Uncoupling direct and indirect components of female choice in the wild

Abstract

One of the most controversial debates in evolutionary biology concerns the fitness consequences of female choice in nature. Discriminating females may benefit from high-quality territories and͞or sires with high-quality genes. Here we experimentally dissociate female preferences for high-quality territories and male body size in a wild population of side-blotched lizards, Uta stansburiana. Females preferred experimentally improved territories but still chose high-quality sires for their progeny. High-quality territories were associated with earlier egg-laying dates and larger eggs. These maternal effects, evidently stimulated by high-quality territories, have been shown to enhance competitive ability and therefore the likelihood that philopatric offspring will capitalize on the direct benefits of superior territories, previously shown to promote progeny growth rate and survival (most offspring do not disperse from their natal area). Paternity analysis within clutches co-sired by two males revealed that female preferences for large males were also adaptive in terms of indirect benefits. Females used sperm from large sires to produce sons and sperm from small sires to produce daughters. Differential allocation of resources and progeny sex was adaptive and demonstrates a high degree of female control in the mating system.

Self-recognition, color signals, and cycles of greenbeard mutualism and altruism

“…First, dyads lack consistency in location among years (n ϭ 15, 8, and 7 dyads in 1992, 1998, and 1999). Minimum distance between nearest dyads across years averaged 18.8 Ϯ 2.7 m. Second, manipulating a likely point of attraction, large rock piles (20,21), does not affect bb dyad formation. Half of the bb dyads formed Ͼ10 m away from piles (n ϭ 7 of 14), and 21 of 38 bb males settled Ͼ10 m from piles.…”

“…Such a relocation strategy is possible. Loner bb males can obtain a territory 2-3 weeks after most males (20,22) and do not lose fitness relative to loners that remain stationary [n ϭ 8 loners that moved (W S ϭ 2.33 Ϯ 0.91, W R ϭ 0.35 Ϯ 0.32) vs. n ϭ 54 that were stationary (W S ϭ 2.09 Ϯ 0.40, W R ϭ 0.20 Ϯ 0.14); W S : F 1,57 ϭ 0.22, P Ͼ 0.64, not significant; no year effect: F 1,57 ϭ 0.43, P Ͼ 0.72; W R : F 1,57 ϭ 0.06, P Ͼ 0.80, not significant; no year effect: F 1,57 ϭ 1.56, P Ͼ 0.20). Potential payoffs of defection would be more appropriately measured for bb males that abandon dyads; however, no bb males that have formed a dyad with a genetically similar male have ever been observed to move (0͞40) despite obvious fitness benefits that donors could obtain via defection.…”

Territory quality and male dominance in Tropidurus torquatus (Squamata, Tropiduridae)

“…Larger males have better territories and, perhaps as a consequence, exhibit better ability to hold harems. Indeed, female preference for larger males has been reported in various lizard species (Cooper and Vitt 1993, Wikelski et al 1996, Calsbeek and Sinervo 2002b, although there are also several lizard species where females' choice is not observed Madsen 1995, Hamilton andSullivan 2005). Female T. torquatus can be actually attracted by the high-quality territories that are secured by larger males (e.g.…”

“…Hews 1993, Calsbeek andSinervo 2002a), or may assess territory quality based directly on the morphometric parameters of a resident male, such as body size and head dimensions (e.g. Pough et al 1998, Calsbeek andSinervo 2002b). Large male lizards may own territories with enhanced prey density (Reaney and Whiting 2003), refuge density and opportunity for thermoregulation Sinervo 2002a, Calsbeek et al 2002).…”

“…This is important because the success of a male defending a high-quality territory does not necessarily indicate its genetic reproductive success. Multiple mating (LeBas 2001) and sperm competition (Olsson and Madsen 1998, Pough et al 1998, Calsbeek and Sinervo 2002b have been observed in several vertebrates.…”