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Sociobiology

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MALE FRIGATE BIRDS : INFLATED SCARLET POUCHES TO ATTRACT FEMALES. Mating systems ... E.g. newly hatched birds require large, continuous food supply and cannot ... – PowerPoint PPT presentation

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Title: Sociobiology


1
Sociobiology
  • BS 111
  • Ecology Biodiversity

2
Learning objectives
  • describe social behaviour in terms of costs and
    benefits
  • discuss the advantages of social behaviour for
    finding food and avoiding predators
  • describe the basic sociobiology of mate
    selection, sexual selection, parental investment
    and of mating systems

3
Social behaviour
  • Interaction between 2 or more animals (usually of
    same species)
  • Aggression, courtship, cooperation, deception
  • Costs/benefits
  • Sociobiology applies evolutionary theory as
    foundation for interpretation of social behaviour

4
Competitive social behaviours
  • Contest for resources
  • Agonistic behaviour e.g. food, mate
  • Tests of strength, threatening displays,
    vocalisations, postures
  • Ritual, symbolic displays, often no harm done
  • E.g. dogs, wolves show teeth, erect ears, tail,
    looser submissive tucks in tail, looks away

5
Cont.
  • Ground squirrels inflict severe injury, even
    kill battling for sexually receptive females
  • Only receptive a few hrs each yr
  • Males reprod. fitness depends on ability to
    compete
  • natural selection favours tendency to end contest
    as soon as winner est. (so victor not also
    injured)

6
Dominance hierarchies
  • E.g. hens put in same pen pecking order
    dominance hierarchy
  • Alpha hen controls behaviour of others- benefit
    assured access to food
  • Wolves packs coop. necessary for killing prey.
    Each pack dom. Hier. Among females.
  • Top female controls mating of others. Food scare
    allows less mating for other females (more for
    her young)

7
Territories
  • Some spp. defend territories only in breeding
    season may form social groups at other times
    e.g. bird pairs defend small breeding territory
    but form large flocks in winter to forage more
    efficiently/protection from preds.

8
Courtship
  • complex set of behaviors communicates that other
    not a threat that species, gender, physical
    condition are suitable for mating.
  • Complex courtship interaction consists of FAPs
    triggered by some action
  • Males more into courtship
  • Females more discriminate parental investment
  • Also genetic can the males counter
    pathogens/parasites etc???

MALE FRIGATE BIRDS INFLATED SCARLET POUCHES TO
ATTRACT FEMALES
9
Mating systems
  • Varies between species
  • Many species promiscuous
  • Monogamous one male one female long period
  • Polygamous an ind. Of one sex (usually male)
    with several of the other
  • Polyandry single female mates with several males
  • Needs of young imp. To evolution of mating
    systems
  • Physical characteristics?????

10
Why are some birds monogamous?
  • E.g. newly hatched birds require large,
    continuous food supply and cannot care for
    themselves
  • One parent may not be able to provide all
  • i.e. in male interest to stay will provide more
    viable offspring by helping a single mate than
    going off to seek more mates
  • May explain why birds are monogamous
  • But what about Pheasants, quail?

11
Others not???
  • Some species young feed and care for
    themselvesless need for parents to stay together
  • Mammals..lactating food source ..males no role
    unless protecting harem.
  • Certainty of paternity???..why parental care by
    malese.g. external fert. By fish often male
    parental care

12
Male jawfish holds the eggs it has fertilised in
its mouth keeping them aerated and protected from
egg predators until the young hatch Certainty of
paternity is higher when mating and egg laying
occur together , as in external fertilisation
e.g. aquatic inverts, fishes, amph, if there is
parental care might be male/female
13
Social Interactions and communication
  • Intentional transmission of info. Between inds.
    (act by a sender produces detectable change in
    behaviour of another)
  • Displays, singing produce response
  • E.g. playing tape recording of another males
    song in a male birds territory agitation/may
    attack speaker

14
Mimicry and murder in the night
  • Fireflies (Photinus)
  • Females respond to male flashes for courtship by
    flashing (charac.)
  • Photurus female fireflies mimic flashes (not for
    courtship but too eat!)
  • males contain defensive chemicals that females
    need to repel predators, such as spiders.
  • Mimicry and murder provide a lifesaving meal!
  • Defensive chemicals called lucibufagins, which
    Photinus fireflies have and Photuris fireflies
    want, are exuded in firefly blood.

15
Deceit within species
  • E.g. lions..dominant male takes control of group,
    kills young that are born too soon to be his
    offspring
  • Without young, females ovulate sooner
  • New dominant male fathers offspring

16
Methods of communication
  • Visual, auditory, chemical (olfactory), tactile,
    electrical signals
  • Which mode related to animals basic lifestyle,
    e.g. nocturnal mammals..visual not effective but
    olfactory/auditory work well
  • But birds, mostly diurnal use visual, auditory

17
European honeybees (Apismellifera carnica)
  • Social, hive bees
  • Max. foraging efficiency comm. Location of good
    food sources
  • Changes as flowers bloom/new patches discovered
  • 1940s Karl von Frisch watched as they returned to
    special observation hives

18
  • Honeybees showed complex communication with
    symbolic language
  • A bee returning from the field - centre of
    attention and performs a dance to communicate
    information about the position of a food source
  • Food source close (lt50 m) tight circles waggling
    abdomen/regurgitates nectar
  • Excited follower bees to leave hive in search

19
  • Bees forage up to 5 km from hive
  • Waggle dance ½ circle swing in 1 direction,
    straight run, ½ circle other direction (
    regurgitates)
  • Indicates both distance direction
  • Angle of open hive same as hor. Angle of food in
    relation to sun
  • Sounds odors????

20
Fig. 51-8c
Waggle dance (food distant)
(c)
A
30
C
Beehive
B
30
Location
Location
Location
B
A
C
21
Altruism
  • Behave in ways that reduce their ind. Fitness and
    increase fitness of recipient of behaviour
  • e.g. ants, bees workers sterile labour for
    queen. Sting intruders..results in death
  • Selection sometimes favours altruism Still have
    enhanced genetic representation in next
    generation

22
Summary
  • Social behaviour dominance hierarchies,
    territories
  • Courtship
  • Social interactions
  • Communication
  • Deceit
  • Altruism

23
Recommended Reading
  • Campbell Reece, Chapter 51, pp1133-1144
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