Limits...
Generalized drivers in the mammalian endangerment process.

González-Suárez M, Revilla E - PLoS ONE (2014)

Bottom Line: We detect several primary threat combinations that are generally associated with distinct species.In general more vulnerable species are affected by a greater number of threats, suggesting increased extinction risk is associated with the accumulation of external threats.Overall, our findings show that endangerment in mammals is strongly associated with increasing habitat loss and degradation caused by human land-use intensification.

View Article: PubMed Central - PubMed

Affiliation: Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC) Calle Américo Vespucio s/n, Sevilla, Spain.

ABSTRACT
An important challenge for conservation today is to understand the endangerment process and identify any generalized patterns in how threats occur and aggregate across taxa. Here we use a global database describing main current external threats in mammals to evaluate the prevalence of distinct threatening processes, primarily of anthropogenic origin, and to identify generalized drivers of extinction and their association with vulnerability status and intrinsic species' traits. We detect several primary threat combinations that are generally associated with distinct species. In particular, large and widely distributed mammals are affected by combinations of direct exploitation and threats associated with increasing landscape modification that go from logging to intense human land-use. Meanwhile, small, narrowly distributed species are affected by intensifying levels of landscape modification but are not directly exploited. In general more vulnerable species are affected by a greater number of threats, suggesting increased extinction risk is associated with the accumulation of external threats. Overall, our findings show that endangerment in mammals is strongly associated with increasing habitat loss and degradation caused by human land-use intensification. For large and widely distributed mammals there is the additional risk of being hunted.

Show MeSH
Main threat combinations observed among mammals with distinct numbers of threats.Each combination is represented by a colored circle with size proportional to the number of species with that combination. For each combination we also plot the mean (small triangle) and the standard error of the mean (error bars) of a PC component representing adult body masses and distribution range areas values. Combinations in the exploitation-habitat loss group are represented by red circles, while those in the habitat loss and degradation group are represented by green circles. Threats are described in Table 1: A =  Habitat: agriculture, L =  Habitat: logging, E =  Direct exploitation, I =  Habitat: intense human use, Q =  Habitat: quality loss.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3936011&req=5

pone-0090292-g003: Main threat combinations observed among mammals with distinct numbers of threats.Each combination is represented by a colored circle with size proportional to the number of species with that combination. For each combination we also plot the mean (small triangle) and the standard error of the mean (error bars) of a PC component representing adult body masses and distribution range areas values. Combinations in the exploitation-habitat loss group are represented by red circles, while those in the habitat loss and degradation group are represented by green circles. Threats are described in Table 1: A =  Habitat: agriculture, L =  Habitat: logging, E =  Direct exploitation, I =  Habitat: intense human use, Q =  Habitat: quality loss.

Mentions: To further describe existing threat combinations we focused on species with 1–4 listed threats. Few species have >4 listed threats and additionally this range matches the median number of threats of each of the Red List status going from least concern to endangered once species listed under criterion B are removed (Fig. 1b). We find diverse threat combinations occurring at varying frequencies, some being quite common while others only affect a few species (Tables S2–S5). Considering the most common combinations (affecting >10% of the species with the same number of threats) we identified two main groups of mammals that differ in their threats and traits (Fig. 3; see Fig. S2 for each trait separately). One group (habitat loss and degradation) includes exclusively threats associated with human land-use intensification that cause habitat loss and degradation, while the second group (exploitation-habitat loss) includes direct exploitation with the addition of habitat loss caused by land-use intensification. Species in the exploitation-habitat loss group are primarily large, widely distributed mammals (median body mass: 3,430 g, median range area: 267,600 km2) compared to those affected by combinations including only habitat loss and degradation (median body mass: 52.0 g, median range area: 34,850 km2). A phylogenetically-corrected model shows that these differences, as described by the first component of a principal component analysis, are statistically significant (N = 734, note that 17 species are not represented in the phylogeny and had to be excluded from the analyses; pgls F = 59.02, P<0.001, R2 = 0.07).


