Circularity and Independence in Phylogenetic Tests of Ecological Hypotheses

It has been asserted that in order to avoid circularity in phylogenetic tests of ecological hypotheses, one must exclude from the cladistic analysis any characters that might be correlated with that hypothesis. The argument assumes that selective correlation leads to lack of independence among characters and may thus bias the analysis. This argument conflates the idea of independence between the ecological hypothesis and the phylogeny with independence among characters used to construct the tree. We argue that adaptation or selection does not necessarily result in the non-independence of characters, and that characters for a cladistic analysis should be evaluated as homology statements rather than functional ones. As with any partitioning of data, character exclusion may lead to weaker phylogenetic hypotheses, and the practice of mapping characters onto a tree, rather than including them in the analysis, should be avoided. Examples from pollination biology are used to illustrate some of the theoretical and practical problems inherent in character exclusion.     

How much can cladistics tell us about early hominid relationships?

Although cladistic analysis has been used to compare hypotheses of relationships among early hominids, the outcomes of different studies have depended entirely on the assumptions made by different investigators. Problems include the close genetic relationship of early hominid taxa, small fossil sample sizes, possible correlations among characters, and a lack of understanding about the evolutionary factors affecting characters. This study investigates the interaction of some of these problems affecting early hominid phylogenetics. Monte Carlo simulations of character state evolution in closely related taxa demonstrate that the sample sizes and close genetic relationships of early hominids do not permit cladistic analyses to obtain unequivocal results. Even with unrealistically good assumptions about the evolutionary dynamics affecting characters, the probability of the most parsimonious hypothesis being true is unacceptably small. In the face of these problems, even phylogenetic statements that are supported by a strong consensus of cladistic studies may nevertheless be in error, and such errors are likely to confound the placement of new specimens and taxa. Advancement in our knowledge of hominid phylogeny can depend only on a fuller understanding of the natural history and evolutionary dynamics of traits.     

Inferring hominoid and early hominid phylogeny using craniodental characters: the role of fossil taxa

Recent discoveries of new fossil hominid species have been accompanied by several phylogenetic hypotheses. All of these hypotheses are based on a consideration of hominid craniodental morphology. However, Collard and Wood (2000) suggested that cladograms derived from craniodental data are inconsistent with the prevailing hypothesis of ape phylogeny based on molecular data. The implication of their study is that craniodental characters are unreliable indicators of phylogeny in hominoids and fossil hominids but, notably, their analysis did not include extinct species. We report here on a cladistic analysis designed to test whether the inclusion of fossil taxa affects the ability of morphological characters to recover the molecular ape phylogeny. In the process of doing so, the study tests both Collard and Wood's (2000) hypothesis of character reliability, and the several recently proposed hypotheses of early hominid phylogeny. One hundred and ninety-eight craniodental characters were examined, including 109 traits that traditionally have been of interest in prior studies of hominoid and early hominid phylogeny, and 89 craniometric traits that represent size-corrected linear dimensions measured between standard cranial landmarks. The characters were partitioned into two data sets. One set contained all of the characters, and the other omitted the craniometric characters. Six parsimony analyses were performed; each data set was analyzed three times, once using an ingroup that consisted only of extant hominoids, a second time using an ingroup of extant hominoids and extinct early hominids, and a third time excluding Kenyanthropus platyops. Results suggest that the inclusion of fossil taxa can play a significant role in phylogenetic analysis. Analyses that examined only extant taxa produced most parsimonious cladograms that were inconsistent with the ape molecular tree. In contrast, analyses that included fossil hominids were consistent with that tree. This consistency refutes the basis for the hypothesis that craniodental characters are unreliable for reconstructing phylogenetic relationships. Regarding early hominids, the relationships of Sahelanthropus tchadensis and Ardipithecus ramidus were relatively unstable. However, there is tentative support for the hypotheses that S. tchadensis is the sister taxon of all other hominids. There is support for the hypothesis that A. anamensis is the sister taxon of all hominids except S. tchadensis and Ar. ramidus. There is no compelling support for the hypothesis that Kenyanthropus platyops shares especially close affinities with Homo rudolfensis. Rather, K. platyops is nested within the Homo + Paranthropus + Australopithecus africanus clade. If K. platyops is a valid species, these relationships suggest that Homo and Paranthropus are likely to have diverged from other hominids much earlier than previously supposed. There is no support for the hypothesis that A. garhi is either the sister taxon or direct ancestor of the genus Homo. Phylogenetic relationships indicate that Australopithecus is paraphyletic. Thus, A. anamensis and A. garhi should be allocated to new genera.     

