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Dark Jaguar · 06-06-2020, 03:05 AM

Misterious and Intriguing Infanticide case and study of Cerrado Jaguars.

https://www.scielo.br/pdf/gmb/v29n4/32128.pdf

ENP = Parque Nacional das Emas - PNE ( Rhea's National Park )

Abstract

We used micro-satellite loci to test the paternity of two male Cerrado Jaguars involved in an infanticide event recorded during a long term monitoring program of this species. Seven micro-satellite primers originally developed for domestic cats and previously selected for the Panthera Onca were used. In order to deal with uncertainty in the mother’s genotypes for some of the loci, 10000 values of W were derived by simulation procedures. The male that killed the two cubs was assigned as the true sire. Although the reasons for this behavior remain obscure, it shows, in principle, a low recognition of paternity and kinship in the species. Since the two cubs were not very young, one possibility is that the adult male did not recognize the cubs and killed them for simple territorial reasons. Thus, ecological stress in this local population becomes a very plausible explanation for this infanticide, without further socio biological implications.

Key words: ecological stress, infanticide, Jaguar, microsatellites, paternity.Received: May 24, 2005; Accepted: April 10, 2006.

Cerrado jaguar being collared. credits: Leandro Silveira

*This image is copyright of its original author

Introduction

Recent developments in molecular analyses have allowed the integration of genetics and ecology to elucidate complex ecological and behavioral phenomena at the population level, in the new field now called ‘molecular ecology’ (Beebee and Rowe, 2004). Molecular data have been used to discern overall patterns in population structure and to estimate demographic parameters, such as dispersion rates and inbreeding levels, making also possible a detailed analysis of some behavioral issues, such as mating systems and parentage (Frankhamet al., 2003). In Emas National Park ( ENP (PNE) Cerrado, in Goiás State, Central Brazil ) in November 2001 two Cerrado Jaguars (Panthera onca) cubs, presumably nine months old, were killed and partially eaten by a 90 kg adult male jaguar, estimated to be eight years old. The two cubs were also radio-tracked since they were three months old and were definitely brother and sister. The identity of the killer was also conclusively identified through its radio-telemetry monitoring. This large male was being radio-tracked and his home range overlapped by 85% for a long time with the home-range of the cubs’ mother and showed similar movements in time andspace. During several days before the infanticide, the killer tracked movements of the female and the two cubs, which had been shifting their home ranges. Because of the large overlap of home ranges in space and time, this male was presumably the sire of the two cubs. This infanticide event was monitored by two of us (LS and ATAJ), during a long term monitoring program of Cerrado Jaguars in ENP.

However, in a subsequent capture event within the female’s (mother) home range area, a previously unrecorded 105 kg adult male was caught and radio-collared. According to preliminary capture-recapture data, the population of Panthera onca in ENP is estimated as comprising about 15 specimens (Silveira, 2004). Finding another male overlapping the female’s home range suggests that the observed infanticide could involve more complex socio biological issues and introduce some uncertain in the paternity of thetwo killed cubs.

Since another male was found in the female’s home range, the basic question becomes: who was the sire of thetwo cubs killed by the first captured male? We used micro-satellite loci to test the paternity of the two Cerrado male jaguars involved in the scenario described above and in this paper we discuss our results and the alternative socio biological and ecological questions involved in the infanticide. To our knowledge, this is the first application of molecular data to address a behavioral ecology question in jaguars.

Material and Methods

Blood samples were obtained from the four jaguars involved in the case described above ( the two cubs (C01and C02) and the two adult males (M01 the killer and M02 the second male found in the area ). No blood sample was available from the cub’s mother.

Note: After that they do a study and paternity test to figure out who the father of the murdered cubs is, check the link above to see the study in details.

Discussion

The paternity test and the ecological scenario. The paternity test performed here strongly indicated that the M01 male that was being radio-tracked and had followed and killed the two sister cubs was actually their sire. We cannot be absolutely certain that the M01 male, and not a close relative, was the true sire of the two cubs. However our field observations and overall knowledge of jaguar ecology suggest a very low jaguar population density in this region ( Silveira, 2004 ), so there would be a very limited number of males close to this female and her cubs.

Indeed, finding the M02 male in the area was the very motive that triggered the paternity investigation presented here. If the M02 male had been assigned as the true sire ofthe two killed cubs, the scenario would be in principle a classical socio biological event in which a new male (in this case the M01 male) entering the area would try to kill the two cubs in order to release their mother for mating. However at approximately 75 days of age, jaguar cubs begin taking solid meat, with suckling lasting for only about five months. Thus it is possible that females resume cycling 2-3 weeks after lactational anestrus, as reported for the domestic cat (Oliveira, 1994). In addition, jaguars are not seasonal breeders (Morato et al., 2004) and thus quickly return to cycling after lactational anestrus.

In this way it is possible that the mother had been free to mate for at least four months before the infanticide, which could help to exclude this first scenario. More importantly since the genetic analyses showed that the M01 male ( the killer ) was the true sire with a very high probability, more complex socio biological and ecological conditions for the event must be considered. It is important to note that telemetry data revealed that the M01 male did not simply find the cubs, kill and eat them but that it followed the mother and the cubs for a few days before the infanticide. The reasons for this behavior remain obscure but may reflect a low recognition of paternity and kinship in the species, although previous papers have proposed that shifts in the home ranges of females ( and associated cubs ) may be a strategy to avoid infanticide in mammalia Carnivora (see Dahle and Swenson, 2003). Since the two cubs were not very young when they were killed, this could represent a competition issue, in that the adult male did not recognize the cubs as his offspring and killed them for simple territorial reasons when under ecological stress.

