Episodic chromosomal evolution in Planipapillus (Onychophora: Peripatopsidae): a phylogenetic approach to evolutionary dynamics and speciation

Planipapillus, a clade of onychophorans from southeastern Australia, exhibits substantial chromosomal variation. In the context of a robust phylogeny based on nuclear and mitochondrial sequence data, we evaluate models of chromosomal evolution and speciation that differ in the roles assigned to selection, mutation, and drift. Permutation tests suggest that all chromosome rearrangements in the clade have been centric fusions and, on the basis of parsimony and maximum-likelihood methods with independent estimates of branch lengths, we conclude that at least 31 centric fusions have been fixed in Planipapillus. A likelihood-ratio test approach, which is independent of our point estimates of ancestral states, rejects an evolutionary model in which the mutation rate is constant and centric fusions are effectively neutral. In contrast to the nucleotide sequence data, which are consistent with neutrality and rate constancy, centric fusions in Planipapillus are underdominant, spontaneous fusion rates vary among lineages, or both. We predict an inverse relationship between rates of chromosomal evolution and historical population size. Chromosomal evolution may play a role in speciation in Planipapillus, both by interactions between centric fusions with monobrachial homology and by the accumulation of multiple weakly underdominant fusions.     

Sexual dimorphism,phenotypic integration,and the evolution of head structure in casque‐headed lizards

Sexes can differ in features associated with differential reproduction, which can be used during courtship or aggressive encounters. Some traits tend to evolve independently between sexes and emerge as sexually dimorphic within the organismal phenotype. We characterize such a relationship by estimating the phenotypic integration of the head morphology and modularity of the crest in the casque‐headed lizards (Corytophanidae). In this clade, some species show extreme sexual dimorphism (e.g., head crests in the genus Basiliscus) while in others, both sexes are monomorphic. To characterize these patterns, we define phenotypic integration at the interspecific level as a pattern or network of traits evidenced by phylogenetically adjusted correlations that persist among species. At this level, modularity is an increased connectedness (e.g., higher correlation) among sections of these networks that persist in a lineage during the evolution of complex phenotypes. To test both concepts, we used phylogenetic geomorphometrics to characterize the head structure of corytophanid lizards, based on a time‐calibrated phylogeny that includes candidate fossil ancestors. We found evidence of an older diversification of corytophanids than previously reported (~67 vs. ~23.5 MYA) and show that this clade includes two morphological head architectures: (1) Sexually dimorphic crests present in males that are evolving independently from the rest of the head structure, and (2) full integration of the head morphology in monomorphic species. We propose that both architectures are optimal evolutionary trajectories of the parietal crest bones in the head of these lizards. In sexually dimorphic species, these bones are elongated and thinner, and gave rise to the extended crest used in male courtship displays. In monomorphic species, the parietal crest grew thicker in both sexes to allow for a better insertion of muscles associated with a stronger bite.     

Molecular phylogeny of the Trechus brucki group, with description of two new species from the Pyreneo-Cantabrian area (France, Spain) (Coleoptera, Carabidae, Trechinae)

A molecular phylogeny of the species from the Trechus brucki clade (previously Trechus uhagoni group)based on fragments of four mitochondrial genes and one nuclear gene is given. We describe Trechus (Trechus) bouillonisp. n. from the western pre-Pyrenees: Sierras de Urbasa-Andía, Navarra, Spain. The species was collected in mesovoid shallow substratum (mss), a subterranean environment. Molecular as well as morphological evidences demonstrate that the new species belongs to the Trechus brucki clade. A narrow endemic species of high altitude in western French Pyrenees merged with Trechus brucki Fairmaire, 1862a, Trechus bruckoidessp. n., is described. A lectotype is designated for Trechus brucki and Trechus planiusculus Fairmaire, 1862b (junior synonym of Trechus brucki). The species group is redefined based on molecular and morphological characters, and renamed as the brucki group, as Trechus brucki was the first described species of the clade. A unique synapomorphy of the male genitalia, a characteristic secondary sclerotization of the sperm duct, which is shared by all the species of the brucki group sensu novo, is described and illustrated. The Trechus brucki group sensu novo is composed of Trechus beusti (Schaufuss, 1863), Trechus bouillonisp. n., Trechus brucki, Trechus bruckoidessp. n., Trechus grenieri Pandellé, 1867, T. uhagoni uhagoni Crotch, 1869, T. uhagoni ruteri Colas, 1935 and Trechus pieltaini Jeannel, 1920. We discuss the taxonomy of the group and provide illustrations of structures showing the differences between the species, along with distribution data and biogeographical comments.     

