Biogeography and the evolution of flightlessness in a radiation of Hawaiian moths (Xyloryctidae: Thyrocopa)

Abstract

Aim Although the ability to fly confers benefits to most insects, some taxa have become secondarily flightless. Insect flightlessness may be more likely to evolve in environments such as islands and other windswept and alpine areas, but this prediction has rarely been tested while controlling for phylogenetic effects. Here we present a phylogeny for the endemic Hawaiian Lepidoptera genus Thyrocopa, which has two flightless species that occur in alpine areas on Maui and Hawaii islands, in order to determine whether the flightless species are sister to each other or represent separate losses of flight. We also explore divergence times and biogeographic patterns of inter‐island colonization in Thyrocopa, and present the first Hawaiian study to sample a genus from nine islands. Location The Hawaiian Islands. Methods The phylogeny is composed of 70 individuals (including 23 Thyrocopa species and 7 outgroup species) sequenced for portions of cytochrome c oxidase subunit I, elongation factor 1α and wingless genes, for a total of 1964 base pairs, and was estimated using both parsimony (paup*) and Bayesian inference (MrBayes). Divergence times were estimated using the beast software package. Results Our results indicate that two independent invasions of alpine habitats with concomitant loss of flight have occurred in Thyrocopa. Based on current taxon sampling, Thyrocopa colonized the Hawaiian Islands slightly before the formation of Kauai. In terms of overall patterns of diversification, subclades generally follow a progression from older to younger islands. The genus has the greatest number of species on Kauai, with species numbers generally decreasing with decreasing island age. Main conclusions Loss of flight ability has evolved twice in a short period of geological time in Thyrocopa, perhaps as a result of low temperatures, high winds and/or a lack of predation pressure. However, several other Thyrocopa species that live on small islands with consistently high winds, such as Necker and Nihoa islands, retain the ability to fly.

Repeated range expansion and niche shift in a volcanic hotspot archipelago: Radiation of C4 Hawaiian Euphorbia subgenus Chamaesyce (Euphorbiaceae)

“…Species under closed vegetation that are generally in higher elevation (black squares in Figure ) evolved independently on O`ahu versus Kaua`i, from open vegetation on the same island. A similar pattern of “upslope migration” is also evident in Hawaiian Artemisia (Hobbs & Baldwin, ) and in flightless alpine moths in Hawai`i and Maui (Medeiros & Gillespie, ). By contrast, in Hawaiian violets a nuclear ITS phylogeny recovered a “dry clade” and a “wet clade,” each having species from multiple islands (Havran, Sytsma, & Ballard, ).…”

Anisomeriini diving beetles—an Atlantic–Pacific Island disjunction on Tristan da Cunha and Robinson Crusoe Island, Juan Fernández?

“…Reaching the islands required transoceanic dispersal or passive transport, as neither archipelago had land connections with mainland South America. Rhantus selkirki and R. tristanicola have vestigial wings, reduced probably in response to harsh environmental conditions on windy islands (McCulloch et al, 2009;Medeiros and Gillespie, 2011;Vogler and Timmermans, 2012). Wing and wing musculature reduction allow for habitus modification (Vogler and Timmermans, 2012) and might lead to the ground beetle-like habitus observed.…”

An enigmatic Hawaiian moth is a missing link in the adaptive radiation of Schiedea

“…Diversification in island settings has received special attention because of the large number of monophyletic lineages that have arisen in situ , and the ability to identify selective factors involved in these radiations. Within island lineages, diversification is often linked to habitat specialization (Baldwin, ; Sakai et al ., ; Roderick & Percy, ; Givnish et al ., ; Medeiros & Gillespie, ), and for flowering plants speciation may be associated with changes in mating system, or evolution of different modes of pollination. A striking example of convergent specialization in response to pollinators is the likely influence of honeycreepers on floral morphology in diverse plant families in the Hawaiian Islands (Elmore, ; Baldwin & Wagner, ; Aslan et al ., ).…”