Angiosperm wood evolution and the potential contribution of paleontological data

Wood anatomy is often viewed as a source of independent data that may be used to assess evolutionary relationships among angiosperms. Comparative anatomical studies document suites of correlated characters that have been interpreted as general evolutionary trends, of which several have been asserted to be irreversible. Paleobotanical data summarized by Wheeler and Baas provide broad chronological corroboration of some wood anatomical trends, such as evolution from scalariform to simple perforation plates and long to short vessel elements. However, the focus on general evolutionary trends rather than on analyzing character distribution patterns in a cladistic phylogenetic context obscures a more detailed understanding of the evolution of wood anatomical features. Patterns of character evolution, including the assertions of irreversibility, need to be tested through cladistic analyses. In this paper selected wood anatomical features from families of Magnoliidae and “lower” Hamamelididae are summarized and mapped onto previously published cladograms as a preliminary means of testing previous hypotheses of wood evolution. The results show that many of the characters are homoplasious and have evolved both in accord with, and counter to, the hypothesized general trends in different groups of flowering plants. In general, changes that confirm generalized trends are more common than changes that are counter to those trends. Future studies should combine wood anatomical characters with other features as part of a cladistic analysis. Fossil woods have not yet contributed significantly to phylogenetic studies, but in the very few cases where they have been linked to fossil reproductive structures, the woods have provided a better understanding of wood anatomy in early members of some families. Data from fossil wood expand the diversity of anatomical structure known in some angiosperm taxa and thus provide additional evidence that might be used in phylogenetic analyses. Fossil woods have the greatest potential to affect phylogenetic analyses where they can be linked to other fossil organs. The best chance for establishing such a linkage is through the study of fossil charcoalified woods that co-occur with other dispersed mesofossils.     

Masticatory biomechanics and its relevance to early hominid phylogeny: an examination of palatal thickness using finite-element analysis

It has been proposed that morphological characters functionally related to mastication may be unreliable indicators of early hominid phylogeny. One hypothesis states that masticatory characters are highly prone to homoplasy. A second hypothesis states that such characters are likely to be morphologically integrated and thus violate the assumption of character independence implicit in all phylogenetic analyses. Evaluation of these hypotheses requires that masticatory features be accurately identified, but, to date, there have been relatively few attempts to test precisely which early hominid features are functionally related to chewing. This paper uses finite-element analysis to evaluate the functional relationships of a character--palatal thickness--that is one of several Paranthropus synapomorphies putatively related to mastication. A finite-element model of 145,680 elements was created from sixty-one 2-mm-thick CT scans of a Macaca fascicularis skull. The model was assigned the elastic properties of facial bone and loaded with muscle forces corresponding to the moment of centric occlusion during mastication. The model was constrained so as to produce a reaction force (corresponding to the bite force) at M(1). With a few exceptions, the strain patterns in the finite-element model compare well with those gathered from published and unpublished bone-strain experiments. The model was then modified to have a thick palate. The model was reloaded using an identical loading regime, and the strain patterns of the original and thick-palate models were compared. Although a thickened palate acts to reduce palatal strain, strains are elevated in other facial regions. This suggests that a thick palate would not have evolved in isolation as an adaptation to withstand masticatory stress. Rather, a thick palate may have evolved in concert with a suite of other facial features that share a stress-resistance function. This appears to be consistent with hypotheses positing that at least some facial features related to chewing evolved in an integrated fashion. More functional studies of other facial features are needed, as are formal studies of morphological integration.     

Inferring and testing hypotheses of cladistic character dependence by using character compatibility

