Behavioural Ecology

Posted on Jun 5, 2024 in Psychology and Sociology

DEFINITIONS:

Behavioural Ecology

      • study of the evolutionary basis for animal behaviour due to ecological pressures

Semiochemicals

      • Chemicals that mediate interactions between organisms

Evolutionary arms race

      • ongoing struggle between competing sets of co-evolving genes, phenotypic and behavioural traits that develop escalating adaptations and counter-adaptations against each other, resembling the geopolitical concept of an arms race

Altruism

      • behaviour of an animal that benefits another at its own expense

Reciprocity

      • the practice of exchanging things with others for mutual benefit, especially privileges granted by one country or organization to another.

Cooperative breeders

      • social system characterized by alloparental care: offspring receive care not only from their parents, but also from additional group members, often called helpers

Sexual selection

      • Sexual selection is natural selection through sexual preference by one sex for certain characteristics of another sex

Conservation


Biology

      • Is the study of conservation of nature and of Earths biodiversity with the aim of protecting species, their habitats and ecosystems from excessive rates of extinction and the erosion of biotic interactions

Disassortative mating

      • mating pattern in which individuals with dissimilar phenotypes mate with one another more frequently than would be expected under random mating

Reproductive Suppression

      • Reproductive suppression is the prevention or inhibition of reproduction in otherwise healthy adult individuals.

Individual variation

      • The genetic variation within a particular species

Personality

      • the combination of characteristics or qualities that form an individual‘s distinctive character.

Behavioural syndromes

      • behavioural syndrome is a correlated suite of behavioural traits, often measured across multiple contexts

Attenuation

      • the reduction of the amplitude of a signal, electric current, or other oscillation

Interpreting Results

      • How can you avoid confirmation bias?
        • Double blind experiments and randomisation

      • Uses for Behavioural Ecology in Conservation


      • Survivorship bias
        • We tend to focus on the winners rather than loses
        • Or successes rather than failures
      • What are the four main reasons for loss of biodiversity?
        • Loss of habitat
        • Overexploitation
        • Introduced species
        • Pollution
        • Global climate change
      • What is the first approximation of endangerment?
        • Number of individuals in a population
        • The number of breeding individuals
        • Variation in breeding success
        • Sex ratios
        • Anything else that affects genetic variation
      • What is fitness?
        • The quantitative representation of individual reproductive success as well as the average contribution to the gene pool of the next generation
      • What are some surrogates for fitness?
        • Population size
        • Heterozygosity
        • Quantitative genetic variation
        • Epigenetics (study of how behaviours in environment may cause changes that affect the way your genes work, and methylation (mechanism for epigenetics)
      • What is genetic drift?
        • Random fluctuations in the number of alleles in a population
        • Takes place when alleles increase or decrease by chance over time
        • Occurs in small populations where alleles have a greater chance of being lost
        • Once it begins, GD will continue until the allele is lost or the only allele present
        • Hot, cold, exposed to a chemical -> these epigenetics can turn off
        • Common after a population bottlenecks (TRANSLOCATIONS)
        • Can make a new population genetically distinct -> plays a role in evolution
      • Inbreeding and Outbreeding depression
        • Inbreeding occurs when mates are related to each other due to incest, small population size, or population sub-structuring
        • Excess of homozygotes and a deficiency of heterozygotes
        • Reduces GV or increases
        • Outbreeding depression is where mating from 2 distant groups results in the reduction of fitness in the offspring
        • -> generating intermediate genotypes that are less fit than parental form
        • -> breakdown of biochemical or physiological compatibility
      • Effective population size
        • Number of breeding individuals
        • Ne decreases with decreasing m or f or by skewing sex ratios
      • Reproductive suppression
        • Seychelles warbler (breeding success depends on territory quality and helpers at the nest)
      • Mate choice
        • No mating unless some characteristics are present
        • -> The kakapo Richard Henry
      • Dispersal
        • Mechanism for gene flow
        • Habitat fragmentation increases distances and changes visual cues
        • Disturbances may impede dispersal
        • Gene flow may be reduced
        • Patterns of dispersal of parasites may also change
        • Breeding or winter grounds may be destroyed
      • CONLCUSIONS
        • Need to Know the behaviour of the animals as manipulations would not work at all
        • Species with natural low R may not increase reproductive output after more habitat is available
        • Lekking species may not benefit either as males are selected for own characteristics not for holding territories
        • Knowledge of causes of reproductive suppression would help managers
        • RS caused by low resources, increasing them would help
        • RS caused by dominant individual suppression may need to produce patchy distribution of resources

