Does the Refuge Availability Influence the Spawning Behavior of Mature Male Parr in Salmonids? A Test in the Miyabe Charr

In many salmon and charr, both 'migratory males' and 'precocious males' are maintained as alternative life-histories within a population. During breeding, precocious males gather around the mating pair of migratory fish and attempt to sneak in the spawning between larger male and female charr. Refuges such as debris and shallow areas may provide shelter from aggressive attacks and allow precocious males to hold positions closer to the pair (nest) and/or sneak more easily during the mating. Here we examine whether the availability of refuges influences the breeding behavior of precocious male parr of the Miyabe charr under experimental and natural conditions. Aggressive attacks directed toward precocious parr by the mating pair or other parr was not influenced by the refuge availability either under experimental conditions or in the wild. We did not find the effect of high refuge availability on the proximity of parr to the nest beyond the experimental conditions where the density of refuges was probably higher than in the natural stream. There were no effects of high refuge availability either on parr's attempts at sneak mating or on their success in spawning. Thus, our results provide little evidence that the refuge availability influences parr sneaking behavior. Other possible effects of high refuge availability, for example, the increase of fertilization success and the decrease of energy expenditure and risk taking, remain to be considered.     

Territorial male gobies respond aggressively to sneakers but do not adjust their sperm expenditure

We investigated whether mating behavior (sperm expenditure,courtship rate, and nest guarding) varied according to differentlevels of sperm competition in territorial males of two gobyspecies, the grass and the black gobies. We measured sperm expenditure(sperm released after 30 min from the beginning of the spawning),male courtship rate, and nest-guarding behavior in territorialmales of both species during simulated spawnings, in which wevaried the number of attending sneakers. Our results showedthat, in both species, territorial males adjusted their effortin nest guarding to the presence of rival sneakers by increasingthe time spent patrolling the territory and attacking the sneakers.In contrast, sperm expenditure and male courtship rate werenot influenced by the number of attending sneakers. These resultsare in agreement with those reported for other fish with alternativemating tactics and help to interpret previous inconsistenciesbetween theoretical predictions and measured levels of spermreleased at different levels of sperm competition by sneakersof the two gobiids studied here.     

Competition from large males and the alternative mating tactics of small males of dawson’s burrowing bee (Amegilla dawsoni) (apidae, apinae, anthophorini)

Males of Dawson’s burrowing bees (Amegilla dawsoni) search for virgin females at three locations: (1) open clay patches where females are emerging from underground brood cells, (2) the vegetated peripheral zone adjacent to emergence areas (through which females pass after emerging), and (3) clusters of flowering plants, which are often some distance from emergence areas. Males of Dawson’s burrowing bees exhibit a size dimorphism with large major and small minors. Major males patrol only the open emergence sites, whereas minor males may be found in all three locations. Although most females are mounted and presumably mated immediately upon emergence, some are not, and these females make up a pool of potential mates for the small males patrolling the peripheral zone and flower patches. The density of males at emergence sites and the probability of male-male aggression change over the course of a day and over the entire flight season. When the level of competition is low, some minor males hunt for mates at emergence areas, where potential mates are relatively numerous. But when the presence of many large rivals makes it unlikely that a small male can avoid being displaced from emerging females, minors make the best of a bad job by shifting to areas where majors are absent.     

Male mating strategies and the mating system of great-tailed grackles

Great-tailed grackles (Quiscalus mexicanus) are sexually dimorphic,dichromatic, colonially nesting blackbirds. In this study, males pursued three basic types of conditional mating strategies,each of which employed a different set of mating tactics. Territorialmales defended one or more trees in which several females nested.They achieved reproductive success by siring the offspringof their social mates and through extrapair fertilization.Resident males lived in the colony but did not defend territoriesor have social mates. Transient males passed through the colony, staying no more than a few days, and probably visited more thanone colony. Residents appeared to queue for access to territories,but transients did not. Residents and transients gained allpaternity through extrapair fertilizations and provided noparental care. Territorial males sired the majority of offspring,but residents and transients also sired small numbers of nestlings. Territorial males were larger and had longer tails than nonterritorialmales. The number of social mates was related to body size,and males that sired nestlings were heavier and had longertails than males with no genetic reproductive success. Malesthat gained paternity through extrapair fertilization wereheavier and had longer tails than males that did not. The matingsystem of great-tailed grackles can best be categorized as "non-faithful-female frank polygyny."     

