Ecological and genetic evidence that low-order streams inhibit dispersal by red-backed salamanders (Plethodon cinereus)

Abstract

While many studies have examined the barrier effects of large rivers on animal dispersal and gene flow, few studies have considered the barrier effects of small streams. We used displacement experiments and analyses of genetic population structure to examine the effects of first-order and second-order streams on the dispersal of terrestrial red-backed salamanders, Plethodon cinereus (Green, 1818). We marked red-backed salamanders from near the edges of one first-order stream and one second-order stream, and experimentally displaced them either across the stream or an equal distance farther into the forest. A comparison of return rates indicated that both streams were partial barriers to salamander movement, reducing return rates by approximately 50%. Analysis of six microsatellite loci from paired plots on the same side and on opposite sides of the second-order stream suggested that the stream did contribute to genetic differentiation of salamander populations. Collectively, our results imply that low-order streams do influence patterns of movement and gene flow in red-backed salamanders. We suggest that given the high density of first-order and second-order streams in most landscapes, these features may have important effects on species that, like red-backed salamanders, have limited dispersal and large geographic ranges.

Comparative landscape genetics reveals the evolution of viviparity reduces genetic connectivity in fire salamanders

“…This potentially indicates reproduction largely governs the effects of lotic waters on genetic connectivity in S. salamandra , with pueriparity increasing the barrier effects imposed by these aquatic systems. This result appears to corroborate the elevated genetic differentiation found in other terrestrial‐breeding amphibians across rivers and streams (Fouquet et al, ; Marsh et al, ), which suggests, in general, water courses comprise significant barriers to dispersal for terrestrial‐breeding amphibians in particular. The relationship between this variable and landscape resistance was nonlinear (Figure ) and, thus, some caution is warranted when interpreting this effect, since it could potentially represent a statistical artefact arising from the underrepresentation of raster cells with very high density values.…”

Conservation genetics of extremely isolated urban populations of the northern dusky salamander (Desmognathus fuscus) in New York City

“…However, these authors focused on a terrestrial species, Plethodon cinereus , in Montréal that can persist in even the smallest woodlots; other genetic results indicate that this species is unaffected by all but the largest roadways (Marsh et al, 2007). P. cinereus occurs in many NYC parks, community gardens, and other semi-natural spaces, suggesting that it is less strongly affected by urban fragmentation (Pehek, 2007).…”

“…Other small vertebrates with limited dispersal ability also exhibit population genetic patterns consistent with loss of population connectivity. Terrestrial plethodontids (Marsh et al, 2007; Noël & Lapointe, 2010), small mammals (Munshi-South & Kharchenko, 2010), birds, and lizards (Delaney, Riley & Fisher, 2010) all exhibit substantial genetic differentiation and isolation among isolated urban populations.…”

Limited genetic structure in a wood frog (Lithobates sylvaticus) population in an urban landscape inhabiting natural and constructed wetlands

“…Red-backed salamanders (Plethodon cireneus) in Montreal, Canada, show genetic differentiation among populations in urban fragmented areas, despite being entirely terrestrial (Noel et al 2007). However, this species occupies extremely small home ranges, rarely moves greater than 50 m, and even minor rivers can impede their movement (Noel et al 2007 and citations within;Marsh et al 2007). For stream breeding salamanders, urbanization does not necessarily lead to genetic differentiation.…”