The notion that two characters evolve independently is of interest for two reasons. First, theories of biological integration often predict that change in one character requires complementary change in another. Second, character independence is a basic assumption of most phylogenetic inference methods, and dependent characters might confound attempts at phylogenetic inference. Previously proposed tests of correlated character evolution require a model phylogeny and therefore assume that nonphylogenetic correlation has a negligible effect on initial tree construction. This paper develops "tree-free" methods for testing the independence of cladistic characters. These methods can test the character independence model as a hypothesis before phylogeny reconstruction, or can be used simply to test for correlated evolution. We first develop an approach for visualizing suites of correlated characters by using character compatibility. Two characters are compatible if they can be used to construct a tree without homoplasy. The approach is based on the examination of mutual compatibilities between characters. The number of times two characters i and j share compatibility with a third character is calculated, and a pairwise shared compatibility matrix is constructed. From this matrix, an association matrix analogous to a dissimilarity matrix is derived. Eigenvector analyses of this association matrix reveal suites of characters with similar compatibility patterns. A priori character subsets can be tested for significant correlation on these axes. Monte Carlo tests are performed to determine the expected distribution of mutual compatibilities, given various criteria from the original data set. These simulated distributions are then used to test whether the observed amounts of nonphylogenetic correlation in character suites can be attributed to chance alone. We have applied these methods to published morphological data for caecilian amphibians. The analyses corroborate instances of dependent evolution hypothesized by previous workers and also identify novel partitions. Phylogenetic analysis is performed after reducing correlated suites to single characters. The resulting cladogram has greater topological resolution and implies appreciably less change among the remaining characters than does a tree derived from the raw data matrix.     

Origins of Hippopotamidae (Mammalia, Cetartiodactyla): towards resolution

The old debate on hippopotamid origins is still unresolved, balancing between two main phylogenetic hypotheses: origins within the Anthracotheriidae vs. origins within the Tayassuidae. The characters used in the literature to support one, the other, or both hypotheses were re-examined in light of a better known primitive hippopotamid morphology. A cladistic analysis was performed on the basis of these characters. On the one hand, although many features similar in hippopotamuses and anthracotheres appear to have evolved in parallel, the family Anthracotheriidae remains the best putative hippopotamus stem group on the basis of the reviewed characters. However, the precise identification of a stem group within this family is still uncertain. On the other hand, the lineage proposed in the tayassuid hypothesis should not be retained, being mostly based on some incorrect observations and without taking into account the derived or primitive nature of the features. The anatomic similarities seen between modern peccaries and Hippopotamus amphibius are the results of convergences between advanced species of both families.     

Hierarchical nature of morphological integration and modularity in the human posterior face

Morphological integration and modularity are important points of intersection between evolution and the development of organismal form. Identification and quantification of integration are also of increasing paleoanthropological interest. In this study, the "posterior face," i.e., the mandibular ramus and its integration with the associated midline and lateral basicranium, is analyzed in lateral radiographs of 144 adult humans from three different geographic regions. The null hypothesis of homogenously pervasive morphological integration among "posterior-face" components is tested with Procrustes geometric morphometrics, partial least squares, and singular warps analysis. The results reveal statistically significant differences in integration. Only loose integrative relationships are found between midline and lateral components of the basicranium, which may indicate the presence of at least two different basicranial modules. This modularity can be interpreted in terms of spatiotemporal dissociation in the development of those basicranial structures, and gives support to hypotheses of independent phylogenetic modifications at the lateral and midline basicranium in humans. In addition, morphological integration was statistically significantly stronger between the middle cranial fossa and the mandibular ramus than between the ramus and the midline cranial base. This finding confirms previous hypotheses of a "petroso-mandibular unit," which could be a developmental consequence of well-known phylogenetic modifications in coronal topology of the posterior face and base in hominoid evolution, related to middle cranial fossa expansion. This unit could be involved in later evolutionary tendencies in the hominid craniofacial system.     

The larval hyobranchial apparatus of discoglossoid frogs: its structure and bearing on the systematics of the Anura (Amphibia: Anura)

The morphology of the larval hyobranchial apparatus of discoglossoid frog species representing the genera Ascaphus, Alytes, Bombina, and Discoglossus is described and the resulting characters were analysed cladistically. Seven species representing seven major lineages of frogs were included in the cladistic analysis of characters. Several changes in the terminology of the musculature are introduced, and a new interpretation of the subarcualis-muscle system is presented. The phylogenetic analysis suggest that the hyobranchial apparatus was substantially altered in the lineages leading to and within the Pipanura. This notably involved fusion, reduction and loss of skeletal structures and muscles, and splitting of certain muscles into muscle groups. The result confirm previous hypotheses based on the study of adults: discoglossoid species retain the most numlerous plesiomorphic characters among extant ianurans. The larval hyobranchial apparatus is in many features structrually similar to that of urodeles. Many of their character states were most likely present in the most recent common ancestor of all living forgs. The cladistic analysis of 31 characters of ithe larval hyobranchial apparatus supports major clades: Anura, Bombinanura, Pipanura, and Pelobatoidea + Neobatrachia. The cladiostic analysis and interpretation of larval characters is in part compatible with phylogenetic hypotheses based on characters of adults and rRNA sequences, but is in conflict with the Mesobatrachia and Archaeobatrachia concepts of other authors.     

