Color and behavior differently predict competitive outcomes for divergent stickleback color morphs

Abstract

Our knowledge of how male competition contributes to speciation is dominated by investigations of competition between within-species morphs or closely related species that differ in conspicuous traits expressed during the breeding season (e.g. color, song). In such studies, it is important to consider the manner in which putatively sexually selected traits influence the outcome of competitive interactions within and between types because these traits can communicate information about competitor quality and may not be utilized by homotypic and heterotypic receivers in the same way. We studied the roles of breeding color and aggressive behaviors in competition within and between two divergent threespine stickleback Gasterosteus aculeatus color types. Our previous work in this system showed that the switch from red to black breeding coloration is associated with changes in male competition biases. Here, we find that red and black males also use different currencies in competition. Winners of both color types performed more aggressive behaviors than losers, regardless of whether the competitor was of the same or opposite color type. But breeding color differently predicted competitive outcomes for red and black males. Males who were redder at the start of competition were more likely to win when paired with homotypic competitors and less likely to win when paired with heterotypic competitors. In contrast, black color, though expressed in the breeding season and condition dependent, was unrelated to competitive outcomes. Placing questions about the role of male competition in speciation in a sexual signal evolution framework may provide insight into the “why and how” of aggression biases and asymmetries in competitive ability between closely related morphs and species.

Predator‐induced maternal and paternal effects independently alter sexual selection

“…In sticklebacks, redder males are better able to defend territories (Bakker and Sevenster ; Tinghitella et al. ) and gain access to more concealed nesting sites (Kraak et al. ).…”

“…This finding is consistent with the predator risk allocation hypothesis when direct benefits of mating with more conspicuous males are especially high (e.g., Kim et al 2009). In sticklebacks, redder males are better able to defend territories (Bakker and Sevenster 1983;Tinghitella et al 2018) and gain access to more concealed nesting sites (Kraak et al 2000). Additionally, redder fathers confer an immunity advantage to offspring (Folstad et al 1994;Barber et al 2001).…”

Phenotypic divergence among threespine stickleback that differ in nuptial coloration

“…First, we selected red coloration using the Threshold Color plugin within FIJI, capturing all areas ranging from yellow to red to purple (Y = 32-255, U = 0-143, V = 141-255; following Wong et al, 2007 andTinghitella, Lehto, et al, 2018). To select black coloration, we converted the image to 8-bit grayscale and used the Threshold Color plugin (Y = 0-25, U = 0-255, V = 0-255), with which the entire area of the selected pixels was measured.…”

“…Recent work in red and black stickleback from Washington State similarly supports a role for sexual selection in the divergence of red and black stickleback, albeit through changes in male competition behavior, rather than female preferences (Tinghitella et al, 2015;Tinghitella, Lehto, et al, 2018). In simulated secondary contact in the laboratory, females from populations containing only red or only K E Y W O R D S color morph, Gasterosteus aculeatus, phenotypic divergence, threespine stickleback black males retain their ancestral preference for the red mating signal (McKinnon, 1995) and prefer to interact with red males (Tinghitella et al, 2015).…”

A unique neurogenomic state emerges after aggressive confrontations in males of the fishBetta splendens

“…Regarding the coloration changes, our initial analysis showed that both fighting opponents spent a considerable proportion of the initial 20 min of the fight (~70%) in changing their color patterns i.e., switching to a darker or lighter shade (S5 Table). Whereas coloration has important roles in the immune response, sexual discrimination, and fighting coordination in B. splendens (39), sticklebacks (40), and cichlids (41) at the behavioral level, the involvement of pigmentation-related genes in this study suggested the molecular basis for color signaling in territorial aggression.…”