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Lecture 1

BIOA02H3 Lecture 1: BIOA02 Module 3 lecture 1-12 notes
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Department
Biological Sciences
Course
BIOA02H3
Professor
Ivana Stehlik
Semester
Fall

Description
Lecture 1:Animal Behavior Part 1 Types of Questions Ultimate (evolution history and adaptive function) • Why are most male birds more colorful than females? • Why do social insects have non-reproductive castes? • Why do ground squirrels give a warning cry? Proximate (causation and development) • How do male birds develop and use their colors in displays? • How does a social insect’s genetics and development affect caste? • How are an animal’s nervous and muscular systems integrated to respond to aggression? Tinbergen’s Four questions 1. Causation 2. Development 3. Adaptive function 4. Evolution history • To understand a behavior --> answer all four Q • Ethos (greek) - ‘character’of ‘habit’ Who Was Tinbergen? • Niko Tinbergen – Dutch Ethologist • Founder of ‘experimental’ethology (simple, elegant, classic experiments) • Ex) digger wasp experiments Who Was Tinbergen? • Lorenz, Tinbergen, von Frisch Nobel Prize in Medicine or Psychology (1973) (Recognition for animal behavior as a rigorous science) Who are those other guys? • Konrad Lorenz • Founder, coined term ‘ethology’ • Discovered and published most of the classical phenomena of ethology: • FixedAction Pattern (FAP) • Releasers • Innate Releasing Mechanism (IRM) • Famous for work on ‘imprinting’in geese • Imprinting – a type of pre-programmed learning in young animals during critical period of development Who are those other guys? • Konrad Lorenz • FixedAction Pattern (FAP) • Motor response that is initiated by an environmental stimulus • Once initiated, behavior goes to completion • Characteristics: 1. Sequence of events unalterable 2. Innate (not learned) 3. Can be triggered under inappropriate circumstances 4. Remarkably similar among members of a species (i.e. is highly stereotyped) Who are those other guys? • Karl von Frisch • Showed that bees are sensitive to color, but to a different range than we are (can see UV) • Decoded the ‘dance language’of honeybees (remarkably sophisticated behavior) How are BehaviorsAcquired? • Innate behaviors – instinctive, carried out regardless of an animal’s prior experiences, genetic basis • Learned behaviors – depend on an individual’s prior experiences (environment + genetics) • Experience is an important developmental process that may take several different forms Innate Behavior Characteristics: 1.Behavior consistent, independent of rearing (i.e. produced correctly without experience) 2. Mistakes are very costly 3. Variation is minimal, though behavior is not always ‘invariant’ Innate Behaviors Examples: 1. FAPs • Goose egg-rolling • Flicker ‘mustache’eliciting attack • Stickleback fish attacking stimuli with red bellies Innate Behaviors Examples: 2. Mate recognition signals (in some animals) • Courtship displays in ducks • Claw-waving displays in fiddler crabs • Frog calls 3. Predator avoidance behavior • Motmots avoiding attacks on coral snakes Innate Behaviors Ex) Predator avoidance behavior • Motmots eat insects, arthropods, snakes, etc. • They will NOT attack coral snakes (which are poisonous) THINK- PAIR SHARE We’ve just discussed innate behaviors, which are coded for by genes and lack variation. Mistakes in these behaviors tend to be very costly. Why do you think natural selection would lead to behaviors like this becoming innate in the first place? Innate can be modified by experience Ex) Color preference in foraging wasps • Parasitic wasp, hymenopteran Venturia canescens • Innate preference for yellow (and orange) color Learning Behaviors Non-associative Learning • Learning in absence of an outcome • Types: • Habituation – reduction or elimination of behaviur through repeated exposure to stimulus • Ex) Reduced ‘startle’response in rats exposed to repeated loud noises • Sensitization – enhancement of response through repeated exposure to stimulus • Ex)Achild that is being tickled laughing harder the longer the stimulus continues Learning Behaviors Associative Learning • Learning that occurs when two events are linked • Types: • Imprinting • Classical conditioning • Operant conditioning Imprinting Characteristics 1.Behavior develops in response to environmental stimuli. Often limited to sensitive period. 