Physiology and the Evolution of Behaviour

      • Mating systems
      • Monogamy, polyandry, polygyny, polygynandry, promiscuity (indiscriminate mating)
      • Testes are physiologically expensive and reflect mating system (polyandry, in monogamy, testes reduce over time)
      • Behaviour can drive phenotypic changes in animals
      • Sexual selection, hormones, and behaviour all effect each other
      • Non-consumptive effects: the result of the prey initiating anti-predator behavioural and/or physiological trait changes that can aid in predator avoidance
      • Fear can lead to evolutionary changes:
      • Less fear = less vigilant and more time eating = more offspring (predator rare)
      • More fear = more vigilance and less time eating = average offspring (predator abundant)
      • Less fear = less vigilance and more time eating = no offspring (predator abundant)

HOW CAN PHYSIOLOGICAL CHANGES DRIVE THE EVOLUTION OF MATING SYSTEMS?

      • Hormonal influences: direct impact
      • Sex hormones: variations of sex hormones can affect mating displays, aggressiveness and sexual receptivity
      • Oxytocin: Influence bonding and social behaviours
      • Sensory perception: Can alter how individuals perceive potential mates
      • Visual and auditory cues
      • Olfactory cues: changes in ability to detect pheromones or other chemical messages
      • Reproductive physiology: evolution of reproductive organs and mechanisms
      • Internal vs external fertilisation
      • Sperm competition
      • Developmental timing: changes in the time of maturation
      • Late vs early maturation: species that mature early may favour promiscuity or polygamy than those who mature later (monogamy or polygyny due to longer investment periods

Behavioural Ecology and Biosecurity

      • Why consider animal behaviour in biosecurity and pest management?

      • Animal behaviour is central to management (sociality, basic needs)
      • Look at interactions (species and devices) -> risk allocation, fear, trophic cascades (stoats fear and avoid cats and ferrets)
      • Use of sound smell (sensory ecology) -> dogs can be used to find rats, and rare endemic species (smelly)
      • Biological control (pheromones and attractants)
      • 3 main uses: 1. Monitoring, 2. Mass trapping (attraction-annihilation), 3. Mating disruption (pheromones create noise)
      • 3 types of biological control: 1. Classic control (importation), 2. Augmentation (supplementation of existing natural enemies, 3. Conservation (protect or enhance activities of natural enemies)
      • Understanding the behaviour of both the pest/predator and the species at risk is the key to successful pest/predator control
      • Drivers of hunting behaviour in domestic cats?
      • Evolutionary origins
      • Early life history
      • Personality environment
      • Sensory ecology use?
      •  1. Sounds to detect invasive species
      •  2. Sounds to attract pests
      •  3. Sounds to deter pests from at risk species
      • Some animals are attracted to specific smells
      • Why important? -> biological control

Animal Intelligence

What is animal cognition?


      • How animals perceive, process, learn and store information

What are some ways to study cognitive abilities?


      •  1. Brain size
      •  2. Cephalisation index (K value) measure of deviation from the regression line
      • PROBLEMS: flying animals weigh less and have smaller brains, larger creatures may have larger brains -> who’s smarter? LOOK AT NEO-CORTEX (only in mammals) WHAT ABOUT DENSITY OF NERVE CELLS
      •  3. Learning set – choice between options
      • Some animals brains are small -> consider habitats (what makes them better at choosing?)
      •  4. Imitation? You know you are you and someone else is someone else (understanding the motivation of others)
      • Stimulus enhancement: ducks more likely to escape from pen if another duck does so (cats playing with keyboard)
      • Social facilitation: Imitate others without any other deeper intention (laughing, feeding)
      • Pavlovian Response: type of learning process where an individual develops an involuntary response to a given stimulus

Theory of mind

      • How much an animal understands the motivation of another, and how much insight does it have of its own actions
      • Competitive colleague advice
      • Lost friend asking for directions
      • Self-awareness

