Bio1B Evolution 8 Last lecture Coevolution mutualism vs antagonistic Why have sex advantages v disadvantages of sexual reproduction Sexual selection Mating systems Today Sexual selection pp 295 297 Intra vs intersexual selection Female preference Direct benefits resources vs indirect good genes Evolution of sacrifice altruism kin selection pp 815 8 Species speciation Ch 17 What is a species anyway Speciation processes introduction geographic modes Intra v inter sexual selection A few males dominate reproduction Female choice manipulation of taillength in male widowbirds Number nests per male Competition and mating success in male elephant seals Futuyma Evolution 1st Ed See also Fig 15 9 Benefits of multiple mating sperm competition winner increased survival of offspring Fisher et al 2006 Nature 444 89 92 Antechinus marsupial mouse Stud M multiple polyandry single Wimp M 1 Female choice good gene hypothesis Females prefer males with long calls LC Do females select males based on signals that indicate high fitness of offspring Offspring of LC males have higher fitness Sensory bias males exploiting pre existing preferences of females Evidence from phylogeny P F preference T M trait Futuyma When to sacrifice if it helps a relative lots Kin selection theory W Hamilton Help if rB C r shared genes B benefit C cost Tuco tuco coparenting by females in social groups Eileen Lacey IB Haldane I would not lay down my life for a brother but would do so for 2 brothers or 8 cousins Social insects inheritance system higher r increased cooperation Belding s ground squirrels females more related and give more alarm calls Fig 51 29 2 Estimates of relatedness from molecular data 2005 Nature 434 69 What is a species Typological pre evolutionary eg Aristotle Linnaeus Evolutionary NeoDarwinists Systematists Character change Reproductive isolation Biological SC Darwin Discontinuities DWM extinction Phylogenetic SC Morphological SC Diagnosable clusters with common ancestry molecular or morphological Phenotypically distinct sets of populations Groups of populations reproductively isolated from others Reconciling different perspectives Forms of Reproductive Isolation Prezygotic Separation of mating Viability F1 or later Fertility Postzygotic RI increases with genetic divergence Increasing RI phenotypic divergence Habitat Timing Behavior Mechanical Gamete recognition Postzygotic General lineage concept focuses on the process not how to recognize species also Fig 17 5 3 Species of Hominidae Pygmy chimp Ensatina eschscholtzii One ring species Or 2 biological species Or 11 Phylogenetic species k e overlap hybrids k e overlap no hybrids Geographic modes of speciation Futuyma 2005 4
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