2. Tracks large-scale changes in the environment. Variation depends on the environment. 3. Flexibility limited by HOW and WHEN sensitive. Environment must be likely to present appropriate stimuli at the appropriate time. 4. Mistakes can be very costly (often in terms of fitness, not life-threatening). Imprinting Examples: 1. Filial – social attachment of young to parent (in particular, precocial young) 2. Habitat – attachment to a particular environment. Ex) Salmon returning to spawn use chemical cue to locate correct river 3. Sexual – social attachment to a sexual parter Ex) Cross-species fostering in nestling finches leads to adult finches attracted to foster species Classical Conditioning • Two stimuli are paired together • Ex) Pavlov’s dog experiments: dog, bell, meat powder • Unconditioned stimulus (US) – animal innately responds to stimulus (ex. Food stimulus) • Unconditioned response (UR) – animal’s innate response (ex. Salivation) • Conditioned stimulus (CS) – can condition animal to respond to CS by pairing CS with US (ex. Pairing bell with meat powder) • Conditioned response (CR) – animal learns to salivate when hears bell Classical Conditioning Operant Conditioning Characteristics: 1. Exploratory behavior leads to accidental reward 2. Subsequent rewards reinforce behavior 3. Termination of rewards leads to EXTINCTION of behavior Used to ‘shape’behavior (e.g. to train animals) • Occurs whenever an animal can encounter the same task repeatedly Operant Conditioning • Reward (reinforcement) Vs. Punishment Operant Conditioning Examples • Reinforcement – providing food to encourage behavior • Punishment - spraying water at cat to discourage behavior • Negative reinforcement– seat belt alarm encourages use of seatbelts • Negative punishment – No food / no television to discourage bad behavior Lecture 2 -Animal Behavior Part 2 Nervous System Receives / Responds to Signals • Adaptive behavior depends on interactions between the nervous system, the body, and the environment: Pathways Afferent - ascending/toward CNS (usually sensory) Receptor cell -> spinal cord -> brainstem -> higher brain areas Efferent - descending/away from CNS (usually motor) Higher brain regions -> brainstem -> periphery (effector) Feature Detection Hormones can Trigger Behaviors • Hormone – chemical substances secreted in one part of the body that cause changes in other parts of the body (provoke longer lasting / more widespread responses). • Endocrine gland – ductless glands (as compared to exocrine glands that have ducts and provide saliva, sweat) • Hormones are produced by endocrine glands and carried by blood to their (distant) targets THINK-PAIR-SHARE Why do you think it was necessary to inject testosterone into castrated males in the experiment just discussed? Why not stop at castration since the behaviour of interest stopped when males were castrated? Artificial Selection • Selective breeding can demonstrate effects of genes on behavior • Alleles favoring direction of selection will increase in subsequent generations of the population Ex) Fox Domestication • Belyaev – silver fox domestication • Selected for traits similar to those of dogs (social behavior) • Within 40 years, produced foxes that were highly social and interact with humans in playful, friendly manner Habitat Selection Species vary in distributions • Why does this variation exist? • How do animals decide where to live? Two factors to consider: 1. Resource availability - can be important aspect of habitat quality 2. # of individuals within a habitat - can indicate level of competition for resources Habitat Selection Dispersal – permanent movement from one area to another (relatively short-distance) Versus Migration – movement from one location to another and back (round-trip movement) Dispersal • Often, one sex disperses more than the other • Mammals – males disperse • Birds – females disperse (there are exceptions) • Why disperse? 1. Competition hypothesis – dispersal decreases competition for resources Ex) Natural Dispersal in Northern Goshawks • Resource quality impacts dispersal versus fidelity • With food supplementation, young Goshawks stayed significantly closer to former nest • Goshawks disperse based on estimation of habitat quality • Why disperse? 2. Inbreeding avoidance hypothesis – dispersal decreases chances of breeding with close kin Ex) Belding’s Ground Squirrels • First 4 weeks underground in mother’s burrow • Another 5-6 weeks above ground, then MALES disperse • Females move later, but not as far • Why disperse? 