Summary

      • Cognition has many forms:
      • Physical spatial, social
      • Other factors:
      • Phylogeny, neurological capability, individual variation
      • Challenges in this discipline:
      • Quantifying cognitive performance
      • Experiments in the field
      • Definitions:
      • Mind and mental life: totality of the behaviour of an animal and the operations it performs to create those behaviours
      • Intelligence: wide ranging problem solving abilities
      • Thought: for some implies human language so no use in animal intelligence
      • Cognition: the act of perceiving, thinking, reasoning and analysing reflected in the full richness of animal behaviour
      • Learning: the cognitive process of acquiring skill or knowledge; the change in behaviour that results from experience and practice
      • Individual variation: the genetic variation within a particular species
      • Personality: the combination of characteristics and qualities that make an individual distinct
      • Behavioural syndrome: correlated suite of behavioural traits, often measured across multiple contexts
      • Plasticity: the adaptability of an organism to changes in its environment or differences between its various habitats.

WHAT DRIVES PERSONALITY VARIATION IN ANIMALS?


      • Environmental availability:
      • Resource availability: in environments where resources are inconsistent, different personality traits are advantageous (bolder animals may be more adventurous)
      • Predation pressure: high predation risk can select for cautious individuals
      • Social structure:
      • Competition: aggression and assertiveness can be beneficial, or more cooperative traits such as sociability and tolerance may be more advantageous
      • Mating systems: species that compete for mates may favour aggressive and bold individuals
      • Genetic factors:
      • Heritability: traits have a genetic basis
      • Mutations: new traits
      • Life history strategies:
      • Reproductive strategies: animals with different strategies may have different traits (species that have high parental care may want more nurturing behaviours
      • Developmental stages: juveniles may be more exploratory whereas adults may be more cautious
      • Physiological constraints:
      • Hormonal influences: cortisol, testosterone, serotonin can influence behaviour
      • Trade-offs:
      • Trade-offs: bold animals may bet better at acquiring resources but may be more vulnerable to predation

Animal Personality

      • Why does phenotypic variation persist?
      • Individual variation creates a buffer against selection in changing environments

How does individual personality play a role in life?


      • Biological invasions
      • Population dynamics
      • Dispersal
      • Predator-prey interactions

What are some characteristics of individual variation?


      • Boldness
      • Aggressiveness
      • Neophobia
      • Exploratory behaviour
      • Sociability

Behavioural syndromes

      • A suite of correlated behaviours expressed either:
      • Within a behavioural context or,
      • Across different contexts
      • Most studies measure animals twice to assess repeatability
      • Rapid assays of behaviour may underestimate repeatability

Personality differences have broad implications

      • Population growth
      • Species interactions
      • Community dynamics
      • Social evolution
      • Speciation
      • Create niche axes where none would exist otherwise, enhance the stabilizing effects of existing species-level niche differences, or equalize species-level fitness differences.
      • WHAT PRESSURES DRIVE INDIVIDUAL VARIATION?
      • Natural selection: environmental factors that favour certain traits
      • Sexual selection: traits favoured because the enhance reproductive success
      • Genetic drift: random changes in allele frequencies
      • Mutation: random changes in DNA
      • Gene flow: the movement of genes within a population
      • Balancing selection: selection that maintains genetic diversity

Olfactory (Chemical) Communication

Uses of olfaction?


      • Finding and obtaining food
      • Recognition of sex
      • Discrimination between individuals of the same or different species
      • Defence against predators
      • Parental care
      • Orientation and migration
      • Emitter -> Signal -> Receiver
      • Odours are used when other signals are harder to use
      • Distance (close to medium)
      • Can provide information cheaply (low cost to be smelly)
      • Predators can find you
      • Need adaptations – anatomy and physiology

What are the source of odours?