Molecular phylogeny of the Australian frog genera Crinia, Geocrinia, and allied taxa (Anura: Myobatrachidae).

We present a mitochondrial gene tree for representative species of all the genera in the subfamily Myobatrachinae, with special emphasis on Crinia and Geocrinia. This group has been the subject of a number of long-standing taxonomic and phylogenetic debates. Our phylogeny is based on data from approximately 780 bp of 12S rRNA and 676 bp of ND2, and resolves a number of these problems. We confirm that the morphologically highly derived monotypic genera Metacrinia, Myobatrachus, and Arenophryne are closely related, and that Pseudophryne forms the sister group to these genera. Uperoleia and the recently described genus Spicospina are also part of this clade. Our data show that Assa and Geocrinia are reciprocally monophyletic and together they form a well-supported clade. Geocrinia is monophyletic and the phylogenetic relationships with the genus are fully resolved with two major species groups identified: G. leai, G. victoriana, and G. laevis; and G. rosea, G. alba, and G. vitellina (we were unable to sample G. lutea). We confirm that Taudactylus forms the sister group to the other myobatrachine genera, but our data are equivocal on the phylogenetic position of Paracrinia. The phylogenetic relationships among Crinia species are well resolved with strong support for a number of distinct monophyletic clades, but more data are required to resolve relationships among these major Crinia clades. Crinia tasmaniensis and Bryobatrachus nimbus form the sister clade to the rest of Crinia. Due to the lack of generic level synapomorphies for a Bryobatrachus that includes C. tasmaniensis, we synonymize Bryobatrachus with Crinia. Crinia georgiana does not form a clade distinct from other Crinia species and so our data do not support recognition of the genus Ranidella for other Crinia species. Crinia subinsignifera, C. pseudinsignifera, and C. insignifera are extremely closely related despite differences in male advertisement call. A preliminary investigation of phylogeographic substructure within C. signifera revealed significant divergence between samples from across the range of this species.     

Pollination systems, biogeography, and divergence times of three allopatric species of Schisandra in North America, China, and Japan

This study analyses the pollination systems and biogeography of three allopatdc species of Schisandra (Section Euschisandra) consisting of S.glabra (North America),S.bicolor (China),and S.repanda (Japan); the clade is delimited in a phylogenetic tree of Schisandraceae constructed with nuclear and plastid genes.The male and female flowers of these species have similar floral structures,but exhibit different pollination systems.At the base of the clade,S.glabra is pollinated by a wide variety of beetles and flies in a generalist pollination system that also includes floral heat and the use of male and female flowers as brood sites for insects.In Asia,however,S.bicolor and S.repanda are pollinated exclusively by one or two different species of gall midges (Resseliella spp.) in a specialist pollination system.In this system only female,pollen-eating gall midges pollinate the flowers and breed on nearby spiderwebs.The gall midge pollination system is specialized and derived from the generalist system in S.glabra,and basal in the clade.Pollen is the main floral resource,and we hypothesize it is exploited to enrich eggs,and as a result species of gall midges could increase reproductive fitness by feeding on a single dependable food source.Subsequently the life cycles of the plants and insects evolved into a tight association in old stable plant communities in the Sino-Japanese flora.Divergence times for the plant species are presented and correlated with past distributions and migration routes.     

The phylogeny of the Pentaschistis clade (Danthonioideae, Poaceae) based on chloroplast DNA, and the evolution and loss of complex characters

We construct a species-level phylogeny for the Pentaschistis clade based on chloroplast DNA, from the following regions: trnL-F, trnT-L, atpB-rbcL, rpL16, and trnD-psbA. The clade comprises 82 species in three genera, Pentaschistis, Pentameris, and Prionanthium. We demonstrate that Prionanthium is nested in Pentaschistis and that this clade is sister to a clade of Pentameris plus Pentaschistis tysonii. Forty-three of the species in the Pentaschistis clade have multicellular glands and we use ancestral character state reconstruction to show that they have been gained twice or possibly once, and lost several times. We suggest that the maintenance, absence, loss, and gain of glands are correlated with leaf anatomy type, and additionally that there is a difference in the degree of diversification of lineages that have these different character combinations. We propose that both glands and sclerophyllous leaves act as defense systems against herbivory, and build a cost/benefit model in which multicellular glands or sclerophyllous leaves are lost when the alternative defense system evolves. We also investigate the association between leaf anatomy type and soil nutrient type on which species grow. There is little phylogenetic constraint in soil nutrient type on members of the Pentaschistis clade, with numerous transitions between oligotrophic and eutrophic soils. However, only orthophyllous-leaved species diversify on eutrophic soils. We suggest that the presence of these glands enables the persistence of orthophyllous lineages and therefore diversification of the Pentaschistis clade on eutrophic as well as oligotrophic soils.     

