Retrotransposons and the Evolution of Genome Size in Pisum

Here we investigate the plant population genetics of retrotransposon insertion sites in pea to find out whether genetic drift and the neutral theory of molecular evolution can account for their abundance in the pea genome. (1) We asked whether two contrasting types of pea LTR-containing retrotransposons have the frequency and age distributions consistent with the behavior of neutral alleles and whether these parameters can explain the rate of change of genome size in legumes. (2) We used the recently assembled v1a pea genome sequence to obtain data on LTR-LTR divergence from which their age can be estimated. We coupled these data to prior information on the distribution of insertion site alleles. (3) We found that the age and frequency distribution data are consistent with the neutral theory. (4) We concluded that demographic processes are the underlying cause of genome size variation in legumes.

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

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.

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

Habitat fragmentation is one of the greatest threats to biodiversity conservation and productivity, that are mediated by direct human impact. Its consequences include genetic depauperation, including phenomena such as inbreeding depression or reduction in genetic diversity. While the capacity of wild and domestic herbivores to sustain long-distance 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, with a sustained use by livestock during centuries where transiting herds passed by twice a year en route to winter and summer pastures. We compared genetic descriptors of Plantago lagopus populations in the drove road with populations in the surrounding agricultural matrix, at varying distances from human settlements. We observed significant differences for coefficients of inbreeding between the drove road and the agricultural matrix, as well as significant trends for higher genetic diversity around human settlements. Trends for higher genetic diversity in drove roads may be present, although they were not significant with the available sample size. The resulting functional landscape has human settlements as dispersal hotspots, while the drove road act as a pollinator reservoir and possibly also as a linear structure facilitating long-distance dispersal in an agricultural matrix where local P. lagopus populations depend rather on short-distance dispersal. These results highlight the role of herbivore corridors for conserving the migration capacity of plants, and they contribute as well in understanding the role of human dispersal for the spread of invasive species.

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

Habitat fragmentation is one of the greatest threats to biodiversity conservation and productivity, that are mediated by direct human impact. Its consequences include genetic depauperation, including phenomena such as inbreeding depression or reduction in genetic diversity. While the capacity of wild and domestic herbivores to sustain long-distance 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, with a sustained use by livestock during centuries where transiting herds passed by twice a year en route to winter and summer pastures. We compared genetic descriptors of Plantago lagopus populations in the drove road with populations in the surrounding agricultural matrix, at varying distances from human settlements. We observed significant differences for coefficients of inbreeding between the drove road and the agricultural matrix, as well as significant trends for higher genetic diversity around human settlements. Trends for higher genetic diversity in drove roads may be present, although they were not significant with the available sample size. The resulting functional landscape has human settlements as dispersal hotspots, while the drove road act as a pollinator reservoir and possibly also as a linear structure facilitating long-distance dispersal in an agricultural matrix where local P. lagopus populations depend rather on short-distance dispersal. These results highlight the role of herbivore corridors for conserving the migration capacity of plants, and they contribute as well in understanding the role of human dispersal for the spread of invasive species.