THE HOLY GRAIL OF THE PERFECT CHARACTER: THE CLADISTIC TREATMENT OF MORPHOMETRIC DATA

Abstract— Data scored for cladistic analyses may be quantitative or qualitative, continuous or discrete, and show overlapping or non-overlapping values between taxa. Quantitative and qualitative are modes of expression of data, while continuous or discrete refer to properties of the set of numbers that express the data; both these pairs of terms have been confused with overlapping and non-overlapping. The degree of overlap of values between taxa is often used to filter characters in cladistic analyses: if a minimum amount of overlap is exceeded, or a minimum amount of disjunction not reached, characters are rejected as "not cladistic". However, this rests on a confusion between features of taxa and features of individual organisms (attributes). Cladistic characters are features of taxa, and comprise frequency distributions of attribute values over individuals of a taxon. Cladistic characters logically cannot overlap, although taxa may have overlapping attribute values. Thus, a priori rejection of characters that have overlapping attribute values is non-sensical. Such data may still be rejected from consideration for cladistic analysis if it could be demonstrated that they contain little recoverable phylogenetic signal. Few published analyses have empirically tested this. An analysis of overlapping morphometric data from three series of Banksia suggests that, at least in these cases, they map phylogeny almost as accurately as more conventional, qualitative morphological data. While more such tests are required, morphometric data should not be rejected a priori from cladistic analyses.     

Homoplasy, character function, and nemertean systematics

We question recent claims that cladistic analysis is inapplicable in nemerteans (phylum Nemertea) due to a supposedly high degree of convergence. We further argue that terms like convergence and parallelism are historical sayings and only make sense in a phylogenetic context. Therefore, an approach aiming to produce phylogenetic hypotheses cannot be rejected on the grounds of a high degree of convergence before the actual hypothesis. Convergence is not an empirical observation, but a conclusion made after an analysis. We also discuss the view that knowledge of a character's function is a prerequisite for phylogenetic analysis and conclude that this is an invalid approach. Function, like any other way of sharpening our observations, helps in formulating non-phylogenetic hypotheses of homology, but the crucial test is congruence with other characters on a phylogeny.     

Phylogenetic analysis of the African papionin basicranium using 3‐D geometric morphometrics: The need for improved methods to account for allometric effects

The basicranium has been argued to contain a strong phylogenetic signal in previous analyses of primate cranial morphology. Therefore, further study of basicranial morphology may offer new insights into controversial phylogenetic relationships within primate groups. In this study, I apply 3‐D geometric morphometric techniques in a phylogenetic analysis of the African papionin basicranium. The effects of allometry strongly influence African papionin basicranial morphology and, unless these size effects are controlled or eliminated, phylogenetic analyses suggest traditional phylogenetic groupings of small taxa (mangabeys) and large taxa (geladas, mandrills, drills, and baboons). When the effects of allometry are eliminated by excluding size‐correlated principal components (PCs) or by regression analysis with retention of residuals, phylogenetic analyses of African papionin basicranial morphology are incongruent with recent molecular and morphological studies. By contrast, a cladistic analysis of basicranial characters using the narrow allometric coding method suggests the same phylogenetic relationships as recent molecular and morphological studies. These results suggest that important phylogenetic information is contained within the size‐correlated data, and this information is being discarded during the attempt to eliminate the effects of body size. Future 3‐D morphometric studies of phylogeny should focus on the development of new methodologies to adjust for allometric effects, as current techniques appear to be ill‐equipped to deal with the case of a size‐disparate, lower‐level taxonomic group. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.     

Cladistics and the comparative morphology of linyphiid spiders and their relatives (Araneae, Araneoidea, Linyphiidae)

This paper provides the first quantitative cladistic analysis of linyphiid morphology. Classical and novel homology hypotheses for a variety of character systems (male and female genitalia, somatic morphology, spinneret silk spigot morphology, etc.) are critically examined and studied within a phylogenetic context. Critical characters have been illustrated. A sample of linyphiid taxa (nine genera in four subfamilies), five species of Pimoa (Pimoidae), and two other araneoid families (Tetragnathidae and Araneidae, represented by Tetragnatha and Zygiella , respectively) were used to study the implications of the phylogeny of Pimoidae for the systematics of linyphiids. The phylogenetic relationships of these 16 exemplar taxa, as coded for the 47 characters studied, were analysed using numerical cladistic methods. In the preferred cladogram Pimoidae and Linyphiidae are sister groups, Stemonyphantinae are sister group to the remaining linyphiids, and Mynogleninae are sister group to the clade composed of Erigoninae plus Linyphiinae. These results agree with the relationships recently proposed by Wunderlich, except by finding erigonines as the sister group to linyphiines rather than to mynoglenines.     

