LECTURE 08. Today: 3/3/2014

Transcription

1 Spring 2014: Mondays 10:15am 12:05pm (Fox Hall, Room 204) Instructor: D. Magdalena Sorger Website: theantlife.com/teaching/bio295-islands-evolution LECTURE 08 Today: Quiz follow up Follow up on minute papers Evolutionary trees (cont.) Interpret a phylogenetic tree Explain how to infer phylogenies Describe different methods to infer phylogenies Discuss difficulties in phylogenetic analysis Give an example how phylogenetic tree is used to test a hypothesis Patterns of evolution Describe the different between homologous and analogous structures Explain the difference between convergent, parallel and divergent evolution Give examples of convergent and parallel evolution Guest speaker: Dr. Brian Langerhans EXERCISE Summary 1

2 FOLLOW-UP MINUTE PAPERS Follow up on minute papers Lek mating examples? How does it work? Why is female attracted to male display if they don t indicate male s ability to survive? Runaway selection more examples Next step after creating phylogeny? Use of classifying taxa? Tell us about future of a species/predict speciation? Phylogenetic trees determine conditions that led to extinctions? Coevolution Bootstrap values??? 2

3 compete for 3

4 ? 4

5 CHOOSE THE FITTEST ONE: HONEST SIGNALS Resistance to parasites e.g.: carotenoids signifies resistance to parasites 5

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8 CHOOSE THE FITTEST ONE: HONEST SIGNALS Access to more resources 8

9 ? e.g.: larger tail signifies access to more resources 9

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12 Direct benefits INCREASE OWN FITNESS THROUGH MATERIAL BENEFITS Resources (food & territory) Parental care Protection from predators EXTREME Indirect benefits INCREASE GENETIC FITNESS FOR OFFSPRING Good genes Sexy sons exaggerated phenotypes, dance flies presenting empty nuptial gifts, polyandrous females (damselflies, dunnocks) to secure help with parental care, 12

13 Sensory bias vs. Runaway selection pathway already established e.g.: orange spots resemble orange fruit random preference (sons express it, daughters inherit preference) preference for bigger, longer, brighter until natural selection puts a cap on it! EVOLUTIONARY TREES cont. 13

14 PATTERNS OF EVOLUTION One of the most important principles of evolution: Features almost always evolve from pre existing features of ancestors 14

15 Patterns of evolution Homologous vs. analogous structures Coevolution Convergent evolution Parallel evolution Divergent evolution Homologous traits are due to descent from a common ancestor 15

16 Homologous vs. analogous structures COEVOLUTION closely interacting species exert selective pressures on each other, evolve together in a kind of conversation of adaptations 16

17 Evolutionary arms races: Coevolution Interspecific competition for resources Predator prey Host parasite Plant herbivore Flower pollinator Sexual conflict CONVERGENT EVOLUTION (HOMOPLASY) Evolution of similar features in independent lineages usually from different developmental pathways 17

18 PARALLEL EVOLUTION Evolution of similar features in related lineages by similar developmental modifications DIVERGENT EVOLUTION Evolution of increasing differences between groups (can lead to speciation) 18

19 Convergent evolution: eyes Convergent evolution: marcupials & placentals 19

20 Parallel evolution: porcupine quill structures New World Old World Convergence: trap jaws 20

21 Convergence: Cichlids in African lakes BEETLES & HOST PLANTS CASE STUDY 21

22 Biology Distribution: North & Central America Tetraopes (longhorn beetle, milkweed beetle ) species affiliated with specific Asclepias (milkweed) species (only few exceptions) Tetraopes larvae attack roots, adults feed on upper foliage and flowers Females oviposit eggs inside grass stems close to milkweed plant BEETLES & HOST PLANTS Farrell & Mitter 1998 Methods 29 species Morphological & allelic data analyzed Parsimony tree BEETLES & HOST PLANTS Farrell & Mitter

23 Results BEETLES & HOST PLANTS Farrell & Mitter 1998 Results BEETLES & HOST PLANTS Farrell & Mitter

24 CASE STUDY ECHOLOCATION: BATS & DOLPHINS Biology Echolocation evolved independently in bats & whales (dolphins) Involves production, reception & auditory processing of ultrasonic pulses for obstacle avoidance, orientation & hunting ECHOLOCATION: BATS & DOLPHINS Parker et al

25 Methods Genome wide sequence data from: 4 bat species encompassing paraphyly of echolocating bat lineages Non echolocating bat species Echolocating bottlenose dolphin (Tursiops truncatus) 15 additional mammal species Maximum likelihood phylogenetic reconstruction ECHOLOCATION: BATS & DOLPHINS Parker et al Hypotheses ECHOLOCATION: BATS & DOLPHINS Parker et al

26 Results ECHOLOCATION: BATS & DOLPHINS Parker et al Results Natural selection acted on 3 echolocating lineages Convergence in genes linked to hearing/deafness Also: Convergence in genes linked to vision ECHOLOCATION: BATS & DOLPHINS Parker et al

27 GUEST SPEAKER Dr. Brian Langerhans 27

28 Recap Evolutionary trees (cont.) Interpret a phylogenetic tree Explain how to infer phylogenies Describe different methods to infer phylogenies Discuss difficulties in phylogenetic analysis Give an example how phylogenetic tree is used to test a hypothesis Patterns of evolution Describe the different between homologous and analogous structures Explain the difference between convergent, parallel and divergent evolution Give examples of convergent and parallel evolution Bahamas Blue Holes SUMMARY 28

29 1. What was the most important thing you learned during this class? 2. What important question regarding what you learned remains unanswered for you? (What would you like to know about next?) SUMMARY NAME & DATE 3/3/2014 For next week: The Beak of the Finch: Read Chapter 12 & 13 Read paper (will be posted) Draft script due this Friday! (7 Mar, 5 pm) 29