3. Mate competition hypothesis – competition for mates drives dispersal Ex) Lions • Male-male competition fierce (for offspring and adult males) • When not kicked out, young males often leave anyway after 2-3 years • Male-male competition proximate cause for dispersal? • Inbreeding avoidance also fits! • Females stay with the pride for life, males are kicked out after 2-3 years (avoid breeding with daughters) • Males born there kicked out even sooner • Why disperse? 4. Win-stay lose-shift hypothesis – past breeding success drives dispersal Ex) Breeding Dispersal Kittiwakes • Nest in large colonies on sea cliffs in N. Europe • Breed once / year and are more likely to return to a site if had success there last year • Also make decisions about staying / leaving based on colony’s success rate (use public information) • Are more likely to exhibit site fidelity after ’lose’if neighbors were successful Migration Requires Orientation Long distance migrants face two issues 1. Orientation - the process of determining and maintaining a proper direction • Many environmental cues can provide directional information • Compass systems can include: • Sun compass • Star Compass • Geomagnetic compass Biological Clocks Can Provide Cues • Biological clock – produced by interacting proteins that cycle on own to create regular rhythms • Different clocks have different time scales • Circadian clock – daily cycle, regulates daily rhythms (e.g. feeding, sleeping, hormones) • Lunar clock – cycle based on moon’s orbit (important for tidal species) • Annual clock – yearly or multi-year cycles Ex) Monarchs UseASun Compass • Resource base disappears (milkweeds) • Migrate in search of moderate temperatures and moist Migration Requires Orientation Long distance migrants face two issues 2. Navigation - the process of determining a particular location and moving towards it • Most animals use multiple cues to orient • Bicoordinate navigation allows individuals to identify their location relative to a goal (to use a ‘map’) Navigation in Homing Pigeons • Proper navigation • Temporarily blind birds • Clock-shifted birds on CLOUDY days • Birds with magnets glued to their heads on SUNNY days • Improper navigation • Clock-shifted birds on SUNNY days • Birds with magnets glued to their heads on CLOUDY days • Conclusions • Pigeons use a sun compass (PRIMARY) and a geomagnetic compass (SECONDARY) to navigate • Some evidence they also use chemical cues Lecture 2 -Animal Behavior Part 3 What is Communication? Communication • process in which a specialized signal produced by one individual affects the behavior of another individual Signal • An evolved trait that is selected for its effect on the behavior of the receiver • Ex) focus of this part of the lecture Cue • Consistent aspects of the environment that can guide the behavior of an individual in a way to enhance its fitness • Ex) Mosquitos using CO2 concentrations to detect prey Outcomes of The CommunicativeAct Outcomes of the Communicative Act Development of Behavior • Sensitive period – a critical period in an organism’s development during which the nervous system is especially sensitive to certain environmental stimuli Onset of sensitive periods • Triggered by external stimuli (presence of ‘teacher’) and by development of nervous system (ability to perceive/respond to stimuli) Decline in sensitive periods • Ends when an organism matures (maturation triggers hormones to signal end of period of learning) • Ends because have individual has achieved goal (ex., young birds stop learning once learn song) QUALITATIVEAspects of Information Transmission Ritualization: • Complex communication behavior • Originated from other functions: thermoregulation, maintenance behaviors, etc. Example: Piloerecton Ritualization of Signals Ritualization involves 1.Increasing the conspicuousness of the behavior 2. Reducing the amount of variation in the behavior so it can be immediately recognized 3.Increasing its separation from the behavior’s original function What can signals say to receiver? Potential message information 1. Recognition of social group members 2. Mate attraction 3. Courtship and act of mating 4. Maintaining social bond 5.Alarm 6.Aggregation 7.Agonistic encounters 8. Share information about resources Agonistic Encounters in Wolves • Communication can also be part of