NPB102: Animal Behavior

Hypothesis

• testable explanation based on assumption

  • Becomes a theory if its tested a bunch w/o rejection

Theory

• well-substantiated explanation that forms basis of our understanding of the natural world

  • EXPLAINS facts

  • Theories ARE NOT FACTS

Ethogram (and how it is used). What is time budget & stereotypic behavior?

• Formal inventory & descriptions of animal’s behavior

• Determine the total & relative time an animal is engaged in behavior

• Time Budget: summary of total time & relative frequency 

• Stereotypic Behavior: captivity-induced behavioral anomalies (repetitive behaviors that lack purpose)

Proximate Reason

• focus on IMMEDIATE causes of behavior

  • CAUSE, DEVELOP

Ultimate Questions

• focus on EVOLUTIONARY causes of behavior 

  • FUNCTION, EVOLUTION

Methods Used to Study Animal Behavior

• Observational Method: observe/record animal without manipulating the environment (no contact)

• Experimental Method: manipulate/change a variable and see how it affects the animal’s behavior

• Comparative Method: examine differences and similarities between species to understand evolution of behavior traits

3 Conditions Needed for Evolution

• Trait variation

• Trait heritable

• Traits confer fitness (survivorship & reproduction)

Variation Sources

• Crossing Over: exchange of genetic material between 2 homologous chromosomes → recombinant chromosomes

• Mutations: any change in cell’s DNA sequence 

• Epigenetics

• Methylation

3 Modes of Natural Selection

• Directional Selection       

  • Animals w/ extreme trait value at one end of spectrum have higher fitness

• Stabilizing Selection →←

  • Animals w/ most average trait have highest fitness 

• Disruptive Selection ← → 

  • Animals w/extreme traits on either end of the spectrum have highest fitness

Ethical Considerations of Animal Research

• Replacement

  • Encourage use of computer modeling

• Reduction

  • Try to use as few animals as possible

• Refinement

  • Minimize pain & stress

• Respect

Instinct (and the 2 examples)

• Innate behaviors; fully expressed the 1st time they are exhibited

• Reflexes: involuntary movement to stimulus

• Fixed Action Pattern: no variation & can’t be stopped until completed

Genotyping Techniques

• Gel Electrophoresis

• DNA Sequencing

• SNP (Single Nucleotide Polymorphism)

• PCR: Polymerase Chain Reaction

• qPCR: Real-Time PCR/Quantitative

Gel Electrophoresis

DNA SIZE

• Crucial in identifying specific genetic markers

DNA Sequencing

Reading Chemical Bases (ATGC)

SNP (Single Nucleotide Polymorphism)

Looks for tiny differences in genetic code between individuals

• Help identify specific traits or susceptibility to diseases

PCR: Polymerase Chain Reaction

AMPLIFY DNA sections ; Like photocopying

qPCR: Real-Time PCR/Quantitative

• Measure amount of DNA present in a sample in real time

• See WHICH GENES ACTIVE & WHEN

Methods for Pinpointing & Modifying Genetic Foundations of Behavior

• Statistical Methods

  • GWAS: Genome-Wide Association Studies

    • Analyze BROAD POPULATION. of UNRELATED individuals

    • Explore genetic associations in pop.

  • QTL: Quantitative Trait Loci Mapping

    • Analyzed individuals must be RELATED

    • NUMBER OF GENES involved & LOCATION on chromosomes

    • Link traits to genes

• Molecular Methods - Gene Editing

  • Knockout Method

    • Disable gene to study what happens when it doesn’t work

  • CRISPR-Cas9

    • Precise tool to delete, add, alter sequences

GWAS: Genome-Wide Association Studies

• Analyze BROAD POPULATION. of UNRELATED individuals

• Explore genetic associations in pop.

QTL: Quantitative Trait Loci Mapping

• Analyzed individuals must be RELATED

• NUMBER OF GENES involved & LOCATION on chromosomes

• Link traits to genes

Knockout Method

Disable gene to study what happens when it doesn’t work

CRISPR-Cas9

Precise tool to delete, add, alter sequences

HPG Axis Hormones

• Hypothalamus: GnRH / GnIH(increases with stress)

• Pituitary: LH, FSH

• Gonads: Testosterone, Estradiol

Gene Transcription (what it produces)

information in gene’s DNA sequence is copied to make mRNA (mRNA goes on to make proteins that coordinate behavior during translation)Bioinformatics