      • Scent glands – exocrine glands
      • Urine, faeces

Scent glands can be found in

      • Area around eye (antelope)
      • Hands/feet/paws
      • Chest
      • Genital region

Semiochemicals

Allelochemicals (interspecific) and pheromones (intraspecific)

Functions of social odours


  1. Territory
  • To define, mark, and claim territory
  • THREE HYPOTHESES
  1. Intimidations: claim on area and potential of being attacked if encountered
  2. Border maintenance: scent marks territory, communicating it is occupied
  3. Orientation: primarily used as a compass
  1. Reproduction
  • Scent mark more when reproductively active (cats), male rats can be aroused by female cues
  1. Social awareness
  • Use scent mark within territory (Aardwolves)
  1. Interspecies communication
  • Scent marking may facilitate the dispersal of species that are similar and live in the same area
  1. Protection by defence
  • Dart frogs use steroidal alkaloids

Take Home Message:


      • Chemical communication is important in all animal groups – basal in animal evolution
      • Lots to be found
      • Important to look for several lines of evidence (anatomy, physiology, and behaviour, and epigenetics)

Acoustic Communication

Communication

      • Sender -> information -> receiver
      • Acoustic communications sends signals that animals can hear
      • Where the receiver makes use of the acoustic component/ fraction of the mechanical signal
      • Purely longitudinal waves in a homogenous medium
      • Can be seen in invertebrates (only insects)
      • PROS:
      • Easily transmitted, fast, spread broadly, can amplify easily, source can be determined easily, easily produced
      • CONS:
      • Attenuate quickly, spread broadly, source can be determined easily
      • FUNCTIONS:
      • Body size:
      • Sensory biases (male Asin corn borer moths can male deceptive ultrasonic calls and exploit bias towards bat echolocation calls)
      • Innate vs learnt:
      • Field crickets that are crossbred can have similar calls to the species of the parents
      • WHATS EASIEST TO CHANGE?
      • Loudness, frequency, modulation
      • WHAT DRIVES ACOUSTIC SIGNAL FORM AND FUNCTION?
      • Environmental Factors
      • Habitat acoustics (different environments have different acoustic properties)
      • Noise (background noise levels)
      • Predation pressure
      • Eavesdropping predators may use signals to locate them
      • Avoidance of detection (can use signals less likely to attract predators
      • Communication needs
      • Mating calls
      • Territory signals
      • Species-species factors
      • Physiological constraints
      • Social structures
      • Group living
      • Individual recognition
      • Human influence
      • Urbanisation (noise pollution)
      • Habitat modification

Vibratory Communication

      • Vibratory communications sends vibrations that animals can feel
      • Where the receiver makes use of the surface-borne component/ fraction of the mechanical signal
      • Waves (Rayleigh or bending) at a boundary between two distinct media
      • Techniques: Laser vibrometry
      • PROS:
      • Travel more effectively than sound, fast, less confounding directional information than sound, easily produced
      • CONS:
      • Source can be determined easily
      • WHO USE?
      • Elephants (fat pad in foot), Assassin bugs (aggressive mimicry of prey vibrations to lure spiders), Spiders (prey capture, courtship, contests, predator detection), Treehoppers (vibratory duets)
      • Spider courtship:
      • Drumming behaviour encodes information about male quality -> strength and quality, duration, age and experience, health status
      • Signal divergence:  process by which communication signals (such as visual displays, vocalizations, chemical cues, or other forms of signalling) evolve and become different among populations or species
      • Physiological limitations
      • Selection pressures-> ECOLGOCIAL SELECTION (different environments, noisy), SEXUAL SELECTION, DRIFT
      • Constraints on signal divergence:
      • Physical environment, community compositions, noise, phylogenetic history, sender morphology and neurophysiology, receiver morphology and neurophysiology
      • WHAT DRIVES VIBRATORY COMMUNICATION?
      • Environmental factors:
      • Habitat structure : dense vegetation or substrates can absorb or block sound, making vibrations better
      • Environmental noise: environments with high noise
      • Predation and eavesdropping:
      • Predator avoidance: less detectable by predators
      • Intraspecific eavesdropping
      • Mate attraction:
      • Species-specific communication: can be tuned to specific frequencies
      • Honest signalling: require a certain amount of energy and physical capability to produce
      • Efficiency and energy conservation:
      • Energy efficiency: producing signals may cost less energy
      • Signal clarity: can be more direct and less subject to distortion

Host and Parasites

Diversity

      • Endoparasites
      • Ectoparasites
      • 3 factors that determine impacts of parasites on host:
      • Prevalence in the host population
      • Virulence of the parasite (how lethal)
      • Co-evolutionary history – duration of the relationship (arms race)

