Hawaiian picture‐winged Drosophila exhibit adaptive population divergence along a narrow climatic gradient on Hawaii Island

Abstract

Anthropogenic influences on global processes and climatic conditions are increasingly affecting ecosystems throughout the world. Hawaii Island’s native ecosystems are well studied and local long‐term climatic trends well documented, making these ecosystems ideal for evaluating how native taxa may respond to a warming environment. This study documents adaptive divergence of populations of a Hawaiian picture‐winged Drosophila , D. sproati, that are separated by only 7 km and 365 m in elevation. Representative laboratory populations show divergent behavioral and physiological responses to an experimental low‐intensity increase in ambient temperature during maturation. The significant interaction of source population by temperature treatment for behavioral and physiological measurements indicates differential adaptation to temperature for the two populations. Significant differences in gene expression among males were mostly explained by the source population, with eleven genes in males also showing a significant interaction of source population by temperature treatment. The combined behavior, physiology, and gene expression differences between populations illustrate the potential for local adaptation to occur over a fine spatial scale and exemplify nuanced response to climate change.

A holobiont view of island biogeography: unraveling patterns driving the nascent diversification of a Hawaiian spider and its microbial associates

“…However, sampling of additional sites, individuals, and species will be required to disentangle the historical sequence of events explaining the relationship between these sites. Our results are consistent with other population genetic studies on Hawaiʻi Island showing strong differentiation and potential speciation of lineages on the different volcanoes within the island (Funk & Wagner 1995; Holland & Cowie 2007; Muir & Price 2008; Croucher et al 2012; Goodman et al 2019; Eldon et al 2019; Blankers et al 2018). Interestingly, spiders on the mainland would not show this isolation by volcano pattern, because they do efficiently disperse by ballooning; here, our data, in contrast, suggest that the species does not efficiently balloon anymore in this island system (Gillespie et al 2012).…”

“…Sampling of additional sites, individuals, and species will be required to disentangle the historical sequence of events explaining the relationship between these sites. Our results are consistent with other population genetic studies on Hawai’i Island showing strong differentiation and potential speciation of lineages on the different volcanoes within the island (planthoppers, Goodman et al 2019; flies, Eldon et al 2019; crickets, Blankers et al 2018).…”

“…Even on the youngest island of Hawai’i, the volcanoes are arranged chronologically, from approximately 430,000 years old (Kohala), to the active flows of Kīlauea, with population structure of local flora and fauna generally shaped by progressive colonization of the newly emerged volcanoes (e.g. Blankers et al 2018; Eldon et al 2019; Goodman et al 2019).…”

“…Even on the youngest island of Hawaiʻi, the volcanoes are arranged chronologically, from approximately 430,000 years old (Kohala), to the active flows of Kīlauea, with population structure of local flora and fauna generally shaped by progressive colonization of the newly emerged volcanoes (e.g. Simon 1987; Wagner & Funk, 1995; Blankers et al 2018; Eldon et al 2019; Goodman et al 2019). Stick-spiders in the genus Ariamnes (Theridiidae) have diversified rapidly across the landscapes in the Hawaiian archipelago (Gillespie & Rivera 2007) and exhibit repeated diversification into ecomorphs adapted to specific microhabitats such as the “gold” ecomorph that is are entirely cryptic on the underside of leaves (Gillespie & Rivera 2007; Gillespie et al .…”

A holobiont view of island biogeography: Unravelling patterns driving the nascent diversification of a Hawaiian spider and its microbial associates

“…The Hawaiian archipelago consists of a chain of volcanic islands that increase in age from southeast to northwest, providing an ideal system for tracking the interplay between a host and the different components of its microbial community within an isolated setting (Shaw & Gillespie, 2016). Even on the youngest island of Hawaiʻi, the volcanoes are arranged chronologically, from ~430,000 years old (Kohala), to the active flows of Kīlauea, with population structure of local flora and fauna generally shaped by progressive colonization of the newly emerged volcanoes (Blankers et al, 2018; Eldon et al, 2019; Goodman et al, 2019; Simon, 1987; Wagner & Funk, 1995). Stick‐spiders in the genus Ariamnes (Theridiidae) have diversified rapidly across the landscapes in the Hawaiian archipelago (Gillespie & Rivera, 2007) and exhibit repeated diversification into ecomorphs adapted to specific microhabitats such as the “gold” ecomorph that is are entirely cryptic on the underside of leaves (Gillespie et al, 2018; Gillespie & Rivera, 2007).…”