Resumen

AGUILERA-MILLER, Eduardo Felipe. Ethology may be related to the genetic structure of a population: Chaetodipus siccus as a study case. Therya [online]. 2016, vol.7, n.3, pp.371-392. ISSN 2007-3364.  https://doi.org/10.12933/therya-16-391.

Philopatry is a biological trait observed in a wide variety of zoological taxa. It is considered as the basis of social behavior in rodents as well as a driver of spatial distribution of individuals. Females are typically philopatric, whereby they have access to resources to breed their offspring. This philopatric tendency is partly responsible for the genetic structuring in the natural populations of mammals. Heteromyid rodents conform complex communities and the agonistic interactions among them are common. Aggressiveness is the way to establish dominance hierarchies. By setting a hierarchy, dominant individuals have priority access to critical resources. Chaetodipus siccus is an heteromyid endemic to the Baja California peninsula, distributed across an area of ~270 km2, where a particular pattern of high variation of matrilineal lineages has been observed. The presence of multiple spatially segregated matrilineal lineages has been proposed, reinforced by the aggressive nature of the species, which leads to limited panmixia within the range of C. siccus. To test this hypothesis, a statistically parsimonious haplotype network study was conducted using matrilineal markers and behavioral experiments of intra- and interspecific dominance. Thirty four localities were surveyed throughout the C. siccus distribution range to capture specimens (n = 143) for the statistically parsimonious network. Muscle tissue was used for DNA extraction, and fragments of Cytb and COI genes were sequenced. To study intraspecific and interspecific dominance, ethological experiments were conducted between females under different conditions. For this purpose, 52 adult females of C. siccus and five adult females of C. arenarius, C. ammophilus, C. spinatus and C. rudinoris were captured alive and maintained in captivity. Encounters took place inside neutral arenas every other night. Individuals were housed individually in social cages. Fifty three haplotypes of Cytb and 15 of COI were identified from 143 C. siccus individuals. A high variety of private haplotypes was observed (31 for Cytb and 5 for COI). The presence of a dominant individual over another was observed in all conditions in the intraspecific and interspecific dominance experiments. Dominant females were statistically more aggressive than subordinate females (p < 0.001), and C. siccus dominated over the other species. A marked genetic structure was observed, with a considerable presence of private haplotypes. It is considered that genetic structure occurs when subpopulations are at least partially isolated from each other. There are no appreciable physical barriers within the distribution range of the species. For this reason, it is suggested that ethological interactions rather than geographical features may limit gene flow within the population of C. siccus. Structures with an unusual number of haplotypes in small geographical areas, as in C. siccus, have been previously recognized for other mammal species. It is argued that this pattern is the result of a philopatric character of females; this behavior restricts gene flow between areas. The existence of several geographically restricted matrilineal lineages suggests that females do not disperse, but remain within a very small geographic area. This points directly to the presence of philopatry in females. Agonistic behaviors are the means through which an individual maintains its hierarchy over others, defining its preferential access to resources. it's the extremely aggressive nature and a territorial behavior of females of C. siccus have resulted in the segregation of matrilineal lineages.

Palabras llave : agonistic encounters; gene flow; Heteromyidae; hierarchies of dominance; matrilines.

        · resumen en Español     · texto en Español     · Español ( pdf )