Phylogenomics of peacock spiders and their kin (Salticidae:Maratus), with implications for the evolution of male courtship displays

Abstract

Understanding diversity has been a pursuit in evolutionary biology since its inception. A challenge arises when sexual selection has played a role in diversification. Questions of what constitutes a ‘species’, homoplasy vs. synapomorphy, and whether sexually selected traits show phylogenetic signal have hampered work on many systems. Peacock spiders are famous for sexually selected male courtship dances and peacock-like abdominal ornamentation. This lineage of jumping spiders currently includes over 90 species classified into two genera, Maratus and Saratus. Most Maratus species have been placed into groups based on secondary sexual characters, but evolutionary relationships remain unresolved. Here we assess relationships in peacock spiders using phylogenomic data (ultraconserved elements and RAD-sequencing). Analyses reveal that Maratus and the related genus Saitis are paraphyletic. Many, but not all, morphological groups within a ‘core Maratus’ clade are recovered as genetic clades but we find evidence for undocumented speciation. Based on original observations of male courtship, our comparative analyses suggest that courtship behaviour and peacock-like abdominal ornamentation have evolved sequentially, with some traits inherited from ancestors and others evolving repeatedly and independently from ‘simple’ forms. Our results have important implications for the taxonomy of these spiders, and provide a much-needed evolutionary framework for comparative studies of the evolution of sexual signal characters.

Phylogenomics and loci dropout patterns of deeply diverged Zodarion ant‐eating spiders suggest a high potential of RAD‐seq for genus‐level spider phylogenetics

“…RAD methods do not require previous taxon-specific information, imply relatively simple wet-lab work, routinely produce tens of thousands of loci per sample instead of hundreds to a few thousand, and are more cost-effective to implement than transcriptomics or target capture techniques. Whereas multiple spider studies have used RAD-seq for assessing population genomics, phylogeographic and species delimitation questions (Graham et al, 2020;Hedin et al, 2020;Ivanov et al, 2018;Ortiz et al, 2021;Settepani et al, 2017), to the best of our knowledge, only Girard et al (2021) have used it for reconstructing genus-level phylogenetic relationships, obtaining overwhelmingly high support at all divergence levels for 48 species of peacock spiders of the genus Maratus (Salticidae) plus outgroups.…”

“…Whereas multiple spider studies have used RAD‐seq for assessing population genomics, phylogeographic and species delimitation questions (Graham et al., 2020; Hedin et al., 2020; Ivanov et al., 2018; Ortiz et al., 2021; Settepani et al., 2017), to the best of our knowledge, only Girard et al. (2021) have used it for reconstructing genus‐level phylogenetic relationships, obtaining overwhelmingly high support at all divergence levels for 48 species of peacock spiders of the genus Maratus (Salticidae) plus outgroups.…”

A novel probe set for the phylogenomics and evolution of RTA spiders

“…We also accommodated the loci targeted by the other probe sets in this newly designed probe set, so that the data obtained in previous studies (e.g. Starrett et al., 2017; Wood et al., 2018; Kulkarni et al., 2020a; Maddison et al., 2020a; Girard et al., 2021) can be efficiently integrated with sequences captured using the new probe set.…”

Maratus nemo: A new wetland species of peacock spider from South Australia (Araneae, Salticidae, Euophryini)

“…Males of Maratus nemo share some similarities to members of the Western Australian Maratus personatus group (Otto and Hill 2019;Otto and Hill 2021) in having the anterior ocular area ornamented with coloured scales, so as to form a 'mask', and in lacking opisthosomal colouration or flaps. It is thus tentatively placed in this species group (see Girard et al 2021;Otto and Hill 2021; and Schubert 2020 about the tentative nature of subgeneric clades within Maratus). Maratus nemo, however, can be readily separated from members of this species group and all other congeners by the following combination of characters: bright orange field of scales covering the clypeus and anterior ocular region (Figs 1A-F, 2A-D, 6A-D) light covering of fine white setae on the carapace, legs, and mostly glabrous dorsal opisthosomal plate (Figs 1A-F, 2A-D, 6A-D); relatively compact embolic disc by which the inner and outer rings of the embolus are in close contact or fused to form a single heavy apex (Fig.…”

“…Adult males of Maratus are distinguished from other euophryine genera by the presence of a dorsal opisthosomal plate often covered with vibrantly coloured scales (but not always), an elongated and usually ornamented third pair of legs, and by the courtship behaviour of most species -males of which elevate the opisthosoma and wave the third pair of legs to display to females (Girard et al 2021;Hill and Otto 2011;Schubert 2020).…”