Delimiting species without nuclear monophyly in Madagascar's mouse lemurs

Species delimitation and evolution in morphologically and chemically diverse communities of the lichen-forming genus Xanthoparmelia (Parmeliaceae, Ascomycota) in western North America

PREMISE OF THE STUDY

Accurate species delimitation is important for understanding the diversification of biota and has critical implications for ecological and conservation studies. However, a growing body of evidence indicates that morphology-based species circumspection in lichenized fungi misrepresents fungal diversity. The foliose lichen genus Xanthoparmelia includes over 800 species displaying a complex array of morphological and secondary metabolite diversity.

METHODS

We used a multifaceted approach, applying phylogenetic, population genetic, and genealogical analyses to delimit species in a single well-supported monophyletic clade containing 10 morphologically and chemically diverse Xanthoparmelia species in western North America. Sequence data from four ribosomal and two low-copy, protein-coding markers, along with chemical and morphological data were used to assess species diversity.

KEY RESULTS

We found that traditionally circumscribed species are not supported by molecular data. Rather, all sampled taxa were better represented by three polymorphic population clusters. Our results suggest that secondary metabolite variation may have limited utility in diagnosing lineages within this group, while identified populations clusters did not reflect major phylogeographic or ecological patterns.

CONCLUSIONS

In contrast to studies revealing previously undiscovered fungal lineages masked within lichen species circumscribed by traditional morphological and chemical concepts, the present study suggests that species diversity has been overestimated in the species-rich genus Xanthoparmelia.

"Same same but different": replicated ecological speciation at White Sands

Understanding the factors that promote or inhibit species formation remains a central focus in evolutionary biology. It has been difficult to make generalities about the process of ecological speciation in particular given that each example is somewhat idiosyncratic. Here we use a case study of replicated ecological speciation in the same selective environment to assess factors that account for similarities and differences across taxa in progress towards ecological speciation. We study three different species of lizards on the gypsum sand dunes of White Sands, New Mexico, and present evidence that all three fulfill the essential factors for ecological speciation. We use multilocus nuclear data to show that progress toward ecological speciation is unequal across the three species. We also use morphometric data to show that traits other than color are likely under selection and that selection at White Sands is both strong and multifarious. Finally, we implicate geographic context to explain difference in progress toward speciation in the three species. We suggest that evaluating cases from the natural world that are "same same but different" can reveal the mechanisms of ecological speciation.