Generalized drivers in the mammalian endangerment process.

González-Suárez M, Revilla E - PLoS ONE (2014)

Main threat combinations observed among mammals with distinct numbers of threats.Each combination is represented by a colored circle with size proportional to the number of species with that combination. For each combination we also plot the mean (small triangle) and the standard error of the mean (error bars) of a PC component representing adult body masses and distribution range areas values. Combinations in the exploitation-habitat loss group are represented by red circles, while those in the habitat loss and degradation group are represented by green circles. Threats are described in Table 1: A =  Habitat: agriculture, L =  Habitat: logging, E =  Direct exploitation, I =  Habitat: intense human use, Q =  Habitat: quality loss.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3936011&req=5

pone-0090292-g003: Main threat combinations observed among mammals with distinct numbers of threats.Each combination is represented by a colored circle with size proportional to the number of species with that combination. For each combination we also plot the mean (small triangle) and the standard error of the mean (error bars) of a PC component representing adult body masses and distribution range areas values. Combinations in the exploitation-habitat loss group are represented by red circles, while those in the habitat loss and degradation group are represented by green circles. Threats are described in Table 1: A =  Habitat: agriculture, L =  Habitat: logging, E =  Direct exploitation, I =  Habitat: intense human use, Q =  Habitat: quality loss.
Mentions: To further describe existing threat combinations we focused on species with 1–4 listed threats. Few species have >4 listed threats and additionally this range matches the median number of threats of each of the Red List status going from least concern to endangered once species listed under criterion B are removed (Fig. 1b). We find diverse threat combinations occurring at varying frequencies, some being quite common while others only affect a few species (Tables S2–S5). Considering the most common combinations (affecting >10% of the species with the same number of threats) we identified two main groups of mammals that differ in their threats and traits (Fig. 3; see Fig. S2 for each trait separately). One group (habitat loss and degradation) includes exclusively threats associated with human land-use intensification that cause habitat loss and degradation, while the second group (exploitation-habitat loss) includes direct exploitation with the addition of habitat loss caused by land-use intensification. Species in the exploitation-habitat loss group are primarily large, widely distributed mammals (median body mass: 3,430 g, median range area: 267,600 km2) compared to those affected by combinations including only habitat loss and degradation (median body mass: 52.0 g, median range area: 34,850 km2). A phylogenetically-corrected model shows that these differences, as described by the first component of a principal component analysis, are statistically significant (N = 734, note that 17 species are not represented in the phylogeny and had to be excluded from the analyses; pgls F = 59.02, P<0.001, R2 = 0.07).

Bottom Line: We detect several primary threat combinations that are generally associated with distinct species.In general more vulnerable species are affected by a greater number of threats, suggesting increased extinction risk is associated with the accumulation of external threats.Overall, our findings show that endangerment in mammals is strongly associated with increasing habitat loss and degradation caused by human land-use intensification.

View Article: PubMed Central - PubMed

Affiliation: Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC) Calle Américo Vespucio s/n, Sevilla, Spain.

ABSTRACT
An important challenge for conservation today is to understand the endangerment process and identify any generalized patterns in how threats occur and aggregate across taxa. Here we use a global database describing main current external threats in mammals to evaluate the prevalence of distinct threatening processes, primarily of anthropogenic origin, and to identify generalized drivers of extinction and their association with vulnerability status and intrinsic species' traits. We detect several primary threat combinations that are generally associated with distinct species. In particular, large and widely distributed mammals are affected by combinations of direct exploitation and threats associated with increasing landscape modification that go from logging to intense human land-use. Meanwhile, small, narrowly distributed species are affected by intensifying levels of landscape modification but are not directly exploited. In general more vulnerable species are affected by a greater number of threats, suggesting increased extinction risk is associated with the accumulation of external threats. Overall, our findings show that endangerment in mammals is strongly associated with increasing habitat loss and degradation caused by human land-use intensification. For large and widely distributed mammals there is the additional risk of being hunted.

Show MeSH