Basicranial flexion,relative brain size,and facial kyphosis in Homo sapiens and some fossil hominids

Comparative work among nonhominid primates has demonstrated that the basicranium becomes more flexed with increasing brain size relative to basicranial length and as the -upper and lower face become more ventrally deflected (Ross and Ravosa [1993] Am. J. Phys. Anthropol. 91:305–324). In order to determine whether modern humans and fossil hominids follow these trends, the cranial base angle (measure of basicranial flexion), angle of facial kyphosis, and angle of orbital axis orientation were measured from computed tomography (CT) scans of fossil hominids (Sts 5, MLD 37/38, OH9, Kabwe) and lateral radiographs of 99 extant humans. Brain size relative to basicranial length was calculated from measures of neurocranial volume and basicranial length taken from original skulls, radiographs, CT scans, and the literature. Results of bivariate correlation analyses revealed that among modern humans basicranial flexion and brain size/basicranial length are not significantly correlated, nor are the angles of orbital axis orientation and facial kyphosis. However, basicranial flexion and orbit orientation are significantly positively correlated among the humans sampled, as are basicranial flexion and the angle of facial kyphosis. Relative to the comparative sample from Ross and Ravosa (1993), all hominids have more flexed basicrania than other primates: Archaic Homo sapiens, Homo erectus, and Australopithecus africanus do not differ significantly from Modern Homo sapiens in their degree of basicranial flexion, although they differ widely in their relative brain size. Comparison of the hominid values with those predicted by the nonhominid reduced major-axis equations reveal that, for their brain size/basicranial length, Archaic and Modern Homo sapiens have less flexed basicrania than predicted. H. erectus and A. africanus have the degree of basicranial flexion predicted by the nonhominid reduced major-axis equation. Modern humans have more ventrally deflected orbits than all other primates and, for their degree of basicranial flexion, have more ventrally deflected orbits than predicted by the regression equations for hominoids. All hominoids have more ventrally deflected orbital axes relative to their palate orientation than other primates. It is argued that hominids do not strictly obey the trend for basicranial flexion to increase with increasing relative brain size because of constraints on the amount of flexion that do not allow it to decrease much below 90°. Therefore, if basicranial flexion is a mechanism for accommodating an expanding brain among non-hominid primates, other mechanisms must be at work among hominids. © 1995 Wiley-Liss, Inc.     

Evolution of the Vertebrate Central Nervous System: Patterns and Processes

AS brains do not fossilize, most proposed phylogenetic sequencesfor central nervous system characters must be based on the patternsof variation of those characters in living organisms. Similarly,hypotheses regarding how brains change through time, and theevolutionary processes that produce these changes, are ultimatelybased on the character patterns recognized. It is critical inthese analyses to distinguish between homologous and homoplasouscharacters if errors in the reconstruction and interpretationof phylogenies are to be minimized. Definitions of homologyand homoplasy are reviewed, as are the concepts that bear ontheir application. Cladistic definitions are adopted, and criteriafor distinguishing homologous from homoplasous characters arediscussed. Analysis of a number of CNS characters that are usuallyassumed to be homologous reveals that homoplasous charactersappear among them. As in other organ systems, homoplasous charactersare actually common. A number of previous hypotheses regardingCNS evolution are reviewed in the context of new data on neuralconnections and their cladistic analysis. Some of these hypothesesmay be falsified by a cladistic treatment of CNS characters,whereas sufficient data do not exist to evaluate others.     

CLADISTIC ANALYSIS OF METAZOAN RELATIONSHIPS: A REAPPRAISAL

Abstract— A recently published cladistic analysis of metazoan relationships based on 77 embryological and morphological characters is shown to be defective with respect to both methodological issues and the interpretation of certain characters. Consequently, many conclusions of this analysis are not supported by the data. Alternative phylogenetic hypotheses are therefore proposed, based on a re-evaluation of an adapted data set.     