Bioinformatics

• combine biology, computer science, math, and statistics to analyze & interpret biological data

  • Focus on analysis of genetic & genomic info to uncover the functions, relationships, and evolutionary histories of genes & genomes

Big Data

extremely large data sets requiring analysis beyond the ability of commonly used software tools

Transcriptomics

complete set of genes ACTIVE/EXPRESSED in a given tissue

Active vs. Transcribing vs. Expressed

• Active

  • Gene is actively being transcribed

• Transcription

  • DNA→ mRNA via RNA polymerase

• Expressed

  • Protein formed

    • May or may not affect phenotype/function

Transcriptomic Assembly

catalog of all RNA transcripts, gene activity, present in a cell/tissue/organism at a specific time

MA Plot

• type of scatter plot used in bioinformatics/genomics to visualize differences between measurements between 2 experiment conditions

  • Depict differentially expressed genes

  • In Big Data

Learning (and what affects evolution of learning)

Relatively permanent change in behavior as result of experience

• Affects Evolution of Learning

  • 1) Regularity of Environment

    • If environment barely changes → evolution will fix behaviors (less learning)

  • 2) Reliability of Past Experience

    • If an animal can rely on its experience within the environment → high fitness among those who have high learning ability

Habituation

• Simplest form of learning

• Reduction & then lack of response to stimulus over time

Imprinting

• Type of rapid learning

• In young animals during short, intensive period (has lasting effects)

• Filial Imprinting: where offspring learn phenotype & identity of parents due to it being 1st object encountered

Stimulus-Response Associations

• Classical/Pavlovian Conditioning

  • Novel stimulus paired w/ existing stimuli and associated to elicit a response

    • Eventually novel stimulus elicits same response as existing stimulus

    • Allows individuals to be better prepared for future events by learning new associations

  • PAVLOVIAN CONDITIONING CAN AFFECT FITNESS

    • Japanese Quails & Reproduction

    • Predator Avoidance in Fish

Operant Conditioning

Associate a behavior with a particular consequence

• Trial-and-Error Learning: learning to solve problem via repetition

  • Behavior often changes incrementally as animal makes progress

• Learning Curves: graphical representation of this change in learning over time

  • developed by Charles Turner

Pioneers of Operant Conditioning

• Charles Turner

  • How bees recognize colors + patterns → intelligence

  • Insect cognition

  • Animals are more than instinctual beings

• Edward Thorndike

  • Law of Effect

    • Behavior followed by satisfying consequence → repeated

    • Behavior followed by unpleasant consequence → less likely to be repeated

  • Cat + Puzzle Boxes

  • Reward → Repeat behavior

• B.F Skinner

  • Skinner Box: study active behavioral response in lab animals

    • Measure rates of behaviors under different conditions of reinforcement

  • Consequences shape behavior

Cognition

ability to generate & store mental representations of the physical & social environment to motivate behavior/solve problems

Insight Learning

spontaneous problem-solving without the benefit of trial-and-error learning

Local Enhancement

strategy where individual uses presence of another as a cue for focusing on a particular part of the environment

Public Information

info obtained from the activity/performance of others about the QUALITY of an environmental parameter/resource

Social Learning (and how it can evolve)

• individuals are the source of learning

  • Allows a trait to spread rapidly through population

  • Can develop into Behavioral Traditions (differences in behavior among pop. that are transmitted between generations through social learning)

    • Differences in multiple traditions among pop. might be evidence of ANIMAL CULTURE

Synaptic Pruning

• unused synapses undergo pruning → free up resources for more important functions/new connections

  • Happens before adulthood

  • Signaling molecules cause microglia cells (CNS immune cells) to engulf unused synaptic material

Measuring Non-Human Intelligence

• self-recognition tests, mazes, puzzles, novel object recognition tests

• Mirror Test: assesses self-recognition abilities

  • Only few species pass: great apes, elephants, whales, dolphins, magpies, pigeons

  • NOT DOGS (they rely on olfactory)

  • Cleaner Wrasse (fish)

    • Put mark (that looks like parasite) on fish throat → present mirror → fish rubbed throat after seeing reflection

    • Same results from photographic mark test (saw non-marked reflection → picture of marked throat)

Cache

• store food in hidden location for later retrieval

• Important for bird fitness + ecosystem (missed seeds end up planted)

• bigger hippocampus

Episodic Memory

memory of a specific object, place, and time (where they cached)

Neuroplasticity

• CHANGE IN ENVIRONMENT ALTERS NEUROANATOMY

• Marion Diamond: 1st to publish evidence that brains change with experience & improve w/enrichment

• Structural brain changes (In the number & chemical strength of synapses between neurons)

Cognitive Buffer Hypothesis

Why do animals have big brains despite the energy cost?

