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The sequential stages culminating in the publication of a morphological cladistic analysis of weevils in the Exophthalmus genus complex (Coleoptera: Curculionidae: Entiminae) are reviewed, with an emphasis on how early- stage homology assessments were gradually evaluated and refined in light of intermittent phylogenetic insights. In all, 60 incremental versions of the evolving character matrix were congealed and analysed, starting with an assembly of 52 taxa and ten traditionally deployed diagnostic characters, and ending with 90 taxa and 143 characters that reflect significantly more narrow assessments of phylogenetic similarity and scope. Standard matrix properties and analytical tree statistics were traced throughout the analytical process, and series of incongruence length indifference tests were used to identify critical points of topology change among succeeding matrix versions. This kind of parsimony-contingent rescoping is generally representative of the inferential process of character individuation within individual and across multiple cladistic analyses. The expected long-term outcome is a maturing observational terminology in which precise inferences of homology are parsimony-contingent, and the notions of homology and parsimony are inextricably linked. This contingent view of cladistic character individuation is contrasted with current approaches to developing phenotype ontologies based on homology-neutral structural equivalence expressions. Recommendations are made to transparently embrace the parsimony-contingent nature of cladistic homology.
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Anatomy of a Cladistic Analysis
Nico M. Franz
School of Life Sciences, Arizona State University
XXXI Willi Hennig Meeting – UC Riverside
June 26, 2012; Riverside, CA
• "The monophyly of the Neotropical entimine weevil genus Exophthalmus Schoenherr, 1823 (Curculionidae: Entiminae: Eustylini Lacordaire) is reassessed."
• […] "The present study scrutinizes these traditional perspectives, based on a cladistic analysis of 143 adult morphological characters and 90 species, representing 30 genera and seven tribes of Neotropical entimine weevils."
• The character matrix yielded eight most-parsimonious cladograms (length = 239 steps; consistency index = 66; retention index = 91), with mixed clade support that remains particularly wanting for some of the deeper in-group divergences."
From the abstract:
(A) E. agrestis (Boheman); (B) E. consobrinus (Marshall); (C) E. hieroglyphicus Chevrolat
(D) E. impressus (Fabricius); (E) E. nicaraguensis Bovie; (F) E. quadrivittatus (Olivier)
(G) E. quinquedecimpunctatus (Olivier); (H) E. roseipes (Chevrolat); (I) E. sulcicrus Champion
(J) E. triangulifer Champion; (K) E. verecundus (Chevrolat); (L) E. vittatus (Linnaeus)
Fig. 2. Preferred cladogram & character state optimizations
Dissecting the process – motivating themes
"Cladists may use the congruence test to iteratively refine assessments of homology, and thereby increase the odds of reliable phylogenetic inference under parsimony. This explanation challenges alternative views which tend to ignore the effects of parsimony on the process of character individuation in systematics."
Franz. 2005. Outline of an explanatory account of cladistic practice. Biol. Phil. 20: 489–515.
"Cladists may use the congruence test to iteratively refine assessments of homology, and thereby increase the odds of reliable phylogenetic inference under parsimony. This explanation challenges alternative views which tend to ignore the effects of parsimony on the process of character individuation in systematics."
Franz. 2005. Outline of an explanatory account of cladistic practice. Biol. Phil. 20: 489–515.
"The identification of the valid scope for character statements cannot be a matter
of mere ostension, or rigid designation, but must be a matter of scientific theory
construction. Scope expansion of character statements can result in a situation
where purportedly similar structures, apparently denoted by the same name
(proper name or kind name), are in fact not the same. The nonhomology of such
characters may be revealed through morphological complexity at the comparative
level, by tree topology at the analytical level, or both."
Rieppel. 2007. The performance of morphological characters in broad-scale phylogenetic analyses. Biol. J. Linn. Soc. 92: 297–308.
Dissecting the process – motivating themes
Sneak preview: 60 matrices, 8 stages – tracking the analysis
Legacy character assembly
Source: Champion. 1911. Otiorhynchinae Alatae. In: Biologia Centrali-Americana, Vol. 4, Part 3. London.
Stage 1: legacy character assembly
Champion (1911) – winged vs. wingless entimine groups
Character has a length of 10 steps in a narrowly scoped analysis (Exophthalmus and closely related genera).
Stage 1: legacy character assembly
Initial characters and states had a reputable pedigree
Lacordaire. 1863. Histoire naturelle des insectes, Vol 6. Paris, Roret.Champion. 1911. Otiorhynchinae Alatae. Biologia Centrali-Americana, Vol. 4, Part 3. London; pp. 178–317.van Emden. 1944. A key to the genera of Brachyderinae of the world. Ann. Mag. Nat. Hist. 11: 503–532, 559–586.Anderson. 2002. Family 131. Curculionidae. In: American B, Vol. 2. Boca Raton, CRC Press; pp. 722–815.Franz. 2010. Redescriptions of critical type species in the Eustylini Lacordaire (Coleoptera: Curculionidae: Entiminae). J. Nat. Hist. 44: 41-80.