aggressive interactions (conflict) Signals can coney a) Aggression (threats, attacks) b)Submission (appeasement, avoidance) THINK-PAIR SHARE In the below examples, identify i) the signaler, ii) the receiver, iii) the information is that is being sent. Cooperation What is cooperation? • Cooperation aimed at close relatives is a form of kin selection (costs actor/benefits kin recipients) • Mutualisms are when actor and recipients benefit Cooperation - Behaviors that benefit recipients and that have been selected for because it benefits recipient Many behaviors of an actor can befit recipients and NOT be cooperation (if actor is doing behavior for selfish reasons) Ex) During beetles and animals that produce dung • Beetles benefit because resource that they use • Animals are not producing dung to benefit beetles (not a cooperation), but to rid themselves of wastes (selfish behavior) Cooperation Ex) Cooperative breeding • Meerkats, Florida Scrub Jays • Dominant pair do majority of breeding, subordinates help care for dominants’offspring • Subordinates may be in natal group or immigrants who have joined group • Eusocial organisms = extreme cooperative brood care, have giving up ability to reproduce (sterile worker castes) Cooperation andAltruism Altruism - acting to increase another’s individual lifetime reproductive success at a cost to ones own survival and reproduction Some potential hypotheses to explain altruism 1. Mutualism 2. Manipulation 3. Reciprocity 4. Kin Selection Hypotheses for the Evolution ofAltruism 1. Mutualism (by-product benefit) • Actor and recipient both benefit immediately • Cooperation is actually a by-product of selfish behavior that benefits self (and others as a side- effect) Ex) Cooperative hunting • Consider an animal that can capture small prey alone, and larger prey in groups (lions, wolves) • Cooperation is ESS if they get a larger net benefit (B – C) by working together then by hunting alone Hypotheses for the Evolution ofAltruism 2. Manipulation • What looks like altruism on the part of the donor may be manipulation on the part of the recipient (donor B < C) Ex) Blood parasites - the host gains nothing from feeding unrelated offspring (but it is being duped into this behavior) Hypotheses for the Evolution ofAltruism 3. Reciprocity (reciprocal altruism) • The trading of altruistic acts (mutualism with a delay benefit) Over a period of time, both participants enjoy a NET gain (paying back a favor in future) Ex) Vampire bats - blood sharing (Wilkinson) (TFT) A. Donors and recipients recognize each other individually (no need to be related) B. Sufficient pairwise interactions that there are interchanges of roles and a net benefit toALL C. Benefit of receiving aid outweighs cost of giving it Hypotheses for the Evolution ofAltruism 4. Kin selection Parental care = altruism aimed at descendant offspring • Natural selection favors behaviors that increase survival/reproductive fitness • So parental care favored by NS if leads to higher reproductive fitness (direct fitness) • But, what if aim behavior at closely related NON-DESCENDANT kin? r Descendant kin Non-descendant kin 0.5 Offspring Full siblings 0.25 Grandchildren Half-siblings, nephews/ nieces 0.125 Great grandchildren First cousins Altruism and Kin Selection 4. Kin selection Altruism: where individuals act ‘selflessly’and are NOT repaid (here, B < C!) W. D. Hamilton: altruism is favored when the WEIGHTED benefit is greater than the cost (Br – C > 0) Kin selection: aid given both to A) descendant kin (offspring) predators would drive prey numbers down (prey persist in refuges only), then decline themselves • Prey numbers in refuges increase, promoting dispersal to areas with predators, causing predator numbers to increase again Predator-Prey Cycles • In absence of other interactions, predators and prey populations tend to show linked cycling • However, in nature, other factors can override this tendency (competition, resource availability, etc.) Mutualisms Mutualism: When both individuals benefit from an interaction (+/+) Characteristics • Believed to be more common in harsh environments (species act as each other’s buffers) • Can involve protection from predators/herbivores/ competitors, or increased access to resources • Taken to the extreme -> obligate mutualism • Can lead to tight coevolutions Examples of Mutualisms • Pollinators and the plants they pollenate • Ants and acacia • Cleaners and the