Presentation on theme: "Behavioral Plasticity in Cichlids"— Presentation transcript:
1 Behavioral Plasticity in Cichlids A dominant male cichlid fish courts and breeds with females, and confronts other males – dominance is indicated by bright coloration and a dark eye barA subordinate male cichlid flees dominant males, does not court or breed, and has a drab colorationRemoval of a dominant male initiates cascade of changes in gene expression in a subordinate male that rapidly transforms its behavioral and physical phenotype to dominant
3 Epigenetic EffectsEpigenetic mechanisms cause heritable changes in behavior without altering DNA sequenceExample: Lack of tactile stimulation early in a female rat’s life causes methylation of its DNA, resulting in changes in gene expression that suppress oxytocin’s effectsThe methylated DNA is passed on from generation to generation, disrupting oxytocin’s influence and negatively affecting female parental behavior
4 Take-Home Message: How does the environment affect behavior? With behavioral plasticity, environmental factors influence an individual’s behavior during its lifetime.The environment can also cause heritable changes in behavior through epigenetic modifications of DNA.
5 43.5 Movements and Navigation All animals are motile during some part of their life cycleAn innate directional response is called a taxisExample: Planarians are negatively phototactic and positively geotacticKinesis is a response that causes an animal to increase or decrease its movements without regard for directionExample: Planarians are photokinetic
6 MigrationDuring a migration, an animal interrupts its daily pattern of activity to travel in a persistent manner toward a new habitatMigration most often involves seasonal movement to and from a breeding siteSome animals (e.g. birds) migrate every year; others (e.g. eels) migrate only once to spawn and die
7 Navigation and Migration Some animals have an innate magnetic compass – they use variations in Earth’s magnetic field to determine directionExample: A European robin “sees” directional differences in Earth’s magnetic field with its right eyeSome animals navigate by the sun and starsA migrating animal may gauge its progress relative Earth’s magnetic field, or to visual or olfactory landmarks
8 Vision-based Magnetic Compass in European Robins Figure Vision-based magnetic compass in European robins. (a) Triangles indicate predominant direction of movements made by 12 robins tested indoors in the spring. Arrow indicates average result. (b) A robin with a frosted lens in front of its right eye and a clear one over its left eye shows no directional preference in its movements.
9 Take-Home Message: What factors influence animal movements? Innate responses to specific stimuli can influence the rate or direction of animal movements.Some animals migrate between habitats. Navigating to a specific site requires an ability to determine compass direction and a mental map.
10 43.6 Communication Signals Communication signals transmit information between members of the same speciesChemical signals such as bee pheromonesAcoustical signals such as prairie dog barkingVisual signals such as threat displaysTactile signals such as honeybee dancesBird courtship often involves both visual and acoustic signals
11 Prairie Dog Barking a Warning Figure Prairie dog barking a warning. The bark provides information about whether the threat is an eagle or coyote. Other prairie dogs that hear the alarm call behave accordingly, diving into burrows when the call warns of a flying predator, or standing erect to observe the movements of a ground predator such a coyote.
12 Courtship Display in Albatrosses Figure Courtship display in albatrosses. The display involves a series of movements, some accompanied by calls.
13 Threat Display: Male Collared Lizard Figure Threat display of a male collared lizard. This display allows two rival males to assess one another’s strengths without engaging in a potentially damaging fight. The display also is called into service to deter potential predators.
14 Tactile Display: Honeybee Dances When bee movesstraight up comb,recruits fly straighttoward the sun.When bee moves straight down comb, recruits fly to source directly away from the sun.When bee moves to right of vertical, recruits fly at 90° angle to right of the sun.Figure Animated Honeybee waggle dance, a tactile display. The orientation of the “waggle run” conveys information about the direction of a food source.Stepped Art
15 ANIMATED FIGURE: Honeybee dances To play movie you must be in Slide Show ModePC Users: Please wait for content to load, then click to playMac Users: CLICK HERE
16 CommunicationChemical and acoustical signals typically are effective over longer distances than visual or tactile ones – also, they are more effective in the darkThe same signal may function in more than one contextExample: In dogs and wolves, a play bow indicates that any seemingly aggressive signals that follow, such as growling, should be interpreted as play behavior