Promiscuity, paternity and personality in the great tit

Understanding causes of variation in promiscuity within populations remain a major challenge. While most studies have focused on quantifying fitness costs and benefits of promiscuous behaviour, an alternative possibility--that variation in promiscuity within populations is maintained because of linkage with other traits-has received little attention. Here, we examine whether promiscuity in male and female great tits (Parus major)--quantified as extra-pair paternity (EPP) within and between nests--is associated with variation in a well-documented personality trait: exploration behaviour in a novel environment. Exploration behaviour has been shown to correlate with activity levels, risk-taking and boldness, and these are behaviours that may plausibly influence EPP. Exploration behaviour correlated positively with paternity gained outside the social pair among males in our population, but there was also a negative correlation with paternity in the social nest. Hence, while variation in male personality predicted the relative importance of paternity gain within and outside the pair bond, total paternity gained was unrelated to exploration behaviour. We found evidence that males paired with bold females were more likely to sire extra-pair young. Our data thus demonstrate a link between personality and promiscuity, with no net effects on reproductive success, suggesting personality-dependent mating tactics, in contrast with traditional adaptive explanations for promiscuity.     

The rate of fertilization in male mating tactics of the polygynous grey seal

Studies using molecular markers have shown that some grey seal males may be gaining success through exhibiting alternative mating tactics. We estimated the probability of fertilization success of grey seal males exhibiting the primary tactic of female defence and one alternative tactic of mating with departing females on Sable Island, Nova Scotia, Canada, during the breeding seasons of 1997-2002. Although the fertilization rate of the primary tactic (27-43%) was greater than that of the alternative tactic (10-12%), these low rates indicate the potential fitness value of alternative mating tactics in this size-dimorphic pinniped species.     

Ephemeral lekking behavior in the buff-breasted sandpiper, Tryngites subruficollis

We studied male reproductive behavior of the buff-breasted sandpiperTryngites subruficoills for three yean on a 16-km² study sitein northern Alaska to document variation in male lekking behaviorand to explore the causes of that variation. During the breedingseason, about 75% of males on the study area displayed on leks,with the remainder displaying solitarily. Leks averaged between2.3 and 3.0 males each (maximum size = 20). Most leks (69%)were present in only one year and about one-tenth were activeall three years. Half of the leks were active for only one survey(maximum of 3-4 days) in a given year. Individual male behaviorvaried substantially, from remaining at a tingle lek for mostof the breeding season or attending multiple leks during theseason, to displaying solitarily or displaying both on leksand solitarily. Some males (30% or fewer) displayed near nestsduring the later part of the breeding season, perhaps attemptingto copulate with females during egg-laying. The pro-portionof males that displayed on leks remained consistently high throughoutthe breeding season despite changes in the operational sex ratioand in the intensity of male-male competition. However, theabsolute number of males (lekking and solitary) in the studyarea was positively correlated with the number of fertile femalesduring both breeding seasons. We suggest that buff-breastedsandpipers may be unusual among lek-breeding birds in that maleshave the option of leaving areas when the number of fertilefemales becomes depressed and flying to new areas where breedingopportunities are still available. Breeding opportunities maybe especially variable in the high arctic because of unevensnow accumulation and differential melt-off that can delay breedingby two or more weeks. This interpretation suggests that themating system of the buff-breasted sandpiper must be viewedat a much larger scale than what has typically been used inmating system studies     

Male pioneering as a mating strategy: the case of the beetle Maladera matrida

1. The phenomenon of male pioneering, whereby males are active (daily) before females, is compared with protandry, a phenomenon whereby males are sexually matured before females. The effects of natural selection and sexual selection on both phenomena are discussed. 2. In Maladera matrida Argaman (Coleoptera: Scarabaeidae), males emerged from the soil a few minutes before females, every evening, to feed and mate. 3. Aggregations of males and females are formed at sites of plant damage where males initiated feeding. 4. All copulations were initiated at the beginning of the activity period so males that emerge earlier may increase their probability of finding a mate. 5. Females mate only once in an evening. 6. Males that emerge later may not find receptive females with which to mate. 7. The aggregation of beetles per se did not contribute to the individual mating success because it occurred during and after the copulating had begun. 8. Male pioneering may evolve through sexual selection by means of male–male competition in time to achieve receptive females.