• Role of Brain: buffer animals against environmental variation

• Bigger brain → more novel/altered behavioral patterns possible → more successful against problems

Methods of Studying the Brain

• Invasive Methods

  • Lesions in specific regions & see how it affects function

  • Manipulate aspects of animal’s life & kill them to see brain structure

  • ECoG: Electrocorticography: implant electrodes under the scalp to detect electrical activity in specific brain regions

  • MEA: Multi-Electrode Array: electrode inside brain to detect APs of neurons

  • Fluorescent Imaging: remove part of skull → inject dye into specific neuron groups to track activity

  • Patch-Clamp Recording: inject electrode into a neuron to track activity

• Less-Scary Methods

  • fMRI: Functional Magnetic Resonance Imaging

    • Detect the presence of oxygenated vs. deoxygenated blood

    • Active regions use more oxygenated blood

    • Fairly high spatial resolution: cognitive function can be correlated with specific brain regions

    • low temporal resolution: 1-2 sec. Delay

  • EEG: Electroencephalography

    • Detect electrical activity in brain via electrode

    • Different frequencies associated with different cognitive functions

    • Low spatial resolution: function can’t be correlated with region

    • High temporal resolution: 1-ms delay

Communication

• Process in which a specialized signal produced by one individual affects the behavior of another

• REQUIRES:

  • Signaler: individual that produces a signal affecting behavior of another (the receiver) & has evolved for the purpose of communication

  • Receiver: individual that detects a signal

Signal vs. Cue

Signal

• Evolved means of actively conveying information & influencing the behavior of receivers

• DIFFERENT FROM

  • Cues: passive, non-evolving biological & environmental traits that inherently provide the observer with info

Waggle Dance

Example of signal

• by honeybee scouts to recruit workers to food source

  • 1) Direction of waggle → direction of food source

  • 2) Waggle Duration → Longevity

  • 3) Repetition of whole dance → How great food source is

  • SOCIAL INFO - learn from elders

    • Those who were taught were better with waggle direction

      • Those who weren’t taught corrected over time (not perfectly)

      • Those who weren’t taught overshot communication distance (did not correct over time) - TEACHING & CRITICAL PERIODS

    • Animal Culture

Alarm Call

Example of Signal

unique vocalizations produced by social animals when predator is nearby - is it language?

Signals are perceived by Sensory Systems

Sensory Receptors: nerve endings that respond to an internal/external environmental stimulus

Auditory Receptors

nerve endings that respond to an internal/external environmental stimulus

• Transmit info along axons to CNS for processing → appropriate response

Photoreceptors

specialized neurons sensitive to light; visual receptor

• Rods: peripheral vision

• Cones: color vision

  • within-species variation

  • depending on life evolutionary history: more cones =/= more color vision

Electroreceptors

 specialized sensory cells that detect electrical currents

• mostly aquatic (except bees & echidnas)

• Communication Purposes

  • Species, courtship/biological sex, motivational status (attack warning, submission, etc), environmental conditions

• EOD: Electrical Organ Discharge: produces electricity

  • positively correlated w/fish size

  • Use EOD to assess RHP (Resource Holding Potential) - chances of winning aggressive contact - assessed via signals/cues

Chemoreceptors

detect chemical stimuli (substances secreted into environment & detected by odor-binding proteins in sensory structures)

• via olfaction & gustation (taste)

• Volatile Chemical Signals: transmitted readily through water or air

Pheromones

volatile (gaseous) compounds that are species-specific & affect behavior of another individual (of same species)

• can indicate sex, food trails, predation, etc

Signals are Influenced by the Environment

Ex: Urban Great Tit’s acoustic transmissions are altered based on obstacle shape/ size.