client fish they clean Close Mutualisms Can Lead to Coevolution • Plants that are bird and mammal dispersed have bright colored fruit (apples, cherries, etc) to attract their dispersal agents • Others produce fruit that have strong odors to attract nocturnal bats • Ex. Parrot beaks show a variety of shapes due to coevolution between them and the plants each species disperses Mutualisms can Become Symbioses • Symbioses – close, long-term mutualistic interaction between two different species • Ex)Aphids and bacteria • Aphids suck plant sap for food, plant sap is low in nutrients • Bacteria within aphids also rely on plant sap for food, provide aphids with essential amino acids • Mutualism dated to 100 million years ago (or more) • Both species have COEVOLVED (aphids contain bacteria genes, bacteria can no longer live independent of aphids) Obligate Mutualism • Mutualism can be such a tight relationship that at least one organism cannot exist without the other one – this is an obligate mutualism 1. Lichens • Fungi and algae form mutualism in which algae provide photosynthate and fungi provide safe habitat for algae to live on • Often occurs in more arid environments where algae couldn’t exist without the environment the fungi provides (deserts, tundra) 2.Ruminants and symbiotic gut bacteria • Ruminants: mammals that digest plan matter by swallowing it and using bacteria to break it down, then regurgitating it to chew it and re-swallow it • Ruminants could not break down plant matter without bacteria – so are obligates because they would otherwise starve • Bacteria live inside ruminants, relying on them for habitat and food supply Commensalism Commensalism: When one individual benefits from an interaction and the other neither benefits nor is harmed (+/0) • Army ants hunt small insects while marching, disturbing potential prey • Antbirds follow marching ants, picking off prey that they have kicked up • Antbirds BENEFIT from interaction, while ants neither benefit nor are harmed Other Examples of Commensalism 1. Orchids in tropical rainforests • Orchids grow as vines on trees, orchids gain sunlight while tree is not hurt but does not benefit 2. Cattle egrets and cattle • Cattle egrets hang out with cattle eating insects that cattle stir up as they move around fields • Cattle gain nothing, but are not harmed Lecture 7- Community Ecology Part 2 (Ecological Communities) Community Structure • The number of species, their relative abundance, and the types of species are all aspects of community structure • Ongoing debate about how predictable structure is Clements - Gleason Dichotomy • Clements’s climax community – communities are stable and do not change, and are determined by the area’s climate • Gleason’s view – communities are neither stable nor predictable, individual species respond independently to physical variables to determine their distributions Populations are Part of Communities Population dynamics related to: • Available conditions/resources • Connectivity of patches (metapopulation structure) • Competition • Predation/parasitism • Mutualisms and commensalisms • And how all of above influence life history traits Populations within a community share physical conditions (rainfall, climate, soil conditions) and interact with one another Activities of populations within a community can vary in time and space -> communities do not have clearly defined boundaries, but can be characterized by the species within them. What is Biological Diversity? Biological diversity = all life on earth 1. Genetic diversity – variation within a species’genes 2. Species diversity – species richness (total # species in an area) 3. Ecosystem diversity • Variation of species across ecosystems • Variation of ecosystems within an area Generally, # species is most common measurement Biodiversity VariesAcross the Globe 1. Climatic variation – climates that are more stable may have higher species richness than ones that undergo seasonal changes 2. Disturbances – disturbances can lead to gaps in climax communities, allowing poorer competitors to flourish 3. Environmental age and evolutionary time – environments that have remain stable for longer time periods may have higher species richness due to lack of large scale disturbances and due to longer evolutionary periods 1) Climatic Variation • Tropical climates lack seasonality -> increased opportunity
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