The mating patterns of females when territorial differences among males are reduced: A test in the polygynous beaugregory damselfish

Using the Caribbean beaugregory damselfish (Stegastes leucostictus) we test ed whether patterns of male reproduction could be modified by reducing diff erences among males, in this case by giving males identical artificial bree ding sites. Previous studies have shown that very few males using the natur al small rubble habitat reproduced and variations in male reproductive succ ess were based mainly on the differences in the quality of their natural br eeding sites. By providing males with identical artificial breeding sites, we tested whether females would be less likely to confine their reproductio n to only a few of the available males. We examined male reproductive patte rns by first simulating females choosing males (1) 'randomly,' (i.e. the nu mber of males that receive eggs is based on each female randomly choosing a mate from a group of males), or (2) 'exclusively' (i.e. only one female ma tes with one male on a given day), or (3) 'highly selectively' (i.e. this i s the typical polygynous pattern in which many females select the same few males). We tested these simulations against the actual daily amounts of egg s deposited and the number of different males that received eggs in each of 4 summers. Although the regression trend line from the daily patterns did resemble the Random Mating Pattern, egg clutches were more widely dispersed than random but less dispersed than the Exclusive Mating Pattern. That is, with more females mating on a particular day, more males received eggs. We speculated that this might have resulted from females aggressively excludi ng other females from mating with the same male on a given day. In contrast , males using the variable quality natural sites rarely mated and those tha t did receive eggs, received them in larger amounts than males using the ar tificial sites. Thus, for natural sites, more females seemed to be mating w ith the same few males. Perhaps for these natural sites any intra-female ag gression may have been ineffective when so few superior spawning sites were available. For males using the artificial sites, the total amount of eggs received over a two-month period was nonrandom and resembled the 'highly se lected pattern.' This resulted from some males receiving egg clutches on mo re days. Other traits, besides breeding site structure, may have been impor tant in causing different females to select the same males on subsequent da ys.