• surrounded by low-freq urban sounds —> ADAPT / BEHAVIORAL PLASTICITY —> now sing with higher min. freq / shorter / faster

Ex: White-Crowned Sparrows

• sing at higher. min. freq in urban areas —> narrower freq. range / slower trill rate / less effective at defending territories

• During shutdown: they sang quieter & could be heard from 2x the distance

• Anthropogenic noise reduce call efficacy —> plastic behavior over a shorter time

Signals can indicate reproductive readiness & quality

Multimodal Signals: communicates more than 1 thing

• Ex: Mexican boulder spiny lizards

  • color change in female varies w/ reproductive hormone & egg —> signal best time for fertilization - red

  • color brightness —> signal health info (parasite = duller color) —> affects mate choice

Conditions that favor evolution of signals as accurate / honest indicators

1. Signaler & receiver have similar fitness interests.

2. Signals will be accurate when they cannot be faked.

3. Signals will be accurate indicators when they are costly to produce / maintain.

Aposematic Coloration

brightly colored morphology that stand out from environment

• associated with noxious chemicals / poisons to make them dangerous/ unpalatable to prey

• How it evolves:

  • Bright colors = more likely to be eaten by naive predators

  • Theories on how it evolved BEFORE predators learned to avoid it:

    • Evolved in prey that already had other defenses

    • Evolved gradually enough that prey weren’t too conspicuous initially but still enhanced predator learning

    • Evolved in gregarious (high-grouping) prey species —> dilute predation effects

Signals can be INACCURATE when fitness interests of signaler & receiver differ:

• Interspecies (between species)

  • Mimicry

• Intraspecies (within-species) Deception

  • False Alarm Calls

  • Signal Interception

Types of Mimicry

• Batesian: tasty mimic resembles yucky model

• Aggressive Mimicry: predator mimics non-threatening model to gain access to food

• Mullerian: 2 different species that share a common predator mimic each other’s warning signals

  • predator learns to avoid all those species based on their similar mimicked phenotype

Intraspecies Deception

False Alarm Calls: produced when no threat nearby

• Sexual Deception Hypothesis: males produce deceptive signals to females to enhance their own reproduction

Signal Interception

• Bystanders / Eavesdroppers: 3rd-party individuals that detect & respond to a signal transmitted between another set of signalers & receiver

• benefit by learning about the presence of females, competitors, predators, etc

• Ex: Tungara frogs eavesdrop on conspecific & sympatric (species living close to them) heterospecifics to assess predation risk.

  • Audience Effect: bystander presence influence behavior of a signaler

Extended Phenotype Signal

Signals expressed beyond the body of an individuals

• often includes environmental modification

• persists longer than behavioral signals

• functions even in absence of signal

• costly to produce & maintain —> reliable indicators of quality/ condition of signaler

Animals find food using Sensory Modalities

Natural selection favor modalities that are most efficient & effective at providing info about food location

Lateral Line System

system of tactile sense organs that detect movement & pressure changes in the surrounding water

• made of mechanoreceptors called neuromasts (lateral line organs)

  • interconnected network along side of the body

Search Image

distinctive visual features of a distinctive prey type that, once learned, can enhance prey detection

• how predators find cryptic prey more effectively

• favored evolution of prey adaptations (behavioral & morphological)

  • Red Queen Hypothesis - counter-adaptation!

OFT: Optimal Foraging Theory

• Assumptions

  • 1) Natural selection has favored feeding behaviors that maximize fitness

  • 2) Fitness increases with feeding (energy intake) rate

• “Optimal Behavior”: maximizes fitness in an optimal foraging model

Optimal Diet Model

mathematic model to predict food types an animal should include in diet to maximize net energy intake/unit of time

• Prey Selection

• Energy Maximization

• Decision Rules

  • Profitability: (energy it contains / handling time)

• Average Energy Intake per Item

  • (Avg. Energy Obtained ) / [ (avg, search time) + (avg. handling time) ]

Optimal Patch Use Model / Marginal Value Theorem

predicts how long forager should exploit a food patch

• Assumptions:

  • Foragers try to maximize emergy intake rate

  • All patches are identical

  • Travel time (between patches) is constant 

    • If travel is SHORT → optimal patch time is SMALL

    • If travel is LONG → optimal patch time is LARGE

  • Harvest rate declines as forage depletes patch (experiences diminishing returns in each patch)

• Patch = discrete area that contains a concentrated resource/set of resources that an animal might exploit

• Diminishing Returns: decline in instantaneous harvest rate as food patch is depleted

  • Marginal Benefit: examine benefit forager can gain by spending just a bit more time in patch 

    • Decreases declines with time spent due to diminishing returns

Antipredator Behavior to Reduce Predation Risk

• Cryptic Coloration

• Reducing Activity

• Startle Displays (look bigger / scarier)

• Mobbing Behavior

• Evasive Behaviorr

• Increased Vigilance

  • Vigilance = scanning environment for predatorsr

  • Behavioral Trade-Off: more vigilance = less feeding time

• Find Refuge before Eating

• Associating with Others

Antipredator Behavior: Find Refuge before Eating

• Assumptions

  • Squirrel’s fitness increases with:  energy intake increase & chances of being killed decreases

  • Squirrel is at risk on ground but safe in trees.