EXAMPLE: AVIAN MALARIA

      • Introduced mammalian predators and pests
      • Invasive species
      • Habitat loss and fragmentation
      • Increased environmental stressors
      • Host:
      • Immune system adaptations (changes in gene responsible for recognising and attacking pathogen)
      • Behavioural changes (may change behaviour by changing nest site or feeding habits
      • Physiological adaptations (controlling the rate of replication within their bodies of the parasite)
      • Plasmodium
      • Antigenic variations (change proteins on their surface to evade immune system)
      • Rapid reproduction (reproduce quickly increases transmission)
      • Drug resistance (resistance to antimalarial drugs)
      • Malaria prevalence varies with location, age, sex and time of year
      • We need to understand:
      •  1. Dispersal patterns (who, what, where, when?)
      •  2. Parasites, diseases, wildlife health
      •  3. Training
      • Summary
      • Complex and diverse systems
      • Multiple factors influence the impacts on hosts
      • Examples of evolutionary arms race

Human Mating Strategies

HUMAN MATNG STRATEGIES

      • Long term mating
      • Both sexes are choosy
      • They are going to spend a lot of time with this person and you want to make sure they’ll look after the offspring right
      • – > mate guarding (less attractive men mate guarded more during estrous, less attractive women were especially mate-guarded during estrous whereas more attractive women were guarded all the time
      • Hypothesis about the evolution of concealed evolution
      • Evolved to be lost or hidden from males
      • Behavioural differences between humans and non-human primates: morphological, ecological and cultural factors
      • Bipedalism may have an effect on swollenness
      • Results argue against the concealed ovulation model: men can detect female fertility but not 100%.
      • Short term mating (EPC)
      • Variable:
      • Sex ratio
      • Male quality
      • Cultural norms
      • WHAT PRESSURES ACT ON MATE CHOICE?
      • Reproductive ability
      • Genetic compatibility
      • Cultural influences
      • Economic stability
      • Parental investment

Cooperation and Helping Game Theory

      • What is kin selection?
      • If you cannot breed yourself, you should help your family raise their children for the best possible chance of survival
      • Why is cooperative behaviour important to understand?
      • Evolutionary insights (kin selection, altruism, social evolution)
      • Ecological impact (population dynamics, ecosystem functioning)
      • Behavioural ecology (resource acquisition, protection and defence)
      • Individual selection vs group selection:
      • Differential extinction/ reproduction, time scale important (rate of changes higher at the individual level), cheating often benefits individuals
      • HELPING BEHAVIOUR
      • Cooperation (mutualism) (shared gain of direct fitness)
      • Reciprocity (pied flycatchers, vampire bats) (weight pros and cons, animals more related to each other will show higher reciprocity)
      • Altruism (facultative and obligate)

-> MANIPULATION

RECIPROCITY

      • Benefit to recipient > cost to actor + later reciprocity
      • Donors must be able to recognise cheaters
      • Long term associations
      • EXAMPLE 1:
      • Pied flycatchers (mobbing of predators at the nests of distant neighbours

ALTRUISM

      • +- relationship between actor and recipient
      • Facultative altruism
      • Temporary loss of direct fitness
      • Potential for indirect fitness fain followed by personal reproduction
      • Example (Florida scrub jay)
      • Obligate altruism
      • Permanent loss of direct fitness
      • Potential for indirect fitness gain
      • Example (honeybees, ants, naked mole rat)

MANIPULATION

      • Long tailed cuckoos

COOPERATIVE BREEDERS

      • Florida scrub jay (reason for helping is change in hormonal levels)
      • How do helpers help?
      • Increase the success of individual breeding attempts, reduce breeder workload, enhance breeder survival
      • Success may not be because of the helpers but because of the territory
      • REMOVING HELPERS
      • e.G. Grey crowned babblers S, Florida scrub jays S, moorhens NS

WHY DELAY BREEDING?


