Experimental manipulation of reproductive tactics in Seba’s short-tailed bats:consequences on sperm quality and oxidative status

To reproduce,males have to fertilize the female’s eggs,sometimes in competition with ejaculates of other males.In species where males display alternative reproductive tactics,whereby territorial males secure mating and non-territorial males have to sneak copulations,the latter might be expected to invest relatively more resources towards sperm quality compared with the territorial males.Sperm cells are especially vulnerable to oxidative stress,which reduces male fertility.Therefore,antioxidant resources are expected to modulate sperm quality,and might be allocated differently between reproductive tactics.To test the link between reproductive tactics,redox profile and sperm quality,we experimentally induced changes in the reproductive tactics of 39 captive males Seba's short-tailed bats Carollia perspicillata.We monitored the blood and ejaculate oxidative balance,and the sperm quality before,7 days and 21 days after the manipulation of reproductive tactic.Although ejaculates'oxidative damage was negatively related to sperm velocity,males exhibited similar blood and ejaculates redox profiles and similar sperm quality,regardless of their reproductive tactic.Possibly,these results arise as a consequence of some constraints having been lifted during the experiment.Our results also suggest that,in Seba's short-tailed bats,the expression of alternative reproductive tactics is not subjected to strong oxidative constraints.Furthermore,our results could reflect an absence of trade-off between pre-and post-copulatory traits in harem males,as they could be selected to invest both in female attraction and sperm quality,as a consequence of their inability to fully monopolize females.

Reproductive Behavior and Underwater Calls in the Emei Mustache Toad,Leptobrachium boringii

The Emei mustache toad, Leptobrachium boringii （Megophryidae）, is terrestrial but breeds in permanent streams. Primarily, it has a polygynous mating system and polyandry also occurs. The species vigorously defends submerged nest sites. We report on a reproductive study at Mt. Emei, western China conducted in 2004, 2006, 2007, 2009, and 2011 during the breeding season. Males produce both advertisement and courtship calls underwater, and the latter differs from the former in having an additional trill-like last note of low intensity. Females might determine the oviposition location and hence the egg mass location. A low, submissive posture can be adopted by the male to avoid being attacked by other males. When fighting, the maxillary nuptial spines are employed as weapons, and males hold their opponents on their spines with the forelimbs that enlarge during the breeding season. Male body size and the quantity of fight wounds on its ventral side are positively correlated. Satellite male mating might exist in L. boringii. Additionally, underwater calls from another population of this species and a population of L. leishanense generally are similar to those of the population from Mt. Emei.

Attacks on adult females with infants by non-resident males in the Franois langur

Infanticide by males is a common phenomenon in mammals, especially primates, as lactation lasts much longer than gestation in many species. Usually, infanticidal episodes occur soon after group takeovers, and are traditionally considered a male reproductive strategy （i.e., support the sexual selection hypothesis, Hrdy, 1974）. To verify the validity of this conception, we observed one group of Franqois＇ langurs in the Nonggang Nature Reserve, China, between August 2003 and July 2004. During the study period, a Francois＇ langur female with the youngest infant in the group was attacked three times by immigrating males, and later disappeared by the third day after the final attack. We suggest that these attacks on the female-infant dyad represent infanticide attempts by males, and may be the cause of the adult female and her infant＇s disappearance. Presumably, that female dispersed with her infant to avoid infanticide and was not killed. Though these observations do not completely verify the sexual selection hypothesis, they are not inconsistent with it.

Attacks on adult females with infants by non-resident males in the François langur

Infanticide by males is a common phenomenon in mammals,especially primates,as lactation lasts much longer than gestation in many species.Usually,infanticidal episodes occur soon after group takeovers,and are traditionally considered a male reproductive strategy(i.e.,support the sexual selection hypothesis,Hrdy,1974).To verify the validity of this conception,we observed one group of François’langurs in the Nonggang Nature Reserve,China,between August 2003 and July 2004.During the study period,a François’langur female with the youngest infant in the group was attacked three times by immigrating males,and later disappeared by the third day after the final attack.We suggest that these attacks on the female-infant dyad represent infanticide attempts by males,and may be the cause of the adult female and her infant’s disappearance.Presumably,that female dispersed with her infant to avoid infanticide and was not killed.Though these observations do not completely verify the sexual selection hypothesis,they are not inconsistent with it.