• Predictions

  • Larger food carried to tree more often

    • Assumption that larger items take more handling time

    • When handling time increases, predation chances increases too.

  • As distance between food patch & tree increases, individuals should reduce carrying behavior.

    • More distance = more running = more time exposed

• Results

  • Small cookie carried to tree

  • Big cookie: big back to tree (handling time)

  • Further away → eat it right there

• Trade-Off between maximizing energy intake rates & minimizing time exposed

Antipredator Behavior: Associating with Others

• Dilution Effect: reduction in chances of dying by associating with others

• Selfish Herd Hypothesis: individuals keep trying to adjust position strategically in group

Predation Risk affected Mating Behaviors

• Ex: Water striders reduce mating when predators near.

• Ex: Fiddler crabs use big ass claw to attract mate & hide from predators

  • take longer to emerge from refuge if no females present

Dispersal

Relatively SHORT-distance, 1-way movement to settle in a new area/ habitat

• Natal Dispersal (movement away from an individual’s place of birth)

  • A one-time event, relatively early in an animal’s life

  • Competition Hypothesis

  • Inbreeding Avoidance Hypothesis

• Adult Dispersal (adults move from 1 breeding site to another)

  • Competition Hypothesis

  • Breeding Dispersal: when adults move from 1 breeding site to another

    • Site Fidelity

    • Win-Stay Lose-Shift Strategy

    • Public Information

Natal Dispersal

• Natal Dispersal (movement away from an individual’s place of birth)

  • A one-time event, relatively early in an animal’s life

  • Competition Hypothesis

  • Inbreeding Avoidance Hypothesis

    • inbreeding depression (low reproductive success)

    • Explains sex-based natal dispersal (when 1 sex disperses more/ farther than the other —> less chance sibling settle near each other)

Adult Dispersal

• when adults move from 1 breeding site to another

  • Competition Hypothesis

  • Breeding Dispersal: when adults move from 1 breeding site to another

    • Site Fidelity: stay/ return to same site regardless of outcome

    • Win-Stay Lose-Shift Strategy: based decision based on their own previous reproductivity success

    • Public Information: obtained from activity/ performance of others about environmental quality

Migration

Relatively LONG-distance, 2-way movements

• PRO: move to more favorable conditions

• CON: loss of time / energy, risk of injury & predation

• Partial Migration: individuals WITHIN SAME SPECIES differ in migratory behavior

Partial Migration

individuals WITHIN SAME SPECIES differ in migratory behavior

• If fitness of migrants better → population will evolve to be fully migratory

• If fitness of residents better → population will evolve to be fully resident

• How does a pop maintain Fixed Dimorphism in migratory behavior? 

  • 1) Migratory behavior could be FIXED, GENETIC TRAIT

    • To maintain dimorphism, both behaviors must have equal fitness at equilibrium

  • 2) Migratory behavior could DEPEND ON INDIVIDUAL CONDITION (has genetic disposition, but only expressed in some)

    • Two behaviors will not have equal fitness

Orientation

The process of determining and maintaining a consistent direction

• Environmental Cues

  • Physical Landmarks

  • Olfaction

  • Compass Systems

Compass Systems

• Sun Compass (diurnal)

  • give directional information if time of days is known

  • animals have circadian clock (corrected daily by onset of dusk & dawn)

• Geomagnetic Compass (diurnal & nocturnal)

  • Polarity/Direction of Field Lines → indicate North vs. South hemispheres

  • Inclination Angle of Field Lines → Latitude

  • Intensity/Strength of Field varies across globe

  • Magnetite Cells & Cytochrome Molecules (if exposed to light)

  • Can provide info for bicoordinate navigation)

    • Inclination Angle (latitude) + intensity variation

• Star Compass (Nocturnal)

  • North Star - used to orient or navigate

  • Stars move slowly, so over short time scales, animals use current star location as guide to orient in consistent direction

Navigation & Bicoordinate Navigation

• Navigation: The process of moving towards a particular geographic location

  • If blown off route, likely NOT able to find the goal

• Bicoordinate Navigation: use 2 varying environmental gradients to identify their location relative to their goal