Early cladistic outcomes (Stage 1)
52 taxa
Early cladistic outcomes (Stage 1)
100 characters
547 steps!(~ 5.5 / char.)
Early cladistic outcomes (Stage 1)
Matrix 10
Select legacy characters
Consistency index and retention index
rapid decline
Character coding – binary, multi-state
~ 40%multi-state characters
Character provenance – external, internal
initiallyall external
Number of MPTs and nodes collapsed in consensus
3 trees,3 collapsed
Not publication worthy.
Return to initial homology assessments (chars./states).
Rescoping starts…
Matrices 11-17: rescoping phase I – some examples
Intermediate stages 2-5 – rescoping, taxon/character addition
addressingpoorest
characters
Intermediate stages 2-5 – rescoping, taxon/character addition
evidence of large gaps in
sampling
Intermediate stages 2-5 – rescoping, taxon/character addition
addition of out-/ingroup taxa (52 90)
Intermediate stages 2-5 – rescoping, taxon/character addition
new taxa new (unscoped)characters
Intermediate stages 2-5 – rescoping, taxon/character addition
rescoping all in expanded context
Consistency index and retention index
steadyincrease
Character coding – binary, multi-state
> 90% binary characters
"exploratory" reductive
coding
Character provenance – external, internal
> 20% internal
characters
Number of MPTs and nodes collapsed in consensus
Still not ready for publication.
> 1200 trees,> 35 collapsed
Focus on detail homology, perform "aggressive scope reduction"
And so…
Contingent rescoping – tricarinate rostrum of Diaprepes spp.
17. "Rostrum tricarinate, …
7 species
17. "Rostrum tricarinate, …
Contingent rescoping – tricarinate rostrum of Diaprepes spp.
Exophthalmus Otiorhynchus
Pachnaeus Phaops Rhinospathe
7 species
Are these rostra also tricarinate (in homology to Diaprepes)?
17. "Rostrum tricarinate, with a characteristic combination of one median carina and two (dorso-) lateral, apically slightly diverging carinae, each carina narrow, moderately sharp."
Contingent rescoping – tricarinate rostrum of Diaprepes spp.
Exophthalmus Otiorhynchus
Pachnaeus Phaops Rhinospathe
7 species
(1) present (0) absent
(0) absent
(–) inapplicable
(–) inapplicable (–) inapplicable
No, not if intermittent phylogenetic insights are transparently included.
Narrowly scoped, deep-level homologies
Narrowly scoped, deep-level homologies
Narrowly scoped, deep-level homologies
Terminal stages 6-8 – added resolution, robustness
narrowly rescoped characters, more stable tree length
Consistency index and retention index
approaching "maximum" levels
Character coding – binary, multi-state
> 20% characters with inapplicables
Character provenance – external, internal
~ 40% internalcharacters
Number of MPTs and nodes collapsed in consensus
8 trees,3 collapsed
Ready for publication.
Review…from matrix 10 to 60
Topology, Optimization, Language
Overview of significant topology changes – matrices 1-60
Transition of matrix 30-31 yielded earliest "reliable" results.
Matrix 10[topology]
• 52 taxa• 100 characters• 4 MPTs• L = 547 steps• CI = 28• RI = 66• 3 nodes collapsed• Bremer support
Exophthalmus spp. Nested within Exoph.
• 52 taxa (=)• 69 characters (– 31)• 3 MPTs (– 1)• L = 159 steps (– 388) • CI = 48 (+ 20)• RI = 83 (+ 17)• 3 nodes collapsed (=)• Bremer support
Matrix 20[topology]
Exophthalmus spp. Nested within Exoph.
• 90 taxa (+ 38)• 91 characters (+ 22)• 2192 MPTs (+ 2189)• L = 205 steps (+ 46) • CI = 45 (– 3)• RI = 83 (=)• 38 nodes collapsed (+ 35)• Bremer support
Matrix 30[topology]
Exophthalmus spp. Nested within Exoph.
• 90 taxa (=)• 143 characters (+ 52)• 8 MPTs (– 2184)• L = 239 steps (+ 24) • CI = 66 (+ 21)• RI = 91 (+ 8)• 3 nodes collapsed (– 35)• Bremer support
Matrix 60[topology]
Exophthalmus spp. Nested within Exoph.
