment. This includes the locations of nests, dangers, food and mates. ie.Tinbergen’s digger wasps

Figure Does a digger wasp use landmarks to find her nest? A female digger wasp excavates and cares for four or five separate underground nests, flying to each nest daily with food for the single larva in the nest. To test his hypothesis that the wasp uses visual landmarks to locate the nests, Niko Tinbergen marked one nest with a ring of pinecones. EXPERIMENT When the wasp returned, she flew to the center of the pinecone circle instead of to the nearby nest. Repeating the experiment with many wasps, Tinbergen obtained the same results. RESULTS The experiment supported the hypothesis that digger wasps use landmarks to keep track of their nests. CONCLUSION Nest No Nest After the mother visited the nest and flew away, Tinbergen moved the pinecones a few feet to one side of the nest.

Cognitive maps An internal representation or “code” of the spatial relationships between objects in an animals surroundings ie. Clark’s nutcrackers

Clark’s Nutcracker

Associative Learning The ability of an animal to associate one feature of the environment with another..

Cognition/Problem solving The ability of an animals nervous system to perceive, store, process and use information gathered by sensory receptors. ie. Bernd Heinrich’s Ravens Video link

IV. Behavior can evolve by natural selection Because genes influence behavior, natural selection can influence the evolution of behavioral traits in populations. Best seen within species. Variation in prey, aggression, foraging and mating behaviors has been documented.

Figure Aggressiveness of funnel web spiders (Agelenopsis aperta) living in two environments Time to attack (seconds) Field Lab-raised generation 1 Lab-raised generation 2 Population Desert grassland population Riparian population

Figure Energy costs and benefits in foraging behavior Average number of drops Height of drop (m) Average number of drops Drop height preferred by crows Total flight height (number of drops  drop height) Total flight height

Figure Relationship between mating system and male and female forms (c) In polyandrous species, such as these Wilson’s phalaropes, females (top) are generally more ornamented than males. Since monogamous species, such as these trumpeter swans, are often monomorphic, males and females are difficult to distinguish using external characteristics only. (a) Among polygynous species, such as elk, the male (left) is often highly ornamented. (b)

Nest of the Satin Bowerbird (Ptilonorhynchus violaceus)

VI. Inclusive fitness and altruistic behaviors Selfish behaviors benefit one individual while indirectly harming another. The theory of natural selection favors this. ??What about un-selfish behaviors??

Behaviors that reduce an individuals fitness but increase the fitness of others in the population  ALTRUISM Altruism is favored by natural selection because the behavior also maximizes the genetic representation in the population  INCLUSIVE FITNESS.

Evolutionary Biologist William Hamilton developed the concept of inclusive fitness. A quantitative measure for predicting when natural selection would favor an altruistic act.

Natural selection favors altruism when rB > C This is known as Hamilton’s Rule This type of selection is known as  Kin Selection which weakens with hereditary distance.

Reciprocal Altruism Occasionally altruistic behavior occurs between unrelated individuals. This behavior can be adaptive if the aided individual returns the favor in the future.

Social Learning As much as genetics and the environment influence behavior there is also those that are learned by observation of others. ie. Mate choice copying

Figure Mate choice copying by female guppies (Poecilia reticulata) Male guppies with varying degrees of coloration Control Sample Female guppies prefer males with more orange coloration. Experimental Sample Female model engaged in courtship with less orange male Female guppies prefer less orange males that are associated with another female.

Summary Ethologists study behaviors and develop p/u questions. Most behaviors have a strong genetic component. Environment interacting with genes influence development of behavior. Behavioral traits can evolve by natural selection that increases survival and reproductive success. Inclusive fitness can account for altruistic behaviors.