**4. Molecular genetic analysis of mating strategy**

### **4.1 Introduction**

As our understanding on mating systems increases, it becomes obvious that apparently species-specific mating behaviors often vary both between and within population [91]. Reproductive strategies are shaped by natural selection favoring individual with the greatest lifetime reproductive success. However, not all mature individuals adapt to the same reproductive strategies [69]. When competition for access to mates is severe, young reproductive individuals sometimes opt for alternative mating behaviors. Environmental or demographic factors may constrain the number of males that were able to employ the most successful strategy [92]. Alternative tactics in reproductive behavior enable individuals to maximize their fitness in relation to competitors of the same population. Among polygynous mammals, territorial behavior is almost exclusively a male trait believed to function primarily as a reproductive strategy to secure mates. Because mammals are committed to their progeny through gestation and lactation, female reproductive success usually is more readily quantified than male reproductive success. Male reproductive success in polygynous mammals is largely attributed to the spatial and temporal patterns of female aggregation [43, 44, 91].

Most known mating associations in bats are composed of a single male and several females and such organization are usually called harems [46]. *C. sphinx* is *Dispersal Patterns, Mating Strategy and Genetic Diversity in the Short Nosed Fruit Bat… DOI: http://dx.doi.org/10.5772/intechopen.100496*

known to exhibit polygynous mating system (that is, prolonged association of one male with more than one female) based on resource availability and such behavior is popularly known as resource defense polygyny [4]. Though, several studies have shown that the nonharem males also occupy the roots nearby harems most of the time [4, 8–10, 93]. Although, the role of nonharem males as probable fathers has not been studied well in *C. sphinx* population.

### **4.2 Materials and methods**

Bats were collected from the foliage tents of *P. Longifolia* (mast tree) and *B. labellifer* (palm tree) using a hoop net with an extensible aluminum pole. Bats were sampled over a period of four weeks immediately following each of four annual parturition periods: March–April (dry season) and July–August (wet season). A medical punch will be used for the excision of tissue (4 mm2 ) and care will be taken to place it in an area between the blood vessels to avoid injury (wing membranes healed within 3–4 weeks [93, 94]. After each sampling, the punched hole and the punch will be disinfected with 70% ethanol. No negative effects of this treatment on the health of the bats will be observed. It should also be noted that the bats frequently have natural injuries of this type in their wing membranes.

The collected blood samples will be immediately mixed with Anticoagulant Citrate Dextrose (ACD), transferred to microcentrifuge tubes and sealed with parafilm. The blood and tissue samples will be stored in ice, transported to the lab and stored at −20°C until DNA extraction [93, 94]. No bats will be killed or retained as specimens during this project. We will be following the Institutional Ethical and Bio-safety Committee Guidelines of Madurai Kamaraj University. PCR based RAPD strategy was used to study the paternity of harem males and nearby nonharem males to the young born in the harems.

### **4.3 Results and discussion**

During the wet (July–August) season, we captured 27 harem males, 30 nonharem males and 125 offsprings were analyzed to assign the reproductive success of harem and nonharem males. Out of the 125 offsprings the nonharem males sired 73 offsprings (average 58%) and the harem males sired only 52 offsprings (average 42%). During the dry (March–April) season 14 harem males, 18 nonharem males and 142 offsprings were captured and analyzed to assign the reproductive success of harem and nonharem males. Of the 142 offsprings the harem males sired 132 offsprings (average 94%) and the nonharem males sired only 10 offsprings (average 6%). From these results, we identified that the reproductive distribution is unequal between harem and nonharem males. It indicates that the harem males failed to control harem females thereby increasing the chances of nonharem males to fertilize some of the harem females. In addition, in southern India, during the dry season the spatial dispersion of female *C. sphinx* is highly clumped due to limited roosting sites and the harem male sires 96% of offspring conceived during this period [58]. In total contrast during the wet season, more roost sites are available and females are dispersed more widely. In this case, the harem male sired only 40% of offspring, while the other 60% offsprings were sired by other (solitary) males. The possible movement of females between harems was suggested as one of the reasons for this observation. Similarly, among the polygynous bats *A. jamaicensis* [59, 78], *P. hastatus* [20], *D. rotundus* [76] and *S. bilineata* [77, 95], incomplete monopolization of females by harem males has been observed. The harem males failed to control the harem females as result the increases the chances for nonharem males to fertilize some of the females.

The most commonly described mating system in bat species is polygyny, in which males defend a resource to recruit and have exclusive mating access with a large number of females. The resource may be a foraging area or a roosting site or the females themselves. However, several genetic analyses have shown that paternity is biased in polygynous mating systems. For e.g. a paternity study in *S. bilineata* demonstrated that 71% of offspring born into a harem are not sired by the resident harem male, but are instead fathered by non-territorial males [77, 95]. Similarly, in *P. hastatus*, harem male fathered 60–90% offspring [20], while the harem male in *D. rotundus* fathers approximately 45% of young [76] and the estimated paternity for dominant males of *A. jamaicensis* ranged from 33 to 83% [78].
