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On the decline of biodiversity due to area loss.

Keil P, Storch D, Jetz W - Nat Commun (2015)

Bottom Line: We show that extinction estimates based on endemics-area and backward species-area relationships are complementary, and the crucial difference comprises the geometry of area loss.In inward destruction, species loss is almost proportional to area loss, although the decline in phylogenetic and functional diversity is less severe.These trends are explained by the geometry of species ranges and the shape of phylogenetic and functional trees, which may allow baseline predictions of biodiversity decline for underexplored taxa.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect Street, New Haven, Connecticut 06520-8106, USA.

ABSTRACT
Predictions of how different facets of biodiversity decline with habitat loss are broadly needed, yet challenging. Here we provide theory and a global empirical evaluation to address this challenge. We show that extinction estimates based on endemics-area and backward species-area relationships are complementary, and the crucial difference comprises the geometry of area loss. Across three taxa on four continents, the relative loss of species, and of phylogenetic and functional diversity, is highest when habitable area disappears inward from the edge of a region, lower when it disappears from the centre outwards, and lowest when area is lost at random. In inward destruction, species loss is almost proportional to area loss, although the decline in phylogenetic and functional diversity is less severe. These trends are explained by the geometry of species ranges and the shape of phylogenetic and functional trees, which may allow baseline predictions of biodiversity decline for underexplored taxa.

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Schematic of inward and outward area loss and the corresponding endemics–area (EAR) and species–area (SAR) curves.The squares in (a) represent a hypothetical region with part of its habitable area lost. (b) Empirical curves for birds that inhabit 2,200 × 2,200 km2 placed in South America (region SA2) as an example. In both panels, A, S and E are area, number of species and number of extinct species in the inner (in) and outer (out) area, respectively, all expressed as proportions of total (tot) area and diversity.
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f1: Schematic of inward and outward area loss and the corresponding endemics–area (EAR) and species–area (SAR) curves.The squares in (a) represent a hypothetical region with part of its habitable area lost. (b) Empirical curves for birds that inhabit 2,200 × 2,200 km2 placed in South America (region SA2) as an example. In both panels, A, S and E are area, number of species and number of extinct species in the inner (in) and outer (out) area, respectively, all expressed as proportions of total (tot) area and diversity.

Mentions: We begin by showing the complementary nature of different ways to calculate the decline of species richness under area loss (Fig. 1), independent of any specific SAR model (for example, power-law as in refs 12, 18): Imagine a region of total area Atot that hosts Stot species, with a contiguous plot of area Ain (Ain<Atot) somewhere within the region, with area outside the plot Aout=Atot−Ain. The number of species that live exclusively within (are endemic to) the plot (Ein) is then given by Ein=Stot−Sout, where Sout is the total number of species (both endemic and non-endemic) that live in Aout. With Sin defined as all species occurring in Ain, it follows that Eout=Stot−Sin. When habitats in Ain are destroyed, we speak about outward loss (Fig. 1a, left), whereas inward loss happens when habitats in Aout are destroyed (Fig. 1a, right). The Ein and Eout scale with area according to their respective EARin and EARout relationships, whereas the Sin and Sout do so according to the SARin and SARout relationships (Fig. 1b). The EARin thus follows a point reflection symmetry with SARout and analogically EARout is symmetrical to SARin (ref. 13).


On the decline of biodiversity due to area loss.

Keil P, Storch D, Jetz W - Nat Commun (2015)

Schematic of inward and outward area loss and the corresponding endemics–area (EAR) and species–area (SAR) curves.The squares in (a) represent a hypothetical region with part of its habitable area lost. (b) Empirical curves for birds that inhabit 2,200 × 2,200 km2 placed in South America (region SA2) as an example. In both panels, A, S and E are area, number of species and number of extinct species in the inner (in) and outer (out) area, respectively, all expressed as proportions of total (tot) area and diversity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660053&req=5

f1: Schematic of inward and outward area loss and the corresponding endemics–area (EAR) and species–area (SAR) curves.The squares in (a) represent a hypothetical region with part of its habitable area lost. (b) Empirical curves for birds that inhabit 2,200 × 2,200 km2 placed in South America (region SA2) as an example. In both panels, A, S and E are area, number of species and number of extinct species in the inner (in) and outer (out) area, respectively, all expressed as proportions of total (tot) area and diversity.
Mentions: We begin by showing the complementary nature of different ways to calculate the decline of species richness under area loss (Fig. 1), independent of any specific SAR model (for example, power-law as in refs 12, 18): Imagine a region of total area Atot that hosts Stot species, with a contiguous plot of area Ain (Ain<Atot) somewhere within the region, with area outside the plot Aout=Atot−Ain. The number of species that live exclusively within (are endemic to) the plot (Ein) is then given by Ein=Stot−Sout, where Sout is the total number of species (both endemic and non-endemic) that live in Aout. With Sin defined as all species occurring in Ain, it follows that Eout=Stot−Sin. When habitats in Ain are destroyed, we speak about outward loss (Fig. 1a, left), whereas inward loss happens when habitats in Aout are destroyed (Fig. 1a, right). The Ein and Eout scale with area according to their respective EARin and EARout relationships, whereas the Sin and Sout do so according to the SARin and SARout relationships (Fig. 1b). The EARin thus follows a point reflection symmetry with SARout and analogically EARout is symmetrical to SARin (ref. 13).

Bottom Line: We show that extinction estimates based on endemics-area and backward species-area relationships are complementary, and the crucial difference comprises the geometry of area loss.In inward destruction, species loss is almost proportional to area loss, although the decline in phylogenetic and functional diversity is less severe.These trends are explained by the geometry of species ranges and the shape of phylogenetic and functional trees, which may allow baseline predictions of biodiversity decline for underexplored taxa.

View Article: PubMed Central - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, Yale University, 165 Prospect Street, New Haven, Connecticut 06520-8106, USA.

ABSTRACT
Predictions of how different facets of biodiversity decline with habitat loss are broadly needed, yet challenging. Here we provide theory and a global empirical evaluation to address this challenge. We show that extinction estimates based on endemics-area and backward species-area relationships are complementary, and the crucial difference comprises the geometry of area loss. Across three taxa on four continents, the relative loss of species, and of phylogenetic and functional diversity, is highest when habitable area disappears inward from the edge of a region, lower when it disappears from the centre outwards, and lowest when area is lost at random. In inward destruction, species loss is almost proportional to area loss, although the decline in phylogenetic and functional diversity is less severe. These trends are explained by the geometry of species ranges and the shape of phylogenetic and functional trees, which may allow baseline predictions of biodiversity decline for underexplored taxa.

Show MeSH