17 A Wolf’s Play BowFigure A wolf’s play bow tells another wolf that its next behavior is meant as play, not aggression.
18 Eavesdroppers and Counterfeiters Predators can benefit by intercepting signals sent by their preyExample: Frog-eating bats locate male tungara frogs by listening for their mating callsCounterfeit signalers can also pose a threatExample: A predatory beetle imitates the flash of a female firefly to lure a male firefly close enough to eat him
19 Take-Home Message: What are the benefits and costs of communication signals? A communication signal transfers information from one individual to another individual of the same species. Such signals benefit both the signaler and the receiver.Signals have a potential cost. Some individuals of a different species benefit by intercepting signals or by mimicking them.
20 43.7 Mates, Offspring, and Reproductive Success Males and females behave in ways that maximize their own reproductive successMales compete for females and seek many matesFemales select for quality of a mate, not quantityMicroevolutionary process favor characteristics that provide an advantage in obtaining and keeping mates
21 Mating SystemsPromiscuity: Members of both sexes mate with multiple partnersPolygamy: One sex has multiple partnersMonogamy: A male and female mate only with one anotherMembers of a species may vary in their behavior, and formation of pair bonds does not preclude extrapair matings
22 Sexual SelectionWhen one sex is the limiting factor for the other’s reproduction, sexual selection occursExamples:Female hangingflies mate only with males that supply foodFemale fiddler crabs judge a male’s burrow-building skill before selecting a mateMale sage grouse display at a lek to be chosen by femalesMale bison fight to hold a territory with access to females
23 Male Hangingfly Bearing Food Figure How to impress a choosy female.A. Male hangingfly dangling a moth as a nuptial gift for a potential mate.
24 Male Fiddler Crab with Large Claw Figure How to impress a choosy female.B. Male fiddler crabs (top) wave their one enlarged claw to a attract a female (bottom).
25 Male Sage Grouse at a Lek Figure How to impress a choosy female.C. Male sage grouse gather on a communal display ground called a lek, where they dance, puff out their neck, and make booming calls.
26 Male Bison Defending Territory Figure Male bison locked in combat during the breeding season. A few males will mate with many females. Some males will not mate at all.
27 Parental Care Parenting requires time and energy Increase in survival of young may outweigh costsExamples:In mammals, females are typically sole caregiversMale midwife toad cares for eggsCooperative care of young by both parents occurs most frequently in birds
28 Female as Sole Caregiver Figure Caring for offspring.A. Female grizzlies care for their cub for as long as two years. The male takes no part in its upbringing.
29 A Male Caregiver Figure 43.19 Caring for offspring. B. A male midwife toad carries developing eggs.
30 Cooperative Care Figure 43.19 Caring for offspring. C. A pair of Caspian terns cooperate in caring for their chick.
31 Take-Home Message: What factors affect mating systems and parental care? The positive effects of genetic diversity among offspring make monogamy rare.In many species, a few males monopolize mating opportunities either by enticing females to choose them or by defending a territory with many females.Parental care evolves only when the benefit of parental care outweighs the costs in lost opportunity for more offspring.
32 43.8 Living in GroupsAnimals that live in social groups may benefit by cooperating in predator detection, defense, and rearing the youngSuch groupings evolve only if benefits of close proximity to others outweigh the costs
33 Defense Against Predators In some groups, cooperative responses to predators reduce the net risk to allAlarm calls (e.g. birds, monkeys)Presenting a united front (e.g. sawfly caterpillars)A selfish herd forms when animals hide behind one another to avoid predators
34 Group Defenses: Sawfly Caterpillars Figure Group defenses.A. Cluster of sawfly caterpillars regurgitating fluid (yellow) that predators find unappealing.
35 Group Defenses: Musk Oxen Figure Group defenses.B. When threatened, musk oxen adults (Ovibos moschatus) form a ring of horns, often around their young.
