Stridulations Reveal Cryptic Speciation in Neotropical Sympatric Ants

Abstract

The taxonomic challenge posed by cryptic species underlines the importance of using multiple criteria in species delimitation. In the current paper we tested the use of acoustic analysis as a tool to assess the real diversity in a cryptic species complex of Neotropical ants. In order to understand the potential of acoustics and to improve consistency in the conclusions by comparing different approaches, phylogenetic relationships of all the morphs considered were assessed by the analysis of a fragment of the mitochondrial DNA cytochrome b. We observed that each of the cryptic morph studied presents a morphologically distinct stridulatory organ and that all sympatric morphs produce distinctive stridulations. This is the first evidence of such a degree of specialization in the acoustic organ and signals in ants, which suggests that stridulations may be among the cues used by these ants during inter-specific interactions. Mitochondrial DNA variation corroborated the acoustic differences observed, confirming acoustics as a helpful tool to determine cryptic species in this group of ants, and possibly in stridulating ants in general. Congruent morphological, acoustic and genetic results constitute sufficient evidence to propose each morph studied here as a valid new species, suggesting that P. apicalis is a complex of at least 6 to 9 species, even if they present different levels of divergence. Finally, our results highlight that ant stridulations may be much more informative than hitherto thought, as much for ant communication as for integrative taxonomists.

Through thick and thin: Cryptic sympatric speciation in the submersed genus Najas (Hydrocharitaceae)

“…Cryptic sympatric species occur across a spectrum of phenotypically simple and complex organisms including ants (Ferreira et al, 2010), butterflies (Hebert et al, 2004), fish (Feulner et al, 2006), flies (Condon et al, 2008), frogs (Stuart et al, 2006), fungi (Bidochka et al, 2005), mammals (Baker, 1984), onychophorans (Trewick, 1998), and protists (Amato et al, 2007). In contrast, there are surprisingly few reports of cryptic sympatric plant species (e.g., Heinrichs et al, 2011) despite inferences that ''instant speciation'' via polyploidy (Coyne and Orr, 2004;Linder and Rieseberg, 2004; http://dx.doi.org/10.1016/j.ympev.2014.09.022 1055-7903/Ó 2014 Elsevier Inc. All rights reserved.…”

Behavioural Contexts of Sound Production in<I>Pachycondyla</I> Ants (Formicidae: Ponerinae)

“…Behavioural contexts of stridulation tested in P. apicalis speciescomplexants. 3and 4are newvalid species that await formal taxonomic description (Ferreira et al 2010)a nd P. apicalis Morph 2d oes not have its taxonomic status confirmed yet, we decided to refer to these taxa using the classification proposed by Delabie et al [24], with ants being classified into morphs within their currently named species. Ant colonies were reared in the laboratory in artificial plastered nests installed in plastic boxes (19x15x6cm 3 ).…”

“…gynes and males) of different morphs and/or species were constituted (Table II). Fore ach group, 5-8 gynes from as ingle colony were associated to 10-12 males from 5-6 distinct colonies (2 males/colony) ( Table I).I nt hese groups, besides being from different colonies, males were also from distinct morphs or species thus allowing different categories of potential pairing: homocolonial (between males and gynes from the same colony),h eterocolonial of the same morph, heterocolonial of different morphs of P. apicalis or heterospecific (between P. apicalis gynesa nd P. verenae males), since these latter are still the only taxonomically described species for the group that are considered in this study,albeit Ferreira et al [22] findenough evidence to consider each P. apicalis morphasav alid species (Table II). Homocolonial pairing constituted ac ontrol, as in most ant species, incest avoidance during mate choice occurs [16] and as no intranidal fertilization has ever been observed in our laboratory colonies (Ferreira and Fresneau, pers.…”

“…Among Ponerinae, in the Neotropical Pachycondyla apicalis species complex, stridulations are produced by all castes (i.e. queens, workers and males)a nd present temporal and frequencys pecificities ranging from caste (unpublished data)t os pecies [22]. Hence, it is possible to discriminate sympatric cryptic species from the P. apicalis speciesc omplext hrough the analysis of acoustic parameters in the temporal and the frequencyd omains of their stridulations.…”

“…Conversely,i fh omospecificstridulations carry the information of an alarm signal and indicate ap otential danger we expected them to generate repellent behaviour in the receiverants. In addition, in the broadly sympatric P. apicalis and P. verenae the species-specificsignals could have evolved in response to competitive interactions [22]. Indeed, as these species share the same niche and are thus likely to compete for resources and nesting sites [21,23] as imilar avoidance response can be expected from P. apicalis workers to the heterospecificstridulations of P. verenae.…”