TAMAÑO DE LAS EMPRESAS COMO DETERMINANTE DE LA

In this chapter, I provide a phylogenetic analysis of the genus Hadramphus using a multilocus multispecies coalescent approach. The advantage to using the multilocus coalescent method to construct species trees is that it takes into account different lineage sorting across markers (Heled and Drummond 2010). A study by Melo-Ferreira et al. (2012) found significant discordance among gene trees when building a phylogeny of hares (Lepus spp.) and resolved the problem using the multilocus coalescent framework allowing for a more accurate species tree. This approach was applied in this study to take advantage of the multiple individuals sequenced for each species for both the mitochondrial and nuclear loci. The divergence times in the COI tree suggest that Hadramphussensu stricto is a relatively recent lineage and the 1

multilocus multispecies coalescent approach can provide more accuracy in the phylogenetic analysis if incomplete lineage sorting is occurring.

The taxonomic tree based on morphological characters presented by Craw (1999) placed all four Hadramphus species into a well-supported clade. Lyperobius huttoni was the closest related species from the sister genus. The genetic data does not fully support the

morphological character tree. H. pittospori branched off early from all the other species including the putative outgroup. Originally H. pittospori was placed into its own genus, Karocolens (Kuschel 1987), until it was incorporated into Hadramphus in 1999 (Craw 1999). The genetic phylogeny suggests that H. pittospori may not be part of the genus Hadramphus. To help demonstrate conclusively if H. pittospori does not belong to Hadramphus, sequences from other Lyperobius species should be included in the data. Depending on which

morphological characters are chosen for phylogenetic analysis, the traits may be biased depending on if the characters of interest are chosen to be included or removed from the data (Queiroz 1996). In Craw (1999) he states there are some unique characters remaining that separate H. pittospori from other Hadramphus species, such as the prothorax being as, or nearly as, long as wide and diverging into a straight line. The remaining characters separating H. pittospori may be more important to the evolutionary history of the species and should be analysed in more detail. Placing H. pittospori into a genus of its own may not negatively affect the conservation status of the species as at the moment the Poor Knights Islands are protected, therefore protecting the habitat of the species.

The phylogenetic relationship between H. tuberculatus,H. spinipennis and H. stilbocarpae in the genetic trees differs from that of the morphology based tree in which H. spinipennis and H. stilbocarpae were considered sister taxa. Morphological characteristics, such as low, median rostral carina and a distinctive tubercle on interval 3 of the elytra declivity (Craw 1999), placed H. spinipennis and H. stilbocarpae as sister species. Goldberg and Trewick (2011) reported H. spinipennis and H. tuberculatus to be sister taxa based on the results of their COI Bayesian tree. In my study, H. tuberculatus is shown to be sister taxa to H.

stilbocarpae; however, the relationship is only supported by a posterior probability of 0.82. A difference in phylogenetic trees inferred from morphological and molecular data has been reported for other species in New Zealand. The beetle genus Prodontria showed marked differences in the molecular and morphological phylogenetic trees (Emerson and Wallis 1995). In particular the sister-species relationship of the group P. modesta and P. lewisi to P. capito was unsupported. Similarly, the molecular phylogeny of Hadramphus disagrees with the morphological tree in regards to sister-species.

Little variation is present between H. spinipennis, H. tuberculatus and H. stilbocarpae as is represented in the genetic trees. Goldberg and Trewick (2011) found similar results for these three species in their study. Hadramphus pittospori splits from all the species in the ITS2 tree, although this value is likely overestimated as the ITS2 sequence was not collected for the analysis).

The divergence times in for COI suggest that Hadramphus is a relatively recent genus that radiated during the Pleistocene. Although the Pleistocene was marked by glacial cycles that may have caused range reductions, in New Zealand some species have been shown to have undergone range expansions during this period. The cicada, Maoricicada cambelli, split into two major lineages during the early Pleistocene and underwent a range expansion in the late Pleistocene (Hill et al. 2009). It has been hypothesised that these two major clades are divergent enough to be in the early stages of speciation. In the genus Hadramphus, the common ancestor of H. spinipennis, H. tuberculatus and H. stilbocarpae was rather recent (53,300 years ago), which may indicate that these species were isolated during the glaciation and began to diverge into separate species at that time. The 95% confidence interval for the date of divergence for the genus provides a relatively broad range for the age of the genus. For more precise dating, the inclusion of geological changes into the analysis may reduce the 95% confidence interval; however, precise dates for some of the geological events on the Canterbury Plains which would affect H. tuberculatus are difficult to ascertain.

The study presented in this chapter provides clarification on the taxonomic groupings in the genus Hadramphus. The phylogeny provides an indication of evolutionary relationships that were not predicted based on morphology alone. The four species in Hadramphus range from protected to critically endangered and are all managed by the Department of Conservation. By combining the evolutionary history of species with their taxonomy rather than relying on morphology alone, more educated decisions can be made regarding their conservation status.