Sperm ultrastructure of hoplocercid and oplurid lizards (Sauropsida, Squamata, Iguania) and the phylogeny of Iguania

Abstract

We describe the morphology of the spermatozoa of members of the iguanian lizard families Hoplocercidae and Opluridae for the first time. Their spermatozoa are quite similar and resemble the sperm of other iguanian lizards. Through a re-evaluation of sperm descriptions supplied in the literature we coded continuous and discrete characters through a combination of four methods: gap-weighting, step-matrix gap-weighting, reductive coding and composite coding. Parsimony analyses revealed that different methods produced highly incongruent outcomes. In view of the pros and cons of each method, we defend that the combination between composite coding and step-matrix gap-weighting are the most appropriate for our data. The cladogram derived from this analysis is totally resolved and comparatively well supported. We conclude that although the preferred cladogram was not strongly supported in some instances, sperm characters could be a good predictor of relationships among iguanian groups. We compare our hypothesis with preceding studies and we show that some previous groupings are in accordance with our results. Finally, we discuss the validity of those groupings in the light of methodological reasoning.

Ultrastructural study of spermiogenesis in the Jamaican Gray Anole, Anolis lineatopus (Reptilia: Polychrotidae)

“…The midpiece can be easily distinguished from the principle piece because of the mitochondrial sheath surrounding the midpiece axoneme and the large peripheral fibers associated with microtubule doublets 3 and 8, which are absent in the principle piece axoneme. The observation of peripheral fibers associated with the 3 and 8 microtubule doublets within the Jamaican Gray Anole midpiece axoneme corroborates this proposed synapomorphy for lepidosaurs (Vieira et al. 2005, 2007).…”

“…in press). Some aspects of spermiogenesis, however, have been reported in Anolis carolinensis (Clark 1967), and many iguanid lizards have mature spermatozoal characters previously described in an evolutionary context (Vieira et al. 2004, 2007).…”

Ontogenic development of spermatids during spermiogenesis in the high altitude bunchgrass lizard (Sceloporus bicanthalis)

“…However, the nuclear lacuna does not penetrate the entire nucleus and thus may have been missed in previous studies. The midpiece region is relatively short with the fibrous sheath beginning at mitochondria tier two which is consistent among phrynosomatids 7 but differs among other Iguania taxa 5 , 33 , 35 …”

A morphometrics-based phylogeny of the temperate Gondwanan mite harvestmen (Opiliones, Cyphophthalmi, Pettalidae)

“…Phylogenetic independence of characters means that each changes state due to genetic events isolated from those causing state changes in other characters. It has been called Ôthe fundamental attribute of a useful characterÕ (Doyle 1997), and the interplay of coding methods and character independence has been the subject of some discussion with discretized data (Kluge and Farris 1969;Pimentel and Riggins 1987;Pleijel 1995;Lee and Bryant 1999;Fitzhugh 2006;Vieira et al 2007). Combining suspected non-independent characters to create multistate discrete characters mitigates the probability of counting dependent events multiple times in phylogenetic reconstruction, although this can also eliminate important information (Lee and Bryant 1999;Strong and Lipscomb 1999).…”