SOCIAL ANIMALS. -Spectacular -Photographed -Studied -Appreciated. The PINNACLE of evolution???

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2 SOCIAL ANIMALS -Spectacular -Photographed -Studied -Appreciated The PINNACLE of evolution???

3 QUALITIES Social animals are aggregations of conspecifics that may have enhanced communication abilities some degree of self-sacrifice some division of labor increased genetic relatedness

4 Social species can range from the merely gregarious to the EUSOCIAL Gregarious tending to associate with others of one s kind. EUSOCIALITY (extreme sociality) 1) cooperation in the care of young by adults other than parents 2) overlap of generations one generation rears the next 3) CASTES that forego personal reproduction!! (1) and (2) are not surprising. (3) is radical

6 Locust Swarm Social Animals? no Gregarious?

7 Fall webworms gregarious yes. Social?

8 Gregarious yes Social?

10 SOCIAL ANIMALS

11 EUSOCIAL

12 CAUTION!! Sociality is NOT superior to solitary living why? Both are simply strategies for survival. Solitary wasp Social wasp

13 COST:BENEFIT ANALYSIS OF SOCIALITY Benefits: (1) protection from predators (2) Food-finding efficiency (3) Miscellaneous

14 (1) Protection from Predators a) The Many Eyes Hypothesis Summed sensory capacities of group members makes surprise attacks less likely.

15 Looking Foraging

16 Safety in Numbers in redshanks?

17 (1) Protection from Predators (continued) b) Group response causes CONFUSION

18 Minnow Schools: FLASH EXPANSION (advancing predator)

19 ???

20 The Fountain Effect

21 Swirling Confusion which bird to attack?

22 (1) Protection from Predators (continued) c) Selfish Herd Hypothesis ( you first hypothesis) Individuals at the center of the group are safer

24 (1) Protection from Predators (continued) d) Numbers help defensive animals Muskoxen

26 (1) Protection from Predators e) the best defense is offense

27 Fire ant soldiers defend nests by being massively aggressive!!

28 Lethal temperature for invader

29 Bird Offense - Does Mobbing Reduce Predation? Black-headed gulls [predators are egg-eating crows] Gull colony border = gull nest Selfish Herd? outside edge center Chicken eggs placed every 10 m from outside the colony to the colony center

30 Effects of Mobbing by Black-headed Gulls Nest Location

31 (2) Food-finding Efficiency Previous examples (review): -Osprey - Honey Bees

32 Passive transfer of information about food location minnow school

33 3) Miscellaneous Benefits: Thermoregulation A small endotherm has a bad SA:VOL But, a cluster of small endotherms has a good SA:VOL High heat loss Bat cluster Low heat loss Single bat

34 3) Miscellaneous Benefits: Cooperation

37 Weaver ants cooperating to dismember a red ant

38 3) Miscellaneous Benefits: Cooperation Colony Heating & Cooling

39 3) Miscellaneous Benefits: Cooperation Weaver Ant Nest-Building

40 Body Bridge Group Grasping

41 Larva used as a weaving tool

43 Termite FORTRESS

44 Costs of Social Living: (1) Increased competition (2) Increased aggression (3) disease (4) inbreeding

45 Competition Example: Mexican free-tailed bat Bracken Cave (TX) 20,000,000 bats

46 Colony food requirement: 250,000 lbs of flying insects per night Hunting radius from cave: 100 miles!! (YCP to Philadelphia = 100 miles) BC 100 mi

47 Cliff Swallows Nests Swallow Bug parasites infest nests

48 Likelihood of Swallow Bug Infestation Infestation Level Swallow Colony Density

49 Effects of Swallow Bugs on Swallow Nestlings Infested nestling Insecticide-treated

50 Big Observation: Solitary animals are selfish e.g., bobcats don t help other bobcats rabbits don t help other rabbits Social animals are altruistic e.g., female lions will nurse some other mother s kitten soldier ants will give up their lives to protect the colony

51 Giant Question: Why are solitary animals selfish?? Why are social animals altruistic?? Example 1: Worker honey bee When she stings an invader, she eviscerates herself. She has committed suicide for the good of the group. WHY???

52 WHY?

54 By the time the paramedics found him near a cavern in the central Mexican highlands, the man was swollen and losing consciousness, with his pulse racing and his blood pressure plummeting. Twelve hours later, still semi-conscious and bloated and drifting into heart, kidney and liver failure, he was transferred to a Mexico City hospital. After 21 days he was released from the hospital in good health. He had been stung by Africanized honeybees more than 2000 times on the face, trunk, arms, and legs Venomous sacs were removed from all over his body, and bees were removed from his ears and nose.

55 Bee sting result

56 Honeybee Abdomen WHY??

57 Example 2: suicidal ant (Camponotus saundersi) Workers possess a gland that fills their abdomen. Arrival of an invader elicits massive abdominal contractio Body explodes spraying invader with sticky GOO. WHY??

58 WHY?.. Answer: GENETICS Social animals will make large sacrifices for genetic relatives. Class Insecta Example: Order Hymenoptera (bees, wasp, ants) Considered to be EUSOCIAL animals

59 Eusocial Hymenoptera have castes = group members specialized for some purpose: Queen reproduction Worker work Soldier defense CLOSE GENETIC RELATIONSHIPS

60 Q Order Isoptera (termites)

63 CONCLUSION: Sacrificing for a very close relative is no sacrifice!! If your sacrifice promotes a relative s survival, your genes are being propagated. PROFOUND CONCLUSION You don t need to reproduce to be genetically successful!!

64 Only 1 mammal can approach the insects in eusociality Hint: not Homo sapiens

65 Colony of NMRs

67 Zoogeography Of the NMR

68 NMR Observations -Not moles or rats -Underground colonies of up to 300 nmr -Poikilothermic!! Autocoprophagic!! -Castes: 1 Queen (other females don t ovulate) 2-3 mating males (other males produce sperm but don t mate) Everyone else is a worker EXTREMELY INBRED GENETIC RELATEDNESS VERY HIGH

69 Behavioral Castes

12. Social insects. Is it better to be social? Is it better to be social? What is social? Some costs of being social

12. Social insects. Is it better to be social? Is it better to be social? What is social? Some costs of being social Is it better to be social? 12. Social insects Cost and benefit viewpoint Social behavior is not always adaptive (costs exceed benefits) What are some costs of being social? What are some benefits of being