Affiliation in the social interactions in captivity of the torch tail rat, Trinomys yonenagae (Rodentia: Echimyidae)

Abstract

In a previous paper, we measured the affiliation between male individuals of Trinomys yonenagae and concluded that the intensity of affiliation was high and did not differ between animals from the same social group and from different social groups. In this paper, we report the results obtained with the same experimental procedure with female individuals. We also discuss sexual differences in the social interaction of this species. The experimental procedure was based on 40-min encounters between residents, which remained alone in an arena for 24 h, and introduced intruders, in a round-robin design. We quantified one variable indicative of activity level (number of squares crossed), one indicative of anxiety (time in marginal squares), three indicative of affiliation (number of physical contacts, mean distance between rodents, and total duration of physical contact), and the number of sound emissions. No aggressive behaviors were exhibited. The results indicate that there is a high level of affiliation mediated by acoustic communication both for males and females and that no anxiety is associated with social context, especially in females. The evolution of sociality in T. yonenagae was probably linked to an increase of tolerance especially among adult females. We also suggest that predation was a stronger selective pressure than resource availability in the evolution of sociality in this species.

Stability and acceleration of phenotypic evolution in spiny rats (Trinomys, Echimyidae) across different environments

“…In contrast, T. yonenagae is endemic to a desert‐like region with patchy vegetation lacking a conspicuous herbaceous or arboreal layer, with almost 50% of the ground with exposed sand, where this species is the only mammal so far recorded (Pessôa, Von Zuben & dos Reis, ; Rocha, Queiroz & Pirani, ; Santos & Lacey, ). The level of ecological disparity with respect to the Atlantic Forest and the rate of overall phenotypic change ( Δ′ ) were consistently higher in T. yonenagae than in T. albispinus , in agreement with the former's remarkable morphological, behavioural and physiological specialization to a desert‐like environment (Rocha, ; Barros et al ., ; Marcomini & Oliveira, ; Freitas et al ., ; Santos & Lacey, ). The morphology of the mandible of T. yonenagae was also very different from its closely related species (Monteiro & dos Reis, ), further suggesting an evolutionary acceleration of phenotypic change associated with habitat constraints.…”

Comportamento e dinâmica social de duas espécies de ratos-de-espinho em cativeiro sob a visão das redes sociais

“…O que teria acontecido se tivessem permanecido mais do que 40 minutos juntos? Após esse tempo de oportunidade de interação social, os animais voltavam para suas caixas solitárias (DE FREITAS et al, 2010;FREITAS;EL-HANI;DA ROCHA, 2008;RIOS, 2009;SALDANHA FILHO, 2008). Esses estudos, contudo, embora sugerirem o valor do conhecimento de T. setosus para a compreensão da evolução dos padrões comportamentais do grupo, ou ao menos na especialização da espécie da Caatinga, pouco esclarecem sobre a socialidade de T. setosus e nos permite questionar: como a espécie se organiza socialmente -de forma hierárquica ou socialmente flexível?…”

O espaço subterrâneo do rato-de-espinho Clyomys bishopi: caracterização e previsões possí­veis sobre sua biologia comportamental

“…Na família Echimyidae, além dos Clyomys, há espécies de nível de socialidade mais alto, como Trinomys yonenagae (Luchesi, 2010;Manaf & Spinelli Oliveira, 2000;Rocha, 1995), um rato-de-espinho endêmico da Caatinga, de hábitos semifossoriais, e T. setosus, um rato-de-espinho cursorial, de mata atlântica (Cantano, 2018;Freitas, El-hani, & Rocha, 2003;Freitas et al, 2008;Freitas, Silva Carvalho, El-Hani, & Rocha, 2010).…”

“…yonenagae cuja fossorialidade e alto nível de socialidade têm sido consideradas adaptações à vida no ambiente árido (Freitas et al, 2003(Freitas et al, , 2008(Freitas et al, , 2010Rocha, Renous, Abourachid, & Höfling, 2007). Essa espécie foi considerada a de maior índice de afiliação, entre outras três (Freitas et al, 2008), e compartilha com C. bishopi a vida fossorial e o ambiente seco.…”