• 52 taxa• 100 characters• 4 MPTs• L = 547 steps• CI = 28• RI = 66• 3 nodes collapsed• Diagnoses unwieldy• Synapomorphies rare
Matrix 10[optimization]
Select legacy characters
• 90 taxa (+ 38)• 143 characters (+ 43)• 8 MPTs (+ 4)• L = 239 steps (– 308) • CI = 66 (+ 38)• RI = 91 (+ 25)• 3 nodes collapsed (=)• Diagnoses concise• Synapomorph. common
Matrix 60[optimization]
Matrix 10 [language]
Lacordaire. 1863. Histoire naturelle des insectes, Vol 6. Paris, Roret.Champion. 1911. Otiorhynchinae Alatae. Biologia Centrali-Americana, Vol. 4, Part 3. London; pp. 178–317.van Emden. 1944. A key to the genera of Brachyderinae of the world. Ann. Mag. Nat. Hist. 11: 503–532, 559–586.Anderson. 2002. Family 131. Curculionidae. In: American B, Vol. 2. Boca Raton, CRC Press; pp. 722–815.Franz. 2010. Redescriptions of critical type species in the Eustylini Lacordaire (Coleoptera: Curculionidae: Entiminae). J. Nat. Hist. 44: 41-80.
Matrix 60 [language]
Related issue…
Which characters should constitute
phenotype anatomy ontologies?
Related issue – the value of parsimony-contingent homology
Special emphasis on constructing phenotypic anatomy ontologies.
"We have taken an integrative approach in the building of Uberon, and in doing so embrace multiple axes of classification. […] This homology-neutrality of Uberon is a deliberate design feature of the ontology. We believe that specifying homology relationships and descent from common ancestral structures is of obvious high value, but that this need not be tightly coupled to the development of an upper anatomical ontology."
Mungall et al. 2012. Uberon, an integrative multi-species anatomy ontology. Genome Biol. 13: R5.
Related issue – the value of parsimony-contingent homology
Special emphasis on constructing phenotypic anatomy ontologies.
"We have taken an integrative approach in the building of Uberon, and in doing so embrace multiple axes of classification. […] This homology-neutrality of Uberon is a deliberate design feature of the ontology. We believe that specifying homology relationships and descent from common ancestral structures is of obvious high value, but that this need not be tightly coupled to the development of an upper anatomical ontology."
"Explanatory homology hypotheses should not be mistaken and blended with morphological descriptions, which in their turn are by nature descriptive and not explanatory. […] Instead, we differentiate phylogenetic investigations into the step of producing data and the step of phylogenetic reasoning."
Mungall et al. 2012. Uberon, an integrative multi-species anatomy ontology. Genome Biol. 13: R5.
Vogt et al. 2010. The linguistic problem of morphology: structure versus homology and the standardization of morphological data. Cladistics 26: 301–325.
Source: Davis. 2011. Delimiting baridine weevil evolution (Coleoptera: Curculionidae: Baridinae). Zool. J. Linn. Soc. 161: 88–156.
So then is this what we have in mind for classes in phenotype ontologies?
• Analytical phylogenetic methods not only organize character information, but may furthermore have the purpose of shaping character individuation.
• In the case of the Exophthalmus analysis, I would have been hard pressed to arrive at the final descriptions of characters and states without benefitting from intermittent parsimony-driven inferences that led to the reweighting and rescoping of earlier homology assessments. It is not always conducive to a researcher's reputation to expose these practices, but they do and must occur frequently.
Conclusions
• Analytical phylogenetic methods not only organize character information, but may furthermore have the purpose of shaping character individuation.
• In the case of the Exophthalmus analysis, I would have been hard pressed to arrive at the final descriptions of characters and states without benefitting from intermittent parsimony-driven inferences that led to the reweighting and rescoping of earlier homology assessments. It is not always conducive to a researcher's reputation to expose these practices, but they do and must occur frequently.
• Under the cladistic paradigm, the most precise inferences of homology are often parsimony-influenced and parsimony-contingent, and the two notions are inextricably linked and entrenched in our maturing observational terminology.
• By integrating expressions of structural equivalence at increasingly greater scales, phenotype ontologies also run the risk of 'dialing down' the most precise and phylogenetically scoped assessments of homology that systematics can produce.
Conclusions
Acknowledgments
WHS XXXI Organizers
Juliana Cardona Duque, Jennifer Girón, Anyimilehidi Mazo Vargas, Quentin Wheeler
NSF-DEB 1155984: "Systematics of eustyline and geonemine weevils: Connecting and contrasting Caribbean and Neotropical mainland radiations"
Source: Lacordaire. 1863. Histoire naturelle des insectes, Vol. 6. Paris: Roret.
Lacordaire (1863) – typically a 1-3 character system for tribes/genera.
Stage 1: legacy character assembly
van Emden (1944) state-of-the-art for entimine tribes / genera
Source: van Emden. 1944. A key to the genera of Brachyderinae of the world. Annals and Magazine of Natural History 11: 503-532, 559-586.
Anderson (2002) – identifies subfamilies, genera; not tribes
Source: Anderson. 2002. Family 131. Curculionidae. In: Arnett et al. (Eds.): American Beetles, Vol. 2. Boca Raton, CRC Press; pp. 722-815.
Initial characters and states had a reputable pedigree
Examples of poorly performing characters ( recode / eliminate)
Matrix 18: Examples of deactivated characters
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