A phylogenetic analysis of Pseudonaja (Hydrophiinae, Elapidae, Serpentes) based on mitochondrial DNA sequences

A phylogenetic analysis of mitochondrial ND4 and adjacent tRNA sequences for a geographically extensive series of specimens reveals nine major clades within Pseudonaja, of which six are largely coincident with nominal taxa (P. affinis, P. guttata, P. inframacula, P. ingrami, P. modesta, and P. textilis). The remaining three clades are composed of specimens presently referred to P. nuchalis. Two of these clades correspond with the "Darwin" and "Southern" morphs of previous authors, while the third clade incorporates the "Orange with black head" and "Pale head, grey nape" morphs. We are unable to confirm the presence of consistent karyotypic differences between "Orange with black head" and "Pale head, grey nape" specimens, however, P. inframacula, P. textilis, and P. nuchalis "Darwin" are found to exhibit distinctive karyotypes, as previously reported. These results, in conjunction with additional observations of karyotpic and morphological variation, are consistent with nine historically-independent lineages (i.e., species) within Pseudonaja. There is strong support for a clade composed of P. affinis, P. inframacula, P. ingrami, P. textilis, and the three P. nuchalis lineages, and for the relationships (P. inframacula, P. nuchalis "Southern") and (P. nuchalis "Darwin", P. nuchalis "Orange with black head"--"Pale head, grey nape" ).     

Species-Specificity of Chemical Signals: Silk Source Affects Discrimination in a Wolf Spider (Araneae: Lycosidae)

Female spiders deposit chemical cues that elicit male courtship behavior with silk. These cues are often assumed to be species-specific although male spiders may court in response to chemical cues of closely-related species. We used behavioral assays to test the extent of species discrimination of female chemical cues by male Schizocosa ocreata, a wolf spider (Lycosidae). Discrimination, expressed as relative courtship intensity of males, varied significantly with phylogenetic distance. Males did not discriminate between female cues of conspecifics and a sibling species, S. rovneri. Courtship response was intermediate for another species within the ocreata clade and not different from control for spiders outside the clade. These findings support the sibling species status of S. ocreata and S. rovneri, and also suggest the composition of female chemical signals is conserved across closely related wolf spider species.     

Phylogenetic systematics of the gondwanan Empis macrorrhyncha group (Diptera,Empididae, Empidinae)

The Empis macrorrhyncha group (Diptera: Empididae) from cool to warm temperate areas of South America and Australia is diagnosed and cladistically analysed, and five new species, Empis animosa sp.n. , E. austera sp.n. , E. maculosa sp.n. , E. occidentalis sp.n. and E. pedivillosula sp.n. , are described. Cladistic analysis of 23 adult morphological characters for 14 species of the group generated a single tree of 28 steps (CI = 0.82; RI = 0.93). Monophyly was established on the basis of a single apomorphy, possession of a bilobed cercus of the male hypopygium. Three main clades were inferred: clade 1 included three Patagonian and a single southwestern Australian species; clade 2 included two species from southeastern Australia; clade 3 included a large Patagonian group of five species and a single southeastern Australian species. The E. fulvicollis complex (clade 1) is a sister‐group of the E. macrorrhyncha complex (clades 2 + 3). A provisional historical biogeographic hypothesis is advanced correlating the appearance of the South American and Australian sister lineages with the timing of the break‐up of Gondwana.     

