The functional roles of mammals in ecosystems

Abstract

The diverse functional roles of over 6,000 species of extant mammals that range in body size across eight orders of magnitude, from blue whales (Balaenoptera musculus) to tiny Etruscan shrews (Suncus etruscus), contribute to shaping Earth's ecosystems. Large mammalian herbivores (e.g., African elephants [Loxodonta africana], American bison [Bison bison], hippopotamuses [Hippopotamus amphibius]) and carnivores (e.g., wolves [Canis lupus], pumas [Puma concolor], sea otters [Enhydra lutris]) often have significant effects on primary producers in terrestrial, aquatic, and marine systems through nutrient cycling, energy flow, and the exertion of bottom-up and top-down processes. Small mammals, like bats, are important pollinators, dispersers of fruits, and consumers of arthropods, and others, especially rodents and primates, are important predators and dispersers of seeds. Many of these mammal-mediated processes occur simultaneously in the same ecosystem, and have significant effects on community structure of primary producers that in turn alter communities of other vertebrates and invertebrates. Many mammals also are ecosystem engineers (e.g., elephants, American beavers [Castor canadensis], porcupines [Erithezon dorsatum], prairie dogs [Cynomys spp.]) that create, significantly modify, or destroy habitat, and by doing so, they alter ecosystem structure and function and increase habitat heterogeneity and biodiversity. The extensive influence mammals have on ecosystems results in important services that contribute to human wellbeing, such as pollination, insect pest control, and bioturbation of soils. The rapid declines in abundance of many mammal populations and the associated increase in extinction risk raise conservation concerns for mammals. To maintain mammalian diversity and the critical ecosystem processes they provide, scientists need to mobilize concern for their status and strive for more effective and comprehensive conservation action. We provide insights and synthesis on the ecological role of mammals and highlight key research questions and future directions for their conservation.

Marmots from space: assessing population size and habitat use of a burrowing mammal using publicly available satellite images

“…; Lacher et al. ). However, empirical work on burrowing mammals is usually restricted to small study sites, and it remains unclear what drives their distribution and abundance at biogeographic scales.…”

Marked decline in forest-dependent small mammals following habitat loss and fragmentation in an Amazonian deforestation frontier

“…In Neotropical forests, small mammals (rodents and marsupials) are highly diversified in terms of locomotion habits and diet, playing important ecological roles, including seed predation and dispersal [24], pollination [25], and arthropod predation and control [26,27]. In the aftermath of habitat loss and fragmentation across agricultural frontiers, the loss of small mammal species is potentially compounded by changes in species composition that may entail unprecedented impacts on ecosystem functioning [28].…”

Co‐declining mammal–dung beetle faunas throughout the Atlantic Forest biome of South America

“…Food specialization, particularly on mammalian dung, has clearly played an important role in driving the evolution (Davis et al 2002) and current distribution of dung beetles globally (Frank et al 2018). However, virtually all tropical forests of South America have experienced an unprecedented decline in their mammal assemblages (Peres 2001, Ceballos et al 2017, which reduces the strength of their functional roles for other organisms such as dung beetles in natural ecosystems (Galetti and Dirzo 2013, Dirzo et al 2014, Lacher et al 2019. However, virtually all tropical forests of South America have experienced an unprecedented decline in their mammal assemblages (Peres 2001, Ceballos et al 2017, which reduces the strength of their functional roles for other organisms such as dung beetles in natural ecosystems (Galetti and Dirzo 2013, Dirzo et al 2014, Lacher et al 2019.…”

“…The Neotropical realm is one of the most biodiverse ecoregions worldwide for both mammals (Ceballos and Brown 1995) and dung beetles (Davis et al 2002). However, virtually all tropical forests of South America have experienced an unprecedented decline in their mammal assemblages (Peres 2001, Ceballos et al 2017, which reduces the strength of their functional roles for other organisms such as dung beetles in natural ecosystems (Galetti and Dirzo 2013, Dirzo et al 2014, Lacher et al 2019. Mammal species losses are induced primarily by overhunting, and habitat conversion, degradation and fragmentation (Galetti et al 2017, Bowyer et al 2019, Ripple et al 2019.…”