Light triggers habitat choice of eyeless subterranean but not of eyed surface amphipods

Abstract

Boundaries of species distributions are the result of colonization-extinction processes. Survival on the boundary depends on how well individuals discriminate optimal from suboptimal habitat patches. Such behaviour is called habitat choice and was only rarely applied to macroecology, although it links species ecological niche and species distribution. Surface and subterranean aquatic species are spatially strongly segregated, even in the absence of physical barriers. We explored whether a behavioural response to light functions as a habitat choice mechanism that could explain species turnover between surface and subterranean aquatic ecosystems. In a controlled laboratory experiment, we studied the behavioural response to light of ten pairs of surface and subterranean amphipods that permanently co-occur in springs. Surface species showed a weak photophobic, photoneutral, and in one case, photophilic response, whereas all subterranean species showed a strong photophobic response. Eyeless subterranean but not eyed surface amphipods appear to orient themselves with light cues. On a local scale, this difference possibly diminishes harmful interactions between the co-occurring amphipods, whereas on a regional scale, photophobia could explain limited dispersal and a high degree of endemism observed among subterranean species.

How blind are they? Phototactic responses in stygobiont diving beetles (Coleoptera: Dytiscidae) from calcrete aquifers of Western Australia

“…Similarly, the larvae of Drosophila melanogaster have also displayed light mediated responses that have been linked to simple neurons (Xiang et al ). The brain is thought to be the source of phototactic perception in the eyeless cave amphipods, Niphargus frasassianus , N. ictus (Borowsky ) and other Niphargus species (Fišer et al ). However, the location of photoreception has yet to be examined in these groups.…”

“…Future studies investigating different light intensities and also wavelengths may provide a better understanding of how P. macrosturtensis perceive light (e.g. as per Fišer et al ), and we have now provided a behavioural index (dark ratio) so that any subsequent data can be directly compared to the current study. In addition, a comprehensive investigation into dytiscid eye anatomy (i.e.…”

“…Similar, albeit less pronounced, trends were also observed in the apparently eyeless amphipods, Niphargus frasassianus and N. ictus , leading to the conclusion that they had the ability to detect light (Borowsky ). Additionally, light facilitated responses have been established in various subterranean animals including crustaceans (Borowsky , and references therein; Fišer et al ), a roundworm ( Caenorhabditis elegans ; Edwards et al . ), salamanders (Taylor ), cavefish (Tarttelin et al .…”

Day–night and seasonal variations of a subterranean invertebrate community in the twilight zone

“…Light availability plays a crucial ecological role for organisms on the earth surface (e.g., Panda et al 2002, Bradshaw and Holzapfel 2010, Gaston et al 2013, Tierney et al 2017. Alternatively, the absence of light, at least from a biological point of view (see Badino 2000), represents the most crucial factor conditioning the ecology of subsurface habitats and the evolution of subterranean inhabitants (Pipan and Culver 2012, Battiston and Marzotto 2015, Culver and Pipan 2015, Konec et al 2015, Fišer et al 2016, Tierney et al 2017. As a direct consequence of the lack of solar irradiation, primary phototrophic producers are absent in the deep parts of the caves, with the exception of plant roots growing from the soil into sub-superficial subterranean habitats (Gibert and Deharveng 2002).…”

Do Salamanders Limit the Abundance of Groundwater Invertebrates in Subterranean Habitats?

“…It is widespread and primarily inhabits groundwaters, but several Niphargus species/populations live in subterranean habitats at the interface with the surface and can more or less occasionally exploit epigean environments like springs and streams [34,61,62]. Even if eyeless, Niphargus species retain the ability to detect light [63] suggesting that the connection with surface environments and exploitation of transitional habitats can be important for these crustaceans. Salamander larvae can exhert major predatory pressure on these animals; it is also important to consider that the occurrence of salamander larvae is seasonal and, even if their development can be quite long [64,65], periods in which larvae are absent are likely to occur.…”