How to maintain underground social relationships? Chemosensory sex, partner and self recognition in a fossorial amphisbaenian

Abstract

Maintaining social relationships depends on the ability to recognize partners or group members against other individuals. This is especially important in animals with relatively stable social groups. The amphisbaenian Trogonophis wiegmanni is a semi blind fossorial reptile that spends its entire life underground where it interacts with mates and social partners. In this environment, visual cues are limited. Chemosensory cues may rather allow conspecific social and partner recognition. We recorded the number of tongue-flick (TF) rates of T. wiegmanni amphisbaenians to scents of both sexes with different pairing social bonds (familiar vs. unfamiliar) presented on cotton swabs to test discrimination of social groups. As seen from a rise in the number of TFs, males discriminated unfamiliar females from unfamiliar males. This suggests that chemical cues may be used by males to locate new mates. In contrast, females detected scent of unfamiliar conspecifics, but did not show sex discrimination. Both males and females discriminated the scent of an individual with which they had formed a pair bond from an unfamiliar individual of the same sex as the partner. Also, males, but not females, were capable of self-recognition, suggesting that scent marks of males in home ranges may provide individual information in intrasexual relationships. We conclude that conspecific discrimination based on chemical cues may allow the maintenance of social relationships and relatively stable pairs in fossorial reptiles inhabiting visually restricted environments.

A new tale of lost tails: Correlates of tail breakage in the worm lizard Amphisbaena vermicularis

“…For example, sexual differences may arise because of behavioral differences between males and females (Papenfuss, 1982). Despite the lack of empirical evidence of male–male competition in amphisbaenians, experiments show that males respond aggressively to scents of conspecific males (López & Martín, 2009; Martín et al, 2020). Thus, sexually dimorphic species where males are larger than females (e.g., Gomes et al 2009; Souza e Lima et al 2014) could indicate male–male competition, ultimately leading to tail breakage.…”

Offspring and adult chemosensory recognition by an amphisbaenian reptile may allow maintaining familiar links in the fossorial environment

“…Similarly, in some lizards and other amphisbaenians, males have a higher number, diversity and interindividual variability of lipophilic compounds in femoral or precloacal secretions than females ( García-Roa et al, 2016 ; Martín & López, 2006). Nevertheless, in T. wiegmanni , both male and female adults are capable of discriminating between cloacal scent of familiar and unfamiliar partners ( Martín et al, 2020 ), suggesting that interindividual chemical signatures are different enough as to allow discrimination, at least after some learning. There may be stronger selection for juveniles to recognize different individual males because the male found in a group might or might not be the father of the juvenile.…”

“…The existence of a correlation between elevated TF rates and vomeronasal organ use, and the necessity of an intact vomeronasal system for normal TF responses to scents have been experimentally tested ( Graves & Halpern, 1990 ; Halpern, 1992 ). It is assumed that an increase in TF rates in response to a scent stimulus, with respect to the basal TF rates, indicates detection of that scent, and that differential TF rates to different chemical stimuli indicate discrimination of the different stimuli ( Cooper & Burghardt, 1990 ; Cooper, 1994 ; Cooper, 1998 ; Martín et al, 2020 ). We compared TF rates of amphisbaenians in response to scents of different types of conspecifics and we also measured responses to distilled water as an inodorous scent control to gauge baseline TF rates in the experimental setup ( Cooper & Burghardt, 1990 ).…”

“…The amphisbaenian Blanus cinereus uses chemical cues in conspecific and sex discrimination and in self-recognition ( Cooper, López & Salvador, 1994 ; López, Cooper & Salvador, 1997 ; López & Martín, 2009 ), and this species is thought to be able to scent-mark and identify its own home range ( López, Martín & Barbosa, 2000 ). Similarly, both male and female adult T. wiegmanni can discriminate the scent of an adult individual with which they had formed a pair bond from an unfamiliar individual of the same sex as the partner, and males, but not females, have self-recognition abilities ( Martín et al, 2020 ). We hypothesized that similar chemosensory abilities could allow the unexplored possibility of kin-recognition, and, therefore, that conspecific chemical cues may be very important in the formation and maintenance of stable family groups in fossorial animals.…”

Going underground: short- and long-term movements may reveal the fossorial spatial ecology of an amphisbaenian

“…Similarly to other amphisbaenians, it spends all of its life underground, which likely explains the lack of information available for its movement ecology. However, there is increasing knowledge on its habitat selection patterns [ 30 , 31 ], thermal biology [ 32 , 33 ], feeding ecology [ 23 , 34 – 36 ], reproduction [ 34 ], population and social biology [ 37 – 40 ] and conservation problems [ 41 – 43 ].…”