A method for estimating the relative importance of characters in cladistic analyses

The method of character importance ranking (CIR) is proposed here as a means for estimating the relative "importance" of characters in cladistic analyses, especially those based on morphological features. CIR uses the weighting variable to incrementally remove one character at a time from the analysis, and then evaluates the impact of the removal on the shape of the cladogram. The greater the impact, the more important the character. The CIR method for determining which characters drive the shape of a particular cladogram has several applications. It identifies the characters with the strongest (though not necessarily most accurate) signal in a cladistic analysis; it permits the informed prioritization of characters for further investigation via genetic, developmental, and functional approaches; and it highlights characters whose definition, scoring, independence, and variation should be reviewed with particular care. The application of CIR reveals that at least some cladograms depend entirely on a single character.     

THE AUDITORY REGION OF EARLY PALEOCENE PUCADELPHYDAE (MAMMALIA, METATHERIA) FROM TIUPAMPA, BOLIVIA, WITH PHYLOGENETIC IMPLICATIONS

Abstract:  New petrosal bones, assigned to Pucadelphys and Andinodelphys , from the Lower Paleocene of Tiupampa, Bolivia, are described. These remains provide new information on the anatomy of the ear region of these taxa. The re-examination of characters from the petrosal and basicranium shed light on the phylogenetic relationships of the three Tiupampan genera known from complete cranial remains (i.e. Mayulestes , Pucadelphys and Andinodelphys ). The combination of dental, general cranial and basicranial characters led to two alternative hypotheses. The first is that borhyaenoids (including Mayulestes ) are nested within Notometatheria. Pucadelphyds (i.e. Pucadelphys and Andinodelphys ) are the sister group of a clade comprising MHNC 8369 (one isolated petrosal from Tiupampa) and Marsupialia. The second favours the paraphyly of 'borhyaenoids' (i.e. the exclusion of Mayulestes from borhyaenoids) and the polyphyly of 'Notometatheria'. In this case, Mayulestes and borhyaenids represent the stem group of a clade including Asiatic, American and Australian metatherians. This analysis of combined datasets (dental, general cranial and basicranial) highlighted contradictory information in the dental and cranial characters, serving to emphasize that in a large anatomical complex like an entire skull mosaic evolution of the characters is likely.     

Phylogenetic analysis of the Blephariceromorpha,with special reference to mountain midges (Diptera: Deuterophlebiidae)

Abstract. A cladistic analysis of the Blephariceromorpha (here including the Nymphomyiidae, Deuterophlebiidae and Blephariceridae) and related Diptera provides a test of the phylogenetic hypotheses of Rohdendorf (1964, 1974), Hennig (1973), Wood & Borkent (1989) and Courtney (1990a). In particular, monophyly of the Blephariceroidea and Blephariceromorpha (sensu Wood & Borkent), and their relationship to other Diptera, is tested. Evaluation of larval, pupal and adult characters supports the hypothesis of Wood & Borkent, as modified by Courtney. Four larval features suggest that the Blephariceromorpha + Psychodomorpha form a monophyletic group, although an alternate hypothesis predicting that the Blephariceromorpha is the sister group of the Psychodomorpha + (Ptychopteromorpha + Culicomorpha), is discussed. Monophyly of the Blephariceromorpha (Nymphomyioidea + Blephariceroidea) is supported by one adult and five larval characters. Monophyly of the Blephariceroidea (Deuterophlebiidae + Blephariceridae) is supported by thirteen synapotypies, including features of the larva (six), pupa (three) and adult (four). Nineteen, nineteen and nine hypothesized synapotypies support monophyly of the Nymphomyiidae, Deuterophlebiidae and Blephariceridae, respectively.     

Higher level phylogeny for the passion-vine butterflies (Nymphalidae, Heliconiinae) based on early stage and adult morphology

A higher level phylogeny for the passion-vine butterflies (Nymphalidae, Heliconiinae) was generated by cladistic analysis of 146 morphological characters from all life stages. The 24 species studied were selected representatives of the ten currently accepted genera of the sub-tribe Heliconiiti. Analyses of only characters from larvae and pupae did not produce well resolved trees. However, some characters of the immature stages provided critical support for the monophyly of two clades. Analysis of only adult characters yielded a tree that closely resembled that obtained from all data combined. The phylogeny here derived from the combined analysis of early stage and adult characters differed in topology from all previously proposed hypotheses, and supported the monophyly of all currently recognized genera. Characters supporting each clade are described and illustrated, and various hypotheses of phylogenetic relatedness of passion-vine butterfly taxa are discussed.