Although ENP (Parque Nacional das Emas - PNE) is a relatively large national park (132,000 hectares) only about 40% of this area includes very suitable jaguar habitat and therefore competition among individuals for food and mates may be higher than observed in a large, continuous and well preserved population ( Silveira, 2004 ). Maximum jaguar home ranges can be very large in some instances, up to 18,000 hectares (Keltand Van Vuren, 2001; Diniz-Filhoet al., 2005), so that only 2 or 3 males would be found in the area with minimum home range overlap. This is a little higher than our findings using preliminary capture-recapture data using camera traps (see Silveira et al., 2003), which suggested a total population of 10-12 cerrado jaguars (about half of these would be males) in the ENP region and surroundings ( Silveira,2004 ). Population density in the ENP would be thus a little higher than expected. Another factor is that the region surrounding the park is highly fragmented and occupied by large soy bean plantations, which probably limit jaguar dispersion and migration. Thus, ecological stress becomes a plausible explanation for this infanticide, without further complex socio biological implications (Sandell, 1989). It is also interesting to note that this scenario would lead to high levels of inbreeding, that still need to be investigated in this particular population. However, a first insight towards sup-porting relatively high levels of inbreeding in this particular population would start by noticing that one of the individuals genotyped, the excluded parent M02, is homozygous for six out of the seven loci analyzed here.

Infanticides, including those committed by females, are not rare in mammals (Hausfater and Hardy, 1984;Tuomiet al., 1997; Ebensperger, 1998; Dobsonet al.,2000), with non-parental infanticide having usually been considered to be an adaptive behavioral strategy to enhance the reproductive success of the aggressor (Agrellet al.,1998). In some circumstances, infanticide can become an evolutionary stable strategy (ESS; Tuomiet al., 1997;Ebensperger, 1998). Although parental infanticide is usually expected to reduce individual fitness, it is important to consider that other complex ecological and demographic components may be associated with this behavior (Puseyand Packer, 1994; Wolff, 1997; Wolff and Peterson, 1998;Whitmanet al., 2004). Due to their carnivorous habits and because most species bear altricial young, carnivores are more likely toexhibit infanticide than any other mammalian order. However, the reasons that lead to infanticide are still fairly unclear for most species (see reviews by Hausfater and Hardy,1984; Tuomiet al., 1997). Although infanticide has been recorded for almost all large cats from the Panthera group, distinct socio biological interpretations are discussed for these species (see Davies and Boersma, 1984; Bailey,1993; Smith, 1993). Besides an expected natural rate of infanticide among wild populations, it is also expected that stressful environmental conditions may favor abnormal infanticide rates in solitary carnivores (Sandell, 1989) and infanticide is sometimes considered to be part of the mammalian population regulation process (Wolff, 1997). In the case of Emas National Park presented here, we are more prone to believe that the isolation of the local cerrado jaguar population may be leading to stress-based infanticide behavior among male cerrado jaguars that are disputing the few available females.

Methodological issues

With respect to methodological issues, the analyses performed using simulation procedures were intended toe valuate how the uncertainty in mother genotypes (for four out of the seven loci used) and allele frequencies could qualitatively affect decisions about paternity.

The uncertainty about the genotype of the mothercould introduce a problem, since one of the possible genotypes, for the C01 cub, would also exclude the paternity of the M01 male. Because frequencies of all four possible genotypes are very low in the data of Eiziriket al. (2001) we assumed that the probability of this excluding genotype would be 0.25. However, under Bayesian reasoning this high probability is only the ‘a priori’ probability and it isalso necessary to take into account previous results using the three loci for which genotype of the mother is known for sure, which means that the a posteriori probability of hav-ing these genotypes is much less than 0.01.

The other main source of error in our analyses is the lack of knowledge of allele frequencies in the studied population. We used as initial values of allele frequencies for stochastic simulations the overall data for 44 individuals distributed throughout the range of the species. It would also be possible to restrict allele frequency estimates to the 17 jaguars from the South America and southern region inrelation to the Amazon River (the southern clade) describedby Eiziriket al. (2001), but this would reduce the sample size a lot. Anyway, the FST values estimated for micro-satellites by Eiziriket al. (2001) were always smaller than0.085 (although a significant phylogeographic structure was detected using mt DNA sequences). Also, although the 20% error assumed for allele frequencies in the simulations was arbitrary, our results with higher error values of up to 50% (not shown) did not qualitatively change the main conclusions, with median paternity indexes always higher than 99%.

Thus, by considering these three main methodologi-cal points, there is a high probability that the M01 male wasthe sire of the two killed cubs, and this conclusion is not qualitatively affected by uncertainties in the data. The socio biological and ecological conditions that triggered this infanticide remain unclear, but our analyses show that under the conditions prevalent in the Emas National Parkeven the probable sire of a cub can become that cubs killer,with obvious consequences for the maintenance and conservation of the Cerrado Jaguar populations in the area. In a more general sense, our analyses demonstrate the use of statistical approaches to assess and improve the power of molecular methods in behavioral studies in cases when uncertainties are present in the data set.

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