Geographical and seasonal variation of plant taxa detected in faces of Cervus nippon yakushimae based on plant DNA analysis in Yakushima Island

Abstract

Recently, plant DNA analysis of feces has been successfully used to evaluate the food species composition of sika deer Cervus nippon. Here, we applied this method to Yaku‐sika C. nippon yakushimae, which increased its population and had a great negative impact on understory vegetation in Yakushima Island. We identified food plants of C. nippon yakushimae by sequencing chloroplast DNA fragments (rbcL region) of plants remaining in feces collected in the field in April, June, August, and October 2018, using a next‐generation sequencer. We collected feces from populations in two areas where populations have been managed by capture and three areas where those were not managed. The top two food plants in terms of the number of sequences determined were evergreen tall trees in all five areas. In addition to evergreen trees, understory herbaceous plants, including ferns, were included in the top 15 taxa in all areas. The diversity of food plants was higher in the managed areas than in the unmanaged areas. These results indicate that evergreen tall trees are the primary food plants of C. nippon yakushimae, but deer also forage on herbaceous plants as a side dish. Under this side dish effect, understory vegetation is reduced even under the high availability of food resources from tall trees. The high diversity of food plants in the managed areas suggested that understory plant diversity was restored when deer density was reduced by management.

Dynamics of rumen microbiome in sika deer (Cervus nippon yakushimae) from unique subtropical ecosystem in Yakushima Island, Japan

“…For instance, a previous study in woodrats showed an increase in microbiome diversity associated with intake of PSCs, which is considered to be the result of adaptation to plant toxins 50 . Recent studies showed that Yaku sika selectively forages small plants in understory vegetation, if they are available, and also utilize evergreen tall trees 28 , 29 . Among the evergreen trees, Fagaceae and Lauraceae (in specific, Machilus spp.)…”

“…In low deer density areas, the availability of the small plants is higher and more species-rich understory vegetation is found, thus the dependence of Yaku sika on food derived from tall trees is lower in those areas 27 . The deer in high density areas have expanded their feed to include tannin-rich unpalatable plants, fallen leaves 27 , 54 , and woody material to meet their nutritional needs 28 , 34 . Thus, the higher diversity of RBM in Yaku sika under high population density may enable deer to scavenge a wider variety of plants and tolerate plant toxins, thus maintain nutritional status even under high density conditions 29 , 55 .…”

“…April, June, August, and October), and showed that Yaku sika were selectively foraging on some small plants, including ferns, shrubs, herbs, and bryophytes. In addition, the evergreen tall trees including Fagaceae and Lauraceae were also detected in deer feces across all seasons 28 , 29 .…”

“…On Yakushima Island, wild C. n. yakushimae graze on a range of food including woody plants, vines, herbaceous plants, ferns, moss, and fungi 27 . Recent study by Higashi et al 28 determined DNA sequences of plant taxa contained in feces of Yaku sika collected in different seasons (i.e. April, June, August, and October), and showed that Yaku sika were selectively foraging on some small plants, including ferns, shrubs, herbs, and bryophytes.…”

“…1 ), western, and southern parts of the island 33 . The deer in these high density areas have expanded their feed to include tannin-rich unpalatable plants, fallen leaves, and woody material to meet their nutritional needs 28 , 34 . Wild Ezo sika deer ( C.n.…”