Behavioral Ecology Monkemeier AP Biology 2011
Why Behavioral Ecology? • Ecology is the study of the interactions between organisms and their environment • A key theme in ecology is INTERDEPENDENCE • Behavioral Ecology: studies how behavior is controlled and how it develops, evolves and contributes to survival and reproductive success.
Behavior • Everything an animal does and how it does it, including muscular activities such as chasing prey, certain non-muscular processes such as secreting a hormone that attracts a mate, and learning.
PROXIMATE Focus on the environmental stimuli that trigger a particular behavioral act, as well as the genetic, physiological, and anatomical mechanisms underlying it. ULTIMATE Focus on the evolutionary significance of a behavioral act. Proximate and Ultimate Causes of behavior
Proximate How it all works – how does the animal’s senses, nerve networks, or internal state provide a physiological basis for the behavior. The HOW of a behavior is a question about proximate causation. Ultimate WHY a behavior evolved – an investigation of its adaptive value. The WHY of a behavior is a question concerning ultimate causation. Behavior’s Two Components
PROXIMATE Proximate questions are often referred to as HOW questions. Examples: Why does a male stickleback fish attack another male predator? ULTIMATE Ultimate questions answer why did natural selection favor this behavior and not a different one? Example: Does attacking behavior in male stickleback fish benefit his offspring or his breeding choices? Proximate Questions vs. Ultimate Questions
What causes male songbirds to sing during breeding season? To analyze the proximate cause of the behavior, we might measure hormone levels or record the impulse activity of neurons in the animal. Why did singing during breeding season evolve – how does it influence the animal’s survival and reproductive success? Investigate how the song itself, or timing of song, etc. relates to the number of mate choices, size of breeding territory, number of offspring produced, etc. How do we ANALYZE and MEASURE?
Behavioral Ecology - Ethology • The scientific study of how animals behave, particularly in their natural environment. • Early research in ethology focused on behavioral patterns that are always exihibited by members of a species in response to a particular stimulus; that is, they appeared to be instinctive, or innate behaviors.
Innate Behavior Does NOT require LEARNING • Fixed action pattern (FAP) a sequence of unlearned behavioral acts that is essentially unchangeable and, once initiated, is usually carried to completion. • Sign stimulus: a sensory stimulus that triggers or initiates a FAP
Innate Behaviors – Strong Genetic Component • Innate behaviors are under strong, genetic influence. • Directed Movements: (types of innate behaviors) Movements that are strongly controlled by genes.
Directed Movements • Orientation: a process that involves tracking stimuli in the environment. • Kinesis: simple change in activity or turning rate in response to a stimulus. Some animals just become more or less active when stimulus intensity increases. • Taxis: movement toward or away from a stimulus
Orientation and Migratory Behavior • Orientation: the ability to follow a bearing, analogous to a using a compass. • Navigation: the ability to set up or adjust a bearing, and follow it, analogous to using a compass and a map. • Migrations are long – range, two – way movements of animals using orientation or navigation (or both). • Inexperienced animals migrate by orientation, and experienced animals navigate by navigation.
Learning • Many behavioral patterns displayed by animals are not solely the result of instinct. • Learning: the modification of behavior based on specific experiences.
Learning • Habituation: the loss of responsiveness to stimuli that covey little or no information. • Spatial learning: the modification of behavior based on experience with the spatial structure of the environment, including the locations of nest sites, hazards, food and prospective mates. (landmark = location indicator)
Associative Learning • Associative Learning is the change in behavior that involves an association between two stimuli or between a stimulus and a response. The ability of many animals to associate one feature of the environment (a stimulus, such as color) with another (bad taste).
Classical Conditioning An arbitrary stimulus is associated with a reward or punishment Operant Conditioning An animal learns to associate its behavioral response with a reward or punishment. Aka trial and error learning. Associative Learning
The Development of Behavior • Behavior has both genetic (nature) and learned components. (Environment - nurture has an effect) • Imprinting: a form of learning in which a young animal forms a social attachment to other individuals or develops preferences that will influence behavior later in life. • Sensitive period: time in the organism’s life when imprinting is effective. • Animals may have an innate genetic template that guides their learning as behavior develops.
