Evolution of Caste in Neotropical Swarm-Founding Wasps(Hymenoptera: Vespidae; Epiponini)

Abstract

Reproductive castes are compared in species of swarming wasps representing all currently recognized genera of Epiponini (Polistinae). New morphometric data for nine measures of body parts and ovarian data are presented for 13 species. These are integrated with all similarly conducted available studies, giving a total of 30 species. Analysis reveals several syndromes relating reproductive and nonreproductive individuals: no meaningful distinction, physiological differences only, reproductives larger than nonreproductives with intermediate individuals present, reproductives different in shape from nonreproductives with no intermediates, and reproductives smaller in some aspects than nonreproductives. Distribution of these syndromes among species is consistent with phylogenetic relationships derived from other data. Optimizing these syndromes on the cladogram indicates that the basal condition of Epiponini is a casteless society that is not comparable to the primitively social genus Polistes where dominant queens control reproduction. Castes originate several times in Epiponini, with different results in different lineages. The best documented evolutionary sequence passes from casteless societies, to those with reproductives larger, to those with reproductives differing in shape from nonreproductives, to those with reproductives smaller in some measures. This sequence is consistent with Wheeler's theory of the origin of caste through developmental switches, and represents the most thorough test of that theory to date.

Comparative analysis of constraints and caste differences in brain investment among social paper wasps

“…We used two response variables to identify factors that could influence the magnitude of caste differences in the ratio of central:peripheral tissue investment: the raw difference between queen and worker mean ratios for each species, and a weighted difference (queen mean ratio -worker mean ratio/worker mean ratio). We analyzed relationships of the magnitude of the queen-worker differences with two behavioral and developmental covariates related to species differences in social complexity (22): mode of colony founding [independent vs. swarm founding (20)] and whether or not queens are morphologically distinct from workers [data from Noll et al (17)]. We also analyzed whether the magnitude of caste differences covaried with overall brain size, as indicated by the volume of all brain structures we measured.…”

“…Larger relative brain sizes in three orders of mammals (ungulates, carnivores, and primates) are correlated with an increase in sociality and the cognitively demanding behaviors that come with it (17).…”

An adaptive view of caste differentiation in the neotropical wasp Polybia (Trichothorax) sericea Olivier (Hymenoptera: Vespidae)

“…Queens have higher values in CAN1 than workers (Fig 3), and linking this information with the canonical scores (Table 2), it is possible to define the morphological differences between queens and workers in each colony phase. The values of Wilk´s lambda (Table 2) ranged from 0.4 to 0.8, which indicates, according to Noll et al (2004), that the power of discrimination of the variables ranged from moderate to low. Finally, the classification matrix obtained after discriminant function analysis (Table 3) showed that queens were only 100% correctly classified in colonies II and III, indicating that queens from these colonies were more distinct morphologically from workers, resulting in a higher degree of caste differentiation than in the other colonies.…”

“…According to Noll et al (2004), four different syndromes are now recognized in the Epiponini: (1) casteless -no morphological differences in size or shape and the presence of females with all ovary developmental conditions (Shima et al 1998, Mateus et al 2004, (2) without a clear morphological distinction, but physiological differences with the presence of intermediate females (Noda et al 2003, 2010, (3) queens larger than workers, but no shape differences , and (4) caste differences based on shape, with queens smaller than workers in some variables and larger in others (Shima et al 1994, 1996a,b, 2003, Hunt et al 1996, Desuó et al 2011.…”

Morphological and physiological variation between queens and workers of Protonectarina sylveirae (de Saussure) (Hymenoptera, Vespidae, Epiponini)

“…Different patterns of caste differentiation can be found in species of Epiponini (Richards & Richards 1951;Jeanne & Fagen, 1974;Noll & Wenzel, 2008) such as: 1) no morphological differences between queens or workers, found in Angiopolybia pallens (Lepeletier, 1836) (Richards 1978; Clypearia sulcata (Saussure, 1854) ; Leipomeles dorsata (Fabricius, 1804) ; Metapolybia aztecoides Richards, 1978; Nectarinella championi (Dover, 1925) ; Synoeca surinama (Linnaeus, 1767) (Richards 1978;Noll et al 2004); 2) queens larger than workers and intermediates found in Chartergus metanotalis Richards, 1978; Epipona tatua (Cuvier, 1797) (Richards, 1978;Noll et al 2004); Polybia liliacea (Fabricius, 1804) ; P. rejecta (Fabricius, 1798) (Richards 1978;Noll et al 2004); P. spinifex Richards, 1978; 3) females with ovary developed but with spermatheca empty, found in Brachygastra scutellaris (Fabricius, 1804) (Richards, 1978); Polybia bistriata (Fabricius, 1804) (Richards & Richards 1951;Richards 1978); P. emaciata Lucas, 1879 (Richards & Richards 1951;Richards 1978); P. occidentalis (Olivier, 1791) (Richards & Richards 1951;Richards 1978); P. paulista (von Ihering, 1896) (Noll et al 1996); Parachartergus smithii (de Saussure, 1854) (Mateus et al 1997); Protopolybia exigua (de Saussure, 1854) (Noll et al 1996); Psudopolybia vespiceps (de Saussure, 1864) (Shima et al 1998); and 4) queens with smaller heads and larger abdomens than workers, found in Apoica flavissima Van der Vecht, 1973(Shima et al 1994; Agelaia multipicta (Haliday, 1836) ; A. pallipes (Olivier, 1791) …”