Morphological diversity and evolution of the spermatozoon in the mouse‐related clade of rodents

Most species in the three highly speciose families of the mouse‐related clade of rodents, the Muridae, Cricetidae, and Nesomyidae (superfamily Muroidea), have a highly complex sperm head in which there is an apical hook but there are few data available for the other related families of these rodents. In the current study, using light and electron microscopies, we investigated the structure of the spermatozoon in representative species of four other families within the mouse‐related clade, the Dipodidae, Spalacidae, Pedetidae, and Heteromyidae, that diverged at or near the base of the muroid lineage. Our results indicate that a diverse array of sperm head shapes and tail lengths occurs but none of the species in the families Spalacidae, Dipodidae, or Pedetidae has a sperm head with an apical hook. By contrast, a rostrally extending apical hook is present in spermatozoa of members of the Family Heteromyidae which also invariably have comparatively long sperm tails. These findings suggest that the hook‐shaped sperm head in the murid, cricetid, and nesomyid rodents evolved after divergence of this lineage from its common ancestor with the other families of the mouse‐related clade, and that separate, and independent, convergent evolution of a similar sperm head form, and long sperm tail, occurred in the Heteromyidae. J. Morphol. 275:540–547, 2014. © 2013 Wiley Periodicals, Inc.     

中国厚结猛蚁属(膜翅目:蚁科)十三种蚂蚁的形态测量学研究

【目的】为了探索形态测量学方法在蚁科昆虫分类中的应用价值和我国厚结猛蚁属Pachycondyla种间的系统发育关系,对国内保存有标本的厚结猛蚁属13种进行了形态测量学研究。【方法】选取厚结猛蚁属13种各9个个体进行测量,以体长(TL)、头长(HL)、头宽(HW)、触角柄节长(SL)、前胸背板宽(PW)性状特征及头长宽比(CI)、触角柄节比(SI)共12个度量特征为变量,进行主成分分析和聚类分析。【结果】研究表明,3个主成分在头长、头宽、头长宽比及触角柄节比有较高的载荷值,差异显著。聚类结果显示,13种厚结猛蚁聚成4支:第1支(短背厚结猛蚁P.brevidorsa(Xu)、拟黑厚结猛蚁P.melanaria(Emery)、红足厚结猛蚁P.rufipes(Jerdon)和列氏厚结猛蚁P.leeuwenhoeki(Forel))与第2支(片突厚结猛蚁P.lobocarena Xu、郑氏厚结猛蚁P.zhengi Xu和敏捷厚结猛蚁P.astute Smith)的相似度最高,亲缘关系最近;与第3支(多毛厚结猛蚁P.pilosior(Wheeler)、安南厚结猛蚁P.annamita(Andrè)、邵氏厚结猛蚁P.sauteri(Forel)和爪哇厚结猛蚁P.javana(Mayr))的相似度次之,亲缘关系较远;与第4支(中华厚结猛蚁P.chinensis(Emery)和黄足厚结猛蚁P.luteipes(Mayr))相似度最低,亲缘关系最远。聚类关系与传统分类的结果基本一致:中华厚结猛蚁与黄足厚结猛蚁外部形态特征相似,聚为一支;郑氏厚结猛蚁、敏捷厚结猛蚁、邵氏厚结猛蚁、爪哇厚结猛蚁与片突厚结猛蚁外部形态特征相似,聚为另一支,亲缘关系较近。【结论】研究结果证明形态测量学方法具有很好的应用价值,适用于蚁科昆虫分类研究。     

Remototrachyna, a newly recognized tropical lineage of lichens in the Hypotrachyna clade (Parmeliaceae, Ascomycota), originated in the Indian subcontinent

Biogeographical studies of lichens used to be complicated because of the large distribution ranges of many species. Molecular systematics has revitalized lichen biogeography by improving species delimitation and providing better information about species range limitations. This study focuses on the major clade of tropical parmelioid lichens, which share a chemical feature, the presence of isolichenan in the cell wall, and a morphological feature, microscopic pores in the uppermost layer. Our previous phylogenetic studies revealed that the largest genus in this clade, Hypotrachyna, is polyphyletic with a clade mainly distributed in South and East Asia clustering distant from the core of the genus. To divide the Hypotrachyna clade into monophyletic groups and to reevaluate morphological and chemical characters in a phylogenetic context, we sampled ITS, nuclear large subunit (nuLSU) and mitochondrial small subunit (mtSSU) rDNA sequences from 77 species. We are erecting the new genus Remototrachyna for a core group of 15 former Hypotrachyna species. The segregation of Remototrachyna from Hypotrachyna receives support from morphological and chemical data, as well from maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses of the DNA. We used a likelihood approach to study the geographic range evolution of Remototrachyna and Bulbothrix, which are sister groups. This analysis suggests that the ancestral range of Remototrachyna was restricted to India and that subsequent long-distance dispersal is responsible for the pantropical occurrence of two species of Remototrachyna.     

