Multiple paternity and mating patterns in the American alligator, Alligator mississippiensis

Abstract

Eggs were sampled from 22 wild American alligator nests from the Rockefeller Wildlife Refuge in south-west Louisiana, along with the females guarding the nests. Three nests were sampled in 1995 and 19 were sampled in 1997. Females and offspring from all clutches were genotyped using five polymorphic microsatellite loci and the three nests from 1995 were also genotyped using one allozyme locus. Genotypes of the hatchlings were consistent with the guarding females being the mothers of their respective clutches. Multiple paternity was found in seven of the 22 clutches with one being fathered by three males, and the remaining six clutches having genotypes consistent with two males per clutch. Paternal contributions of multiply sired clutches were skewed. Some males sired hatchlings of more than one of the 22 clutches either as one of two sires of a multiple paternity clutch, as the sole sire of two different clutches, or as the sole sire of one clutch and one of two sires of a multiply sired clutch. There was no significant difference between females that had multiple paternity clutches and those that had singly sired clutches with respect to female total length (P = 0.844) and clutch size (P = 0.861). Also, there was no significant correlation between genetic relatedness of nesting females and pairwise nest distances (r2 = 0.003, F1,208 = 0.623, P = 0.431), indicating that females in this sample that nested close to one another were no more related than any two nesting females chosen at random. Eleven mutations were detected among hatchlings at the five loci over the 22 clutches. Most of these mutations (eight of 11) occurred at Ami(mu)-17, the only compound microsatellite locus of the five used in this study, corresponding to a mutation rate of 1.7 x 10-3. Finally, most of the mutations (82%) were homoplasious, i.e., mutating to an allelic state already present in this Louisiana population.

The Australian saltwater crocodile (Crocodylus porosus) provides evidence that the capacitation of spermatozoa may extend beyond the mammalian lineage

“…Such findings are of interest as crocodilians can support prolonged periods of sperm storage within the female reproductive tract. Illustrative of this phenomenon, female caiman have been recorded to lay eggs containing a viable embryo greater than 12 months after isolation from a male [39], and multiple paternity has been shown to be a feature of annual egg clutches of both caiman [40] and American alligators [41,42]. These findings accord with the ovulatory strategy of the alligator whereby each ovary ovulates approximately 20 megalecithal eggs into the oviduct in quick succession [43].…”

The socio-sexual behaviour of extant archosaurs: implications for understanding dinosaur behaviour

“…Vliet (2001) (McIlhenny 1935) and multiple paternity has been well documented (e.g. Davis et al 2001). The modified dorsolateral posture has been reported in many other species (e.g.…”

Assessment of microsatellites in estimating inter- and intraspecific variation among Neotropical Crocodylus species

“…Because they are hypervariable and occur ubiquitously, microsatellites have widely been used as tools for a variety of fields of study such as population and conservation genetics, molecular ecology (mating behavior and gene flow), and wildlife DNA forensic analyses (Glenn et al, 1998;Fitzsimmons et al, 2001;Davis et al, 2001Davis et al, , 2002Dever et al, 2002;Avise, 2004;Anmarkrud et al, 2008).…”