Reproductive biology of harvestmen(Arachnida:Opiliones):a review of a rapidly evolving research field

Harvestmen are a major arachnid order that has experienced a dramatic increase in biological knowledge in the 21st century.The publication of the book Harvestmen:The Biology of Opiliones in 2007 stimulated the development of many behavioral studies.Although the book is relatively recent,our understanding of the reproductive biology of harvestmen is already outdated due to the fast accumulation of new data.Our goal is to provide an updated review of the subject to serve as a benchmark for the following years.In the pre-copulatory phase,we explore the evolu-tion of facultative parthenogenesis,the factors that may affect the types of mating system,and the role of nuptial gifts in courtship.Regarding the copulatory phase,harvestmen are unique arachnids because they have aflagellate spermatozoa and a penis with complex morphology.We discuss the implications of these two features for sperm competition and cryptic female choice.In the post-copulatory phase,we connect ovi-position site selection and climate conditions to the widespread occurrence of resource defense polygyny,alternative reproductive tactics,and sexual dimorphism in several clades of tropical harvestmen.Finally,we present the different forms of parental care in the order,and discuss the benefits and costs of this behavior,which can be performed either by females or males.Throughout the review,we indicate gaps in our knowl-edge and subjects that deserve further studies.Hopefully,the information synthesized here will stimulate researchers worldwide to embrace harvestmen as a study system and to improve our effort to unravel the mysteries of their reproductive biology.

Age of maturation and behavioral tactics in male yellow ground squirrel Spermophilus fulvus during mating season

Life-history theory predicts that in hibemators age of maturation is related positively to body size and negatively to the duration of active season aboveground. Yellow souslik is a large-sized ground squirrel with long hibernation, which suggests late maturation. We used four-year field observations of marked individuals to determine the age of maturation in males through analysis of age-dependent variation in body size, mass, androgen status, timing of spring emergence, ranging patterns and social behavior during the mating season. Yearling males were smaller, lighter, had lower level of fecal testosterone, emerged later and had smaller home ranges than older males. Social activity and the number of females encountered did not differ between age classes. After the second hibernation none of the studied parameters varied with age. Cluster analysis revealed two behavioral tactics： ＂active＂ males （adults only） emerged earlier, ranged more widely, initiated more contacts, encountered more females and were heavier than ＂passive＂ males （both yearling and adult）. Thus, males of S. fulvus reached adult size and matured after two hibernations, which is relatively fast for such a big species with short active period. Indirect evidence for copulations and high variation among yearlings in all parameters suggest that some of them might successfully compete with adults. Active tactic of wandering and searching for females is energetically costly, and probably only adult males in good physical condition can afford it, whereas passive tactic of residing is energy saving and good for adults in poor condition and for yearlings that are continuing to grow.

Sperm traits differ between winged and wingless males of the ant Cardiocondyla obscurior

Size and shape of sperm cells vary tremendously throughout the animal kingdom.The adaptive significance of this variation is not fully understood.In addition to sperm-female interactions and the environmental condi­tions,the risk of sperm competition might affect number,morphology and other“quality”traits of sperm.In the male-diphenic ant Cardiocondyla obscurior,winged sneaker males have limited sperm number,because their testes degenerate shortly after adult emergence,as is typical for males of social Hymenoptera.In contrast,wing­less fighter males continuously replenish their sperm supply due to their exceptional lifelong spermatogene­sis.While winged males usually have to compete with several other winged males for virgin queens,wingless males are able to monopolize queens by killing all other rivals.Hence,this presents a unique system to inves­tigate how alternative reproductive tactics and associated physiology affect sperm morphology and viability.We found that sperm-limited males invest into sperm number instead of sperm size.Variance in sperm length is smaller in winged males,probably reflecting that they have to compete with several other males.Finally,sperm viability is equally high in both male phenotypes.