Phylogeny of selected Sepiidae (Mollusca, Cephalopoda) based on 12S, 16S, and COI sequences, with comments on the taxonomic reliability of several morphological characters

Phylogenetic relationships among 11 species of sepiids from Japanese waters and Sepia officinalis from Mediterranean were studied using partial sequences of the mitochondrial 12S rRNA, 16S rRNA, and cytochrome c oxidase subunit I genes. These three genes had been analyzed in an Atlantic species S. elagans and was obtained from database. In the two-gene set analysis (16S+COI), sequence data of another 4 species were added from database. We also studied morphological characters of radulae, tentacular clubs, and cuttlebones. The molecular phylogeny was not congruent with relationships detected by the number of rows in radulae and the arrangement of suckers on the tentacular club. As to the cuttlebone shape, the molecular phylogeny suggests the separation of two groups, Doratosepion species with a lanceolate cuttlebone and the others with a broad cuttlebone. Our molecular phylogenetic study revealed these sepiids are separated into four clades. The first clade includes Sepia officinalis, S. hierrendda, S. bertheloti, S. pharaonis and Sepiella japonica. The second clade consists of S. latimanus and Metasepia tullbergi from sub-tropical waters. The third clade includes Sepia esculenta, S. madokai, S. aculeata and S. lycidas, which have a cuttlebone with a prominent spine. The fourth clade consists of Doratosepion species complex, S. kobiensis, S. lorigera, S. pardex, S. peterseni, and S. sp., which are characterized by a narrow cuttlebone with a distinct outer cone at the posterior end. The lack of membranous structures in the cuttlebone is a synapomorphy for this clade. S. elegans did not clearly belong to any of these clades and might represent the fifth clade.     

Lipophilic compounds in femoral secretions of male collared lizards,Crotaphytus bicinctores (Iguania,Crotaphytidae)

In many lizards, chemical compounds from the femoral gland secretions are used in intraspecific communication, but most studies describing these chemicals are for lizard species included in the Scleroglossa clade, whereas lizards within the Iguanian clade have been much less studied, probably because these lizards were considered to rely more on visual cues. However, many iguanian lizards have abundant femoral secretions and are able of chemosensory conspecific recognition, which might be based on compounds secreted by femoral glands. By using GC–MS analyses, we found 58 lipophilic compounds in femoral gland secretions of male Great Basin collared lizard, Crotaphytus bicinctores (Iguania, Crotaphytidae). Main compounds were steroids (mainly two triunsaturated steroids and cholesterol), carboxylic acids (mainly hexadecanoic acid), waxy esters of long chain fatty acids, alcohols (mainly hexadecanol), aldehydes and other minor compounds. We compared these compounds with those found in other lizard species and discussed the potential signaling function of some compounds and how the xeric habitat of this lizard could have conditioned the composition of secretions.     

中国尾蛱蝶属系统发育分析——基于雄性外生殖器形态特征

在对中国尾蛱蝶属雄性外生殖器解剖研究的基础上,选取了23个雄性外生殖器解剖特征,利用Paup4.0b10系统发育分析软件,分析探讨了中国尾蛱蝶属系统发育关系。结果表明:中国尾蛱蝶属9个种分为2个支系,一支系由凤尾蛱蝶Polyura arja、窄斑凤尾蛱蝶P.athamas及黑凤尾蛱蝶P.schreiber3种组成,另一支系由二尾蛱蝶P.narcaea、沾襟尾蛱蝶P.posidonius、忘忧尾蛱蝶P.nepenthes、异纹尾蛱蝶P.mutata、大二尾蛱蝶P.eudamippus及针尾蛱蝶P.dolon6种组成。两大支系均以渐次方式演化;凤尾蛱蝶与窄斑凤尾蛱蝶、大二尾蛱蝶与针尾蛱蝶各自互为姊妹群关系。     

A New Species of the Genus Tylototriton （Urodela： Salamandridae） from Northeastern Hunan Province,China