36 Improved Opportunities Many mammals live in social groups and cooperate in hunts, but cooperative hunters are not always more successful than solitary onesGroups are more successful at fending off scavengers, caring for young, protecting territoryGroup living also allows transmission of cultural traits, or behaviors learned by imitation, such as termite “fishing” among chimpanzees
37 Cooperative Hunting in Wolf Packs Figure Members of a wolf pack hunt cooperatively.
38 Chimpanzees Fishing for Termites Figure Chimpanzees (Pan troglodytes) using sticks as tools for extracting tasty termites from a nest. This behavior is learned by imitation.
39 Dominance Hierarchies Many animals that live in permanent groups form a dominance hierarchyDominant animals get a greater share of resources and breeding opportunities than subordinate onesExample: Wolves cooperate in hunting, caring for young and defending territory, but only the alpha male and alpha female breed
40 Regarding the CostsIn most habitats, the costs of living in large groups outweigh the benefitsLarge groups attract predatorsIncreased competition for space and foodIncreased vulnerability to disease and parasitesRisk of being killed or exploited by othersExample: Penguins form dense breeding colonies in which competition for space and food is intense
41 Penguin Breeding Colony Figure A crowded penguin breeding colony.
42 Take-Home Message: Benefits and costs of living in a social group Living in a social group can provide benefits, as through improved defenses, shared care of offspring, and greater access to food.Costs of group living include increased competition and increased vulnerability to infections.
43 43.9 Why Sacrifice Yourself? Extreme cases of sterility and self-sacrifice have evolved in only a few groupsInsects such as honeybees, termites, and antsTwo species of mammals (mole-rats)
44 Eusocial AnimalsA eusocial animal lives in a multigenerational family group with a reproductive division of laborPermanently sterile workers care cooperatively for the offspring of just a few breeding individualsIn some species, sterile workers are highly specialized in form and function
45 Specialized Workers: Honeypot Ant Figure Specialized ways of serving and defending the colony.A. An Australian honey pot ant worker. This sterile female is a living storage container.
46 Specialized Workers: Soldier Ant Figure Specialized ways of serving and defending the colony.B. Army ant soldier (Eciton), also a sterile female, shows her formidable mandibles.
47 Specialized Workers: Soldier Termite Figure Specialized ways of serving and defending the colony.C. Eyeless soldier termite (Nasutitermes). It shoots glue like secretions from its nozzle-shaped head. Termite soldiers include both males and females.
48 Honeybees Queen honeybee The only fertile female in her hive; she secretes a pheromone that makes all other females sterileWorker beesFemales that develop from fertilized eggs; they collect food and maintain the hiveDronesStingless males that develop from unfertilized eggs; they mate with a virgin queen and die
49 TermitesTermites live in huge family groups with a queen who specializes in egg production – a king supplies spermUnlike the honeybee hive, a termite mound holds sterile males and femalesWinged reproductive termites of both sexes develop seasonally
50 Mole-Rats Mole-rats are the only eusocial mammals A reproductive mole-rat queen mates with one to three kingsTheir nonbreeding worker offspring feed the clan, dig burrows, and protect against predators
51 Queen HoneybeeFigure Three queens, fertile females in species that have a reproductive division of labor.A. Queen honeybee with her sterile daughters.
52 Queen TermiteFigure Three queens, fertile females in species that have a reproductive division of labor.B. A queen termite dwarfs her offspring and mate. Ovaries fill her enormous abdomen.
53 Queen Naked Mole-RatFigure Three queens, fertile females in species that have a reproductive division of labor.C. Naked mole-rat queen.
54 Evolution of Altruism Altruistic behavior Behavior that enhances another individual’s reproductive success at the altruist’s expenseTheory of inclusive fitnessAltruistic behavior is perpetuated because altruistic individuals share genes with their reproducing relatives
55 Take-Home Message: How can altruistic behavior be selectively advantageous? Altruistic behavior may be favored when individuals pass on genes indirectly, by helping relatives survive and reproduce.Mechanisms that increase relatedness among siblings may encourage the evolution of eusocial behavior.