Lecture 11 - BIO220

6 we expect females to increase resistance to mating

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Unformatted text preview: aging efficiency • disease • mating conflicts with foraging Proportion mating 0.6 • we expect females to increase resistance to mating when hungry Males Fed Nonfed 0.4 0.2 • hunger treatment: 6 hrs no food Fed Focus on the economics and consequences of female resistance. Nonfed Females • mating rate was determined by female resistance • males are more or less monotonous -Predators strike from below, pull both M a nd F below water, kills the female while the m ale quickly jumps off and gets away -Therefore predation risk higher for Females -Fed and non-fed males will mate the same! (Clearly they do n ot need to eat first in order to want to mate lmao) -Fed females mate MORE because the cost of mating (losing f oraging time) is REDUCED and not as important if they're full Sexually conflict and the evolution of sexually antagonistic traits. Does female resistance bias male mating success? Does resistance act like a preference? • large males were favoured only when females were resistant to mating 0.3 Proportion mating 0.2 • females did not reduce struggle duration with large males • large males withstood struggles for a longer period 0.1 Males Large Small Fed Nonfed Females Female resistance leads to sexual selection on males phenotypes that are bad for females (i.e. “sexually antagonistic traits”) -When females are fed, large and small M mate the same! -When females are NOT fed and they begin to struggle, only large males are able t o overcome the struggle and mate ANYWAY (It is not the result of less female s truggle in the presence of a large male - they struggle the same) Evo-Devo of sexually antagonistic traits. -All females look similar among species, while males vary g reatly among species Morphological divergence with functional convergence in sexually antagonistic traits. F2(0)* A4 M5 H5 A6 F5 AB1 G1 F4 A5 H4 H3 F3 F1 H2 M1 M3 M4 M2 H1 A1 A3 A2 F2(1)* -Can this male diversity be associated with a gene? - Compare gene expression b/w species: Does gene expression c ause appendage variation? -Antennae evolved many different times (red dots) -Each time different 5 2/13/2013 A Near Perfect Antagonistic Adaptation! -Each appendage fits into female perfectly -Appendages are adapted PERFECTLY! They fit like puzzle p ieces A graded and nearly isolated response to knockdown Knocking down expression of distal-less takes us a few steps back in evolutionary time. -Knock out the gene responsible for modifying the antennae (Distal gene) Fitness consequences of reductions in the antennae • Diversity, and the path to it • Selective regime • Genes • Fitness consequences ?? -The response to the knockdown is graded (see next slide) Severity of the Distal gene knockdown Closer to the ancestor Good Luck With The 2nd Half of BIO220 Decreasing mating success -As the severity of the knockdown increases, the antennae b ecomes closer and closer to the ancestor -As the antennae becomes closer and closer to ancestor, m ating success decreases -Clearly, selection is pushing for the modification of these t raits 6...
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