Herbivore corridors sustain genetic footprint in plant populations: a case for Spanish drove roads

Abstract

Habitat fragmentation is one of the greatest threats to biodiversity conservation and ecosystem productivity mediated by direct human impact. Its consequences include genetic depauperation, comprising phenomena such as inbreeding depression or reduction in genetic diversity. While the capacity of wild and domestic herbivores to sustain long-distance seed dispersal has been proven, the impact of herbivore corridors in plant population genetics remains to be observed. We conducted this study in the Conquense Drove Road in Spain, where sustained use by livestock over centuries has involved transhumant herds passing twice a year en route to winter and summer pastures. We compared genetic diversity and inbreeding coefficients of Plantago lagopus populations along the drove road with populations in the surrounding agricultural matrix, at varying distances from human settlements. We observed significant differences in coefficients of inbreeding between the drove road and the agricultural matrix, as well as significant trends indicative of higher genetic diversity and population nestedness around human settlements. Trends for higher genetic diversity along drove roads may be present, although they were only marginally significant due to the available sample size. Our results illustrate a functional landscape with human settlements as dispersal hotspots, while the findings along the drove road confirm its role as a pollinator reservoir observed in other studies. Drove roads may possibly also function as linear structures that facilitate long-distance dispersal across the agricultural matrix, while local P. lagopus populations depend rather on short-distance seed dispersal. These results highlight the role of herbivore corridors for conserving the migration capacity of plants, and contribute towards understanding the role of seed dispersal and the spread of invasive species related to human activities.

Limited effect of a highway barrier on the genetic structure of a gypsum soil specialist

“…In this sense, several studies have showed the role that herbivores plays in seed dispersal in gypsum specialists (Pueyo et al, 2008). Sheep seem to have a remarkable effect in the short and long-distance seed dispersal (Manzano & Malo, 2006;García-Fernández et al, 2019), even when seeds do not have the appropriate surface structures (e.g., seed hooks; Bakker et al, 1996;Kuiters & Huiskes, 2010). Foraging dynamics could profoundly affect the structure of the whole landscape since sheep can graze remnants in an unpredictable pattern and occurs variably as a function of the season and palatable biomass.…”

Domestic Livestock and Rewilding: Are They Mutually Exclusive?

“…Dispersal by large herbivores also facilitates a range of ecological processes including pollination and seed dispersal (Corlett, 2013;Dirzo et al, 2014;Rey Benayas and Bullock, 2015). Where wild large herbivores have been lost from the landscape, it is important to ensure that the use of domestic livestock reproduces the movement patterns, large and small scale in space and time, of those wild species (García-Fernández et al, 2019). This can include active herding the ensures that ecological processes are restored or maintained.…”

Peer Review #1 of "Limited effect of a highway barrier on the genetic structure of a gypsum soil specialist (v0.1)"

“…In this sense, several studies have showed the role that herbivores plays in seed dispersal in gypsum specialists (Pueyo et al 2008). Sheep seem to have a remarkable effect in the short and long-distance seed dispersal (Manzano & Malo, 2006;García-Fernández et al 2019), even when seeds do not have the appropriate surface structures (e.g. seed hooks; Bakker et al 1996).…”