Does sensory expansion benefit asexual species? An olfactory discrimination test in Amazon mollies

Abstract

Why are asexual vertebrates so rare? One seldom explored avenue to understanding the evolutionary persistence of extant asexual species is their sensory ecology-how they perceive and respond to the environment. Asexual species formed by hybridization have been hypothesized to have an expanded sensory repertoire because they carry 1 allele from each of their parental species, including alleles that impact sensory function. The ability to detect odorants in the environment is a likely candidate for this expansion but has never been explored in this context. Here, we explore the olfactory abilities of the asexual Amazon molly, a gynogenetic fish formed by hybridization 100 000 years ago. We test whether Amazon mollies can use only olfactory cues to detect conspecifics, detect heterospecific males, and discriminate between males infected with a common parasite. We further explore whether a female's size, a proxy for age, explains any variation in her behavior. We find strong evidence that Amazon mollies use olfactory cues to detect conspecifics but surprisingly may avoid heterospecific males based on olfactory cues alone. We find no evidence that females use chemical cues to discriminate between infected and noninfected males. We also find that smaller Amazon mollies are more likely to use chemical cues. This study highlights the potential importance of sensory systems in asexual vertebrates.

Kin Recognition in a Clonal Fish, Poecilia formosa

“…Female activity, however, was higher when chemical cues were present, and they entered the preference zones that included the clonal sisters more often ( F 1,17 = 8.285, p = 0.010). Although it is known that Amazons prefer conspecific females when compared to their heterospecific host even when chemical only cues are present [ 30 ], here we show that their discriminatory abilities are even more precise than previously thought. In addition, we found no difference in the strength of kin recognition in the presence of unimodal and bimodal cues ( F 1,70 = 1.256, p = 0.266), suggesting that discrimination is not improved using more than one sensory channel.…”

“…Additionally, Amazon mollies show considerable individual variation in behaviors (i.e., preferences, aggression, etc.) [ 24 , 30 – 31 ] within and among clonal lineages, suggesting that after establishing kin recognition in multiple lineages, the use of a single lineage to further explore kin recognition within this species is sufficient.…”

Kin Recognition in a Clonal Fish,Poecilia Formosa

“…Female activity, however, was higher when chemical cues were present, and they entered the preference zones that included the clonal sisters more often (F 1,17 =8.285, p=0.010). Although it is known that Amazons prefer conspecific females when compared to their heterospecific host even when chemical only cues are present [30], here we show that their discriminatory abilities are even 310 more precise than previously thought. In addition, we found no difference in the strength of kin recognition in the presence of unimodal and bimodal cues (F 1,70 =1.256, p=0.266), suggesting that discrimination is not improved using more than one sensory channel.…”

“…The tank temperature was maintained at 27.8°C during the duration of the experiment. Individuals were raised until [22][23][24][25][26][27][28][29][30][31][32][33][34] weeks old prior to the start of the behavioral experiments.…”

“…Additionally, Amazon mollies show considerable individual variation in behaviors (i.e., preferences, aggression, etc.) [24,[30][31] within and among clonal lineages, suggesting that after establishing kin recognition in multiple lineages, the use of a single lineage to further explore kin recognition 85 within this species is sufficient.…”