      • Habitat saturation hypothesis (stresses the costs of early dispersal)
      • Animals should not move if they do not have to
      • Benefits of philopatry hypothesis (stresses the gains of staying home -> inheritance and competitive edge)
      • Have the advantage of resources

EVOLUTION OF HELPING

      • Step 1
      • Whether or not to attempt independent breeding
      • Step 2
      • Whether or not to become a helper
      • Why do helpers help?
      • Kin selection: by helping relatives they can ensure similar genes are passed on
      • Reciprocal altruism: help to get help
      • Learning and experience: less experienced animals can learn
      • Improves survival: improve overall survival of group
      • Inheritance of territory: may wait for opportunity to take territory
      • HOW DO WE MEASURE?
      • Univariate analyses provide weak evidence
      • Confounding of territory quality and/or experience of breeders
      • Ecological demographic factors constrain independent breeding -> grown offspring delay dispersal: remain at home -> fitness gains from helping > not helping

Altruism -> kin selection

Unusual Behavioural Systems

Communication

      • Someone sends a signal and someone else picks it up and changes their behaviour
      • Plants may communicate by vibrations, chemical signals, electric fields
      • EXAMPLE:
      • Plants (can sense vibrations – reduces cost compared to chemical volatiles?), (Flowers may use electric fields to benefit luring pollinators (bees)

WHAT LEVEL IS SELECTION OPERATING AT?


      • Genes, individuals, kin, groups, species
      • Does it matter?
      • Yes
      • Different levels of selection can result in different outcomes for individuals (cells, populations, species)
      • How can you apply behavioural ecology techniques to unusual behaviours
      • Look at levels of selection that it may be operating at
      • Observational studies: field observations
      • Ethograms: create catalogue of observed behaviours
      • Comparative analysis: compare unusual behaviour across populations
      • Genetic and physiological analysis: investigate genetic predispositions

WHAT DRIVES UNUSUAL BEHAVIOUR?

      • Environmental pressures
      • Natural selection: behaviours that enhance survival and reproductive success
      • Ecological niches: occupy specific or specialised niche
      • Sexual selection
      • Mate choice: behaviours that increase attractiveness
      • Intrasexual competition: Competition among individuals of same sex for access to mates
      • Social dynamics
      • Social structure: can drive cooperative behaviours
      • Cultural transmission
      • Similarities:
      • Both are more likely to engage in extra-pair copulations if their partner exhibit undesirable qualities (FA and small forehead patch)
      • More likely to mate with individuals who are symmetrical
      • The attractiveness of certain traits fluctuates with female fertility cycle
      • Both are influenced by male parent investment
      • Dissimilarities
      • Humans are more impacted by satisfaction during luteal phase and more impacted by FA during fertile phase
      • Humans are influenced by more factors such as economic stability, social norms, social status, and education whereas flycatchers are more influenced by physical traits

HOW CAN PHYSIOLOGICAL CHANGES DRIVE THE EVOLUTION OF MATING SYSTEMS?

      • Hormonal influences: direct impact
      • Sex hormones: variations of sex hormones can affect mating displays, aggressiveness and sexual receptivity
      • Oxytocin: Influence bonding and social behaviours
      • Sensory perception: Can alter how individuals perceive potential mates
      • Visual and auditory cues
      • Olfactory cues: changes in ability to detect pheromones or other chemical messages
      • Reproductive physiology: evolution of reproductive organs and mechanisms
      • Internal vs external fertilisation
      • Sperm competition
      • Developmental timing: changes in the time of maturation
      • Late vs early maturation: species that mature early may favour promiscuity or polygamy than those who mature later (monogamy or polygyny due to longer investment periods

HOW DOES BEHAVIOUR CHANGE PHENOTYPE

      • Epigenetic changes: lead to changes in expression without altering the DNA sequence itself (stress, diet and physical activity can lead to DNA methylation how effects how genes are expressed)
      • Environmental interactions: animals that do lots of physical activity will have varying levels of muscle and fat
      • Social environment: can influence hormone levels which will affect traits such as size, colouration and reproductive status
      • Learned behaviour: birdsong is a phenotypic trait that is learned
      • Stress: Behavioural responses to stress can lead to changes in weight, immune function, and even appearance such as fur colour
      • Quality can be encoded into these signals by the strength of the signal and the duration of the signal, speed. This can show an individual’s health and condition and the experience of the individual (young or old).
      • Ecological selection (different substrates, environment noisy), sexual selection (what do females like more?), drift
      • Breed individuals with specific behaviour and look at if it is pronounced in further generations
      • Cross breed individuals from different populations or species that show specific courtship behaviour and observe it in the offspring
      • Raise individuals in a controlled environment to rule out environmental influences