The effect of environmental diversification on species diversification in New Caledonian caddisflies (Insecta: Trichoptera: Hydropsychidae)

Abstract

Aim To test whether environmental diversification played a role in the diversification of the New Caledonian Hydropsychinae caddisflies.Location New Caledonia, south-west Pacific.Methods The phylogeny of the New Caledonian Hydropsychinae caddisflies was hypothesized using parsimony and Bayesian methods on molecular characters. The Bayesian analysis was the basis for a comparative analysis of the correlation between phylogeny and three environmental factors: geological substrate (ultrabasic, non-ultrabasic), elevation and precipitation. Phylogenetic divergence times were estimated using a relaxed clock method, and environmental factors were mapped onto a lineage-through-time plot to investigate the timing of environmental diversification in relation to species radiation. The correlation between rainfall and elevation was tested using independent contrasts, and the gamma statistic was calculated to infer the diversification pattern of the group. ResultsThe diversification of extant Orthopsyche-Caledopsyche species began in the Middle-Late Oligocene, when much of the island of New Caledonia was covered by ultrabasic substrate and mountain forming was prevalent. Most lineages originated in the Middle-Late Miocene, a period associated with long-term climate oscillation. Optimization of environmental factors on the phylogeny demonstrated that the New Caledonian Hydropsychinae group adapted to ultrabasic substrate early in its evolutionary history. The clade living mostly on ultrabasic substrate was far more species-rich than the clade living mostly on non-ultrabasic substrate. Elevation and rainfall were significantly correlated with each other. The lineagethrough-time plot revealed that the main environmental diversification preceded species diversification. A constant speciation through time was rejected, and the negative gamma indicates that most of the diversification occurred early in the history of the clade. According to the inferred phylogeny, the genus Orthopsyche McFarlane is a synonym under Caledopsyche Kimmins, and Abacaria caledona Oláh & Barnard should also be included in Caledopsyche. Main conclusionsThe age of the radiation does not support a vicariance origin of New Caledonian Hydropsychinae caddisflies. Environmental diversification pre-dates lineage diversification, and thus environmental heterogeneity potentially played a role in the diversification of the group, by providing a variety of fragmented habitats to disperse into, promoting speciation. The negative gamma indicates that the speciation rate slowed as niches started to fill.

Ecological divergence of Chaetopteryx rugulosa species complex (Insecta, Trichoptera) linked to climatic niche diversification

“…120 Graham et al, 2004;Rundle & Nosil, 2005;Espeland & Johanson, 2010). Given the climatic and geological 121 heterogeneity of the Balkan Peninsula and the ubiquity of cryptic diversity and endemism in this region, we 122 hypothesize that ecological divergences played an important role in the formation of the Balkan freshwater 123 biodiversity, and expect to find phylogenetic patterns that point toward this.…”

“…climate change, 103 bedrock geology) is often interpreted as support for the role of environmental heterogeneity in shaping 104 biodiversity (Espeland et al, 2008;Espeland & Johanson, 2010;Previšić et al, 2014b), but such 105 coincidences are also insufficient to completely rule out speciation by non-ecological processes in isolation 106 with subsequent ecological differentiation. Third, parallel evolution of traits (e.g.…”

“…environmental 461 heterogeneity shapes biodiversity, Espeland et al, 2008;Espeland & Johanson, 2010;Previšić et al, 462 2014b), but one has to keep in mind that such coincidences are also insufficient to rule out speciation by non-ecological processes in isolation with subsequent ecological differentiation. Third, the radiation of 464 lineages into 'cold' and 'warm' habitats occurred at several parallel occasions about the same time (around 465 the Pliocene/Pleistocene transition) during the history of the C. rugulosa species complex (Fig.…”

“…in studies showing 491 differentiation during past climatic events (Espeland et al, 2008;Espeland & Johanson, 2010;Previšić et al, 492 2014b), ongoing adaptation to habitat conditions (Evans et al, 2009;Dormann et al, 2010;Zhang et al, 493 2014) or multiple radiation and paraphyletic formation of lineages adapted to current habitat conditions 494 (McKinnon et al, 2004;Elmer et al, 2010b;Kautt et al, 2012 …”

Biodiversity Conservation and Phylogenetic Systematics

“…The geographical isolation of the island and its ultramafi c soils have all been proposed as factors promoting high levels of endemicity. This endemicity exists at the level of the island, but also at fi ner geographical scales, and within New Caledonia microendemism is common with many species restricted to individual mountains, mountain slopes, valleys, watercourses or edaphic 'islands' (e.g., Murienne et al 2005 ;Sharma and Giribet 2009 ;Espeland and Johanson 2010b ;Pillon et al 2010 ;Nattier et al 2012Nattier et al , 2013. This high level of endemism has attracted considerable scientifi c interest in the evolutionary history of the island (see the review in Pellens and Grandcolas 2010 ) and phylogenies for several groups are now available.…”