Friday Lecture: HUM 15 Deep Time Radiometric Dating Google Map Exercise. Friday Lab: Faculty Lounge Animals in Cinema

Transcription

1 Friday Lecture: HUM 15 Deep Time Radiometric Dating Google Map Exercise Friday Lab: Faculty Lounge Animals in Cinema (Tomorrow afternoon practice)

2 - Natural Selection - Sexual Selection - Kin Selection Darwin - Group Selection (20 th century)

3 - Standard Darwin - Sexual Selection (Darwin) - Kin Selection (Darwin) - Group Selection I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection, in order to mark its relation to man s power of selection. We have seen that man by selection can certainly produce great results, and can adapt organic beings to his own uses, through the accumulation of slight but useful variations, given to him by the hand of Nature. But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to man s feeble efforts, as the works of Nature are to those of Art. Origin Chp 3

4 - Standard Darwin - Sexual Selection (Darwin) - Kin Selection (Darwin) - Group Selection Darwin saw traits that didn t make sense in terms of standard natural selection Long-tailed widow bird. MALE!!

5 Male Female STAG BEETLES

6 Male Stag Beetles

7 And this leads me to say a few words on what I call Sexual Selection. This depends, not on a struggle for existence, but on a struggle between the males for possession of the females; the result is not death to the unsuccessful competitor, but few or no offspring. Origin, Chp 4

8 SEXUAL SELECTION 2 types: 1) Intersexual Selection - males advertise their worthiness in the presence of potential mates. Many female animals choose their reproductive partners. Males with particular appearances or courtship behaviors gain advantage over other males.

9 superb bird of paradise Watch the females A bird of paradise (New Guinea)

10 Male satin bowerbirds (Australia) build BOWERS to attract females females check out many bowers and are extremely picky. BOWER

11 BOWER Adornments

12 Female s Location Males of the great bowerbird build a paved runway Male into the Great bower Bowerbird Display Court Larger rocks are placed farther from the beginning Males build a paved path leading out of the bower into a court An illusion of uniform stones is created. Male uses a rock size gradient Done intentionally! An optical illusion of uniform stone size is created

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14 What is the female bowerbird really choosing?? Proper Stone Gradient?? -r +r

15 Some males do very well others don t Nice Bowers Good Dancers Number of Mates Problem Bowers Poor Dancers JACKPOT 0 Offspring

16 2) Intrasexual Selection (= male rivalry ) involves direct competition to gain control over females. EXAMPLES: kangaroos, bighorn sheep, elephant seals

17 Sexual selection results in sexual DIMORPHISM --- differences in size, appearance, & behavior. EXAMPLES: lions, spiders, humans, elephant seals

18 Elephant seals large males do better Intrasexual Selection

19 Body Size Dimorphism & Harem Size 13 species of Marine Mammals polygyny monogamy

20 Intrasexual Selection Dominant Male Female 6 satellite males following 1 dominant male and the female he controls

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22 A male black-winged damselfly removes another male s sperm before depositing his own. M F Intrasexual Selection

23 SPERM COMPETITION Intrasexual Selection Sperm-removal spines on damselfly penis

24 - Standard Darwin - Sexual Selection (Darwin) - Kin Selection (Darwin) - Group Selection Q Order Isoptera Sterile Workers

25 This difficulty [social insects], though appearing insuperable, is lessened, or, as I believe, disappears, when it is remembered that selection may be applied to the family, as well as to the individual, and may thus gain the desired end. Origin, Chp 7 Darwin foreshadowed a huge 20 th century advance: SOCIOBIOLOGY

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27 WHY? Order Hymenoptera

28 Honeybee Abdomen Why?

29 Suicidal ant (Camponotus saundersi) Workers possess a gland that fills their abdomen. Arrival of an invader elicits massive abdominal contractions. Body explodes spraying invader with sticky GOO. WHY??

30 NAKED MOLE RATS - Underground colonies of up to 300 nmr - 1 Queen mating males - Everyone else is a worker WHY?

31 VOCABULARY A special type of natural selection. Kin Selection evolutionary effects of aid given to both offspring and other relatives i.e., effects of supporting those who share your genes

32 VOCABULARY Fitness genes contributed by an individual to the next generation DIRECT fitness genes contributed to the next generation by an individual through personal reproduction INDIRECT fitness genes contributed to the next generation by helping relatives other than offspring succeed INCLUSIVE fitness = DIRECT + INDIRECT **** Sociobiology Theory: Natural Selection acts to increase inclusive fitness ****

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

34 - Standard Darwin - Sexual Selection (Darwin) - Kin Selection (Darwin) - Group Selection Unrelated group-living animals will make self-sacrifices for the good of the group. Groups consisting of altruists will be strong.

35 Evolutionary biologists have often dismissed Group Selection WHY?? (Does group selection apply to humans??) ASSIGNMENT: Explore the attractiveness of this idea Find the main argument against it.

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38 PEPPERED MOTHS

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40 Pitnick and Pfennig 2014 Female mated with 3 unrelated males or 3 brothers Line thickness = intensity Kin selection? Inclusive fitness?

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42 Today: Current views of natural selection Wednesday: Current views of speciation Friday: Phylum Arthropoda

43 Long-tailed widow bird. MALE!!

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45 Female bowerbirds will usually mate once per season

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47 Male Female STAG BEETLES

48 Dung beetle males fight for mates Trade-off: horns vs eyes

49 Cloaca-pecking in the (European dunnock

50 3 Paving Possibilities by female Why does the male create this illusion??? Because females like it?? Because successful mating requires it

51 No illusion: same-sized rock appears smaller Bowerbird illusion: larger rock seems the same size

52 - Standard Darwin - Sexual Selection (Darwin) - Kin Selection (Darwin) - Group Selection Darwin saw traits that didn t make sense in terms of standard natural selection

53 My favorite passage? It may be said that natural selection is daily and hourly scrutinizing, throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working, whenever and wherever opportunity offers Origin Chp 4

54 Agents of Selection Climate Competition Disease Parasites PREDATON etc.