Global patterns in seed germination after ingestion by mammals

• Published in: Mammal review 2020-07, Vol.50 (3), p.278-290
• Main Authors: Torres, Diego A., Castaño, John H., Carranza‐Quiceno, Jaime A.
• Format: Article
• Language: English
• Subjects: Analytical methods; animal–plant interactions; Elephants; frugivory; Germination; global; Ingestion; Mammals; Meta-analysis; Plant communities; Plant populations; Primates; Seed germination; seed survival; seed viability; Seedlings; Seeds
• ISSN: 0305-1838; 1365-2907
• DOI: 10.1111/mam.12195

Mammals play an important role in seed germination through the ingestion of fruits and seeds. Since seed germination is a basic step in seedling recruitment, understanding how mammals affect germination improves our understanding of the effect of loss of mammal populations on the dynamics of plant communities. We used meta‐analytical methods to describe global patterns in the effect of seed ingestion by mammals on seed germination success and rate. We collected data from 154 studies that included 115 mammal species and 448 plant species. Our results showed a positive cumulative effect of mammals on seed germination. However, this effect differed between mammalian orders; thus, some groups such as elephants, primates, and new world marsupials emerged as important enhancers of seed germination. Also, the effect varied depending on the plant family and the bioregion. Increased seed germination after ingestion was positively related to fast germination. This meta‐analysis, the first to synthesise and compare most of the information presently available on how mammals affect seed germination after ingestion, shows a global positive effect of mammals as enhancers of seed germination. However, behind that positive effect lies a diversity of neutral, negative, and positive effects of different magnitudes, which may have multifactorial explanations. We hope that the patterns presented here open up new questions and help guide future research efforts. Seed germination is a crucial step in the life cycles of many plant species. We synthesise and analyse using meta‐analytical methods how ingestion by mammals affects seed germination among taxa and bioregions. Results confirm that ingestion by mammals, in general terms, results in enhanced seed germination. The figure shows the effect on seed germination of ingestion by mammals in different orders (lnOR++, calculated through the accumulation of lnOR, which represents the ratio between germinated and ungerminated seeds both for ingested and not ingested seeds). Cumulative effect sizes (dots) are reported with their 95% confidence intervals (horizontal lines). Effects are significant if the confidence intervals do not overlap zero. Dotted line indicates overall cumulative effect for mammals. Ingestion by elephants, primates and new world marsupials increases seed germination the most, while rodents and diprotodonts reduce germination. The effect that mammals have on germination also varies among different bioregions (see