Animal Communication • Communication between and among species is the key to many behaviors. • Successful reproduction depends on the progressive exchange of appropriate signals and responses. • Courtship signals are usually species-specific and limit communication to members of the same species. • Communication includes visual displays, sounds, electrical signals and pheromones.
Behavioral Ecology: the study of how natural selection influences behavior that increases survival and reproduction. • Natural selection favors optimal foraging strategies in which energy acquisition (cost) is minimized and reproductive success (benefit) is maximized. • Some animals are territorial. Territorial defense has its costs, and territoriality my only occur when the benefits outweigh the costs. • Game Theory – the fitness of a particular behavioral phenotype is influenced by other behavioral phenotypes in the population.
HOW do we KNOW that behavioral traits can evolve by natural selection? • Studies have found that behavioral variation within a species corresponds to variation in environmental conditions. • Laboratory studies of Drosophila populations raised in high- and low- density conditions show a clear divergence in behavior linked to specific genes. • Studies of migratory behavior in European blackcaps over a period of a few decades.
Reproductive Strategies and Sexual Selection • Reproductive strategy is a set of behaviors that maximize reproductive success. • Reproductive strategies are responses to the spatial distribution of food resources, nest sites, and members of the opposite sex. • Reproductive strategies include • Mate choice, number of mates chosen, parental investment in care of offspring.
Examples – Mate Choice • The direct benefits of choosing the right mate offers advantages of territory quality, degree of parental care and an indirect benefit is the quality of genes. • Intrasexual selection involves members of the same sex for the chance to mate. • Intersexual selection refers to a choice of mate by members of the opposite sex.
Examples – Mating Systems • Monogomy • Polygyny • Polyandry ALL of the above are influenced by ecology and constrained by the needs of the offspring.
Altruism and Group Living Altruism refers to the action of an individual that benefits the fitness of another individual or individuals. - Sometimes animals behave in altruistic ways that reduce their individual fitness but increase the fitness of the recipient of the behavior -WHY
Altruism and Group Living • Seemingly altruistic acts may not be altruistic because the helpers benefit by learning valuable experiences, inheriting territories, or increasing the ability to escape from a predator. • Kin selection increases the reproductive success of relatives and frequency of alleles shared by kin. • Hamilton’s rule is a formula for determining if altruistic acts are favored.
The Evolution of Social Systems • A social system is a group of organisms of the same species that are organized in a cooperative manner. • Individuals benefit from social living, and the benefits increase with the numbers of organisms. • Social insects are composed of different castes that each have specialized tasks. • Vertebrate social systems are less rigidly organized and cohesive and are influenced by food availability and predation
How does Behavioral Ecology correlate to the AP THEMES? • Evolution – behavior patterns are selected for by environmental factors. • Interdependence in nature – animals live with other animals of the same and different species. To survive, they must interact with each other.
Preparing for the Unit Test • Use the ppt as a guide and FIND specific experiments or examples that correspond to the ideas on the slide. • Use the review questions at the end of this ppt. • Use the questions at the end of this ppt to help you think scientifically and connect concepts.
Review Questions • Describe two studies that suggest behavior has a genetic basis. • Describe an experiment that supports that the environment (nurture) influences behavior. • Describe two types of associative learning. • Give examples of the different types of communication among members of a social group. • What is territoriality, and how might it increase fitness? • Name three types of reproductive strategies, and describe how they can be related to the environment. • What is sexual selection, and why does it foster female choice and male competition during mating? • Give examples (and supportive experiments) of behaviors that appear to be altruistic but actually increase the inclusive fitness of an individual.
Thinking Scientifically • Meerkats are said to exhibit altruistic behavior because certain members of a population act as sentries. How would you test the hypothesis that sentries are engaged in altruistic behavior?
Sources for this ppt. • Biology 7th edition by Campbell and Reece • Biology 10th edition by Sylvia Mader • Biology 8th edition by Raven and Johnson