Mating system and population analysis of the broad-snouted caiman (Caiman latirostris) using microsatellite markers

Abstract

The knowledge about reproductive strategies of a species contributes to their conservation. Multiple paternity is a reproductive behavior increasing effective population size, which could increase genetic diversity particularly in populations submitted to bottlenecks events. In Argentina, wild populations of Caiman latirostris are subject of a management plan devoted to their preservation and sustainable utilization based on its commercial interest. This program started in response to the evident numeric reduction of the populations, as a consequence of hunting pressure and habitat modification; it had a remarkable success in population recovery allowing the commercial use of C. latirostris. Data on reproductive behavior of C. latirostris are limited because mating occurs in the water and the information about their genetic diversity is scarce too. Our specific aims were to study the mating system and population genetic structure applying microsatellite markers in twelve C. latirostris families. The obtained results showed highly significant difference among populations and a lack of correspondence between geographical distance and genetic differentiation suggesting that populations of C. latirostris represent unstable metapopulations. In the paternity analysis was detected more than one father in two nests, which could be explained by capacity of storage sperm, proposed in females of a related species. The behavior of multipaternity could contribute to maintain viable populations of C. latirostris, since the maintenance of genetic variability within populations could help increase their capacity to respond to selective pressure. Further studies employing genetic and behavioral framework are needed to better understand the reproductive biology of C. latirostris.

How many fathers? Study design implications when inferring multiple paternity in crocodilians.

“…From Table 1, when the total number of alleles for each crocodilian parentage analysis study are tallied, the number of alleles varies from 24 (Amavet et al, 2012;Hu & Wu, 2010) to 91 alleles (Oliveira et al, 2014) with an average of 42 total alleles equivalent to the 5H panel used herein. Following from the findings in this study and given that nest assignment is possible in crocodilians if offspring are being sampled from eggs/embryos, when fewer alleles are available, using GERUD 2.0 or the SLMM is sufficient to accurately infer sire number.…”

“…Of the studies conducted since then, up to ten males have been inferred to sire captive saltwater crocodile (Crocodylus porosus ) nests (Lewis, FitzSimmons, Jamerlan, Buchan, & Grigg, 2013) although 1 -3 sires are most commonly reported (Table 1). Further, between 17% (Amavet, Vilardi, Rueda, Larriera & Saidman, 2012) and 100% (Milián-García et al, 2016) of nests have been shown to be multiply sired. Some studies have used a small subset of nests from only one nesting season (eg n = 4 nests from Amavet, Rosso, Markariani & Piña, 2008) whilst others have conducted longitudinal studies over multiple years (Lance et al, 2009) including up to 151 nests over six consecutive years (Zajdel et al, 2019).…”

Genital anatomy and copulatory interactions in the broad snouted Caiman (Caiman latirostris)

“…In A. mississippiensis , the vagina is surrounded by thick layers of smooth muscle (Gist, Bagwill, Lance, Sever, & Elsey, 2008); similar anatomy in C. latirostris would allow females to prevent fecal matter from entering the reproductive tract and also provide a method by which they can control whether cloacally placed semen or the male glans tip enters the vagina during copulation. There is evidence that female crocodylians are polygamous (Amavet, Vilardi, Rueda, Larriera, & Saidman, 2012; Davis, Glenn, Elsey, Dessauer, & Sawyer, 2001; Lewis, FitzSimmons, Jamerlan, Buchan, & Grigg, 2013; McVay et al, 2008; Oliveira, Marioni, Farias, & Hrbek, 2014) and can store sperm (Davenport, 1995; Gist et al, 2008). In the American alligator, stored sperm is found in oviductal glands rostral to the vagina (Gist et al, 2008); C. latirostris has similar oviduct anatomy (Galoppo et al, 2016) and is likely to store sperm in a similar fashion.…”

Phenotypic variability and heritability of the cephalic region ofCaiman latirostris

“…No. 3, 4, and 5 in Monteiro et al, 2002) The degree of relationship (r) among siblings was taken as r5 0.50 for all nests, as it was assumed that individuals were full siblings (see Amavet et al, 2009Amavet et al, , 2012. Heritability for each univariate character was calculated as h 2 5 t/r (Falconer and Mackay, 1996).…”