Small‐scale patterns of genetic variation in a headwater specialist mayfly: No influence of selective forest harvesting on diversity

Abstract

Terrestrial environments allow the adults of some aquatic insects to disperse between headwater streams, which may be important for maintaining population connectivity and persistence. Winged adult stages of aquatic insects are particularly sensitive to degradation of terrestrial habitat, relying on it for food, reproduction and dispersal. In this study we examined the genetic pattern of the Australian mayfly Ulmerophlebia sp. AV2, in north-eastern New South Wales, and compared the genetic diversity in forested and partially deforested subcatchments. Our hypotheses were (i) patterns of mitochondrial DNA (mtDNA) variation in the Leptophlebiidae mayfly Ulmerophlebia sp. AV2 show a pattern of structuring that reflects low or widespread dispersal along the stream network and across catchments; and (ii) genetic diversity will be lower in partially deforested subcatchments compared to forested sub-catchments.We found gene flow was not restricted among headwater streams within sub-catchments but was restricted at distances >15 km. Genetic diversity was high (mean haplotype diversity >0.85) in both control and harvested sub-catchments. Instead, a historical signature of population expansion was detected which is consistent with findings for other aquatic insect taxa of eastern Australia. Our results suggest that the selective harvesting management strategy, including the use of riparian buffer zones, within these subcatchments does not appear to restrict dispersal between streams or erode diversity within streams for Ulmerophlebia sp. AV2. Selective harvesting therefore appears to have minimal impacts on terrestrial/aquatic links in the life cycle of this insect.

Drought survival strategies, dispersal potential and persistence of invertebrate species in an intermittent stream landscape

“…The capacity to disperse across these distances by flight makes Nousia AV1 a good disperser, with abilities similar to other headwater‐dwelling Leptophlebiidae (e.g. Baggiano et al ., ; Young, Schmidt & Sheldon, ). Nousia may fare better in a drying climate than Agapetus sp.…”

Prairie stream ecology : temporal and spatial patterns of macroinvertebrates

“…This widespread loss of haplotype diversity corresponds to high levels of mortality (Poff et al 2018), which may relate to recent habitat loss. Although mayflies are generally capable of consistent dispersal on the scale of only tens of kilometers (Zickovich and Bohonak 2007, Young et al 2013, Spitzer 2014, they are capable of widespread gene flow by small increments given a continuous habitat and a large time scale (Lester et al 2007, Monaghan andSartori 2009). The habitat of L. konza was once a continuous network of tallgrass prairie and headwater streams (Matthews 1988).…”

“…Adult flight is the major dispersal mechanism for stream insects (Hughes et al 2008, Young et al 2013. The ability of aquatic insects to disperse successfully as adults depends on a suite of life history features.…”

“…Mayflies are widely considered to be weak fliers not capable of consistent longdistance dispersal, although many have been shown to disperse consistently across distances of 15 to 64 km (Zickovich and Bohonak 2007, Young et al 2013, Spitzer 2014. Since the sampling locations at Konza Prairie were separated by a maximum distance of only 5 km, all samples taken from Konza Prairie were considered to represent a single population.…”