We describe a new species from the family Salamandridae from northeastern Hunan Province of China based on morphological and molecular genetic evidences.The new species,Tylototriton liuyangensis,is a member of the T.asperrimus group,and shares a number of similarities with T.wenxianensis and T.broadoridgus.The dorsal surface of the new Tylototriton species is completely black,with nodule-like warts distributed evenly along the lateral margin of dorsal body,and there is no transverse striae between the warts.There are several diagnostic characters of the new species that differ from those of T.wenxianensis and T.broadoridgus as follows：（1）the interorbital space（IOS）is comparatively wide;（2）there is a bony ridge present on the dorsal head surface,running along the upper eyelids;（3）the space between axilla and groin（AGS）is comparatively large,with the mean male AGS approximately equal to 50%of the snout-vent length（SVL）and the mean female AGS being 53%of SVL;and（4）there is a small genital armature on the anterior angle of labial folds present inside the anal fissure of adult males during the breeding season.The result from the molecular phylogenetic analysis of the genus Tylototriton（including the type specimen of the new species）based on the complete DNA sequence of the mitochondrial ND2 gene（1035 bp）indicated that the new species was similar to T.wenxianensis,T.dabienicus,and T.broadoridgus,but formed an independent clade.This result was consistent with the morphological analysis above,supporting that the Liuyang Population represented a distinct species.     

Molecular systematics of a speciose, cosmopolitan songbird genus: defining the limits of, and relationships among, the Turdus thrushes

The avian genus Turdus is one of the most speciose and widespread of passerine genera. We investigated phylogenetic relationships within this genus using mitochondrial DNA sequence data from the ND3, ND2 and cytochrome b genes. Our sampling of Turdus included 60 of the 65 extant species currently recognized, as well as all four species from three genera previously shown to fall inside Turdus (Platycichla, Nesocichla, and Cichlherminia). Phylogenetic trees based on maximum likelihood and maximum parsimony algorithms were congruent. Most of the Turdus taxa sampled fall into one of four clades: an African clade, a Central American-Caribbean clade, a largely South American clade, and a Eurasian clade. Still other taxa are placed either at the base of Turdus, or as links between clades. In no instance is any continent reciprocally monophyletic for the species distributed on it. A general lack of nodal support near the base of the phylogeny seems related to a rapid intercontinental establishment of the major clades within Turdus very early in the history of the genus. The monotypic genus Psophocichla is distantly related to, but clearly the sister of, Turdus rather than a constituent member of it.     

Selection on females can create 'larger males'

In many bird and mammal species, males are significantly larger than females. The prevailing explanation for larger-sized males is that sexual selection drives increased male size. In addition, researchers commonly assume that the extent of dimorphism indicates the strength of selection for increased size in males. Here, through reconstruction of ancestral morphology for males and females of one large avian clade we present data that contradict this assumption and illustrate that selection for decreased female size explains 'male-biased' dimorphism ca. 50% of the time. Our findings are also inconsistent with ecological niche partitioning between the sexes and increased breeding benefits from reduced female size as general explanations for the evolution of size dimorphism within the clade. We conclude that it is incorrect to assume sexual dimorphism results from a single selective factor, such as directional sexual selection on increased male size. Rather, we suggest that the selective forces leading to sexual dimorphism may vary between species and should be tested on a case-by-case basis using a phylogenetic approach.     

Eulemur, me lemur: the evolution of scent-signal complexity in a primate clade

Signal complexity has been linked to social complexity in vocal, but not chemical, communication. To address this gap, we examined the chemical complexity of male and female glandular secretions in eight species of Eulemur. In this diverse clade of macrosmatic primates, species differ by social or mating system and dominance structure. We applied principal component and linear discriminate analyses to data obtained by gas chromatography/mass spectrometry. Beyond the significant effects on chemical signals of gland type, sex, season and species, we found effects of social variables and phylogeny. Notably, female odours were more chemically complex in multimale-multifemale species than pair-bonded species, whereas male odours were more chemically complex in codominant species than female-dominant species. Also, the traditional sexual dimorphism, whereby male signal complexity exceeds that of females, was present in codominant species, but reversed in female-dominant species. Lastly, a positive relationship between the species' pairwise chemical distances and their pairwise phylogenetic distances supported a gradual, but relatively fast mode of signal evolution. We suggest that the comparative method can be a powerful tool in olfactory research, revealing species differences relevant to the understanding of current signal utility and evolutionary processes. In particular, social complexity in lemurs may have selected for olfactory complexity.